Facts and Figures of Biology PDF

Swallowing procedure is regulated by nerves in the medulla oblongata & pons. Lingual lipase, secreted by **Ebner's glands** on the dorsal surface of the tongue. Food travel from the mouth to the stomach in about **4 to 8** seconds. An empty stomach has a volume of approximately **50ml**. Stomach...

Swallowing procedure is regulated by nerves in the medulla oblongata & pons. Lingual lipase, secreted by **Ebner's glands** on the dorsal surface of the tongue. Food travel from the mouth to the stomach in about **4 to 8** seconds. An empty stomach has a volume of approximately **50ml**. Stomach is a muscular organ located on the left side of the upper abdomen. Gastric glands secrete **400-800 ml** of gastric juices. The concentration of H^+^ in the gastric juice is **0.15 M**. Parietal cells secrete hydrochloric acid and intrinsic factor. The length of the duodenum is **10** inches. The length of the small intestine is **17ft**. The length of the large intestine is **5ft**. The length of the jejunum is **4-7ft**. The length of the ileum is **5-7ft**. The length of the rectum is **1.5** inches. The diameter of small intestine is **3-4cm**. Food takes **4-5 hours** to pass through the stomach into the duodenum. Phagocytes of the liver is also called Kupffer cells. The colour of the bile pigment is yellowish green. Acinar cells and ducts constitute **80% to 90%** of the pancreatic mass. Islets of Langerhans constitute **2%** of the pancreatic mass. Islets of Langerhans consists of four major cells. Alpha (A) cells secrete glucagon. Beta (B) cells secrete insulin. Delta (D) cells secrete somatostatin. F cells secrete pancreatic polypeptide. The colour of pancreas is **pink**. **500 to 800 ml** of pancreatic fluid is secreted per day. Enterokinase converts trypsinogen to trypsin. **Secretin** was the first hormone to be discovered. The principal target for secretin is the pancreas. **60%** of peptic ulcer is caused by *H.pylori*. Self-imposed starvation and an obsession with thinness is Anorexia nervosa. The toxic end product of haemoglobin is bilirubin. Ileocecal Valve present in the Junction between the small intestine and the large intestine. Small intestine is three times narrower than the large intestine. **Intrinsic factor** is a protein that binds ingested vitamin B~12~ and enables it to be absorbed by the intestine in intact form. Three layers of stomach: a. [Longitudinal layer (Outer)] b. [Circular Layer (Middle)] c. [Oblique Layer (Inner)] Four regions of Stomach: d. [Cardiac region] e. [Fundus] f. [Body] g. [Pylorus] Mastication is dependent upon powerful muscles (masseter and temporalis). Duodenum is subdivided into four segments: h. [Superior] i. [Descending] j. [Horizontal] k. [Ascending] Bile is absorbed in ileum. Visible light ranges from **390nm-760nm**. Violet blue light wavelength **390-460nm**. Red light wavelength **630-700nm**. Carotenoids absorb light in the visible spectrum ranging between **500-600nm**. About **40%** of the total sunlight that enters our atmosphere reach the earth surface. Chlorophyll ''b'' is found in all higher plants and green algae. Chlorophyll ''a'' has methyl group (-CH~3~). Chlorophyll ''b'' has carbonyl group (-CHO). Chlorophyll ''a'' **C~55~H~72~O~5~N~4~Mg** Chlorophyll ''b'' **C~55~H~70~O~6~N~4~Mg** Photosystem I absorb light of **700nm**. Photosystem II absorb light of **680nm**. Most phages range in size from **24-200 nm** in length. HIV has **72** little spikes. Glycoprotein **gp120** form spike head. Glycoprotein **gp41** form spike base. Protein **p24** form the core. Protein **p17** forms the matrix. Inside the core are three enzymes: l. [Reverse transcriptase] m. [Integrase] n. [Proteases] Flu virus is enveloped virus. Eight separate pieces of ribonucleic acid (RNA) make up the influenza virus genome. Incubation period of Hepatitis o. A is **2-6** weeks. p. B is **4-20** weeks q. C is **2-26** weeks Incubation period of syphilis is **2-4** weeks. Incubation period of CLCuD is **2-3** weeks. Incubation period of COVID-19 is **1-14** days. In Scrapie the central nervous system of sheep and goats is affected. FFI affects the thalamus. GSS is degenerative brain disorder. CJD is fatal degenerative brain disorder. Alpers syndrome is a neurological disorder. The only human disease caused by a viroid is hepatitis D. PSTV-I causes disease in potato. Virions range in size from approximately **20nm** (0.0000008 inch) to **250nm**. Most bacteria are about **2-10 μm** in length and **0.2-2 μm** in diameter. Gram negative bacteria are more resistant than gram positive bacteria. *Clostridium tetani* and *Salmonella typhi* are rod shaped bacteria (Bacilli). Spirilla never form clusters or colonies. *Rhizobium radiciola* develops a symbiotic association with roots of leguminous plants. Phototroph bacteria have photosystem I but lack photosystem II. *Escherichia coli* is used in gene cloning. *Agrobacterium tumefaciens* is used in producing transgenic plants such as Golden rice which prevents blindness. In UHT milk is treated at **140°C for 3 seconds**. In Incineration contaminated items are placed in an oven at **170°C for 2 hours** to kill microbes. The diameter of DNA is **2nm**. The distance between the bases in DNA molecule is **0.34nm**. Our body use right-handed sugar; left-handed sugar is indigestible. Almost all amino acids are left-handed; our body cannot manufacture proteins out of the right-handed version. Specific heat capacity of water is **4.18J**. Heat of vaporization of water is **574 calories per gram**. The diameter of chloroplast is **4-6 μm**. The length of centriole is **0.3-0.5 μm** & width is **0.2 μm**. The diameter of peroxisome is **0.5 μm**. The diameter of ribosome is **20 nm**. The width of plasma membrane is **7 nm**. Thickness of middle lamella is **1 μm**. Thickness of primary wall is **1-3 μm**. Thickness of Secondary wall is **5-10 μm**. Gorter and Grendel Model: **1925** J F Danielle & Davson Model: **1935** Robertson (Unit membrane model): **1959** S J Singer & Nicholson (Fluid Mosaic Model): **1972** NADH are produce in which steps of Kreb's Cycle: r. Isocitrate- α -ketoglutarate s. α -ketoglutarate-Succinyl-CoA t. Malate-Oxaloacetate FADH~2~ are produced between succinate and fumarate. The diameter of capillaries is **8-10 μm**. The average pressure in the veins is only **5-10 mm Hg**. In arteries the pressure **100 mm Hg**. The diameter of venules is **8-100 μm**. The total surface area of capillaries **800-1000 m^2^** (Greater than 3 tennis courts). Adult human being has some 60,000 miles of capillaries. The variable region of antibody, composed of **110-130** amino acids. The cell mediated immunity consists of T-cells. There are three kinds of T-cells: u. [Cytotoxic T-cells] v. [Helper T-cells] w. [Suppressor T-cells] The humoral immune system consists of B-cells. Temperature regulated centre located in the hypothalamus at the base of the brain. There are three main types of interferons: x. [Interferons beta] y. [Interferons alpha] z. [Interferons gamma] Interferons beta and alpha produced mainly by white blood cells and certain connective tissue cells called fibroblast. Interferons gamma produced primarily by activated T cells. Arterioles are the smallest arteries with a diameter ranging from **3 mm-10 μm**. Large arterioles have all three layers, but smaller arterioles have only two. The wall of an artery is made of **three layers**. Every time heart pours about **85 ml** of blood into the aorta. A capsule which is less tightly bound to the bacterial cell is commonly called glycocalyx. Two water molecules are formed when 2-phosphoglyceric acid is converted to phosphoenol pyruvic acid in glycolysis. In lock and key model, substrate is imagined like a lock while enzyme is imagined like a key. Lack of vitamin B produces **beriberi**. The six major enzyme categories are: a. [Oxidoreductase] b. [Transferases] c. [Hydrolases] d. [Lyases] e. [Isomerases] f. [Ligases] Lipase (pancreas): **8.0** Lipase (stomach): **4.0-5.0** Lipase (castor oil): **4.7** The optimum pH for most of the enzymes is **7-8**. Glycolipids are important component of brain and plasma membrane. Glycoproteins are integral component of the plasma membrane. Each steroid is formed of a backbone of four fused carbon rings containing **17** carbon atoms. Unsaturated fatty acids such as oleic acids are stored in plants. Proximal (cis) or forming face present close to nucleus. Distal (trans) or maturing face located towards the cell membrane. Primary macronutrient is **N, P, K**. Secondary macronutrient is **Ca, Mg, S**. Micronutrients are **B, Cu, Fe, Cl**. In dicot plants guard cells are kidney shaped or bean shaped. In monocot plants guard cells are dumb bell shaped. Some Gram-positive bacteria produce highly resistant structures called endospores. Carnivores' plants may be subdivided into **2** major groups: g. Passive traps h. Active traps Pitfall trap is found in plants like Darlingtonia, Sarracenia, and Nepenthes. Flypaper or adhesive trap is found in sundews (Drosera) and butterworts (Pinguicula). Allergens cause the production of immunoglobulin E (IgE). *Bemisia tabaci* is the botanical name of whitefly. Sulphonamide act as a competitive inhibitor. Cyanide, heavy metal ions and some insecticides are all non-competitive inhibitors. Hepatitis C is a common threat in kidney dialysis centres. Collagen is a tough fibrous protein which gives skin the strength and pliability to resist abrasions that could introduce microorganisms. Second line of defense includes macrophages, neutrophils, natural killer cells, and the complement system. The constant region of the antibody determines the mechanism used to destroy antigen. Granulocytes: **BEN** Agranulocytes: **ML** Hodgkin's disease is an enlargement of the lymph nodes in the neck. The lymph nodes are mostly located in the following six areas: i. [The cervical region] j. [The axillary region] k. [Inguinal region] l. [The pelvic cavity] m. [Abdominal cavity] n. [Thoracic cavity] Reduction of blood pressure by **5-6 mmHg** can decrease the risk of stroke by **40%** and of coronary heart disease by **15-20%.** The pressure of the blood is minimum when it enters the right atrium from upper and lower vena cava. Blood flow in the capillaries is adjusted by the precapillary sphincter. Purkinji fibers are the extension of the autonomic nervous system. The digestive tract is surrounded by both circular and longitudinal smooth muscles that allow for rhythmic contraction or peristalsis. The two strands of DNA are held together by hydrogen bonds. The adenine dinucleotide in combination with different vitamins form important compounds called coenzymes. Three important coenzymes are: o. NAD p. NADP q. FAD Rubber and carotenoids are the condensed products of isoprenoid units. The R-group in glycine is H. The companion cells are present in angiosperms but absent in gymnosperms and ferns. Sieve tubes and companion cells are living cells. [Apoplast Pathway:] Non-Living Pathway [Symplastic Pathway:] Living Pathway [Transcellular Pathway:] Living Pathway Palmatic acid (fatty acid) with **16C** atoms breaks down into **8** acetyl groups, these groups would generate net **129** ATP. Hepatitis B is also called serum hepatitis. Rubisco can act both as carboxylase as well as oxygenase. C~3~ plants use **rubisco** to react CO~2~ with RuBP while C~4~ plants use **pepco** to fix CO~2~ to compound called PEP and OOA. C~4~ plants are sugar cane, maize etc. Trachea is approximately **11 cm** long. Trachea is **2-2.5 cm** wide. Right bronchus has larger diameter and is shorter than the left bronchus. There are about **700** million alveoli present in the lungs, representing a total surface area of **70-90m^2^**. Wall of each alveolus is only **0.1μm** thick. Right lungs represent **56%** of the total lung volume and is composed of three lobes. Tidal volume of lungs: **500ml** Residual volume of lungs: **1500ml** Average adult human has a lung capacity of approximately **5L**. The breathing centre communicate with the diaphragm by the phrenic nerves. The partial pressure of oxygen in the tissue is **20 mm Hg**, in capillaries it is **100 mm Hg**, and the difference is **80 mm Hg**. Approximately **70%** of carbon dioxide is carried in the blood as bicarbonate ion. About **23%** carbon dioxide is carried as carboxyhaemoglobin. **7%** carbon dioxide is carried in Plasma. Symptoms of sinusitis last **2-8** weeks. **80%** of cases of otitis media clear up within 3 or 4 days without treatment. Kidney receives about **20%** of the blood coming from the heart each time it beats. Rate of blood flow through both kidneys is approximately **1.5** litres per minute. Length of kidney: **12 cm** Width of kidney: **6 cm** Thickness of kidney: **4 cm** Weight of kidney: **150 gms** The right kidney is little lower than the left one because of a liver lobe above it. Ureters are about **28 cm** long. Length of female urethra: **2-3 cm** Length of male urethra: **20 cm** Oogenesis features two periods of arrest: the primary oocyte is halted in **prophase I** until puberty, and the secondary oocyte is paused in **metaphase II** until fertilization. Each kidney contains **1 million nephrons**. **70-80%** nephrons in kidney are cortical. **20-30%** nephrons in the human kidney are juxtamedullary. About **20%** of the plasma is filtered into Bowman's capsule. Ultrafiltration produces about **125 ml** of glomerular filtrate per minute. This is equivalent to about **180** litres per day. **125 ml** filtrate produces per minute,**124 ml** reabsorbed per min. Poikilotherms are invertebrates, fishes, amphibians, and reptiles. Homeotherms are birds and mammals. Each testis is divided to **250-300** lobules. Each lobule contains **1-4** seminiferous tubules. About **10-20** vasa efferentia collect sperms from inside the testis. Uncoiled length of epididymis is **6m(20ft)**. Length of ovary: **3-5 cm** Width of ovary: **2-3 cm** Length of oviduct: **10 cm** Length of vagina: **8-10 cm** About **450** secondary oocytes are develop which are released from the ovary during the menstrual cycle. Phenotypic ratio of F~2­~ generation of a dihybrid cross: r. **9 round yellows** s. **3 round greens** t. **3 wrinkled yellows** u. **1 wrinkled green** Genotypic ratio of F~2~ generation is **1:2:2:4:1:2:1:2:1** Se gene is present on chromosome 19. I gene is present on chromosome 9. H gene is present on chromosome 19. The gene for sickle cell anaemia, leukaemia, albinism, and haemophilia is found on chromosome **11**. Nilsson Elle studied the genetics of wheat grain colour. Mulatto is an offspring of a black and a white parent. SRY gene trigger the development of maleness in humans, present on the tip of the short arm of Y chromosome. XO Turner's syndrome in human produced through non-disjunction is a sterile female. XO in *Drosophila* is a sterile male. XXY Klinefelter's syndrome in human produced through non-disjunction gametes is a sterile male. XXY in *Drosophila* is a fertile female. J.Seiler in **1914** discovered XX-XY type of sex in birds, butterflies and moths. Rh blood group system is encoded by three genes C,D, and E, which occupy two tightly linked loci. Erythroblastosis foetalis occurs when mother is Rh-negative, and foetus is Rh-positive. Bombay phenotype was discovered by Dr. Y.M.Bhende in 1952. Bombay phenotype is present in about **0.0004%** (about 4 per million) of human population but in Mumbai the percentage is **0.01%** (1 in 10,000) of inhabitants. ABO blood group system was discovered in **1901** at the University of Vienna by Karl Landsteiner. Karl Landsteiner received Nobel Prize in **1930**. Genetic basis of ABO was explained by Bernstein in 1925. Rh system was discovered by Landsteiner in **1930s**. *Drosophila melanogaster* is the botanical name of the fruit fly. Haemophilia allele is recessive and is carried on the X chromosome. In **Alport's syndrome** the tiny blood vessels are damaged in kidneys. CLS is characterized by intellectual disability. IHP is a rare endocrine condition. Mendal, born on **July 22, 1822**, and died on **January 6, 1884**. Mendal delivered his first lecture: **1865** Experiment on plants hybridization: **1866** Carl Correns was working on 4 O'clock plant in **1899**. In Drosophila normal wing shape is dominant over vestigial, and grey body colour is dominant over black. When Morgan crossed F~1~ progeny with their P~1~ recessive the following results were observed: v. GB and NW (parental): **965** w. BD and VW (parental): **944** x. GB and VW (recombinant): **206** y. BD and NW (recombinant): **185** At least three genes regulate the amount of melanin produced. z. Gene A: Melanocytes (PMS) a. Gene B: Tyrosinase b. Gene C: Pheomelanin or eumelanin Qualitative traits have few phenotypes while quantitative traits have large number of phenotypes. Quantitative traits are called polygenic traits. Cinnabar is one of many *Drosophila* genes affecting eye colour. XO-XX type sex pattern found in grasshopper and protenor bug. Haemophilia allele is recessive and is carried on X chromosome. There is **50%** chance that a son will inherit the colour-blind trait from a carrier mother. The spontaneous loss of a foetus before the **20^th^** week of pregnancy is called as miscarriage. Bronchioles are the first airway branches that do not contain cartilage. The lower end of the pharynx is narrower and located at the level of the **6^th^** cervical vertebrae. George Cuvier (**1769-1832**) proposed, theory of catastrophism. James Hutton (**1726-1797**) and Charles Lyell (**1797-1875**) proposed the theory of uniformitarianism. Lous Agassiz (**1807-1873**) proposed that there was a new creation after each catastrophe. French Biologist Lamarck (**1744-1829**) proposed the theory ''Inheritance of acquired characteristics''. Aristotle (**384-322 B.C**) proposed the theory of spontaneous generation. Charles Darwin (**1809-1882**) Von Baer (**1792-1867**) Haeckel (**1834-1919**) **1908** two scientists, Godfrey H. Hardy, an English mathematician, and Wilhelm Weinberg, a German physician. Bone canals are called Haversian Canals. For a simple fracture the healing time is **6-8** weeks. Matrix of bone consists of: c. **65%** Inorganic substances (calcium phosphate, carbonate etc) d. **35%** Organic substances (proteins, collagen) Muscle fibres are cylindrical, unbranched and with a diameter of **10-100 μm**. The diameter of myofibrils is **1-2 μm**. Resting membrane potential e. Non-conducting f. Polarized g. Outer-Positive h. Inner-Negative i. **-70mV** Action membrane potential j. Conducting k. Depolarized l. Outer-Negative m. Inner-Positive n. **+50mV** Gap in the electrical synaptic cleft is **0.2 nm**. Gap in the chemical synaptic cleft is more than **20 nm**. Every square centimetre of our skin contain: o. **200** Pain receptors p. **15** Pressure receptors q. **6** Cold receptors r. **1** warmth receptor There are **31** pairs of spinal nerves. CTLSC (8, 12, 5, 5, 1) There are **12** pairs of cerebral or cranial nerves. In human there are 33 vertebrae. CTLSC (7, 12, 5, 5, 4) Humans have **26** vertebral bones. Cerebellum controls balance and coordination of movement. The Pons effect activities such as sleeping, walking, and dreaming. The midbrain helps us to locate events in space. Length of Spinal cord: **18 inches** Width of Spinal cord: half an inch Parapatric speciation is extremely rare. Most common speciation is allopatric speciation. Sympatric speciation occurs when populations become reproductively isolated. Allopatric speciation occurs when populations become geographically isolated. Parapatric speciation occurs when populations become isolated by an extreme change in habitat. Flight/wings of insects, birds, pterosaurs, and bats are examples of convergent evolution. Analogous organs are structurally different but functionally alike, give rise to convergent evolution. Homologous organs are structurally alike but functionally different, give rise to divergent evolution. **CSF** is found in between pia mater and arachnoid mater. Yellow bone marrow fills the shaft of long bone. From the lacunae radiate fine fibres or canaliculi. Rising estrogen level form channels that facilitate the passage of sperm into the uterus. Lysosomes contain about **40** different digestive enzymes. **Centriole** give rise to basal bodies of cilia and flagella. There are about **40-60** grana found in each chloroplast. Diameter of microfilament: **7nm** Diameter of microtubule: **25 nm** Length of microtubule: **0.2-25 μm** Diameter of intermediate filament: **8-10 nm** Microfilaments are also known as actin filaments. In muscle cells the microfilaments are called myofilaments. \% of water in seeds and bones: **20%** \% of water in brain cells: **85-90%** \% of water in Jellyfish: **99%** All digestion reactions are examples of hydrolysis. Nucleolus appears during interphase and disappears during cell division. If -OH group is found downward on C-1 then it is called **α sugar**. If -OH group is found upward on C-1 then it is called **β sugar**. D sugars are right-handed, and L sugars are left-handed. **[Sucrose:]** α-Glucose + β-Fructose (**α-1,2**-Glycosidic linkage) **[Maltose:]** α-Glucose + α-Glucose (**α-1,4**-Glycosidic linkage) **[Lactose:]** β-Galactose + β-Glucose (**β-1,4**-Glycosidic linkage) **[Amylose:]** Unbranched, Glucoses, (**α-1,4**-Glycosidic linkages) **[Amylopectin:]** Branched, Glucoses, (**α-1,6**-Glycosidic linkage) Amylose is soluble in hot only water while Amylopectin is completely insoluble in water. Glycogens have **α-glucoses**. Cellulose is formed by the condensation of 100s of **β-glucoses**. Chitin is the second most abundant organic molecule on earth. Cellulose is unbranched and has β-1,4-Glycosidic linkage. Chitin is the derivative of **N-acetyl glucosamine** monomers. Chitin: Unbranched, **β-1,4-Glycosidic linkages** Normal haemoglobin (Hb^A^) contains four polypeptide chains: s. Two α-chains (141x2) Amino acids t. Two β-chains (146x2) Amino acids Sickle cell anaemia is caused by a point mutation in β-globin gene, which causes a change in β-chain of haemoglobin. In SCA glutamic acid is replaced by valine at position number **6**. mRNA is about **3-4%** of the total RNA in the cell. rRNA is about **80%** of the total RNA in the cell. tRNA is the smallest one containing **75-90** nucleotides. **60** tRNA have been identified. Human cells contain about **45** different kinds of tRNA molecules. tRNA have three loops. The middle loop in all the tRNA is composed of **7** bases. Each turn of the duplex of DNA consists of **10** base pairs. Ribozymes are enzymes which consists of RNA. Active site consists of **3-12** amino acids. In a bacteriophage capsid there are **12** vertices and **20** faces. The number of capsomere in polio virus is **32**. Herpes virus has **162** capsomers. Adenovirus that causes common cold contains **252** capsomers. rRNA are commonly recommended as molecular clock. Diameter of *Mycoplasmas*: **0.1 -0.2 μm** Diameter of *Escherichia coli*: **1.8 μm** Length of *Escherichia coli*: **7 μm** Diameter of bacterial flagellum: **20 nm** Length of bacterial flagellum: **20 μm** Bacterial flagellum is non-contractile and lacks microtubules. Milk is pasteurized by heating at **71°C for 15 seconds** and at 62 **°C for 32 minutes**. GIT is approximately **9 m (30 ft)** long. Saliva has a pH between 6 and 7. Length of Oesophagus: **25 cm** Length of villi: **0.5-1.5 mm** Length of Vermiform appendix: **9 cm** Length of gall bladder: **8 cm** Width of gall bladder: **4 cm** Length of capillaries: **1 mm** Diameter of Aorta: **23 mm** Diameter of arterioles: **0.2 mm** Diameter of venules: **40-50 μm** Diameter of veins: **2 mm** The cross-sectional area of the aorta is about **2.5 cm^2^**. Speed of blood in aorta: **30 cm/s** Speed of blood in capillaries: **0.26 cm/s** A phospholipid is formed when phosphatidic acid combines with one of the four organic compounds such as: u. **Choline** (a nitrogenous base) v. **Ethanolamine** (an amino alcohol) w. **Inositol** (an amino alcohol) x. **Serine** (an amino acid) The most abundant lipids in living things are acylglycerol. Each intermediate filament is composed of **3** chains of vimentin. **[Amyloplast]**: Store Starch **[Elaioplast]**: Store Lipids **[Proteinoplast]**: Store Protein Functionally, 3 pairs of cranial nerves are sensory in nature (I, II, VIII), 5 pairs are motor in nature (III, V, VI, XI, XII), and 4 pairs are mixed in nature (IV, VII, IX, X). (SMM354) At laryngopharynx, the respiratory and digestive system diverges. Collagen and elastic fibres are present in the alveoli to expand and recoil easily during breathing. Isoniazid and rifampicin are the most common drug used for TB. Molluscs, Annelids, and Arthropods are protostomes. Echinoderms and Chordates are Deuterostomes. Aschelminths or Nematodes or Round worms are pseudocoelomates. Platyhelminths or Flat worms are acoelomates. All the animals from phylum Annelida to phylum Chordata are coelomates. The ectoderm in triploblastic animals forms skin (integumentary system) and nervous system. The endoderm in triploblastic animals forms the lining of the digestive tract and associated glands. Rest of the organs in triploblastic animals are formed by mesoderm like muscular, reproductive, excretory, and skeletal system etc. All sponges except class mykospongida have skeleton. Jelly fishes are fast moving coelenterates. Class Trematoda (Platyhelminths): Poorly developed digestive system Class Cestoda (Platyhelminths): Digestive system is completely absent Regeneration ability is present in **Class Turbellaria** (Planaria) but **Class Trematoda** (liver flukes) and **Class Cestoda** (tape worms) being parasitic do not show any regeneration. Platyhelminthes is a diverse group with about **15000 species** ranging in size from few millimetres **(Planaria is about 10 mm)** to many feet **(tape worm reaches to 16 feet or about 5 meters)**. Non-Segmented Body: **Aschelminths** Superficially segmented: **Platyhelminths** Metamerically segmented: **Annelids and Arthropods** In Molluscs, development is either direct or a larva is formed called **Glochidium larva**. **Trochophore larva** is formed in during life cycle of some annelids especially in marine species. In Echinoderms, development is indeterminate including characteristic larva called **Bipinnaria larva.** In Hemichordates, **Tornaria larva** is formed during the life cycle which resembles bipinnaria larva of echinoderms. External Fertilization (MEHAAF) y. Molluscs z. Echinoderms a. Hemichordates b. Amphibians c. Annelids d. Fish Fishes are the largest group of vertebrates and constitute about **48%** of the total vertebrates. The number of living species of fishes is more than **29000**. **5-7** pairs of gills are present for respiration in Chondrichthyes. In Osteicchthyes, brain is developed with **10** pairs of cranial nerves. Chondrichthyes have ventral mouth. **Dipnoi (Lung fishes)** is the connecting link between** **Pisces and Amphibia. **Archaeopteryx** was a connecting link between reptiles and birds. **Varanope** is considered a connecting link between reptiles and mammals. **Onychophora** is the connecting link between annelids and arthropods. The ancestors of mammals were of the size of mice lived on tree. Mammals became dominant in **Cenozoic era**. **Creatine phosphate** in both echinoderms and chordates are similar which produce energy for muscular activity. Mammals are believed to be evolved from reptiles. Reptiles are believed to have evolved from amphibians. Amphibians are thought to have evolved from fish. Birds: Left aortic arch Humans: Right Aortic Arch Chondrichthyes: Paired arches Birds have no vocal cords in the larynx, but a special sound box **syrinx** is present at the junction of trachea and bronchi. Humans have **12** pairs while osteichthyes have **10** pairs of cranial nerves. Carnivores: e. Reptiles f. Coelenterates g. Chondrichthyes h. Echinoderms Mollusca is the second largest phylum of invertebrates having more than **80,000** species in addition **35,000** fossils forms are also reported. In annelids, excretory system consists of metamerically arranged **nephridia**. In arthropods, excretion takes place either through **malpighian tubules** (as in insects) or **green gland or coxal gland** (as in crustacean). Porifera, Coelentrata, Platyhelminthes, and Aschelminths have no respiratory or circulatory system. Molluscs, respires through **gills** present in mantle cavity. In molluscs, blood vascular system consists of a single heart (with one ventricle and one or two auricles) arteries, veins and haemocoelic chambers.  Annelids have **closed circulatory system**, while respiration occurs through general surface, but some annelids e.g. neries have gills under parapodia. In arthropods, Respiration takes place in aquatic forms through gills and in terrestrial forms **(especially insects) through trachea**. Tracheae are air tubes which divide repeatedly to form numerous fine branches distributed to all the tissues of the body. They communicate with exterior through openings on each side of the body known as Spiracles. **Arachinids**, a group of arthropods including scorpion, spider etc. respire through special structures, arranged side by side like books in a bookshelf, hence called **book lungs**. In arthropods circulatory system is of open type. In Echinoderms, respiration occurs through a variety of structures e.g. i. **Papule** in star fishes j. **Peristomical gills** in sea urchin k. **Genital bursae** in brittle star l. **Cloacal respiratory tract** in sea urchin In Echinoderms, a typical circulatory system is present also called **haemal system**. In Hemichordates, gill slits are present behind the collar which performs the function of respiration. Circulatory system is composed of a dorsal and ventral vessel. Heart in amphibia is **three chambered**; two auricles and a single ventricle. Two additional tubes (sometimes considered chambers) **truncus arteriosus** and **sinus venosus** are also present. Their circulatory system is not very perfect as mixing of oxygenated and deoxygenated blood takes place in the ventricle. In reptiles, heart is **four chambered** with two auricles, a completely or partially divided ventricle and a pair of systemic arches. Colour of the blood is red due to the presence of haemoglobin as respiratory pigment. In birds, heart is **four chambered** with two auricles and two ventricles. In birds, a single aortic arch is present which curves to the right. In mammals, heart is **four chambered** and a complete separation of oxygenated and deoxygenated blood is maintained. Only left aortic arch is present. Blood vascular system of Mollusca consists of a single heart (with one ventricle and one or two auricles) arteries, veins and haemocoelic chambers. Fishes, amphibians, and reptiles are **ectothermic** (cold-blooded), while birds and mammals are **endothermic** (warm-blooded). Examples of **Urochordata**: *Ciona intestinal, Molgula* Example of **Cephalochordata**: *Branchiostoma* (amphioxus) * * Examples of **Cyclostomata or Agnatha**: *Petromyzon marinus* (lamprey) and *Maxine glutinosa* (hag fish) Examples of **Chondrichthyes**: Sharks, Rays, Skates and Chimaeras Examples of **Osteichthyes**: Salmon, Trout, Seahorse, Catfish etc. Examples of **Amphibians**: Frog, Toad (tailless) and Salamander, newt, necturus (tailed) Examples of **Reptiles**: Lizards, Snakes, Komodo dragon, Tortoises, Turtles and the Tuatara (*Sphenodon punctatum*) of New Zealand Examples of **Monotremata**: Duck billed platypus (*Ornithorhynchus*) and  spiny ant eater (*Tachyglossus*) Examples of **Metatheria**: Kangaroo, Koala, Opossum Excretory system of Platyhelminthes consists of few **flame cells** attached with ducts which open at excretory pore. The excretory system of Aschelminths consists of two longitudinal canals on each side which open on the ventral side by a small excretory pore close behind the mouth. The excretory system of Annelids consists of metamerically arranged **nephridia**. In earthworm, **4** to **5** pairs of hearts called **pseudo-hearts** are present. Sleeplessness (insomnia) and loss of appetite is caused by a nematode, *Enterobius vermicularis,* commonly known as pinworm. In female *Ascaris lumbricoides,* the posterior end is not sharply pointed, although the anterior part of both male and female is similar. The locomotory organs of earthworms are called **setae**, while those of Nereis are called **parapodia**. The bodies of nematodes, annelids, and arthropods are all covered by a tough, outer layer called a cuticle. The body of molluscs is protected by a shell of calcium carbonate (CaCO~3~) secreted by the **mantle**. The shell may be in one piece or two pieces. In some molluscs the shell may be internal, reduced or totally absent. Organs of attachment are present in the form of **hooks or suckers** in platyhelminths or flat worms. Platyhelminthes and many Annelids are hermaphrodite. Onychophora, have **70** species classified in **10** genera. Collembolan is ametabolite. Cockroaches and Wasps are hemimetabolites. Flies, Butterflies, Moths, Beetles are holometabolites. **Porifera** Sycon, Spongilla, Leucoselenia, Euplectella, etc -------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Coelenterata** Hydra, Obelia, Aurelia (Jellyfish), Actinia (Sea anemone), Physalia Pelagica, Corals, etc **Platyhelminths** Planaria (*Dugesia*), Liver fluke (*Fasciola Hepatica*), Tapeworm (*Taenia Solium*), Human Tapeworm (Taenia saginata) etc **Aschelminths** *Ascaris lumbricoides*, Pinworm (*Enterobius vermicularis)*, etc **Mollusca** Garden snail (*Helix aspersa*), slug (*Limax maximus*), Freshwater mussel (*Anodonta grandis*), marine mussel (*Mytilus edulis),* oyster (*Ostrea lurida),* squid (*Loligo pealii*), cuttle fish (*Sepia officinalis*) and octopus (*Octopus bairdi*) etc **Annelida** Earthworm (*Pheritema Posthuma*), Medicinal leech (*Hirudinaria medicinallis*), Neries **Arthropoda** Grasshopper, Butterfly, Prawn, Scorpion, Mosquito, Centipede, *Bombyx mori* (Silkworm), Collembolan, Cockroach, Wasps etc **Echinodermata** *Asterias rubens* (star fish), *Ophiothrix fragilis* (brittle star), *Arbacia punctulata* (sea urchin), *Thyone briareus* (sea cucumber) etc. **Hemichordata** *Saccoglossus kowalevskii, (Acron worm), Balanoglossus sp. etc.* 471. In hemichordates cleavage is holoblastic and radial. 472. Among 16 orders of Eutheria some are given below: 473. **[Insectivora:]** Feed on insects, includes moles and shrews. 474. **[Chiroptera:]** Flying mammals like bats, flying squirrels. 475. **[Cetacea:]** Aquatic mammals e.g. whale, dolphin. porpoises, sea lion etc. 476. **[Carnivora:]** Flesh eating like dog, cat, lion. Wolves 477. **[Rodentia:]** Cutting habit like rats, mice, squirrel, beavers etc. 478. **[Edentata:]** Adults with no or poorly developed molar teeth like South American anteater, sloths. 479. **[Pholidota:]** Body covered with large, overlapping, homey scales e.g. Pengulin 480. **[Proboscidea:]** Have a long trunk like elephant. 481. **[Perissodactyla:]** Odd- toed hoofed mammals like, horse, zebra etc. 482. **[Artiodactyla:]** Even- toed hoofed mammals like cow, goat, deer etc. 483. **[Primates:]** Mammals with highest brain development like lemur, monkeys, apes, tarsiers, human beings etc. 484. **Phosphorylase** converts starch into glucose and phosphate. Glucose increases the concentration of cell sap. Water moves into guard cells due to increase diffusion pressure deficit DPD. Guard cells become turgid and swell, opening the stomata. 485. Phosphoenol pyruvic acid combines with CO~2~ to produce malic acid. 486. Malic acid dissociates into malate anions and H^+^ ions. H^+^ ions are transported to epidermal cells, while K^+^ ions are taken into guard cells. 487. Increased K^+^ and malate ion concentrations in the vacuole cause higher osmotic pressure. Guard cells absorb water from surrounding cells due to increased osmotic pressure. The influx of water causes guard cells to swell and open the stomata. 488. At sink osmotic pressure must be reduced. 489. Examples of **Hydrophytes**: *Hydrilla, Vallisneria, Potamogeton* 490. Examples of **Mesophytes**: Citrus, brassica, pea, peach, rose 491. Examples of **Xerophytes**: *Cactus, Opuntia, Aloe, Ruscus, Acacia, Calotropis, Zizyphus* 492. Examples of **Halophiles**: *Salsola* (saltwater) and *Rhizophora* 493. **Flax** (*Linum usitatissimum*) fibres have been used in Europe and Egypt for over **3,000 years**. 494. **Hemp** (*Cannabis sativa*) fibres have been known in China for just as long. 495. Fibres of **jute** (*Corchorus capsularis*) and **ramie** (*Boehmeria nivea*) are **soft and elastic**, making them suitable for textile production. 496. Glucose produced at the source is converted into sucrose, a disaccharide. Sucrose is actively transported into companion cells and then into the living phloem sieve tubes by active transport. 497. Unlike transpiration, which involves a one-way flow of water, phloem transport can occur in any direction as long as there is a source and a sink. The roles of source and sink can reverse depending on the season or the plant\'s needs (e.g., roots can be a source in early spring when buds are growing). 498. Phloem consists of five different types of cells: a. Sieve tubes b. Companion cells c. Phloem parenchyma d. Phloem fibers e. Phloem ray cells 499. The main kinds of xylem are tracheids and vessel elements. Tracheids are elongated cells up to **80 µm** wide with secondary, lignified cell walls. Vessel elements are generally wider, shorter, thinner-walled, and less tapered compared to tracheids. 500. Vessels are characteristic of **angiosperms** and are specialized for efficient water conduction. 501. Nucleolus disappears during cell division. 502. The luteal phase is the longest phase of the menstrual cycle, lasting for about 14 days. (**15-28 days**) 503. Follicle cells after ovulation form the corpus luteum. 504. Money plant is not a carnivore's plant. 505. The immune cells that clean up pus as a part of the healing process is macrophages. 506. Fructose forms **5** cornered ring. 507. The enzymes ATP synthase is located on the membrane of the organelle mitochondria. 508. Glycosylation is the function of Golgi complex. 509. Cell wall of fungi like protest is composed of cellulose. 510. Carotenoids belongs to terpenoids(lipids). 511. All coenzymes are derived from vitamins. 512. Two water molecules are produced in glycolysis when **2-phosphoglyceric acid** is converted to **phosphoenol pyruvic acid**. 513. The moneran devoid of cell wall is mycoplasma. 514. The first successful land vertebrate are **reptiles**. 515. The concentration of water molecules is inversely proportional to the pressure potential. 516. Lacteal is present in villi of ileum. 517. The artificial pacemaker is implanted near **AV node**. 518. Interferon interferes in the replication of virus. 519. Primary spermatocyte, primary oocyte, and zygote are diploid cells. 520. **Prostaglandins** in semen decreases the viscosity of mucus guarding the cervix of uterus and stimulate reverse peristalsis in the uterus. 521. **Cowpers' gland or Bulbourethral gland** neutralizes the acidity of urethra. 522. **Hyaluronidase** is secreted by prostate gland. 523. Shedding of the unnecessary cytoplasm occurs in spermiogenesis. 524. Secondary spermatocytes have **46** chromatids and **23** chromosomes. 525. Most of the seminal fluid is produced by the seminal vesicles. 526. Luteinizing hormone is responsible for stimulating the production of testosterone in the testes. 527. Estrogen inhabits the FSH secretion but stimulates the LH secretion. 528. The first step in the ovarian menstrual cycle is the release of FSH. 529. Mid piece of the sperm provides energy for movement. 530. The primary spermatocyte phase of spermatogenesis replicates DNA. 531. Spermatogonium is a type of cell that gives rise to sperm. 532. Endometriosis is a condition characterized by the growth of tissue similar to the lining of the uterus (the endometrium) outside the uterus. 533. In humans, prophase I in female has the longest duration(**11-13years**). 534. The formation of endometrium starts in proliferative phase. 535. Women typically ovulate one egg per month, totaling about **12** eggs per year, regardless of having two ovaries. The ovaries alternate in releasing eggs, but this does not double the annual count. 536. The endometrial lining thickens and reaches its peak during the secretory phase of the menstrual cycle, preparing for potential implantation of a fertilized egg. 537. During the menstrual cycle, **estrogens** (primarily estradiol) are produced mainly in the **ovaries** by the **developing follicles**. 538. In early pregnancy, the corpus luteum produces progesterone, while in later pregnancy, the placenta takes over this role to maintain the pregnancy. 539. Ovulation aligns with the thickening of the uterine wall; ovulation is part of the ovarian cycle, while the uterine wall thickening is part of the uterine cycle. 540. The outermost layer of a newly ovulated ovum is the **corona radiata**, while the **zona pellucida** is the membrane directly around the egg, the **chorioallantois** is part of the placenta, and the **amnion** surrounds the fetus in the womb(uterus). 541. Corona radiata is cellular layer while zona pellucida is non cellular. 542. **Menarche** is the first menstrual period, while **menopause** is the end of menstruation and reproductive years. 543. Urethra and vagina have independent openings to the exterior. 544. Vaccination against specific disease like tetanus is an example of artificial passive immunity. 545. Antigen binding sites of antibody are present on variable region of both light and heavy chains. 546. Phagocytosis usually involves 2^nd^ line of defense. 547. Disulfide bridges are absent in light and light chain. 548. A vaccine contains antigens. 549. T-lymphocytes recognize the antigen and attack microorganism or transplant organ and tissue. This effect is called cell mediated response. 550. B-lymphocytes name due to their relationship with bursa of fabricus. 551. The genes for 7 characters chosen by Mendel are located on **chromosome number 4**. 552. The ratio of genotypes in the offspring (F~2~) of the monohybrid cross between two heterozygous individuals is **1:2:1** and the phenotypic ratio is **3:1**. 553. A test cross is a cross between a homozygous recessive individual and an individual of unknown genotype. 554. The law of independent assortment is an example of genetic recombination. 555. A person with blood type AB has no antibodies in their blood. 556. The likelihood that a daughter will inherit a Y-linked trait from her father is 0%. 557. Y-linked inheritance is also known as holandric inheritance. 558. Maternal inheritance, also known as mitochondrial inheritance, is a type of inheritance where the mitochondria are passed exclusively from the mother to her offspring. 559. If a heterozygous individual displays the same phenotype as the homozygous dominant individual, then it will be complete dominance. 560. In a cross between a homozygous dominant and a homozygous recessive individual, the genotype of all the F~1~ offspring will be heterozygous. 561. In codominance, both alleles are equally expressed, as exemplified by the AB blood group system. 562. If all the offspring resulting from a test cross display the dominant phenotype, the genotype of the individual being tested is **homozygous dominant**. 563. Color blindness is caused by a genetic mutation that affects the cones in the retina of the eye. 564. In a family where the husband is heterozygous for the Rh-positive trait and the wife is homozygous for the Rh-negative trait, the probability of having a child who is homozygous Rh-negative is **50%**. 565. Linked genes do not follow the law of independent assortment because of tight linkage. 566. Tongue rolling in humans is an example of discontinuous variation or qualitative trait. 567. If gene frequency between genes a and c is 2%; b and c is 13%; b and d 4%; a and b 15%; c and d 17 and a and d 19%. The sequence of genes in a chromosome is a,b,c,d. 568. Individuals with blood type O negative have the genotype ii, dd. 569. X-linked traits exhibit a zigzag (path) inheritance pattern, while Y-linked traits are transmitted in a direct (straight path), paternal lineage. 570. A person with blood group A possesses, antigen A and antibody B. 571. When two or more genes interact in a way that their effect is additive expression, it is called polygenic inheritance. 572. Tobacco mosaic virus was crystalized by **Stanley**. 573. **Iwanowsky**: Credited with discovering viruses 574. **Chamberland**: Provide first evidence about existence of virus. 575. Destroyed by UV rays, suggest the living feature of virus. 576. +ssRNA strand of virus serve as mRNA. 577. Enzyme use to incorporate viral DNA into host DNA is integrase. 578. The process by which foreign DNA is introduced into a cell by a virus or viral vector is **transduction**. 579. Pectin is abundantly present in middle lamella. 580. Primary cell wall is capable of growth and gradually diminishes as the cell matures. 581. Plants differ from animals in that plants lack lysosomes. 582. Animal cells differ from plant cells in possessing centrosomes. 583. Conversion of pyruvic acid into ethyl alcohol is mediated by: Decarboxylase & dehydrogenase 584. During bread formation, it becomes porous due to the release of CO₂ by the action of yeast. 585. After the transmission of an impulse through a synapse, the neurotransmitter adrenaline is primarily broken down by the enzyme monoamine oxidase (MAO). 586. During muscle contraction, the H-zone disappears, the I-band is reduced, and the Z-lines come closer together, but the A-band does not reduce in size. 587. The vaccines against Diphtheria and Tetanus are composed of toxoids. 588. T-cells, which are part of the cell-mediated immune system, originate in the bone marrow and complete their development in the thymus. 589. If **19.4 ml** of oxygen is carried by **100 ml** of blood, the blood is approximately **97%** saturated. 590. Malpighian tubules convert nitrogenous waste into uric acid. 591. The most appropriate term to describe the life cycle of Obelia is metagenesis. 592. Electrical impulses in the human heart originate from the sinoatrial (SA) node. 593. The interval of the pacemaker signal from the SA node to the AV node is approximately **0.1 seconds**. 594. A monohybrid cross typically results in three-fourths (¾) of the individuals being phenotypically dominant. 595. The cells in the testes that produce testosterone are known as **Leydig cells**. 596. Nerve impulse for muscle contraction arise from cerebellum. 597. Cord of strong, flexible tissue, similar to a rope which let use move our limbs: Tendons 598. The contraction of striated muscle is initiated by the release of energy in the presence of calcium ion. 599. **Creatine phosphate** is the rapidly metabolizable reserve of high-energy phosphate in muscles. It can quickly donate a phosphate group to ADP to regenerate ATP, providing a burst of energy for intense muscle activity. 600. The production of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from the pituitary gland in females is controlled by the hypothalamus. 601. Labor pains, which help to expel the fetus, are due to the action of oxytocin on the myometrium. 602. In human females, the small, pear-shaped, muscular, distensible, sac-like organ where gestation takes place is the uterus. 603. Bacterial cells can maintain their shape through the cell wall. 604. The method of bringing oxygenated air into contact with a gas exchange surface is called ventilation. 605. Smooth muscles are found in the trachea, bronchi, and bronchioles, but not in the alveoli. 606. The final destination of lymph is the subclavian vein. 607. The descending aorta bifurcates into two vessels that further divide to form the iliac arteries, which supply blood to the muscles of the thighs. 608. The main point of Darwinism is variation among individuals within a population. 609. According to evolutionary studies, prokaryotes may have arisen around **3.5** billion years ago. 610. Competitive inhibitors are homologous to substrate. 611. Oxytocin is a hormone that dilates the milk ducts of mammary glands. 612. In a typical nerve, the duration of an action potential is approximately 1 millisecond. 613. The chemical messengers that transmit action potentials across synapses in the form of chemicals are called neurotransmitters. 614. The pressure receptors in the human body that detect deep pressure stimuli are called Pacinian corpuscles. 615. Cells of different types can be distinguished based on their surface glycolipids and glycoproteins. 616. In prokaryotic cells, the structure that plays a role similar to that of mitochondria is the mesosome. 617. Most monosaccharides, including ribose, form a ring structure in solution known as ribofuranose. 618. Hydrogen bonds must be broken for water to vaporize. 619. The specific heat of vaporization of water plays an important role in the regulation of heat produced by oxidation. 620. Biologically, hydrophobic exclusion plays key roles in maintaining the integrity of lipid bilayer membranes. 621. The major enzyme involved in the transfer of a phosphate group from ATP to glucose is kinase. 622. Out of 36 ATPs, **32** are produced in the electron transport chain. 623. The major event in the electron transport chain is ATP synthesis. 624. Anaerobic respiration is used in baking, particularly in the fermentation process. 625. Presence of remnant of pelvic girdle in whale and snake although they never have legs, shows evidence from vestigial organs. 626. Photosynthetic bacteria liberate **H~2~S**. 627. Plasma membrane is selectively permeable. 628. Water is the most abundant compound in living organisms, with its amount varying from approximately **70%** to **90%**. 629. The phase in which the bicuspid and tricuspid valves open, and the semilunar valves close, producing the second heart sound (dub or dup), is known as ventricular diastole. 630. Triose and glycerol are used in the synthesis of lipids. 631. Inhibitors of key enzymes in the nervous system include pesticides such as DDT and parathion. 632. The plant hormone associated with apical dominance is auxin. 633. Spikelet inflorescence is characteristic of the family Poaceae. 634. Each myosin molecule is surrounded by **6** actin filaments. 635. The white-eyed trait in *Drosophila* is due to a mutation. 636. Enzymes are generally inactivated rapidly by exposure to UV and X-rays because it alters the shape of the enzymes. 637. The hypothalamus has neurosecretory cells that secrete releasing and inhibiting hormones. 638. The cortex is the seat of all conscious activity. 639. A hormone secreted from the duodenal mucosa that converts inactive trypsinogen into trypsin is enterokinase. 640. Cells become dead due to the deposition of lignin. 641. Rabies is caused by the Rhabdovirus. 642. A loop or set of responses shown by the effectors that weaken the effect of the initial stimuli is known as negative feedback. 643. Crossing over in meiosis occurs during the pachytene stage. 644. A co-enzyme constitutes about **1%** of the total portion of an enzyme. 645. Each chain of DNA is formed by the union of many nucleotides through phosphodiester bonds. 646. *Mimosa pudica* shows seismonastic movements. 647. The most common and abundant lipid that is the richest source of energy in both plant and animal bodies is **acylglycerol**. 648. The hard parts of seeds are due to the presence of **sclereids**. 649. In the heart, the thick-walled chambers are located at the **lower side** (ventricles). 650. The spinal cord comes out from the cranium through an opening known as the **foramen magnum**. 651. When a substrate combines with the active site of an enzyme, it induces a conformational change that enables the enzyme to perform its **catalytic function**. 652. Artificial selection in breeding provides evidence for evolution and is known as **domestication**. 653. The structure that provides protection to coastlines from storms, shelters marine organisms, and assists in carbon and nitrogen fixing is the coral reef. 654. Achatina fulica is an African giant snail that is dangerous as an *agricultural pest*. 655. The average adult human RBC contains approximately **270** million haemoglobin molecules. 656. Influenza virus is a ssRNA virus. 657. The wall of alveoli is made up of moist squamous epithelium. 658. Breathing center of medulla communicates with diaphragm via phrenic nerve. 659. Least blood pressure is seen in vena cava. 660. Hyaline cartilage is most abundant cartilage in human body. 661. Parvovirus contains **ss-DNA** as genome. 662. **Four pyrrole rings** of chlorophyll head form a structure known as porphyrin. 663. Hyperpolarization of nerve fibre occurs due to excessive efflux of K^-^. 664. Endorphins are produced in brain. 665. Prolactin in females enlarge mammary glands. 666. Naturally, restriction endonucleases cut the DNA of bacteriophage. 667. Gastrin is a hormone produced from stomach. 668. Loading of phloem is related to increase sugar in phloem. 669. According to TACT theory, hydrogen bonds among water molecules provide the cohesion which helps in ascent of sap. 670. Oxygenated blood is carried to the heart by four pulmonary veins. 671. Veins and capillaries are non-pulsatile in nature. 672. Artificial passive immunity is rapid but short lived. 673. When the cell wall is removed from plant cell, then the remaining structures are collectively called as protoplast. 674. Pivot joint is formed between upper ends of radius and ulna. 675. In humans, sex of an individual depends upon heterogametic father. 676. Crossing over is important in genetic recombination. 677. Incomplete breakdown of sugars in anaerobic respiration results in the formation of alcohol and CO~2~. 678. In kerb's cycle, oxidation of succinate is done by FAD. 679. Histone proteins are positively charged due to the presence of basic amino acids. 680. A protein having 534 amino acids in 3 chains, the number of peptide bonds in it will be 531. 681. Most of the cellular secretions are glycoproteins. 682. Facilitated diffusion does not require ATP; it relies on transport proteins to move substances across the cell membrane along their concentration gradient. 683. Sieve tube cells do not possess nucleus. 684. Meissner's corpuscles are involved in the sensation of touch. 685. In humans, the neuroglia makes up as much as **50%** of the nervous system. 686. Deficiency of estrogen hormone in females causes sterility. 687. The optimum pH for working of arginase is **9.70**. 688. Gastric gland is not the accessory gland of the digestive system. 689. The non-protein part of haemoglobin can provide binding site for oxygen and carbon dioxide. 690. The main cause of creation of tension between water molecules is hydrogen bonding which helps in ascent of sap. 691. The particular array of chromosomes that an individual possesses is called karyotype. 692. Haemophilia-A is the most abundant type of bleeder disease. 693. Oxygen act as final electron acceptor during aerobic respiration. 694. Glyceraldehyde is an example of aldo-triose. 695. The number of peptide bonds present in insulin molecule is **49**. 696. If an animal has **80** chromosomes in its gametes, its muscle cells will have **160** chromosomes. 697. Dorsal root of spinal nerve has cell bodies of sensory neurons. 698. The hormone responsible for active reabsorption of Na^+^ from the nephron is secreted by adrenal cortex. 699. Enzyme would not be denatured at very low temperature than optimum. 700. Digestion of carbohydrates starts in oral cavity. 701. Secretin inhibits the gastric secretion. 702. Contraction of diaphragm increases the volume of the chest cavity. 703. Mature leave usually not acts as a sink. 704. B-lymphocytes are formed in bone marrow, and they are mature in bone marrow. 705. Gametogenesis in human female starts before birth. 706. Epiglottis direct food and liquids into the esophagus during swallowing. 707. Inhaled food or foreign objects are most likely to lodge in right bronchus. 708. Role of surfactant in the respiratory system is to keep alveoli from collapsing. 709. Main muscle responsible for pulmonary ventilation the diaphragm. 710. Primary regulator of respiration is carbon dioxide. 711. Most of oxygen is transported in the blood in the form of oxyhaemoglobin. 712. Head of a long bone is called the epiphysis. 713. Periosteum is essential to bone survival because it contains blood vessels and bone forming cells. 714. A fetus skeleton is composed primarily of cartilage and fibrous membranes. 715. Structural unit of compact bone is called osteon and Haversian system. 716. **37** bones constitute the rib cage. (Sternum bone + 12 thoracic vertebrae + 24 ribs) 717. Pectoral and pelvic joints are examples of synovial joints. 718. The wall of the larynx is supported by nine cartilages. a. **Three unpaired cartilages:** thyroid cartilage, cricoid cartilage, and epiglottis. b. **Six paired cartilages:** arytenoid cartilages, corniculate cartilages, and cuneiform cartilages. 719. All cartilages supporting the larynx are hyaline except epiglottis which is elastic cartilage. 720. Most of the joints in the body are synovial joints. 721. The joint that allows the head to rotate is the **atlantoaxial joint**. 722. The pituitary gland resides in an indented area in a cranial bone called sphenoid. 723. The **sella turcica**, which translates to \"Turkish saddle\" in Latin, is a saddle-shaped depression located in the sphenoid bone of the human skull. It serves as a crucial anatomical structure housing the pituitary gland, also known as the hypophysis. 724. A continuous state of partial muscle contraction in which muscles are at their optimal resting length is called **muscle tone**. 725. The end of a muscle that\'s attached to the more mobile bone is called the **insertion**. 726. In a contracted muscle, the **I-band** or light band disappears. 727. A tendon is an extension of epimysium. 728. **Afferent neurons** detect sensations such as touch or heat and then relay information about the stimuli to the central nervous system. 729. In **refractory period** a nerve cell does not respond to a new stimulus. 730. Thyroid cartilage is commonly called **Adam\'s Apple**. 731. Thyroid and vocal cartilage is larger in male as compared to female. 732. **Medulla oblongata** contains regulatory centers for such vital functions as heart rate, breathing, and blood pressure. 733. Hypothalamus exerts control over the autonomic nervous system and pituitary gland. 734. Injury to **frontal lobe** of the brain may result in a severe personality disorder and cause socially inappropriate behaviour. 735. **Vagus nerve** supplies most of the organs in the thoracic and abdominal cavities as well as those in the head and neck. 736. **Microglia (phagocytic cell)** clean the synapse. 737. The effect produced by a neurotransmitter (such as whether it constricts or dilates blood vessels) is ultimately determined by the **type of receptor**. 738. A single neurotransmitter can indeed have both inhibitory and excitatory effects, depending on the type of receptors it binds to. This phenomenon is known as **receptor-mediated modulation**. 739. Rods are active in dim light. 740. The pituitary gland is generally larger in females compared to males. 741. Cold temperatures are most likely to stimulate the release of **TSH**. 742. Thyroid surgery, a patient is most at risk for hypocalcemia. 743. Pancreas has more exocrine (90%) tissue than endocrine (10%). 744. A hypersecretion of growth hormone during adulthood causes acromegaly. 745. The first hormone secreted at the onset of puberty in both males and females is GnRH. 746. Gametes are sex cells. 747. Until ejaculation, sperm are stored in the **epididymis**. 748. Testosterone is produced in the interstitial cells of the testes, specifically known as **Leydig cells**. 749. The seminal vesicles contribute most of the fluid volume of semen. 750. The surge in luteinizing hormone (LH) triggers ovulation. 751. Menstruation is triggered by the drop in levels of estrogen and progesterone. 752. William Bateson coined the term \"genetics\" in **1906**. 753. A monohybrid cross is a mating between two individuals with different alleles at one genetic locus of interest. 754. The true breeding organism for a particular trait is called homozygous. 755. Incomplete dominance is when the phenotype of heterozygous individuals is intermediate between the phenotypes of homozygous individuals. 756. Multiple alleles arise through mutations and are present in the population. 757. **Sesamoids** are small bones embedded within tendons or muscles, typically found near joints.  758. The resting membrane potential is expressed as -70mV, the minus sign means that the inside is negative relative to the outside. 759. In RMP the concentration of K^+^ is **30** times greater in the fluid inside the cell than outside, and the concentration of Na^+^ is nearly **10** times greater in the fluid outside the cell than inside. The sodium-potassium pump (Na⁺/K⁺ ATPase) is an essential membrane protein that helps maintain these ion gradients. 760. For every **two** K^+^ that are actively transported inward, **three** Na^+^ are pumped out so, inside becomes more negative than outside. 761. There are more than **100** known neurotransmitters. 762. Acetylcholine is an excitatory neurotransmitter. 763. Glutamate is an inhibitory neurotransmitter. 764. Sympathetic division prepares the body for stressful or energetic activity; ''fight or flight'' 765. Parasympathetic division dominates during times of ''rest and rumination''; directs maintenance activities. 766. The vagus nerve, or the **10^th^** cranial nerve (CN-X), is primarily associated with the parasympathetic division of the autonomic nervous system. 767. The contraction of both smooth muscle and cardiac muscle is controlled by motor neurons of the **ANS**. 768. The somatic nervous system (SNS) is a division of the peripheral nervous system that is responsible for processing sensory information and controlling voluntary movements. 769. Inhibition of bladder contraction occurs in the sympathetic nervous system. 770. **Filiform papillae** are in cone shape and found all over the tongue. 771. **Fungiform papillae** are in mushroom shape and found at the tip and sides of the tongue. 772. **Foliate papillae** are a series of folds along the sides of the tongue. 773. **Circumvallate papillae** are flat mould in shape, found at the back of the tongue. 774. All papillae except filiform contains taste buds, so the center of tongue is **taste-blind**. 775. There are about **1000** different types of olfactory receptor proteins each sensitive to different odors. 776. Removal of hairs decreases touch sensitivity. 777. The fingertip and tongue may have as many as **100** per cm^2^ ; the back of the hand fewer than **10** per cm^2^. 778. **Tactile anesthesia**, also known as **anaphia**, refers to a condition characterized by a total or partial loss of the sense of touch. 779. **Paresthesia** is a sensation of tingling, prickling, or numbness of the skin that may result from nerve damage and may be permanent or temporary. 780. The three types of pain receptors are **cutaneous (skin)**, **somatic (joints and bones)**, and **visceral (body organ)**. 781. Heroin is processed from morphine, naturally occurring substance extracted from the seed pod of certain variety of poppy plants. 782. The heroin is prescribed as a strong analgesic. 783. Cannabis (*Cannabis sativa*), also known as marijuana. 784. Hashish is commonly known as Chars. 785. Nicotine is an alkaloid, mainly found in tobacco leaves but also found in many plants of Solanaceae. 786. Nicotine act as a nerve stimulant. 787. **60mg** of nicotine if absorbed will kill an adult. 788. Alcohol has antiseptic nature. 789. Cirrhosis is a chronic liver disease characterized by the replacement of normal liver tissue with scar tissue (fibrosis) and regenerative nodules.  790. Crystal methamphetamine commonly known as ice (stimulant drug). 791. Photophobia occurs in meningitis. 792. Headache (functional disorder) is also known as cephalalgia. 793. Most of the neurons of our body are multipolar. 794. Telencephalon is referred to cerebral hemispheres. 795. Non contractile portion of muscle is tendon. 796. Muscle bundle is surrounded by perimysium. 797. In one myosin molecule there are six polypeptide chains. 798. Each head of myosin molecule has two binding side. 799. From one myosin filament multiple cross bridges arise. 800. Cross bridge is the part of myosin filament, and these cross bridges bind with actin filament. 801. Actin molecules have two polypeptide chains, tropomyosin have also two polypeptides while troponin have three polypeptide chains. 802. Troponin have three attachments one with actin, other with tropomyosin, and other with **Ca^+2^** ions. 803. Brain has four ventricles a. 1^st^ and 2^nd^ ventricle (Between limbic system and cerebrum) b. 3^rd^ ventricle (Between limbic system and thalamus) c. 4^th^ ventricle (In brainstem) 804. Inner to skull, dura mater is present. 805. Outer to nervous system pia mater is present. 806. Forebrain has two lobe is Telencephalon & Diencephalon. 807. Forebrain is also called prosencephalon. 808. Midbrain is also called mesencephalon. 809. Hindbrain is also called rhombencephalon. 810. The part of hind brain attached to spinal cord is medulla oblongata. 811. Forebrain has three parts: a. **Cerebrum** b. **Limbic system** c. **Thalamus** 812. Limbic system has also three parts: a. **Hypothalamus** b. **Amygdala** c. **Hippocampus** 813. Midbrain is reduced in human. 814. Hindbrain has also three parts: a. **Cerebellum** b. **Medulla Oblongata** c. **Pons** 815. Cerebrum has two hemispheres: right and left, communicated by corpus callosum (Bands of axons). 816. Cerebrum has **4** surface lobes: frontal, parietal, temporal, & occipital. 817. Cerebrum has several areas, which has sub areas: sensory, association, motor. 818. Thalamus, present below the cerebrum, receive all the sensory impulse except smell and send towards limbic system. 819. Limbic system lies on either side of thalamus. 820. Hypothalamus, controls homeostasis (osmoregulation, thermoregulation), hunger, menstrual cycle, biorhythms, sexual behaviour, hormonal control, fight & flight response etc. 821. Amygdala, **2** in number, almond in shape, and present on either side of thalamus. 822. Amygdala controls, emotion, pleasures, punishments, love, hate, fear, rage, and sexual arousal. 823. Hippocampus, two horn shaped curved back from amygdala, controls long term memories involved in learning. 824. Midbrain, reticular formation, relay centre between the fore brain and hind brain, visual & auditory input and send to higher brain. 825. Pons, present above the medulla, act as bridge between cerebrum, medulla & cerebellum. 826. Pons, controls rate & pattern of breathing and transition between sleep and wake cycle. 827. Cerebellum has one central lobe and two lateral lobes. 828. Cerebellum, best developed in birds. 829. Cerebellum, controls position, motion, balancing, bicycle riding, running, delicate work with hands, learning, memory for behaviour. 830. Medulla controls basic phenomena like, heartbeat, breathing, swallowing, cough, sneezing, vomiting, coordinate between brain and spinal cord, and involuntary actions. 831. Diameter of thick filament: **16nm** 832. Diameter of thin filament: **7- 8nm** 833. **Rigor Mortis** lasts for about 34 hours. 834. In human non myelinated fibres, nerve impulses travel at **1 - 3 ms^-1^**. 835. Myelinated fibres conduct at speeds of up to **120 meters per second**. 836. Refractory period lasts for about **4** milliseconds so a neuron can conduct **250** impulses per second. 837. Saltatory conduction is up to **50 times** faster than conduction through the fastest unmyelinated axons. 838. The surface of the cerebrum is called cerebral cortex. Cerebral cortex has many folds or convulsions forming ridges or gyri (singular, gyrus) which are separated by grooves. A shallow groove is called a **sulcus** (plural, sulci) and a deep groove is called a **fissure**. The two hemispheres are separated by longitudinal fissure. 839. **Meissner\'s corpuscles** and **Merkel disks** are touch receptors. 840. T~4~ (also known as thyroxin) is the major hormone, about 90%, secreted by the thyroid; T~3~ is only 10%. T~3~ is four times more potent than T~4~: however, action duration of T~4~ is four times more than T~3~. 841. **Graves\' disease** is believed to be an autoimmune disease. 842. **Renin** monitors blood pressure and takes corrective action if it drops. 843. **Erythropoietin** acts on the bone marrow to increase the production of red blood cells. 844. **Calcitriol** acts on the cells of the intestine to promote the absorption of calcium from the diet. 845. Over secretion of T~3~ and T~4~ causes **Graves\' disease**. 846. Full blow hypothyroid syndrome is called **myxedema**. 847. Hypothyroidism in infants is often referred to as **cretinism**. 848. **Addison\'s disease** is caused by the underproduction of cortical hormones, specifically cortisol and aldosterone, by the adrenal glands. 849. Over secretion of cortical hormone cause **Cushing\'s disease** which is characterized by excessive protein breakdown resulting muscular and bone weakness. 850. The amount of semen propelled out of the male duct system during ejaculation is about **2-5 ml** and there are between **20 to 150 million sperm per ml**. 851. **Azoospermia** is the state of having no sperms. 852. The sperm count below **20 million/ml** is called **oligospermia**. 853. Erythroblast is a type of red blood cell which still retain their nucleus. 854. The expression of **ABO genotypes** (locus is on chromosome **9**) also depends upon another **gene H** (locus is on chromosome **19**) that encodes a particular H substance. 855. **Protanopia** is red blindness; **deuteranopia** is green blindness, while **tritanopia** is blue blindness. (DPT: GRB) 856. Darwin returned to England in **1836** and read Malthus\' work on population growth. **Malthus** noted that populations grow exponentially while food supply grows arithmetically, leading to a struggle for existence. 857. The oldest known fossils are prokaryotes. 858. ***Ambulocetus natans*** was present in early cetacean period. It could walk as well as swim. It is a transitional fossil that shows whales have evolved from land-living mammals. 859. The right and left lungs are separated medially by the heart and **mediastinum**. 860. A breathing centre located in the medulla of the brain carries out involuntary control of breathing. 861. The **ventral portion** of the breathing centre acts to increase the rate and depth of inspiration and is called **inspiratory centre**. 862. The **dorsal and lateral portions** inhibit inspiration and stimulate expiration. These regions form the **expiratory centre**. 863. Maximum oxygen carrying capacity of arterial blood is **20 ml/100 ml** of blood (100% saturated) which is achieved a 100 mmHg PO~2~. The **5 ml** of O~2~ is released to the tissues by each **100 ml** blood. 864. The amount of haemoglobin is **15 gms/100 ml** of blood. Since **1gm** Hb can combine with **1.34 ml** of O~2~, therefore 100 ml blood combines with **20 ml** O~2~ (100% saturated). 865. Normally each 100 ml of arterial blood contains **19.4 ml** O~2~ (i.e., it is 97% saturated; PO~2~ is 95 mmHg), while 100 ml of venous blood contains **14.4 ml** O~2~ (i.e., it is 75% saturated; PO~2~ is 40 mmHg). 866. Haemoglobin loses oxygen at PO~2~ **60 mmHg**. 867. Myoglobin loses oxygen at PO~2~ **20 mmHg**. 868. **Hiccups** is the spasmodic contraction of the diaphragm while the glottis is closed. 869. Sneezing is forceful expiration that results abruptly opens the glottis, sending a blast air through the nasal cavity. 870. The unusual higher concentration than other vertebrates of marine habitat is maintained by high levels of urea and **trimethylamine oxide** (TMAO) in the blood. 871. Some fishes have special salt secreting glands in the wall of rectum called **rectal glands**. 872. Efferent arterioles have somewhat less diameter than that of the afferent vessel. Therefore, a considerable blood pressure is developed in glomerulus. 873. There are **five** major types of urinary stones: calcium oxalate, calcium phosphate, magnesium ammonium phosphate, uric acid and cystine. 874. Uric stones are composed of combination of uric acid and calcium oxalate. They are normally **2-3 mm** in diameter with either smooth or uneven surface. Branching stone is called **staghorn stone**. 875. Increased oxalate level in the urine is called **hyperoxaluria**. 876. High calcium in the urine is called **hypercalciuria**. 877. **Gouty arthritis** results from a metabolic disorder in which an abnormal amount of **uric acid** is retained in the blood and sodium urate crystals are deposited in the joints. The most common joint affected is the joint of the **big toe**. 878. A **sprain** is an injury to a **ligament**. Commonly injured ligaments are in the ankle, knee and wrist. 879. **Intercalated discs:** Specialized cell-to-cell junctions that join adjacent cardiac muscle cells together to form branching fibers. 880. Each thick filament contains about **300** myosin molecules. 881. **Unipolar neurons:** Have a single process that divides into an axon and a dendrite. 882. **Bipolar neurons:** Have two processes: an axon and a dendrite, with the cell body in between. Found in the **retina**. 883. **Multipolar neurons:** Have multiple dendrites and a single axon. 884. The larger and thicker the axon, the faster it transmits information. 885. **Sarin**, a nerve gas, binds irreversibly to acetylcholinesterase, preventing it from breaking down acetylcholine. 886. A transverse section of the adult spinal cord shows white matter in the periphery, grey matter inside, and a tiny central canal filled with CSF at its centre. 887. Endocrine system is the type of glandular system, consists of some **20 ductless glands** lying in different parts of the body. 888. Pineal gland: Attached to the hypothalamus. Primary hormone is **melatonin**. Influences circadian rhythms (daily sleep-wake cycles). 889. Secretin and cholecystokinin control pancreatic and liver secretions. 890. Endorphins are produced in the brain. Endorphins bind to pain receptors and so block sensation of pain. 891. **Pectin** is a polymer of around **200 galacturonic acid** molecules. Majority of its carboxyl groups are methylated (COOCH~3~). It is less **hydrophilic** then pectic acid but soluble in hot water. It is another major component of middle lamella but also found in primary walls. 892. **Pectic acids** are polymer of around **100 galacturonic acid** molecules. These are **very hydrophilic** and form salts with Ca^++^ and Mg^++^ that are insoluble gels. These are major components of **middle lamella** but also found in primary cell walls. 893. The fluidity of membrane is dependent on its lipid components, including phospholipids, glycolipids and cholesterol. 894. At cytokinesis, these Golgi vesicles are arranged on the cell equator, fuse together and form a structure, called **phragmoplast**. 895. Sieve tube cells in plants and red blood cells in human are exceptional living cells that do not possess nucleus. 896. The human body is primarily composed of six essential bio-elements: **OCHNCaP:** 65, 18, 10, 3, 2,1 **Class** **Formula** **Aldoses** **Ketoses** ------------------- ------------- ------------------------------- ------------------ **Trioses (3C)** C₃H₆O₃ Glyceraldehyde Dihydroxyacetone **Tetroses (4C)** C₄H₈O₄ Erythrose Erythrulose **Pentoses (5C)** C₅H₁₀O₅ Ribose, Deoxyribose (C₅H₁₀O₄) Ribulose **Hexoses (6C)** C₆H₁₂O₆ Glucose, Galactose Fructose **Heptoses (7C)** C₇H₁₄O₇ Glucoheptose Sedoheptulose 897. In the Calvin cycle, 6 molecules of 3-phosphoglycerate (3PG) are converted into 6 molecules of 1,3-bisphosphoglycerate (1,3-BPG). This crucial step requires the **consumption of 6 ATP molecules to produce 6 ADP molecules.** 898. In the Calvin cycle, the conversion of 1,3-bisphosphoglycerate (1,3-BPG) to glyceraldehyde 3-phosphate (G3P) actually involves the **consumption of 6 NADPH molecules to produce 6 NADP+ molecules** 899. In a single turn of the Calvin cycle (also known as the light-independent reactions), a total of **9 ATP** and **6 NADPH** molecules are used to convert carbon dioxide into glucose. 900. In preparatory phase of glycolysis, two ATP molecules are consumed to phosphorylate glucose to glucose-6-phosphate and then to fructose-1,6-bisphosphate. 901. Fructose-1,6-bisphosphate is split into glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate. 902. Glyceraldehyde 3-phosphate is oxidized and phosphorylated, producing 1,3-bisphosphoglycerate, NADH, and a proton. 903. 1,3-bisphosphoglycerate transfers its phosphate group to ADP, producing ATP and 3-phosphoglycerate. 904. 3-phosphoglycerate is converted to 2-phosphoglycerate which is dehydrated to phosphoenolpyruvate (PEP). 905. Net Yield: For each glucose molecule, glycolysis produces: a. **2 pyruvate molecules** b. **2 ATP molecules** (net after the investment phase) c. **2 NADH molecules** 906. **Pyruvate,** a product of glycolysis, is transported into the mitochondria for further oxidation. This process, known as the **oxidation of pyruvate** or **link reaction**, serves as a bridge between glycolysis and the citric acid cycle. 907. Pyruvate loses a carbon atom, releasing it as carbon dioxide (CO2). This results in the formation of a two-carbon compound called acetaldehyde. 908. Acetaldehyde is oxidized, losing two hydrogen atoms. These hydrogen atoms are accepted by NAD+, reducing it to NADH. 909. The remaining two-carbon fragment (acetyl group) combines with coenzyme A (CoA) to form acetyl-CoA. 910. **Ubiquinone** is not a protein, but a small molecule soluble in lipids and insoluble in water. 911. Cytochromes literally means \"**cell colour**\". The reduced cytochromes are pink in colour. They are protein plus pigment molecules containing iron. They can gain or lose an electron. 912. **Photorespiration** is a process that occurs in plants, especially under conditions of high temperature and low CO~2~ levels. It involves the fixation of oxygen (O~2~) by the enzyme Rubisco, leading to the production of **phosphoglycolate**, a toxic compound. 913. Phosphoglycolate is dephosphorylated to form **glycolate**. Glycolate is transported to peroxisomes, where it is converted to **glycine** (simplest amino acid). Glycine is transported to mitochondria, where it is converted to **serine**, releasing CO~2~. 914. Photorespiration decreases net photosynthesis because a portion of CO~2~ fixed in photosynthesis escapes from the leave after it is fixed. Under certain conditions, up to **5%** of the photosynthetic potential is lost in photorespiratory metabolism. Thus, photorespiration reduces dry matter production and agricultural yield in tropical climate. 915. **C4 photosynthesis** is a specialized pathway found in some plants, particularly those adapted to tropical and subtropical environments. It is an adaptation to minimize photorespiration, a process that reduces the efficiency of photosynthesis. 916. C4 plants have two types of photosynthetic cells: mesophyll cells and bundle sheath cells. 917. The enzyme **phosphoenol pyruvate carboxylase (PEP carboxylase)** is used to fix CO~2~ onto phosphoenol pyruvate (PEP), forming **oxaloacetate**. 918. The initial products of CO^2^ fixation are four-carbon compounds (C4), hence the name **C4 photosynthesis**. 919. Oxaloacetate is converted to **malate** and then transported to bundle sheath cells. Here, malate is decarboxylated, releasing CO~2~. This increases the CO~2~ concentration in bundle sheath cells. 920. In **bundle sheath cells**, RuBisCO can efficiently participate in the Calvin cycle due to the high CO~2~ concentration, minimizing photorespiration. 921. By concentrating CO~2~ in bundle sheath cells, C4 plants can minimize the competitive binding of O~2~ to RuBisCO. 922. C4 photosynthesis allows plants to maintain high photosynthetic rates under conditions of high temperature and low CO~2~ availability. 923. Examples of C4 plants: Maize, Sugarcane, Sorghum, Millet, Crabgrass 924. The **Hatch-Slack cycle**, also known as the C4 pathway. 925. The carbon chains in the membrane lipids of Eubacteria are unbranched, while those in Archaea are branched. 926. Introns, noncoding sequences within genes, are generally absent in Eubacteria but present in some genes of Archaea. 927. Introns, noncoding sequences within genes, are generally absent in Eubacteria but present in some genes of Archaea. 928. Eubacteria have a cell wall composed of peptidoglycan, while Archaea lack this component. 929. About **one third** of cyanobacteria can fix atmospheric nitrogen. In most cases nitrogen fixation occurs in **heterocyst**, which are thick walled without nuclei. 930. In Pakistan cyanobacteria e.g. *Nostoc, Anabaena* are purposely cultivated to increase the soil fertility, because of nitrogen fixation by these organisms. 931. **Monotrichous**: A single flagellum. 932. **Amphitrichous**: A flagellum at each end of the cell. 933. **Lophotrichous**: Clusters of flagella at the poles of the cell. 934. **Peritrichous**: Flagella distributed over the entire cell surface. 935. **Key points about bacterial flagella**: a. They are composed of the protein flagellin. b. They are non-contractile and lack microtubules. c. They consist of three main parts: basal body, hook, and filament. d. The basal body is the motor that generates rotational motion. e. The filament is a helical structure that propels the bacterium. 936. Polyp reproduces asexually by budding to form medusae. In turn medusae reproduce sexually to form polyp. 937. **Hydra** do not show alternation of generation. 938. **[Crustacea]**: Primarily aquatic arthropods with two pairs of antennae, such as crabs, lobsters, shrimp, and barnacles. 939. **[Insecta]**: Terrestrial arthropods with three pairs of legs and two pairs of wings, including insects like butterflies, beetles, ants, and flies. 940. **[Arachnida]**: Terrestrial arthropods with eight legs and no antennae, such as spiders, scorpions, mites, and ticks. 941. **[Myriopoda]**: Terrestrial arthropods with many legs, including centipedes and millipedes. 942. The gnathostomates have jaws. The tooth bearing bones of the head. Jaws are believed to have evolved from the first pair of gill arches of agnathans. 943. The heart lies deep and obliquely in the mediastinum and slightly to the left of the sternum. The base of heart deep to the sternum, extends to the second intercostals space and the apex of the heart is in the **fifth** intercostals space, approximately **9 cm** to the left of the midline. 944. The atria lie above and behind the ventricles. On the surface of the heart, they are separated from each other by an atrioventricular groove or sulcus (meaning ditch). The atria are separated from each other by an interatrial groove. The ventricles are separated from each other by an interventricular groove. 945. **Heart valves:** Formed by folds of the endocardium. 946. **AV valves**: Located between the atria and ventricles, they prevent blood backflow. 947. **Tricuspid valve**: The right AV valve, with three cusps. 948. **Bicuspid (mitral) valve**: The left AV valve, with two cusps. 949. **Papillary muscles**: Cone-shaped muscles in the ventricles. 950. **Chordae tendineae**: Connective tissue strings that attach the papillary muscles to the AV valve cusps. 951. **Lub**: This sound is produced when the atrioventricular (AV) valves close at the beginning of ventricular systole. The AV valves are located between the atria and the ventricles. 952. **Dub**: This sound is produced when the aortic and pulmonary valves close at the end of ventricular systole. These valves are located at the exit points of the ventricles, leading to the aorta and pulmonary artery, respectively. 953. **Sinoatrial (SA) Node**: Located in the upper right atrium near the entrance of the superior vena cava. Acts as the heart\'s pacemaker, generating spontaneous action potentials at a regular rate. Controls the heart\'s normal rhythm. 954. **Atrioventricular (AV) Node**: Located in the lower right atrium near the junction with the right ventricle. Delays the transmission of action potentials from the atria to the ventricles. Allows for complete atrial contraction before ventricular contraction begins. 955. **Bundle of His (AV Bundle)**: A specialized bundle of cardiac muscle fibers that extends from the AV node through the interventricular septum. Divides into the right and left bundle branches, which run along the interventricular septum to the apex of the heart. 956. **Purkinje Fibers**: Large-diameter cardiac muscle fibers that branch from the bundle branches and distribute action potentials throughout the ventricular walls. Allow for rapid conduction of action potentials, ensuring coordinated ventricular contraction. 957. **P Wave**: Represents the atrial depolarization. Indicates the electrical activity spreading through the atria as they contract. Typically, it is a small, rounded upward deflection. 958. **QRS Complex**: Represents the ventricular depolarization. Indicates the electrical activity spreading through the ventricles as they contract. Consists of a downward deflection (Q), an upward spike (R), and another downward deflection (S). 959. **T Wave**: Represents ventricular repolarization. Indicates the electrical activity as the ventricles relax and prepare for the next cycle. Typically, it is a smooth, rounded upward deflection, although it can be inverted in some conditions. 960. **PR Interval:** The interval between the start of the P wave and the beginning of the QRS complex. It represents the time taken for the electrical impulse to travel from the atria to the ventricles. 961. **ST Segment:** The segment between the end of the S wave and the beginning of the T wave. It represents the time between ventricular depolarization and repolarization. 962. All blood vessels have an internal lining of simple squamous called endothelium, which is continuous with the endocardium of the heart. 963. **Natural Active Immunity**: Acquired through natural exposure to an infectious agent. The body produces its own antibodies and memory cells. Provides long-lasting, often lifelong protection against the specific disease. 964. **Artificial Active Immunity (Vaccination):** Induced by the administration of a vaccine, which contains a weakened or inactivated form of the pathogen or its antigens. Stimulates the body to produce antibodies and memory cells. Provides protection against a specific disease. Often requires booster shots to maintain immunity over time. 965. Golgi complex, in animals have **3-4** cisternae, invertebrates have **30** cisternae, while plants have more than **100** cisternae. 966. Weight of Brain: **1.4Kg** 967. The charged pores in the plasma membrane are involved in both active and passive transport. 968. Golgi vesicles arise from trans face of Golgi apparatus. 969. Peroxisomes were first time isolated from liver cells. 970. Amino group of alanine form peptide bond with glycine to form glycalalanine (dipeptide). 971. A protein will develop globular shape if it attains tertiary structure. 972. In chloroplasts, chlorophyll is present in the thylakoids. 973. Cartilage plates are found in bronchi. 974. Inspiration, which is the process of taking in air, is primarily associated with the **contraction of the diaphragm** and **intercostal muscles**. 975. 100% of glucose is reabsorbed at **PCT**. 976. **Dendrites** are branched extensions of neurons that receive signals from other neurons. **Dendrons** are longer, thicker dendrites that can also receive signals. 977. Total no of cerebral nerves in humans is **24**. 978. Testes acts as endocrine gland in male reproductive system. 979. ADH and oxytocin are stored in axon endings at posterior pituitary. 980. During photosynthesis, oxygen and water are released as products in light and dark reactions respectively. 981. The primary electron acceptor of photosystem-I transfers electrons to ferredoxin. 982. Decarboxylation does not occur in lactate fermentation. 983. Reverse transcriptase used in biotechnology to synthesize cDNA is DNA polymerase. 984. Leading strand is constructed towards replication fork during DNA replication. 985. **GCGCATAT** act as stop signal for transcription. 986. Alleles are not for same phenotype. The alleles influence the same trait but may lead to different expressions of that trait. 987. If probability of round seeded plant is 3/4 and green seeded plant is 1/4 then joint probability of wrinkled green will be 1/16. 988. Potassium act as a macronutrient and help in opening and closing of stomata. 989. Least amount of peptidoglycan is present in gram negative bacteria but absent in mycoplasma. 990. Yeast is non mycelium with plasmid. 991. Intermediate host for plasmodium is female anopheles. 992. Cranium is made up of **2 paired** and **4 unpaired bones**. 993. ACTH stimulates the production of cortisol. 994. Source of illumination in transmission electron microscope is electrons. 995. Food prepared by photosynthesis is stored in **parenchyma cells**. 996. **Telomeres** prevents the two chromosomes to attach with each other from their ends. 997. Amino acid attaches itself with **3\`** ends of tRNA. 998. **Protein** is responsible for selective uptake of materials across plasma membrane. 999. Nuclear mitosis is the exclusive character of fungi. 1000. *Ancylostoma duodenale* is a round worm causes anaemia. 1001. Amphibians are on the border line between aquatic and true terrestrial animals. 1002. Alveoli is preceded by alveolar duct. 1003. Urea and uric acid will be the major excretory products if a man eats a protein rich diet. 1004. Artificial passive immunity is rapid but short lived. 1005. Anaemia is a common symptom in malaria. 1006. Pepsin does not need cofactor. 1007. Translocation of photosynthate from mesophyll to phloem tissue involves **carrier mediated active transport**. 1008. As a result of transpiration, the mesophyll cells of leaf faces drop in water potential. 1009. Troponin is a three-polypeptide complex and bides to calcium ions. 1010. **Break bud and seed dormancy,** is the common function of auxins, cytokinins and gibberellins. 1011. Spermatogenesis starts at puberty under influence of **FSH**. 1012. Healing of uterine wall due to previous menstruation is done by **estrogen**. 1013. If a woman has menstrual cycle comprising of 34 days, then the probable day of ovulation would be 20^th^ day (34-14). **Probable day of ovulation = Cycle length - 14** 1014. **UGA** codon in mitochondria reads for **Tryptophan**. 1015. Actin and myosin are involved in cleavage furrow during cell division of animal cell. 1016. In *Drosophila* w/w^+^ in over dominance result, more than normal fluorescent pigments. 1017. Protanopia is more common in male as compared to female. 1018. In the Hardy-Weinberg equation 2pq represents frequency of heterozygous individuals in population. 1019. If a normal woman marries a man with hypophosphatamic rickets, then the phenotype of the children will be that all daughters are affected. 1020. There are **three** principal sites of digestion in digestive system of man. 1021. Fatty acids and glycerol recombine to form fat in epithelial cells of villi. 1022. Common means of asexual reproduction in Saccharomyces cerevisiae is budding. 1023. Hemocyanin is a respiratory pigment found in snail. 1024. Nonflowering, seed producing plants are gymnosperms. 1025. Site for muscle attachment is compact bone. 1026. The theoretical number of different dipeptides that may be assembled from n different types of amino acids is n^2^, in case of tripeptide the formula will be n^3^. 1027. Sucrose is non reducing sugar therefore it will give negative benedict test result. 1028. Glucose, fructose and maltose is reducing sugar. 1029. Glycogen lacks nitrogen and is a branched molecule. 1030. **Hydrogen bonding** is responsible for stabilizing the secondary structure of a protein. 1031. When increasing the amount of substrate in a reaction, it can reduce the impact of competitive inhibition on the enzyme. However, increasing the substrate concentration has no effect on non-competitive inhibition. 1032. Disulphide, hydrogen, and ionic bonds hold the tertiary structure of a protein molecule. 1033. At low pH values enzymes are denatured. 1034. At tertiary and quaternary structural level hydrophobic interaction occur. 1035. A double-stranded DNA containing 120 nucleotides will yield an mRNA strand of 60 nucleotides, which, with 3 nucleotides coding for each amino acid, can produce a polypeptide of up to 20 amino acids. 1036. Two fatty acids residues are normally present in a phospholipid molecule. 1037. Myoglobin has only one polypeptide chain therefore it does not have a quaternary structure. 1038. RNA is the polymer of ribonucleotide. 1039. Coenzymes are often vitamin. 1040. ADP is not a cofactor. 1041. DNA nucleotides of one strand are attached with each other through covalent bonds. 1042. Most abundant organic compound on earth is cellulose. 1043. Gas exchange occurs in respiratory bronchioles, alveolar ducts, and alveoli but not in tertiary bronchi. 1044. Sertoli cells of testes are under the influence of FSH. 1045. T-tubules surrounds myofibrils at the level of Z-line. 1046. Facilitated diffusion do not require ATP. 1047. Squid is the largest invertebrate animal. 1048. Pyruvic acid oxidation takes place in matrix of mitochondria. 1049. The plant produced by anther culture is haploid. 1050. ''**History of life is like a tree**'', this idea is floated by Darwin. 1051. Sex chromosomes in human female are homologous and homomorphic. 1052. In sickle cell hemoglobin, the genetic mutation involves a change in a single nucleotide of the DNA sequence for the beta-globin gene. Specifically, **adenine (A) is replaced by thymine (T)** at the sixth codon position. This substitution changes the codon from **GAG** (which codes for glutamic acid) to **GTG** (which codes for valine). This results in the production of abnormal hemoglobin, known as hemoglobin S (HbS), leading to sickle-shaped red blood cells. 1053. No vaccination is available for hepatitis C. 1054. Viral enzyme, reverse transcriptase, is used in biotechnology. 1055. Formation of urea and urine occurs in liver and kidneys respectively. 1056. **Liposomes**, microscopic vesicles are used for the cure of cystic fibrosis. 1057. In **diplotene**, the paired chromosomes repel each other and begin to separate. 1058. Corpus luteum is formed in secretory phase. 1059. 92 chromatids are present in Anaphase-I of human cell that is undergoing meiosis. 1060. The hole created in PS-II is filled by electrons from water. 1061. The painful swelling of lymph nodes in mumps is caused by accumulation of dead RBCs, dead platelets, dead WBCs. 1062. In fish the heart never receives oxygenated blood because of single circuit plan. 1063. MN blood group system is related to co-dominance. 1064. Most of the proteins are made of 20 amino acids. 1065. Chemosynthetic bacteria are nitrifying bacteria. 1066. **Discontinuous feeding** is made possible only by stomach. 1067. **Aging** is the negative changes during development of living organism. 1068.