Pre-Med Biology Shortlisting PDF

PreMed.PK Chapter Shortlisting ACELLULAR LIFE VIRUSES AND DISEASES CHARACTERISTICS Cause Common Cold , influenza ,bird flu ,etc Not cells lack independent replication and affecting plants and...

PreMed.PK Chapter Shortlisting ACELLULAR LIFE VIRUSES AND DISEASES CHARACTERISTICS Cause Common Cold , influenza ,bird flu ,etc Not cells lack independent replication and affecting plants and animals. independent activity. Living traits : variety , genetic material ; Non living ; lack cellular structures. DISCOVERY AND CLASSIFICATION ‘’virus’’ from Latin ‘’Venom’’ EXAMPLES Classified based on morphology , nucleic acid , replication, and hosts. Bacteriophage : Hexagonal head , tubular Shapes and Sizes: Varied shapes ( spherical tail , tail pin. rod-shaped , helical ) , sizes ( 17nm-100nm) Influenza virus : A,B,C forms , orthomyxovirus family , RNA , Capsid , Envelop. STRUCTURE Core : DNA or RNA CONCLUSION Capsid : Protective coat Envelop : Additional lipoprotein layer Viruses bridge living and nonliving , causing disease with distinct structure CLASSIFICATION ON THE BASIS OF SHAPES Classification Description Example Helical Viruses Spiral or coil shaped structure Tobbaco Mosaic Virus, Influenza Virus Symmetrical icosahedral ( 20 sided ) Icosahedral Viruses Adenovirus,Herpes Virus shape Complex shapes with additional Complex Viruses Bacteriophages structures Have a lipid envelop surrounding protein Enveloped Viruses HIV , Influenza coat Other Shapes Unique or irregular shapes Pox Virus, certain bacteriophages To practice 60,000 free MCQs, go to www.PreMed.PK  Prep Titans Let's turn Dreams into Stethoscopes 🩺🩺 Founders: Muhammad Tayyab Ali & Mellow FOLLOW OUR OFFICIAL INSTAGRAM ACCOUNT : Preptitans https://www.instagram.com/preptitans 🩺 👉 👈 Follow our Official WhatsApp Channel Click Here 👉 👈 Join Our Official WhatsApp Community and Groups! 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All Acadmies Test Sessions Google Drive : click here Tayyab Sir: Mellow ! +92 341 7964379 +92 326 9526326 WhatsApp: click here WhatsApp: click here  PreMed.PK Chapter Shortlisting ACELLULAR LIFE CLASSIFICATION ON THE BASIS OF VIRAL GENOME Virus Viral Genome Type Influenza Negative-sense single-stranded RNA HIV Position-sense single-stranded RNA Hepatitis B Partial double-stranded DNA Herpes Simplex Double-Stranded DNA Measles Negative-sense single-stranded RNA Hepatitis C Positive-sense single-stranded RNA Human Papillomavirus (HPV) Double-stranded DNA Mumps Negative-stranded single-stranded RNA Rubella Positive-sense single-stranded RNA Polio virus Positive-sense single-stranded RNA Hepatitis A virus Positive-sense single-stranded RNA HUMAN IMMUNODEFFICIENCY VIRUS Retrovirus , spherical , RNA Core , envelop from host. Replication: reverse transcription, integration into host DNA. Parasitic Nature : Obligate parasites , host- specific ( e.g., bacteriophage , tobacco mosaic virus ) To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting ACELLULAR LIFE VIRAL LIFE CYCLE VIRAL DISEASES Reproduction in hosts : Adsorption , Hepatitis A : Penetration , Uncoating , Transcription , HAV (RNA) Virus , fecal-oral route. Translation , Replication , Assembly , symptoms : Fever, anorexia , jaundice. Release. Prevention : vaccine , hygiene. Hepatitis B: HBV (DNA virus), blood, surface contact. HIV CONTROL MEASURES Symptoms: Severe, cirrhosis. Prevention: Vaccine, blood screening. Antiviral treatments aim to reduce viral load. Hepatitis C: Therapy based on symptoms , CD4 count , HCV (RNA virus), blood. viral load. Symptoms: Fever, jaundice. Prevention through safe practices : Prevention: No vaccine, blood screening. avoiding shared needles , blood transfusions screening , sterilizing Herpes: instruments , following Islamic teachings HSV-1 (saliva), HSV-2 (sexual contact). Not transmitted through coughing , Treatment: Antiviral drugs. sneezing , or swimming. No transmission via inanimate objects , Poliomyelitis: mosquitoes , or insects. Polio virus (RNA), fecal-oral. Symptoms: Paralysis, meningitis. Prevention: Killed (Salk) and live (Sabin) vaccines. VIRUSES EVOLUTION Cotton Leaf Curl Disease: Derive from host cells , nucleic acids from Whitefly transmission. host genomes. Symptoms: Leaf curling, stunted growth. Ongoing evolution with emerging new Prevention: Insecticide, removal of affected viruses. plants. Prions: Protein particles, no nucleic acid. INFLUENZA Diseases: Transmissible spongiform encephalopathies. RNA genome , helical nucleoprotein , lipoprotein envelop. Viroids: Circular RNA, no protein coat. Cause plant diseases, not humans. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting BIOENERGETICS BIOENERGETICS Bioenergetics delves into the quantitative examination of energy relationships and conversions within biological systems Energy stands as a fundamental necessity for the sustenance and functionality of all living organisms, serving as the driving force behind essential cellular activities and metabolic pathways. Light energy, a form of electromagnetic radiation, serves as the primary driving force behind photosynthesis, initiating the conversion of light energy into chemical energy. Action Spectrum:The action spectrum of photosynthesis mirrors the absorption spectrum of chlorophyll, elucidating the varying effectiveness of different wavelengths of light in driving photosynthetic processes) PHOTOSYNTHESIS CHLOROPLASTS AND PHOTOSYNTHETIC PIGMENTS: 1). Photosynthesis emerges as a pivotal biological Chloroplasts, intricate organelles primarily process wherein solar energy is harnessed and localized within the mesophyll cells of plant converted into chemical energy, which is leaves, represent the primary sites of subsequently utilized by living organisms. photosynthesis. 2). It entails the absorption of light energy by These organelles exhibit a complex specialized pigments, primarily chlorophyll, initiating a architecture comprising thylakoids arranged series of biochemical reactions. in stacks known as grana, alongside the 3). Carbon dioxide, water, glucose, and oxygen serve stroma, housing an array of enzymes crucial as key components in the photosynthesis for carbohydrate synthesis. 4). Photosynthesis predominantly occurs during Chlorophylls, predominant among daylight hours while respiration remains a continuous photosynthetic pigments, exhibit a process supporting cellular functions. remarkable ability to absorb light energy 6). Water plays a critical role in photosynthesis, across specific wavelengths, particularly in the serving as a primary source of oxygen during the blue and red regions of the electromagnetic light-dependent reactions of the process. spectrum. Additional pigments, such as carotenoids, Van Niel's proposition, speculated on water's broaden the spectrum of light absorption, involvement in oxygen production, a theory later augmenting the efficiency of light capture and validated through experimental techniques energy transfer to chlorophyll molecules. employing isotopic tracers. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting BIOENERGETICS ROLE OF CARBON DIOXIDE: 1)CO2 is essential for the synthesis of sugar during photosynthesis. 2)Sugar formation occurs through the reduction of CO2 using ATP and NADH from light-dependent reactions. 3)While terrestrial plants primarily utilize atmospheric CO2, aquatic organisms use dissolved CO2, bicarbonates, and soluble carbonates for Terrestrial and Aquatic Photosynthesis. 4)CO2 enters leaves through stomata, which regulate gas exchange.CO2 gets dissolved in water absorbed by mesophyll cell walls. REACTIONS OF PHOTOSYNTHESIS: RESPIRATION LIGHT-DEPENDENT REACTIONS (LIGHT REACTIONS): 1). Respiration is the process through which organisms break down complex 1). Sunlight absorbed by photosynthetic pigments drives ATP carbon-containing compounds to and NADPH synthesis. harvest energy. 2). Photosystems I and II organize pigments for efficient energy absorption. 2). Respiration refers to both external 3). Electrons move through photosystems, generating ATP and respiration (gas exchange) and cellular NADPH. respiration (energy production). Non-cyclic Phosphorylation: ATP synthesis via chemiosmosis occurs during non-cyclic electron flow. 3). Cellular respiration can occur LIGHT-INDEPENDENT REACTIONS (DARK REACTIONS): aerobically (with oxygen) or 1). Dark reactions take place in the stroma of anaerobically (without oxygen), leading chloroplasts. to different metabolic 2). Calvin Cycle: Series of enzymatic reactions pathways.Anaerobic pathways yield that fix and reduce carbon dioxide, leading to minimal energy compared to aerobic sugar synthesis. respiration. 3). Three Phases: Carbon Fixation, Reduction, and Regeneration of CO2 Acceptor (RuBP). Anaerobic Respiration: 1-Alcoholic Fermentation: Pyruvic acid is converted to alcohol and CO2, often seen in yeast. ADENOSINE TRIPHOSPHATE (ATP) 2-Lactic Acid Fermentation: Pyruvic acid is converted to lactic acid, common in 1). ATP is crucial for most biological energy muscle cells during intense activity. transformations.ATP contains high-energy phosphate bonds, releasing energy when broken. 2). ATP is used for various cellular functions, including synthesis, transport, and muscle contraction. 3). Mitochondria act as "powerhouses" by converting energy from organic molecules into ATP.Mitochondria have inner membranes with folds called cristae, facilitating energy production. ATP To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting BIOENERGETICS CELLULAR RESPIRATION 1. GLYCOLYSIS 2. PYRUVIC ACID OXIDATION Glucose + 2NAD+ + 2ADP + 2Pi → 2Pyruvate + Pyruvate + NAD+ + CoA → Acetyl-CoA + CO2 + 2NADH + 2ATP + 2H+ NADH + H+ Breakdown of glucose to pyruvic acid Conversion of pyruvic acid to acetyl CoA ,occurs in the cytosol ,Can occur aerobically ,takes place in the mitochondria,Hydrogen or anaerobically. atoms transferred to NAD+. Divided into preparatory and oxidative phases ,Preparatory phase: Phosphate groups added to glucose ,Oxidative phase: 4. RESPIRATORY CHAIN Energy-rich phosphate bonds formed, yielding ATP and NADH. ADP + Pi + H+ + 3NADH + FADH2 + 1/2O2 → ATP + NAD+ + FAD + H2O NADH produced in Krebs cycle ,NADH transfers hydrogen atoms to the respiratory 3. KREBS CYCLE (CITRIC ACID CYCLE) chain. Electrons transported in a series of Acetyl-CoA + 3NAD+ + FAD + GDP + Pi + 2H2O → oxidation-reduction steps ,Involves 2CO2 + 3NADH + 3H+ + FADH2 + GTP + CoA coenzyme Q, cytochrome enzymes, and Series of reactions in mitochondria,Acetyl molecular oxygen ,Oxygen acts as the final CoA combines with oxaloacetate to form electron acceptor, producing water. citrate. Energy released drives ATP synthesis via Multiple oxidation steps generate NADH and oxidative phosphorylation. FADH2 ,ATP synthesized during certain steps. Oxidative Phosphorylation:ATP Synthesis: ATP Cycle regenerates oxaloacetate for is produced through oxidative phosphorylation, continued operation. coupled with the respiratory chain. Proton Movement: Protons are pumped across the inner mitochondrial membrane, driving ATP synthesis via chemiosmosis. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting BIOLOGICAL MOLECULES BIOMOLECULES IMPORTANCE OF WATER Biochemistry studies chemical 1. Medium of Life components and processes in living 2. Solvent Properties organisms. 3. Heat Regulation Essential for understanding anatomy, 4. lonization and Protection physiology, and biochemical organization of organisms. LIPIDS IMPORTANCE OF CARBON Heterogeneous group of compounds insoluble in water but soluble in organic solvents. 1. Carbon's unique properties make it central Include fats, oils, waxes, cholesterol, and in organic compounds. related compounds. 2. Forms stable structures due to Serve as components of cellular tetravalency, enabling the synthesis of membranes complex cellular structures.Ability to form and energy storage. various bonds contributes to the vast Classified into acylglycerols, waxes, diversity of organic compounds. phospholipids, sphingolipids, glycolipids, 3. Carbon-hydrogen bonds provide a and terpenoid lipids. potential source of chemical energy. 4. Forms stable bonds with other elements Acylglycerols like oxygen, nitrogen, and sulfur, crucial for Composed of glycerol and fatty acids, forming the structure and function of triglycerides or neutral lipids. biomolecules.Large organic molecules Important for energy storage, with fatty serve as structural components and acids varying in chain length and energy storage in cells. saturation. Waxes and Phospholipids Widespread protective coatings in plants and animals, composed of long-chain METABOLISM alkanes and other compounds. Phospholipids derived from phosphatidic Cells constantly undergo chemical acid, containing glycerol, fatty acids, and reactions to build new materials and phosphoric acid, crucial for membrane obtain energy. structure. Metabolism involves anabolism (building complex substances) and catabolism (breaking down complex molecules). To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting BIOLOGICAL MOLECULES PROTEINS PEPTIDE BOND FORMATION Over 50% of a cell's total dry weight Amino acids link together by peptide bonds, comprises proteins. formed between the amino group of one Present in all cell types and locations, amino acid and the carboxyl group of performing diverse functions. another. Serve as structural components, enzymes, Sequential peptide bond formation leads to hormones, carriers, antibodies, and clotting the creation of dipeptides, tripeptides, and factors. longer polypeptide chains. Regulate metabolism, defend against 1.Primary Structure: Sequence of amino acids pathogens, and facilitate movement within in a protein molecule cells 2.Secondary Structure: Folding of polypeptide Proteins are polymers of amino acids, chains into helices or sheets, stabilized by containing carbon, nitrogen, oxygen, and hydrogen bonds. hydrogen. 3.Tertiary Structure: Overall 3D shape of a Approximately 170 types of amino acids are protein, influenced by ionic, hydrogen, and found in cells, but most proteins are made disulfide bonds. from 20 amino acids. 4.Quaternary Structure: Arrangement of Amino acids differ mainly due to variations in multiple polypeptide chains in complex proteins, the R group attached to the alpha carbon. stabilized by various bonds. Fibrous Proteins Form fibrous structures, insoluble in aqueous NUCLEIC ACID media, and perform structural roles (e.g., keratin, myosin). Globular ProteinsSpherical or ellipsoidal DNA and RNA are polymers of nucleotides, proteins with diverse functions, soluble in comprising a pentose sugar, nitrogenous aqueous media (e.g., enzymes, base, and phosphoric acid. antibodies). DNA Structure: Composed of two polynucleotide chains forming a double helix, held together by hydrogen bonds between complementary bases.Adenine pairs with thymine, and guanine pairs with cytosine, maintaining the double helical structure RNA Types and Functions: A-Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes for protein synthesis. B-Transfer RNA (tRNA): Transfers amino acids to ribosomes during protein synthesis.C- Ribosomal RNA (rRNA): Major component of ribosomes, involved in protein synthesis. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting BIOLOGICAL MOLECULES CARBOHYDRATES CONJUGATED MOLECULES Abundant in living organisms, found in Formed by the combination of two different various cellular structures. molecules, such as carbohydrates with Classified into monosaccharides, proteins or lipids. Examples include oligosaccharides, and polysaccharides. glycoproteins, glycolipids, and nucleoprotein Monosaccharides Disaccharides Polysaccharides Single sugar molecules act as Number of monosaccharides building blocks for disaccharides Consists of two sugar molecules unit linked together by glycosidic and polyseccharides bond Water soluble Water soluble Insoluble in water Taste sweet Taste sweet Do not taste sweet Reducing sugars Some are reducing sugars Non reducing carbohydrates Composed of large number of Have a single monomor Composed of two monomers monomers Have a simple, linear, Have a single, linear, branched Have complex,branched unbranched structure or unbranched structure structure Have a single ring structure Have two rings structure Have a number of ring structures To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CELL STRUCTURE AND FUNCTION DEFINITION CELL THEORY: All organisms are composed of cells Smallest unit New cells arise from pre existing cells Building block Cell is basic structural and functional unit Discovered by Robert hooke~1665 Robert Brown discovered nucleus~1831 FLUID MOSAIC MODEL: Cell theory~Presented by Schawnn Description of structure of cell membrane as fluid layer and Schleiden of lipids with embedded proteins that move around freely. TYPES OF CELLS THREE BASIC PARTS OF CELL: 1.Prokaryotic cell 1.Nucleus 2.Cytoplasm 3.Plasma membrane(60 to 80% proteins+20 2.Eukaryotic cell to 40% lipids+small quantity of carbohydrates ) (Plant cell have cell wall while it is absent in animal cell) DIFFERENCES EUKARYOTES PRKARYOTES SIZE Larger than 10 micrometer Smaller than 10 micrometer Has a nucleus, mitochondria, Has a nucleus mitochondria COMPOSITION chloroplast and cytoskeleton chloroplast and cytoskeleton Unisexual and multicellular NUMBER OF CELLS Only unisexual organisms organisms REPRODUCTION Sexual and asexual reproduction Only asexual reproduction SHAPE Various forms Rod shaped or spiro-spherical CELL DIVISION By mitosis and meiosis By binary fision To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CELL STRUCTURE AND FUNCTION CELL WALL CELL MEMBRANE: 1.Present plant cell 1) Made of lipids (20-40%), proteins (60-80%), and 2.Outermost boundary some carbohydrates. 3.Provide rigidity,protection and shape to cell. 2) Proteins embedded in a mosaic pattern within 4.Secreted by protoplasm lipid layers. 5.Thickness varies 3) Acts as a barrier between cell contents and the THREE LAYERS environment ,regulating the passage of primary/true cell wall (cellulose, pectin, substances ,maintaining concentration gradients, hemicelluloses) facilitating the movement of materials and ions secondary(inorganic and Facilitates transmission of nerve impulses for salts,silica,waxes,cutin,lignin) coordination middle lamella 4) Endocytosis is a process where the membrane folds to engulf materials, forming vacuoles. RIBOSOMES: Tiny granular structures CYTOPLASM: discovered by plade(1955) Composed~equal amount of RNA and protein Consist of aqueous ground substance,cell Exist in two forms; 1.freely dispersed organelles and insoluble waste/storage products. 2.attached with RER Eukaryotic ribosome contain 2 subunits; large Functions: Store house of vital chemicals subunit-60/smaller subunit-40s Site for metabolic processes GOLGI APPARATUS Rough endoplasmic Smooth endoplasmic Golgi apparatus/Golgi body/Golgi complex: reticulum (RER) reticulum (SER) Discovered by Golgi (1898) Consist of flattened membrane bound Has ribosomes attached Do not have ribosomes sacks(cisternae) to its surface attached to its surface Cisternae+associated vehicles=Golgi complex. TWO FACES: Help in the synthesis of Help in the synthesis of protiens and enzymes glycogen, lipids 1.Outer convex surface~forming face 2.Inner concave surface~maturing face. It is formed by vesicles FUNCTIONS: It is mainly formed by and tubules 1.concerned with cell secretion cisterne and few tubules 2.formation of granules 3.Transportation of protein and enzymes RER is internal SER is peripheral 4.modify protein and lipids it is cnnected with It is cnnected by neuclear envelope plasmalemma ENDOPLASMIC RETICULUM: ~System of channels extending throughout cytoplasm To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CELL STRUCTURE AND FUNCTION PEROXISOMES: LYSOSOMES: Single membraned lyso=splitting contain large amounts of oxidative enzymes. Soma=body ~cytoplasmic organelles De-Duve and co-workers isolated~ 1965 found in eukaryotic cells Also found in protozoa, yeast and cells of Engulf foreign particles known as phagocytosis. higher plants. single membrane cytoplasmic organelles rich in acid phosphate and other enzymes Found in animal/plant cells. Processed enzymes buried of as Golgi vesicles 0.5 um in diameter are called primary lysosomes Number varies between 70-100 per cell. Involved in autophagy FUNCTION: Release enzyme for extracellular digestion (1)Formation and decomposition of (H2O2) Storage diseases~due to accumulation within (ii) Catabolic and Anabolic Pathways the cell of substances (iii) Producing Oxidase and catalase (iv) Contain ẞ oxidation. GLYOXYSOME: VACUOLES: Plant cell organelle Single membranous Abundant in Plant Seedling. Non Living cell Rely upon stored fatty acids to provide them with the FUNCTION: energy and materials to begin the formation of a new STORAGE,RIGIDITY AND SUPPORT. Present in animal/ plant cells plant. Serve to expand the plant cell without diluting Primary Activities: its cytoplasm (1)Conversion of stored fatty acids to carbohydrates. Function as sites of storage of water and cell (2)In Seed: products or metabolic intermediates. a.Breakdown of fatty acid to succinate. Turgor pressure provides support for the b.Present only during a short period in the individual plant cell. germination. Glyoxysomes are absent in lipid poor Contributes the rigidity to leaves and younger parts of the plants. seeds such as pea. MICROFILAMENTS: CYTOSKELETON Made of contractile actin proteins. Slender cylinders linked to the plasma Cytosol: Contains cytoskeletal fabric with membrane. microtubules, microfilaments, and intermediate Involved in internal cell motion. filaments. Proteins include tubulin (microtubules), Play a role in cyclosis and amoeboid actin, myosin, tropomyosin, etc. Gives rise to movements. organelles like cilia, flagella, basal bodies, and centrioles. INTERMEDIATE FILAMENTS Have a diameter between microtubules and MICROTUBULES: microfilaments. Composed of tubulin proteins. Integrate cellular compartments ,Maintain cell Long, unbranched structures. shape. Essential for spindle structure assembly/disassembly in mitosis. Contribute to cilia, flagella, basal bodies, and centrioles. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CELL STRUCTURE AND FUNCTION CENTRIOLE: MITOCHONDRIA/CHONDROSOMES: Two centrioles located near the nucleus's Double membranous,with inner membrane exterior surface ,Each centriole consists of a forming cristae.Involved in energy production for cylindrical array of nine eukaryotic cells ,"powerhouses of the cell." microtubules.Important in cell division, Contains DNA and ribosomes, capable of self- furrowing location, and cilia formation. replication.Involved in metabolic processes like Krebs cycle and aerobic respiration PLASTIDS NUCLEUS: Membrane-bound bodies present in plant cells Three main types:. 1)In animal cells, usually central; in plant cells, Chloroplasts:self-replicating organelles pushed to the periphery. ,Found in photosynthetic plant cells ,Contain 2)Shapes: irregular or spherical ,Cells may be green pigment (chlorophyll) for light energy mononucleate, binucleate, or multinucleate. absorption. 3)Visible during cell division; contains chromatin Double-memberane envelope, stroma, and thylakoids.Involved in fixing CO₂ to network and nucleoplasm ,Chromosomes replace manufacture sugars. chromatin during cell division.Contains DNA, RNA, Chromoplasts:Impart colors to flower petals, proteins , and hereditary material.. ripened fruit and Play a role in pollination. Leucoplasts:>Colorless plastids found in underground plant parts that Store food. NUCLEAR MEMBRANE: Surrounds the nucleus, separating it from cytoplasm. CHROMOSOMES: chromatin material deeply stained with basic dyes ,Converted into chromosomes during cell division NUCLEOLUS: ,Chromosomes have arms and centromeres. Darkly stained body within the nucleus ,No membranous boundary ,One or more nucleoli per nucleus.Synthesizes and stores ribosomal RNA (rRNA). CHART TO REMEMBER DISCOVERY OF ORGANELLES Organelle Discoverer Discovery Year Nucleus Robert Brown 1831 Mitochondria Richard Altmann 1890 Centriole Edouard Van Beneden 1883 Nuclear Membrane James D. Jamieson 1971 Nucleolus Franz Bauer 1804 Chromosomes Walther Flemming 1882 To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CHEMICAL COORDINATION CONCENTRATION TERMS CHEMICAL NATURE OF HORMONES 1. Continuous regulation of cellular functions is Hormones belong to various categories: essential. a-Steroid hormones (e.g., testosterone, estrogen). 2. Nervous system aids in coordination. b-Proteinaceous hormones (e.g., growth hormone, 3. Endocrine system plays a crucial role in insulin). coordinating various body functions. c-Catecholamines, amino acid derivatives, and 4. Hormonal system regulates chemical peptide hormones. reactions and substance transport. 5. Chemical coordination involves hormones, membranes, and growth. MODE OF HORMONE ACTION A)PROTEIN HORMONES: HORMONES AS A CHEMICAL 1-Water-soluble, acts on plasma membrane MESSENGER receptors. 2-Initiate a series of events inside the Hormone as a Chemical Messenger cell, including gene activation. Hormones are small organic molecules that act B)STEROID HORMONES: as chemical messengers. 1-Lipid-soluble, can pass through cell membranes. 2- They transmit signals from messenger cells to Bind to receptors inside target cells, activating gene target cells. transcription and protein synthesis. ENDOCRINE SYSTEM OF MAN Consists of around 20 ductless glands located throughout the body. Key glands include the hypothalamus, pituitary, thyroid, parathyroid, pancreas, adrenal glands, and gonads. ENDCRINE SYSTEM To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CHEMICAL COORDINATION (1)NEUROSECRETORY ROLE OF (2)PITUITARY GLAND HYPOTHALAMUS LOCATION AND STRUCTURE: a)Hypothalamus regulates various physiological Situated below the hypothalamus, connected by the functions, including hunger, sleep, and infundibulum. temperature. Three Lobes: Anterior, posterior, and median. b)Acts as the master controller of the endocrine ANTERIOR PITUITARY: system. Known as the "master gland," secretes six hormones c)Produces releasing and inhibiting factors that regulating other endocrine glands. regulate pituitary hormone secretion Gonadotropic hormones (FSH and LH) Prolactin (PRL) Growth hormone (GH) GH FUNCTION: Regulates growth, cell division, protein synthesis; controlled by hypothalamic factors. DISORDERS: Deficiency leads to dwarfism, excess in childhood causes gigantism, and in adults, acromegaly. (3)THYROID GLAND LOCATION: Two lobes on either side of the trachea. HORMONES: Produces T3, T4 (thyroxin), and calcitonin. (4)PARATHYROID GLANDS: FUNCTIONS: LOCATION: Thyroxine regulates metabolic rate, while calcitonin aids Four glands on the posterior thyroid surface. calcium deposition in bones. HORMONE: DISORDERS: Parathormone (PTH)regulates blood calcium Hyperthyroidism, hypothyroidism, and congenital balance. cretinism. FUNCTIONS: Releases calcium from bones, maintains blood calcium levels. (5)PANCREAS: DISORDERS: COMPOSITION: Oversecretion leads to hypercalcemia, Exocrine tissue for digestion; endocrine tissue in Islets of undersecretion to hypocalcemia. Langerhans. HORMONES: Insulin (from beta cells) and glucagon (from alpha cells) regulate blood sugar. FUNCTIONS: Insulin lowers blood sugar, while glucagon raises it. DISORDERS: Diabetes mellitus due to insulin deficiency or excess. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting CHEMICAL COORDINATION (6)ADRENAL GLANDS: (7)GONADS: (8)OTHER ENDOCRINE LOCATION AND STRUCTURE: OVARIES: TISSUES/CELLS: Rest on kidneys, composed of cortex Produce estrogen and VARIOUS ORGANS; and medulla. progesterone, regulate the female Produce hormones despite non- HORMONES: reproductive system. endocrine primary function. Cortex produces glucocorticoids and TESTES: EXAMPLES: mineralocorticoids; medulla produces Produce testosterone, regulate Stomach (gastrin), duodenal wall adrenaline and noradrenaline. male reproductive system. (secretin, cholecystokinin), FUNCTION: FUNCTION: Control secondary placenta (progesterone), brain Respond to stress, regulate sex characteristics, gamete (endorphins). metabolism and blood pressure. production. FUNCTIONS: DISORDER: DISORDER: Localized effects or systemic Oversecretion leads to hypertension, Hormonal imbalances affect regulation. undersecretion to Addison's disease. reproductive health and fertility. FEEDBACK MECHANISMS POSITIVE FEEDBACK NEGATIVE FEEDBACK Definition: DEFINITION: End product speeds up its production. End product inhibits its own production. RARE: Homeostatic: Maintains stability, Not homeostatic, uncommon in common in physiological processes. healthy individuals. EXAMPLE: EXAMPLE: Blood glucose regulation. Childbirth. Process: PROCESS: 1-High blood glucose detected by Early contractions of labor force pancreas. baby's head against cervix. 2-Pancreas secretes insulin. Stretch-receptor neurons signal 3-insulin allows cells to take up glucose. hypothalamus. 4-Glucose stored as glycogen, reducing Hypothalamus releases oxytocin. blood glucose. Oxytocin stimulates more uterine 5-Low blood glucose detected by contractions. pancreas. Stronger contractions prompt 6-Pancreas secretes glucagon. more hormone release. 7-Glucagon converts glycogen to Cycle ends with the baby's glucose, raising blood glucose. expulsion. 8-Cycle maintains blood glucose homeostasis. THIRST SENSATION: FEEDBACK MECHANISM: NEGATIVE. EXPLANATION: Thirst sensation occurs when blood volume decreases, stimulating the hypothalamus to release antidiuretic hormone (ADH). ADH acts on kidneys to conserve water, restoring blood volume and reducing thirst sensation. This process maintains fluid balance and blood volume homeostasis To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting NERVOUS COORDINATION INTRODUCTION TO NERVOUS NERVE IMPULSE COORDINATION Resting membrane potential & active membrane The body of an animal responds to stimuli potential (action potential). through coordinated activities of body parts. Distribution and movement of ions, negative Coordination involves the nervous and endocrine organic ions, and leakage of K+ ions influence systems. membrane potential. Two types: 1. Continuous impulse STEPS INVOLVED IN NERVOUS 2. Saltatory impulse. COORDINATION Speed of nerve impulse depends on fiber 1. Reception of stimulus morphology. 2. Processing/analysis of information 3. Response to stimulus SYNAPSE 4. Reception of Stimulus Electrical and chemical synapses transmit information between neurons. PROCESSING/ANALYSIS OF Transmission of nerve impulse across synapse involves release of neurotransmitters, binding to INFORMATION receptors, and generation of excitatory or Receptors detect stimuli from internal or inhibitory postsynaptic potentials. external environments. Clearance mechanisms of neurotransmitters from Classification of receptors based on stimuli type: synaptic cleft. photoreceptors, chemoreceptors, mechanoreceptors, thermoreceptors, and nociceptors. MAJOR CLASSES OF Sensory inputs are received by the central NEUROTRANSMITTERS: nervous system (CNS) for coordination. Acetylcholine, biogenic amines, amino acids, Effectors (muscles and glands) produce neuropeptides, and gases.Excitatory and inhibitory appropriate responses upon receiving signals neurotransmitters affect postsynaptic neuron activity from the CNS. differently. NEURONS DIVISIONS OF THE HUMAN NERVOUS Neurons are the chief structural and functional units SYSTEM of the nervous system. CENTRAL NERVOUS SYSTEM (CNS): Brain and spinal cord. STRUCTURE OF A TYPICAL NEURON: Coordinates actions; the brain is more involved Cell Body (Soma), Dendrites, and Axon. in coordination. Spinal Cord Acts as a link between PNS and CLASSIFICATION OF NEURONS BASED brain. ON STRUCTURE AND FUNCTION: Sensory neurons/Afferent Associative/Intermediate neurons Motor neurons/Efferent To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting NERVOUS COORDINATION PROTECTION OF BRAIN AND SPINAL Spinal Cord Description Function CORD: Acts as a pathway for sensory and 1. Cranium (skull) and vertebral column protect Transmission motor information between the brain brain and spinal cord. and the rest of the body. 2. Three layers (dura mater, arachnoid mater, pia mater) provide cushion-like protection. Coordinates reflex actions, allowing 3. Cerebrospinal Fluid (CSF) acts as a cushion Reflexes rapid responses to stimuli without against mechanical shocks and maintains conscious involvement. homeostasis. Receives sensory input from the Sensory Processing body, transmitting it to the brain for STRUCTURE AND FUNCTION OF interpretation and response. BRAIN: Sends motor commands from the 1. Forebrain: Telencephalon (olfactory bulbs, brain to muscles and glands cerebrum) and diencephalon (thalamus, Motor Control throughout the body, enabling hypothalamus). voluntary movements and actions. 2. Midbrain: Coordinates and relays visual and auditory information. 3. Hindbrain:Includes pons, cerebellum, and SOMATIC NERVOUS SYSTEM: medulla oblongata; involved in various functions 1. Responsible for carrying sensory and motor like coordination, muscle activity, and reflexes information between CNS and voluntary parts of the body. SPINAL CORD: 2. Controls skeletal muscles and external sensory organs; voluntary with exceptions for reflex 1. Gray matter (cell bodies) and white matter reactions. (nerve fibers). 2. Conducts sensory and motor impulses, coordinates reflex actions, and receives AUTONOMIC NERVOUS SYSTEM commands from the brain. (ANS): 1. Involuntary system controlling internal organs. PERIPHERAL NERVOUS SYSTEM 2. Divided into parasympathetic and sympathetic (PNS): divisions. 3. Regulates smooth and cardiac muscle 1. Sensory and motor neurons distributed contraction and glandular activity throughout the body. 2. Ganglia: Collections of neuron cell bodies serving as relay points. EFFECTS OF DRUGS ON NERVOUS 3. Bundles of neuron fibers carry impulses. 4. Types of Nerves: Sensory motor, and mixed COORDINATION nerves; classified based on function and origin. CANNABIS (MARIJUANA, HASHISH) Treatment for nausea, appetite stimulation, glaucoma, and pain relief. Anxiety, depression, psychotic episodes, and hallucinations are common adverse effects. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting NERVOUS COORDINATION HEROIN (DIAMORPHINE, ALCOHOL DIACETYLMORPHINE) Stimulates body functions in small doses, used Strong analgesic for acute and chronic pain, as a solvent in medicines. including terminal illnesses. Excessive consumption leads to depression of Injection, sniffing, or smoking can lead to addiction, brain activity, impaired coordination, liver respiratory depression, infectious diseases damage, memory loss, and addiction. (HIV/AIDS, hepatitis), collapsed veins, heart issues, and addiction. INHALANTS (E.G., NAIL POLISH NICOTINE REMOVERS, GLUE) Smoking cessation aid stimulates nerve activity. Toxicity in large doses, leading to nausea, vomiting, Instant euphoria followed by depression, nausea, difficulty breathing, and even death. Smoking vomiting, unconsciousness, hallucinations, loss of during pregnancy can harm the fetus. motor skills, and heart palpitations. NERVOUS DISORDERS STROKE (CEREBROVASCULAR MENINGITIS ACCIDENT - CVA) Fever, chills, headache, stiff neck, nausea, Numbness, weakness, confusion, trouble vomiting, and sensitivity to light. speaking or understanding, vision problems, and Antibiotics and corticosteroids are used to severe headache. combat the infection. Immediate medical attention is crucial; treatment includes clot-busting drugs (thrombolytic therapy) and blood thinners. BRAIN TUMORS Headaches, nausea, vision problems, loss of ALZHEIMER'S DISEASE sensation or movement, speech difficulties, Signs are progressive loss of memory, reasoning, confusion, and personality changes. language, perception, and behavioral changes. Surgery, radiotherapy, and chemotherapy Caused by accumulation of beta-amyloid protein in are common treatments depending on the the brain leading to nerve cell death; risk increases type and location of the tumor. with age. HEADACHE DIAGNOSTIC TESTS FOR NERVOUS DISORDERS Various conditions affecting the head and neck, such as tension, muscle tension, sinus issues, 1. Electroencephalography (EEG) and migraines. 2. Computed Tomography Scan (CT Scan) 3. Magnetic Resonance Imaging (MRI) Pain in the head or neck region. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting DIVERSITY AMONG ANIMALS (A)SUBKINGDOM PARAZOA (B)SUBKINGDOM EUMETAZOA: (PHYLUM PORIFERA): Includes animals with tissues organized into Simplest animals lacking tissues organized organs and organ systems. into organs. Divided into radial (grade Radiata) and bilateral Lack definite shape and symmetry. (grade Bilateria) symmetry. Phylum Cnidaria represents the simplest Eumetazoa with radial symmetry. DIPLOBLASTIC ANIMALS (DIVISION RADIATA): Body consists of two layers: ectoderm and TRIPLOBLASTIC ANIMALS (GRADE endoderm. BILATERIA): Lack specialized organs and transport Body made of three layers: ectoderm, mesoderm, systems. and endoderm. Exhibit radial symmetry and possess a sac-like Show greater specialization and possess digestive system. specialized organs and organ systems. Examples include phylum Cnidaria Have various body cavities: acoelomates, (coelenterate). pseudocoelomates, and coelomates. Acoelomates: Lack of body cavity, with mesoderm forming a loose tissue. PARAZOA (PHYLUM PORIFERA): Pseudocoelomates: Possess a pseudocoelom not General Characteristics: lined by coelomic epithelium. Lack tissue organization and organs, with a Coelomates: Have a true body cavity lined by porous body wall. mesoderm, containing coelomic fluid. Vary in size, with a single internal cavity (spongocoel). Sessile as adults, with larvae capable of movement. Lack a definite nervous system but exhibit coordination. Reproduction: Reproduce asexually by budding and sexually via hermaphroditism or separate sexes. Examples: Sycon, Leucoselenia, Euplectella, Spongilla. Importance: Used commercially for washing, bathing, surgical operations, and sound absorption. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting EUMETAZOA A-GRADE RADIATA B-GRADE BILATERIA 1)PHYLUM PLATYHELMINTHES - FLATWORMS (1)PHYLUM COELENTERATA/CNIDARIA 1)Acoelomates ,Soft, dorsoventrally compressed body (DIPLOBLASTIC ANIMALS): ,Triploblastic, bilateral symmetry, unsegmented. Cnidarians have specialized cells called 2)Mostly parasitic, some free-living. cnidocytes, producing stinging cells 3)The digestive system varies among species, with (nematocysts). some having a poorly developed alimentary canal. Their habitat is predominantly aquatic, Reproduction can be both asexual (fission) and sexual displaying radial symmetry. (hermaphroditic). Coelenterates exist in two primary forms: 4)These organisms possess adaptations such as a polyps and medusae. resistance cuticle, adhesive organs, and simplified Tentacles around the mouth contain systems. Examples include Planaria (free-living), stinging cells for defense and prey capture. Fasciola (liver fluke), and Taenia (tapeworm). These organisms are carnivorous, utilizing 2)Phylum Nematoda - Roundworms nematocysts to immobilize small prey. 1)Pseudocoelomates ,Elongated body with pointed They possess a single digestive cavity ends. serving as both gastrovascular cavity and 2)Triploblastic, pseudocoelom, bilateral symmetry. body cavity, with a sole opening 3)The digestive system typically consists of an (mouth).Food digestion and distribution alimentary canal with two openings. The nervous occur via diffusion. system often includes a nerve ring and longitudinal Coelenterates have a nerve network cords. Respiration occurs through gaseous exchange formed by neuron cells, but they lack a across the body surface. central nervous system. 4)Examples of organisms with these characteristics Many species are sessile, while others are include Ascaris lumbricoides, Enterobius vermicularis, free-swimming or colonial. and Ancylostoma duodenale. 3)Phylum Annelida - Segmented Worms Reproduction involves both asexual (e.g., 1)Coelomates ,Metamerically segmented body budding) and sexual methods.Alternation of ,Triploblastic, coelomate, bilateral symmetry. generations is common, with diploid 2)Organisms possess an alimentary canal with distinct generations exhibiting different forms and parts for digestion. Their circulatory system typically reproductive strategies includes a closed system with blood vessels. Respiration occurs through the skin, which is Coelenterates demonstrate polymorphism, moistened by mucus and coelomic fluid featuring more than two structurally and 3)Examples of such organisms include earthworms functionally distinct types of individuals and leeches. (zooids) within one organism. (4)Phylum Arthropoda - Jointed Legs 1)Largest phylum, segmented body with jointed Examples include feeding individuals appendages.Chitinous exoskeleton, bilateral symmetry, (gastrozooids), asexually reproducing coelom reduced to hemocoel. individuals (gonozooids), and sexually 2)Crustacea (aquatic), Insecta (largest group, reproducing individuals (medusae). metamorphosis), Arachnida (spiders, scorpions), Myriapoda (centipedes, millipedes). 3) Example Includes pests, but also beneficial insects like bees and silkworms To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting B-GRADE BILATERIA B-GRADE BILATERIA (5)Phylum Mollusca (L. Molluscus - soft) (7)Phylum Hemichordata 1. Mollusks are a diverse group including snails, 1. Combination of invertebrate and chordate slugs, clams, and cephalopods, with over characteristics. 50,000 species, making them the second 2. Soft-bodied, worm-like animals with anterior largest invertebrate phylum. proboscis, collar, and trunk. 2. They are triploblastic coelomates with 3. Circulatory system with a median dorsal and ventral bilateral symmetry, often possessing a vessel.Respiratory system composed of gill-slits; protective shell secreted by the mantle. excretory system with a single glomerulus.Sub- Found in aquatic and terrestrial habitats, epidermal nervous system; examples include unsegmented soft body divided into head, Balanoglossus and Saccoglossus. foot, and visceral mass. (8)Phylum Chordata 3. Their complex systems include digestive, 1. Derives its name from the notochord.All members respiratory, circulatory, excretory, nervous, possess a notochord at some stage. and reproductive systems, featuring an open 2. Central nervous system dorsal and hollow. circulatory system with blue respiratory 3. Divided into lower chordates (Protochordata) and pigment (haemocyanin). Locomotion is aided higher chordates (Vertebrata) by a muscular foot, and classification includes Gastropoda, Bivalvia, and Cephalopoda. Sub-Phylum Vertebrate (Craniate) (Higher 4. Some species damaging crops and structures, Chordates) while others like clams and oysters are widely 1. Animals with a cranium enclosing the brain and a consumed as food. Mollusk shells are utilized vertebral column, making them vertebrates. in various industries, and pearl oysters are Divided into two superclasses: valuable for producing pearls. 1. A-Pisces (Fishes): Cyclostomata, Chondrichthyes, (6)Phylum Echinodermata - The Spiny Osteichthyes. Skinned Animals 2. B-Tetrapoda (Four-footed): Amphibia, Reptilia, Aves, 5. Echinoderms, exclusively marine, have over Mammalia. 5,000 species. They possess an endoskeleton Anamniotes vs. Amniota: Division based on the of calcareous plates and exhibit radial presence of fetal membranes. symmetry with the mouth and anus 1. Superclass Pisces includes Cyclostomata positioned opposite each other. Their water Chondrichthyes, and Osteichthyes. Cyclostomata vascular system serves for both locomotion (lampreys, hagfish) have eel-like bodies, lack scales, and feeding. and possess cartilaginous skeletons. Chondrichthyes (sharks, skates, rays) feature 6. Echinoderms come in various body forms like fusiform bodies, placoid scales, and cartilaginous star-shaped or globular. They have poorly skeletons. Osteichthyes (various fish) have bony developed nervous and circulatory systems skeletons, dermal scales, and swim bladders. and separate sexes, with larvae showing 2. Superclass Tetrapoda comprises Amphibia (frogs, bilateral symmetry. salamanders) with bony skeletons and webbed 7. Regeneration is common. Resemblances with feet, Reptilia (lizards, crocodiles) with internal chordates and hemichordates suggest a fertilization and scaly skin, Aves (birds) with common ancestor, sharing characteristics like streamlined bodies and wings, and Mammalia (egg- coelom formation and blastopore retention laying Prototheria, pouched Metatheria, and with hemichordates. placental Eutheria) with hair, 4-chambered hearts, and mammary glands. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting ENZYMES GENERAL CHARACTERISTICS MECHANISM OF ENZYME ACTION: 1) Biologically active proteins crucial for biochemical reactions. 1) Enzyme-substrate interaction occurs at the 2) Enhance reaction efficiency and are specific to active site, consisting of a binding and catalytic each type of reaction. site. 3) Consist of hundreds of amino acids, forming a globular structure with an active site for catalytic 2) Require an aqueous medium for activity. activity. 3) Fischer proposed the Lock and Key Model, 4) Some enzymes have non-protein cofactors. later modified by Koshland into the Induced Fit 5)Vitamins serve as essential raw materials for Model. enzymes. E + S ES E + P 6)Specific, sensitive to pH, temperature, and Enzyme Substrate Enzyme Substrate Enzyme Product substrate concentration. Complex 7)Lower activation energy, accelerating reactions without being consumed. OPTIMUM PH VALUES OF ENZYMES FEEDBACK INHIBITION Pepsin 2.00 Enzymes work step by step in metabolic Sucrase 4.50 pathways. Enterokinase 5.50 They form a chain, passing substrate molecules from one enzyme to the next. Salivary Amylase 6.80 Enables the orderly flow of biochemical reactions in the pathway. Catalase 7.60 Chymotrypsin 7.00-8.00 FACTORS AFFECTING ENZYME ACTION: Pancreatic Lipase 9.00 Enzyme concentration Arginase 9.70 Substrate concentration Temperature pH level INHIBITORS Substances that block enzyme activity temporarily or permanently. TYPES Irreversible inhibitors form covalent bonds, while reversible inhibitors can be Reversible inhibitors include competitive and neutralized by non-competitive types. increasing substrate concentration. 1-Competitive inhibitors have structural similarity with substrates, preventing catalysis. 2-Non-competitive inhibitors form complexes away from the active site, hindering catalysis even with genuine substrates. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting EVOLUTION DEFINITION CONCEPT OF EVOLUTION VS. SPECIAL CREATION Evolution, the process shaping life's diversity, In the 19th century, Creationism and has long intrigued humanity. Charles Darwin's pivotal contributions include Evolutionism emerged as contrasting views evidence for species evolution and the on life's diversity. mechanism of Natural Selection. Creationists advocated for Special Creation, positing that all life forms were individually created. Evolutionists like Darwin, championed the Theory of Natural Selection, proposing species evolve over time CONTRIBUTIONS OF SCIENTISTS Scientist's Name Life Span Achievements Linnaeus 1707 - 1778 Sought and found order in the diversity of life. He introduced binomial nomenclature for naming species. Lamarck 1744 - 1829 Published his theory of evolution. Malthus 1766 - 1832 Published Essay on the “Principle of Population”. Cuvier 1769 - 1832 Contributed much to the science of Palaeontology and explained Earth’s history by catastrophism. Lyell 1797 - 1875 Published Principle of geology. Darwin 1809 - 1882 1- Voyage of the Beagle. 2- Began his notebooks on the origin of species. 3- Wrote his essay on the origin of species. Mendel 1822 - 1913 Published papers on inheritance. Wallace 1823 - 1913 Sent his theory to Darwin. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting EVOLUTION EVOLUTIONARY MILESTONES CONTRIBUTIONS OF LAMARCK Speculation on life's origins suggests underwater hydrothermal vents as potential sites. Lamarck proposed the inheritance of acquired characteristics, suggesting that Early life forms, possibly archaebacteria, thrived traits acquired during an organism's in extreme conditions. lifetime could be inherited. Photosynthesis, emerging in primitive His work laid the groundwork for later organisms, altered Earth's atmosphere, enabling evolutionary theories. aerobic life. Prokaryotic cells, dating back over 3.5 billion years, preceded eukaryotic cells around 1.5 billion years ago. The endosymbiont hypothesis proposes DARWIN'S JOURNEY AND mitochondria and chloroplasts evolved from OBSERVATIONS engulfed aerobic bacteria. Another hypothesis suggests prokaryotic cell Charles Darwin's voyage on the Beagle membranes invaginated, forming organelles. to South America provided him with diverse specimens and observations. Eukaryotic cell evolution spurred life's His observations of unique species complexity and the emergence of multicellular distributions, such as the Galapagos organisms. finches, sparked his interest in adaptation and species variation. DEVELOPMENT OF DARWIN'S THEORY Darwin's observations led him to formulate the TKEY POINTS OF DARWIN'S theory of natural selection, which explains how THEORY new species arise through gradual adaptations to different environments. Darwin's theory emphasized descent The joint presentation of Darwin's and Wallace's with modification, suggesting a ideas to the Linnaean Society marked a common ancestry among all milestone in evolutionary thought. organisms. Natural selection operates through the differential survival and reproduction MODERN EVOLUTIONARY SYNTHESIS of individuals with favorable traits. The modern synthesis, or Neo-Darwinism, integrated discoveries from various fields, including population genetics. It reconciled Mendelian genetics with Darwinian evolution, providing a comprehensive framework for understanding evolutionary mechanisms. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting EVOLUTION MODERN EVOLUTIONARY SYNTHESIS EVIDENCES OF EVOLUTION The modern synthesis, or Neo-Darwinism, BIOGEOGRAPHY integrated discoveries from various fields, Geographic distribution suggests including population genetics. evolutionary relationships. It reconciled Mendelian genetics with FOSSIL RECORD Darwinian evolution, providing a Succession of fossils supports evolutionary comprehensive framework for understanding progression. evolutionary mechanisms. COMPARATIVE ANATOMY APPLICATIONS Homologous structures reveal shared Understanding evolution has broad ancestry. implications for fields such as medicine, COMPARATIVE EMBRYOLOGY agriculture, and conservation. Evolutionary principles inform strategies for Similarities in embryonic development among disease control, crop breeding, and species. biodiversity conservation. MOLECULAR BIOLOGY DNA and protein sequences reflect evolutionary relatedness. NATURAL SELECTION AND ARTIFICIAL SELECTION POPULATION GENETICS Natural selection operates via interaction between environment and genetic variability. Population consists of localized groups of Artificial selection, akin to natural selection, interbreeding individuals. influences traits in domesticated species. Gene pool represents all alleles in a Adaptations acquired during an organism's lifetime aren't heritable. population at a given time. Natural selection leads to adaptation and, Hardy-Weinberg theorem describes allele potentially, speciation. and genotype frequencies in non-evolving populations. FACTORS AFFECTING GENE ENDANGERED SPECIES FREQUENCY Mutation, migration, genetic drift, non- Extinction is a natural process but accelerated by habitat destruction, climate change, and random mating, and selection influence pollution. allele frequencies. Conservation strategies include protected areas, Genetic drift causes chance fluctuations, zoos, and botanical gardens. especially in small populations. Many species in Pakistan, such as cheetah and Selection, both artificial and natural, tiger, are extinct or near extinction, emphasizing urgent conservation efforts. shapes allele frequencies based on fitness. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting NUTRITION AUTOTROPHIC NUTRITION DIGESTION IN MAN 1. Autotrophic organisms, like plants, DIGESTION IN ORAL CAVITY: produce their own organic compounds Tongue plays a vital role in food selection from inorganic sources such as carbon through taste buds. dioxide, water, and nitrates. Saliva from salivary glands aids in lubrication 2. They obtain essential elements from the and contains enzymes like amylase for starch soil, including carbon, oxygen, hydrogen, digestion. nitrogen, phosphorus, magnesium, and iron. PERISTALSIS: Wave-like muscular contractions propel food down the digestive tract. HETEROTROPHIC NUTRITION DIGESTION IN STOMACH: Heterotrophic organisms cannot synthesize Stomach wall layers contain muscles for organic compounds and obtain them from the churning and mixing food with gastric environment as food. secretions. Gastric glands secrete mucus, ANIMAL NUTRITION: hydrochloric acid, and pepsinogen. Animals exhibit diverse feeding methods: Hydrochloric acid creates an acidic Detritivores consume organic debris environment for pepsin activity.Pepsin breaks Herbivores feed on plants, Carnivores prey on down proteins into peptones and other animals polypeptides. Omnivores consume both plant and animal food Resulting chyme is gradually emptied into the Filter feeders extract particles from water Fluid feeders ingest liquid food duodenum through the pyloric sphincter. Macrophagous feeders consume large food DIGESTION IN SMALL INTESTION: pieces. 1)Comprises the duodenum(25cm), Plant Nutrition Methods: jejunum(2.5m), and ileum(3.5m). 1. Saprophytic Nutrition 2)Pancreatic enzymes include amylase, lipase, 2. Parasitic Nutrition and trypsin for carbohydrate, fat, and protein 3. Symbiotic Nutrition digestion.Bile emulsifies fats, enhancing their 4. Insectivorous Plant Nutrition: digestion. Pitcher plants trap insects in modified leaf sacs 3)Villi and microvilli in the small intestine filled with water increase absorption surface area. Venus flytrap leaves rapidly close upon prey contact DIGESTION IN LARGE INTESTION: Sundew plants entangle insects with hair-like 1)Consists of the caecum, colon, and rectum. tentacles. 2)Absorbs water and salts from undigested material. HOLOZOIC NUTRITION Processes: 1. Ingestion 2. Digestion 3. Absorption 4. Assimilation 5. Egestion To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting NUTRITION DISORDERS DYSPEPSIA: BULIMIA NERVOSA Incomplete or imperfect digestion. Neurotic disorder characterized by binge eating Symptoms include abdominal discomfort, followed by purging. flatulence, heartburn, nausea, vomiting. Symptoms include Overeating, self-induced Caused by excessive stomach acidity, faulty vomiting, fasting. stomach/intestinal function, inadequate bile It can cause Electrolyte imbalance, infections. secretion. Treated through Prolonged therapy, hospitalization for strict supervision FOOD POISONING PILES (HEMORRHIDES) Caused by consumption of food containing toxic substances such as Salmonella, Campylobacter. Dilated, tortuous veins in the anorectal Symptoms include Diarrhea, vomiting, mucosa. abdominal pain. Symptoms include Bleeding during bowel Can be Prevented through Proper cooking, movements, aggravated by constipation. avoiding unpasteurized milk/meat, careful defrosting of frozen meat. Treated by Improved hygiene, softening of stools, surgical removal in severe cases. OBESITY ULCER Abnormal accumulation of body fat. Sore on the inner wall of the digestive tract. Caused by excessive food intake leading to fat Caused by breakdown of mucus layer, excessive storage. gastric acid secretion. It causes High blood pressure, heart disease, Symptoms include Abdominal pain, potentially diabetes mellitus. fatal complications if untreated. Reasons include Hormonal imbalance, Prevented by avoiding smoking, spicy food, heredity. alcohol, caffeine, and stress. ANOREXIA NERVOSA CONSTIPATION Loss of appetite due to fear of becoming obese. Infrequent bowel movements or difficulty Common in females aged 12-21. passing stools. Symptoms include Overestimation of body size, Symptoms include Infrequent bowel refusal to eat. movements, straining, hard stools, Treated by psychiatric therapy, often requiring incomplete evacuation, abdominal feeding through alternative routes. discomfort. Treatments include increased fiber intake, staying hydrated, regular exercise, use laxatives/stool softeners cautiously, avoid delaying bowel movements, limit constipating foods. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting GASEOUS EXCHANGE PHOTORESPIRATION AND ITS RESPIRATION IN MAN CONSEQUENCES Properties of respiratory surface 1. Photorespiration is the respiratory activity 1. Large Surface Area and Moisture occurring in plants during the daytime, 2. Thin Epithelium characterized by the release of carbon 3. Ventilation dioxide and absorption of oxygen. 4. An extensive capillary network 2. During photorespiration, ribulose bisphosphate carboxylase/oxygenase RESPIRATORY SYSTEM (rubisco) fixes oxygen instead of carbon dioxide, reducing the overall rate of carbon COMPONENTS dioxide fixation and plant growth. 1. The respiratory system in humans 3. RuBP + O2 -> Glycolate consists of lungs and air passages 4. Rubisco reacts with oxygen, leading to the responsible for transporting fresh air formation of glycolate.Glycolate is converted to the respiratory sites. Nostrils, nasal into glycine in peroxisomes, then further cavities, pharynx, larynx, trachea, metabolized into serine and carbon dioxide in mitochondria. bronchi, bronchioles, and alveolar ducts form the air passageways COMPARISON WITH CALVIN leading to the alveolar sac. 2. Pharynx is a muscular passage CYCLE directing air from the nasal cavity to Photorespiration utilizes ATP and NADPH, similar to the Calvin-Benson cycle, but in reverse. It the larynx.Larynx houses vocal cords releases carbon dioxide instead of fixing it into and has a protective function during carbohydrates. swallowing. 3. The trachea or windpipe extends into IMPACT OF ENVIRNMENTAL bronchi, progressively dividing into CONDITINS smaller bronchioles. 4. Each bronchiole leads into air-sacs, the Photorespiration increases on hot and dry days functional units of the lungs, which due to stomatal closure, leading to elevated oxygen levels and reduced carbon dioxide levels contain alveoli for gas exchange. inside leaves. 5. Lungs, spongy organs containing millions of alveoli, are enclosed in the chest cavity and covered by pleura, a SIGNIFICANCE double-layered membrane. While photorespiration reduces photosynthesis and is not essential for plant growth, it persists due to the dual-binding nature of rubisco, evolved when oxygen levels were lower in the atmosphere. To practice 60,000 free MCQs, go to www.PreMed.PK  PreMed.PK Chapter Shortlisting GASEOUS EXCHANGE MECHANICS OF VOLUNTARY FACTORS EFFECTING AND INVOLUNTARY HEMOGLOBIN OXYGEN BINDING REGULATION OF BREATHING IN Carbon Dioxide MAN Increased carbon dioxide pressure decreases oxygen tension and reduces hemoglobin's Breathing involves two phases capacity to hold oxygen. Inspiration (inhalation) and expiration Temperature (exhalation), rhythmically occurring at 15 to Elevated temperature decreases blood's 20 times per minute during rest. oxygen-carrying capacity, notably during Inspiration brings fresh air into the lungs, increased muscular activity. while expiration expels air with high carbon pH dioxide content. Blood pH influences oxygen binding to Note: hemoglobin, with decreased pH leading to Surfactant deficiency in premature infants can decreased oxygen binding due to increased lead to respiratory d