MDCAT Biology Quick Revision Questions PDF

 Want a guaranteed 1000+ Marks on MDCAT? Visit www.nearpeer.org (and then click MDCAT) today to get enrolled in Online MDCAT Course by Sir M. Shahid on Nearpeer.org. Or call 03470171480 for free Counselling.  Ready to enrol? Visit www.nearpeer.org (an...

 Want a guaranteed 1000+ Marks on MDCAT? Visit www.nearpeer.org (and then click MDCAT) today to get enrolled in Online MDCAT Course by Sir M. Shahid on Nearpeer.org. Or call 03470171480 for free Counselling.  Ready to enrol? Visit www.nearpeer.org (and then click MDCAT) today to get enrolled in Online MDCAT Course by Sir M. Shahid on Nearpeer.org. Or call 03470171480 for free Counselling. Enjoy the MDCAT Biology Quick Revision book by Nearpeer.org.   Full Length Practice Exams The following section includes Full Length Papers of Biology made by Nearpeer.org. Make sure of following pointers: 1. Do not attempt all papers at once. 2. Attempt only one FLP first in case you are just stating up. 3. Once you’ve attempted paper, look for your strengths and weaknesses. 4. When you know your weakness, go through that chapter in this book. 5. Only after your revision of weak chapters, attempt the next paper. 6. These are not past papers. You can attempt past papers on www.nearpeer.org. 7. Discussion of how to attempt FLPs along with detailed tips and tricks are available in our online MDCAT Course on www.nearpeer.org.  FULL LENGTH PRACTICE EXAMS NO. 1 FULL LENGTH PRACTICE EXAMS NO.1 1. Which one of the following constitutes the best reason for distinguishing the living from the non-living? (a) Irritability (b) reproduction and locomotion (c) respiration and excretion (d) growth and locomotion 2. Rate of growth of stem is measured by: (a) hydrometer (b) photometer (c) osmometer (d) auxanometer 3. Characteristic features of the living being are: (a) irritability (b) metabolic activity (c) respiration and reproduction (d) all of these 4. Botanists believe that the first plants, which originated on the earth, were: (a) algae and fungi (b) mosses (c) pine and cycads (d) mosses and their relatives 5. Ultimate source of energy in an ecosystem is: (a) food (b) ATP (c) sunlight (d) glucose 6. There is interdependence amongst living beings, because: (a) they were created to live in this fashion (b) it is a biological miracle (c) it has no significance from the viewpoint of evolution (d) it is a result of adjustments in the long history of biological evolution Page | I  FULL LENGTH PRACTICE EXAMS NO. 1 7. Animals are like plants in that: (a) they respire during night only (b) they respire when required (c) they respire during day and night (d) they respire during day only 8. Animals differ from plants mainly in: (a) structure (b) vital activity (c) nutrition (d) reproduction 9. The fundamental substance of all living beings is: (a) cell (b) nucleus (c) tissue (d) protoplasm 10. What is the most important property of water for which it is needed in the body? (a) it is in a liquid form (b) it is tasteless, colourless and odourless solvent (c it is a universal solvent (d) it is made of H2 and O2 and this O2 can be used in cellular metabolism 11. A plant cell differs from an animal cell in the absence of: (a) endoplasmic reticulum (b) mitochondria (c) centrioles (d) ribosomes 12. Mitochondria will be found in abundance in cells of the tissue having: (a) wound-healing activity (b) average activity (c) minimum activity (d) maximum activity Page | II  FULL LENGTH PRACTICE EXAMS NO. 1 13. To determine the ultra- structure of a cell organelle the most likely method successful observations would be: (a) autoradiography (b) light microscopy (c) electron microscopy (d) phase contrast microscopy 14. Activities of all living cells are controlled by: (a) chloroplast (b) tonoplast (c) nucleus (d) DNA and RNA 15. Golgi body is found in: (a) RBE of man (b) all of the cells (c) bacteria (d) all cells except RBC and bacterial cell 16. A cell increases in volume when placed in a solution which is: (a) isotonic (b) slightly hypertonic (c) extremely hypertonic (d) hypotonic 17. Animal cell is limited by: (a) plasma membrane (b) cell wall (c) cell membrane (d) basement membrane 18. The main difference between animal and plant cells is that: (a) plant cells lack rigid cell wall (b) animal cells lack rigid cell wall (c) plant cells possess small vacuoles (d) animal cells possess large vacuoles 19. Continuity of cytoplasm from cell to cell is maintained through: (a) middle lamella (b) endoplasmic reticulum (c) cell membrane system (d) plasmodesmata 20. Cell organelles are embedded in: Page | III  FULL LENGTH PRACTICE EXAMS NO. 1 (a) mitochondria (b) protoplasm (d) nucleolus (d) cytoplasmic membrane 21. When green tomato turns red, then: (a) chromoplasts are changed into chloroplasts (b) chloroplasts are disintegrated and get converted into chromoplasts (c) new chromoplasts are made (d) leucoplasts are developed 22. Which of the following types of plastids are commonly found in the cells not exposed to light? (a) chloroplast (b) chromoplast (c) leucoplast (d) all kinds of plastid 23. Nucleoli are rich in: (a) DNA and RNA (b) DNA, RNA and proteins (c) DNA (d) RNA 24. Artificial synthesis of DNA was done by: (a) Nirenberg (b) Kornberg (c) Wastson and Crick (d) Khorana 25. Two strands of DNA are attached by: (a) peptide bond (b) phosphate bond (c) hydrogen bond (d) ester linkage 26. The largest cell in the human body is: (a) muscle cell (b) kidney cell (c) liver cell (d) nerve cell Page | IV  FULL LENGTH PRACTICE EXAMS NO. 1 27. Vacuole of plant cell contains: (a) cell sap (b) cytoplasm (c) protoplasm (d) nucleus 28. The important cell inclusions are: (a) nucleus and mitochondria (b) protoplasm and Golgi body (c) ribosome and plastid (d) all of these 29. Which of the following does not have definite membrane bound nucleus? (a) mycoplasma (b) bacteria (c) blue green algae (d) all of these 30. Chromatin is important component of: (a) nucleus (b) nucleolus (c) cell sap (d) semen 31. Plasma membrane is: (a) impermeable (b) formed of cellulose (c) nonselective barrier (d) selective barrier 32. Middle lamella is found in: (a) cell membrane (b) nucleoplasm (c) cytoplasm (d) cell wall 33. The chemical substance most abundantly present in the middle lamella: (a)pectin (b) lignin (c) cutin (d) suberin Page | V  FULL LENGTH PRACTICE EXAMS NO. 1 34. Cilia and flagella develop from: (a) cilium (b) cristae (c) chromosome (d) basal body 35. The cellular structure which always disappears during mitosis is: (a) mitochondria (b) plastid (c) nuclear membrane (d) plasma membrane 36. Meiosis is significant because: (a) it produces identical cells (b) it restores original number of chromosomes (c) there is doubling of DNA content in the cell (d) it occurs only in somatic cells 37. How many times mitotic divisions must occur in a cell of the root tip to from 256 cell? (a) 64 (b) 8 (c) 32 (d) 128 38. Amitosis: (a) cleavage of the nucleus without recognizable chromosomes (b) a division of chromosomes (c) an indefinite division of chromosomes (d) chromosomes are present at the bridge 39. Daughter cell formed as result-of meiosis are not similar to that of parent cell because: (a) crossing over occurs and number of chromosome becomes half Page | VI  FULL LENGTH PRACTICE EXAMS NO. 1 (b) prophase is large (c) there are two divisions (d) synapsis occurs 40. Meiosis involves: (a) one division of nucleus and one division of chromosome (b) one division of nucleus and two division of chromosome (c) two division of nucleus and two division of chromosomes (d) two division of nucleus and one division of chromosomes 41. The structure of chromosomes can be best seen at: (a) prophase (b) metaphase (c) anaphase (d) telophase 42. In mitosis centromere divides at: (a) prophase (b) metaphase (c) anaphase (d) telophase 43. Meiosis and mitosis are unlike because in meiosis: (a) homologous chromosomes pair and exchange part (b) chromosomes number is halved (c) the four nuclei formed are not identical (d) all of the above three are correct 44. In the meiotic division four daughter cells are produced by two successive divisionsin which: (a) first division is educational and second is reductional (b) first division is reduction and second is educational Page | VII  FULL LENGTH PRACTICE EXAMS NO. 1 (c) both divisions are educational (d) both divisions are reductional 45. Which is the longest phase of cell cycle? (a) G0phase (b) s phase (c) G1 phase (d) G2 phase 46. In which of the following would you observe high mitochondrial activity? (a) germinating seeds (b) falling leaves (c) meristematic tissue (d) both in germinating seeds and meristematic tissue 47. Tissues are: (a) a group of cells which are similar in origin and function (b) organs which are similar in origin and function (c) group of cells which are not similar in function (d) group of cells, which are not similar in origin 48. Tracheae, tracheids, wood fibres and parenchymatous tissue are found in: (a) phloem (b) cortex (c) xylem (d) medullary rays 49. Phloem sclerenchyma, sieve tubes, parenchyma and companion cells are found in: (a) xylem (b) phloem (c) cambium (d) medullary rays Page | VIII  FULL LENGTH PRACTICE EXAMS NO. 1 50. The hydathodes are: (a) honey glands (b) water secreting glands (c) oil secreting glands (d) mucilge secretingglands 51. The lateral meristem is responsible for: (a) growth in length (b) growth in parenchyma (c) growth in cortex (d) growth in thickness 52. Increase in length of a stem is caused by: (a) apical meristem (b) cork cambium (c) vascular cambium (d) mitotic division in pith and cortex 53. Companion cells are usually associated with: (a) fibres (b) tracheids (c) sieve tubes (d) vessels 54. The best method to determine the age of a tree is to: (a) count the number ofleaves on a tree (b) find out the number of branches (c) count the number of annual rings (d) any of the above 55. The lateral roots, generally originate in: (a) cortex (b) endoderms (c) pericycle (d) hypoderms 56. Food is transported to different plant parts through: (a) xylem (b) phloem (c) cambium (d) root hair Page | IX  FULL LENGTH PRACTICE EXAMS NO. 1 57. The chief function of the vessels in the plant: (a) is to give mechanical strength to stem (b) to translocate food manufactured in the leaves to other parts of the plant (c) is conduction of water and mineral salts (d) to remove excess of water through root at night when there is no transpiration 58. Active cell division can be seen in: (a) cortex (b) cambium (c) pith (d) pericycle 59. External protective tissues of dicot plants are: (a) epidermis and cork (b) cork and pericycle (c) cortex and epidermis (d) pericycle and cortex 60. Cross section of the trunk of a tree showed 50 annual rings the age of the tree is: (a) 25 years (b) 50 years (c) 50 days (d) 100 years 61. A simple mechanical tissue with unlignified cell wall is: (a) parenchyma (b) sclerenchyma (c) collenchymas (d) chlorenchyma 62. The chief function of sieve tubes is: (a) to translocate the organic materials manufactured in the leaves (b) to conduct minerals (c) to transport water from root to leaves (d) to help the plant in forming wood Page | X  FULL LENGTH PRACTICE EXAMS NO. 1 63. Thickening of cell wall, lignification and specialization for mechanical functions are characteristics of: (a) parenchyma (b) collenchymas (c) sclerenchyma (d) chlorenchyma 64. Tendon is a structure, which connects: (a) a bone with another bone (b) muscle with a bone (c) a muscle with a muscle (d) a nerve with a muscle or bone 65. Fibrous tissue, which connects bones is: (a) tendon (b) adipose tissue (c) ligament (d) connective tissue 66. Tendons and ligaments are tissues of the category of: (a) connective (b) epithelium (c) muscles (d) nerve 67. Axons serve to: (a) bring impulses to cell body (b) bring blood into heart (c) take away impulses from cell body (d) take impulses to cell body and then away from cell body 68. Blood platelet are necessary for: (a) metabolism (b) digestion (c) excretion (d) blood clotting 69. Mast cells secrete: (a) histamine (b) serotonin Page | XI  FULL LENGTH PRACTICE EXAMS NO. 1 (c) heparin (d) all of these 70. Myelin sheath is a layer covering: (a) a vertebrate nerve fibre (b) a vertebrate muscle fibre (c) an insect nerve fibre (d) all of these Page | XII  FULL LENGTH PRACTICE EXAMS NO. 1 ANSWER FULL LENGTH PRACTICE EXAM NO. 1 1. C 11. C 21. B 31. D 41. C 51. D 61. C 2. D 12. D 22. C 32. D 42. C 52. A 62. A 3. D 13. C 23. B 33. A 43. D 53. C 63. C 4. A 14. D 24. B 34. D 44. B 54. C 64. B 5. C 15. D 25. C 35. C 45. B 55. C 65. C 6. D 16. D 26. D 36. B 46. D 56. B 66. A 7. C 17. A 27. A 37. B 47. A 57. A 67. C 8. C 18. B 28. D 38. A 48. C 58. B 68. D 9. D 19. D 29. D 39. A 49. B 59. A 69. A 10. C 20. B 30. A 40. D 50. B 60. B 70. A Page | XIII  FULL LENGTH PRACTICE EXAMS NO. 2 FULL LENGTH PRACTICE EXAMS NO.2 FULL LENGTH PRACTICE EXAMS NO.2 1. The "blood bank" of our body is: (a) spleen (b) lungs (c) heart (d) liver 2. Which of these is a kind of tissue? (a) liver (b) blood (c) gut (d) pancreas 3. Function of nervous tissue is: (a) sensitivity (b) irritability (c) responsiveness (d) contractility 4. Branch of biology dealing with microscopic anatomy of tissues is: (a) cyctology (b) morphology (c) histology (d) taxonomy 5. RBCS of man are: (a) round, biconcave, non-nucleated (b) round, biconcave, nucleated (c) round, biconvex. non-nucleated (d) oval, non-nucleated 6. Which of the following embryonic layers originate from the mesoderm of mammals? (a) skeleton (b) muscle (c) brain (d) both (a) and (b) 7. What is meant by binomial nomenclature? (a) indication of the name, by its species and variety (b) indication of the name by its genus and species Page | XIV  FULL LENGTH PRACTICE EXAMS NO. 2 (c) indication of the name by its family and genus (d) indication of the name by its order and family 8. Strongest muscles in human body are found in: (a) jaws (b) thighs (c) hands (d) neck 9. According to botanist first plants, which originated on the earth were like: (a) mosses and relatives (b) virus and bacteria (c) algae and fungi (d) ferns and lycopods 10. In which of the following groups would you place a plant which produces seeds but lacks flowers? (a) gymnosperms (b) bryophytes (c) pteridophytes (d) fungi 11. Algae and fungi are grouped in which of the following: (a) thallophyta (b) gymnosperms (c) angiosperm (d) bryophytes 12. Which of the following plants have maximum power of adaptability? (a) pteridophytes (b) angiosperms (c) bryophytes (d) algae 13. Thallophytes having chloroplast are: (a) algae (b) fungi (c) bacteria (d) moss Page | XV  FULL LENGTH PRACTICE EXAMS NO. 2 14. Liverworts and mosses are kept under: (a) angiosperms (b) gymnosperms (c) bryophyte (d) pteridophyta 15. Which of the following group of plant produces spores has vascular tissue and lacks seeds? (a) gymnosperms (b) pteridophytes (c) bryophytes (d) fungi 16. The most primitive vascular plants are: (a) cyeas (b) ferns (c) red algae (d) brown algae 17. Embryophyta includes: (a) angiosperms only (b) all the plants (c) algae and fungi (d) bryophyta and pteridophyta 18. Which of the following are kept in tracheophyta? (a) algae and fungi (b) gymnosperms and pteridophyta (c) pteridophyta and angiosperms (d) pteridophyta, gymnosperms and angiosperms 19. Which of the following is not a pteridophyte? (a) selaginella (b) fern (c) equisetum (d) sphagnum Page | XVI  FULL LENGTH PRACTICE EXAMS NO. 2 20. Blue-green mold" name is given to: (a) aspergillus (b) penicillium (c) alternaria (d) agaricus 21. Which one is not a bryophyte? (a) polytrichum (b) dawsonia (c) pellia (d) fern 22. Gymnosperm differs from angiosperm in having: (a) tracheids only (b) naked ovules (c) no ovary (d) all of these 23. Which phylum of animals is exclusively marine’s? (a) porifera (b) coelenterate (c) mollusca (d) echinodermata 24. Which of the following is most un-matching group? (a) cockroach, king-crab, spider, silverfish (b) whale, bat, lizard, sea horse (c) starfish, sea urchin, sea cucumber (d) crayfish, cuttlefish, sawfish, hagfish 25. Body is segmented in: (a) mollusca (b) porifera (c) coelenterate (d) annelida 26. Phylum arthropoda is characterized by: (a) hairs, external segmentation, 3 pairs of legs (b) exoskeletal system, 1 pair of chelicerae (c) external segmentation, a pair of chelicerae, a pair of pedipalp Page | XVII  FULL LENGTH PRACTICE EXAMS NO. 2 (d) chitinous exoskeleton, external segmentation, paired jointed appendages 27. Radial symmetry is seen in: (a) sponges (b) fishes (c) starfish (d) mollusca 28. Integument of arthropoda is covered with: (a) chitinous cuticle (b) smooth muscle (c) strong calcareous shell (d) none of these 29. Air bladder is: (a) excretory organs of mammals (b) reparatory organ of birds (c) hydrostatic organ of bony fishes (d) organ of hydrophytes 30. Peculiarity of fish heart is that it has: (a) all arterial blood (b) all venous and partly arterial (c) partly venous and partly arterial (d) no blood at all 31. Coelentrates differ from the other animals in having: (a) nematocysts (b) skeleton (c) bilateral symmetry (d) polymorphism 32. Cephalopoda is a class of animals in which: (a) notochord extends up to head (b) foot is located upon head (c) head is fused with thorax (d) head is located upon foot 33. Group amniota includes: (a) birds and reptiles (b) birds and mammals (c) reptiles, birds and mammals (d) reptiles and mammals Page | XVIII  FULL LENGTH PRACTICE EXAMS NO. 2 34. Which of the protozoans is considered as connecting link between animal and plants? (a) paramecium (b) monocystis (c) englena (d) entamoeba 35. Which of the following phylais not having vascular, respiratory and excretoryorgans? (a) arthropoda (b) annelid (c) porifera (d) Platyhelminthes 36. Water vascular system is typically found in: (a) sponge (b) hydra (c) starfish (d) leech 37. Chordates are distinguished from non-chordates by the presence of: (a) ventral nerve cord (b) dorsal nerve cord (c) brain (d) dorsal tubular nerve cord 38. Eumetazoa includes: (a) protista (b) coelenterate (c) sporozoa (d) protozoa 39. An endoskeleton is found in: (a) earthworm (b) scorpion (c) snake (d) cockroach 40. The main function of the contractile vacuole in amoeba and other aquatic protozoans is: (a) nutrition (b) osmoregulation (c) circulation of food (d) excretion of nitrogenous wastes Page | XIX  FULL LENGTH PRACTICE EXAMS NO. 2 41. Phylum coelenterata has remained at: (a) cellular level of organization (b) tissure level of organization (c) tis sure level of organization (d) organ level of organization 42. Heretima is: (a) sterile (b) unisexual (c) radially symmetrical (d) hermaphrodite 43. Lung book are the respiratory organs of: (a) scorpion (b) hydra (c) cockroach (d) prawn 44. Acoelomates: (a) have cavity lined with mucus cells (b) have cavity not linked with epithelial cells (c) have coelom (d) lack coelom 45. Paramoecium has: (a) two contractile vacuoles (b) one contractile vacuoles (c) four contractile vacuoles (d) many contractile vacuoles 46. Which one of the following is a genetically transmitted disease? (a) haemophilia (b) blood cancer (c) typhoid (d) bone cancer Page | XX  FULL LENGTH PRACTICE EXAMS NO. 2 47. Which of the following pair is correctly matched? (a) scabies: entamoeba (b) malaria : plasmodium (c) tetanus: haemophilus (d) pneumonia: sarcoptes 48. Which of the following statements is not characteristic of echinoderms? (a) all are marine (b) the body is segmentrical (c) adults are radially symmetrical (d) water vascular system is present 49. Which of the following disease is caused by bacteria? (a) cholera (b) malaria (c) elephantiasis (d) measles 50. Which one of the following is communicable disease? (a) cancer (b) diphtheria (c) rheumatism (d) diabetes 51. Human beings belong to: (a) the order primates under the class chordate (b) the class primates under the phylum chordate (c) the class primates under the phylum chordate (d) the class mammalia under the phylum chordate 52. A person suffering from tetany is treated by the administration of: (a) thvroxin (b) calcitonin (c) aldosterone (d) parathonnone Page | XXI  FULL LENGTH PRACTICE EXAMS NO. 2 53. Which one of the following is not mosquito borne disease? (a) dengue fever (b) filariasis (c) sleeping sickness (d) malaria 54. Wine turns sour because of: (a) aerobic bacteria (b) anaerobic bacteria (c) exposure to light (d) heat 55. Which of the following disease is caused by bacteria? (a) arthritis (b) diphtheria (c) beri-beri (d) small pox 56. The bacterium haemophilous influenzae causes: (a) pneumonia (b) meningitis (c) influenza (d) small pox 57. Bacterium responsible for fermentation of dairy milk and plant product is: (a) lactobacter (b) haybacillus (c) acetobacter (d) rhizobium 58. Bacterial cell division in every minute, it takes an hour to fill a cup, how much time it will take to fill half the cup? (a) 59 minutes (b) 30 minutes (c) 60 minutes (d) 29 minutes 59. Bacterial cell membrane is made up of: (a) lipo-protein (b) cellulose (c) chitin (d) fat Page | XXII  FULL LENGTH PRACTICE EXAMS NO. 2 60. Which are the smallest bacteria among the following? (a) cocci (b) spirilli (c) bacilli (d) vibrios 61. Tobacoo mosaic disease is caused by: (a) virus (b) bacilli (c) vibrios (d) fungi 62. Bacteria multiply: (a) asexuallyby fission (b) fusion (c) spore formation (d) zygospore formation 63. Spirogyra: (a) is filamentous (b) has chloroplast (c) belongs to chlorophyte (d) all of these 64. Which of the following statement is correct? (a) all the blue-green algae can fix nitrogen (b) most of the blue-green algae can fix atmospheric nitrogen (c) none of the blue-green algae ean fix atmospheric nitrogen (d) blue-green algae can fix nitrogen only when present in root nodules of legumes 65. Which of the following is the symbiotic N2fixing prokaryote? (a) anabaena (b) cladophora (c) batrachospermurn (d) coleochaete Page | XXIII  FULL LENGTH PRACTICE EXAMS NO. 2 66. Mycorrhiza, a relationship between fungi and roots of higher plants is: (a) parasitic relationship (b) saprophytic relationship (c) symbiotic relationship (d) epiphytic relationship 67. A mushroom is: (a) agaricus (b) algae (c) fungi (d) pinus 68. The amphibians of the plants kingdom are: (a) Thallophytes (b) pteridophytes (c) angiosperms (d) bryophytes 69. A moss differs from the fern in having: (a) flagellated antherozoids (b) archegonia (c) haploid spores (d) dependent sporophyte 70. In cockroach accessory glands are meant for: (a) circulation (b) respiration (c) excretion (d) reproduction Page | XXIV  FULL LENGTH PRACTICE EXAMS NO. 2 ANSWER FULL LENGTH PRACTICE EXAM NO. 2 1. A 11. A 21. D 31. A 41. C 51. D 61. A 2. B 12. B 22. D 32. D 42. D 52. D 62. A 3. C 13. A 23. D 33. C 43. A 53. B&C 63. D 4. C 14. C 24. D 34. C 44. D 54. A 64. B 5. A 15. B 25. D 35. C 45. A 55. B 65. A 6. D 16. B 26. D 36. C 46. A 56. C 66. C 7. B 17. B 27. C 37. D 47. B 57. A 67. C 8. A 18. D 28. A 38. B 48. B 58. A 68. D 9. A 19. D 29. C 39. C 49. A 59. A 69. D 10. A 20. B 30. B 40. B 50. B 60. A 70. D Page | XXV  FULL LENGTH PRACTICE EXAMS NO. 3 FULL LENGTH PRACTICE EXAMS NO.3 FULL LENGTH PRACTICE EXAMS NO.2 1. Tracheae and trachioles are the: (a) respiratory organs of cockroach (b) respiratory organs of earthworm (c) respiratory organs of ascaris (d) respiratory organs of neries 2. The mode of nutrition in amoeba is: (a) heterotrophic (b) autotrophic (c) saprophytic (d) parasitic 3. The toad is: (a) herbivorous (b) a frog (c) omnivorous (d) carnivorous 4. Parotid glands are found in: (a) frogs and toads (b) toads only (c) frogs only (d) fish 5. Chemically enzymes are: (a) carbohydrates (b) proteins (c) fats (d) amino acids 6. If food intake is greater than greater used, the surplus is deposited as: (a) fat (b) proteins (c) carbohydrates (d) enzymes 7. More energy is produced from 1 gram mol of: (a) fats (b) sugars Page | XXVI  FULL LENGTH PRACTICE EXAMS NO. 3 (c) proteins (d) vitamins 8. Scurvy is a disease caused by: (a) presence of Rh antigen in blood (b) deficiency of vitamin E (c) deficiency of vitamin C or ascorbic acid (d) deficiency of vitamin D 9. Vitamins are: (a) organic substances and cannot be synthesized by animals (b)inorganic substances and can be synthesized by animals (c) organic substances which can mostly be synthesized by animals (d) inorganic substances which one converted into organic by simple animals only 10. Deficiency of vitamin a causes: (a) beri-beri (b) retarded growth and development (c) rikets (d) night blindness 11. Function of vitamin k is in: (a) regulation of phosphorus and calcium metabolism (b) blood dotting (c) carbohydrate metabolism (d) respiration 12. The most common concentrated source of proteins in Pakistan is: (a) potatoes (b) meat (c) eggs (d) pulses 13. Starch is: (a) carbohydrate (b) protein Page | XXVII  FULL LENGTH PRACTICE EXAMS NO. 3 (c) enzyme (d) fat 14. Sucrose is found in: (a) milk (b) honey (c) sugarcane (d) orange 15. Which one of these carbohydrates is a monosaccharide? (a) cellulose (b) sucrose (c) starch (d) glucose 16. Vitamin D is also called: (a) calciferol (b) ascorbic acid (c) retinol (d) folic acid 17. Micro-nutrients: (a) are less important in nutrition than macro-nutrients (b) are as important in nutrition as macro-nutrients (c) may be emitted from culture media without any detriment effect on the plants (d) are called 'micro' because they play only a minor role in plant nutrition 18. Which of the following is not a macro-nutrient? (a) Mg (b) Ca (c) Fe (d) P 19. Mineral salts are absorbed by the roots from the soil, in the form of: (a) very dilute solution (b) dilute solution (c) concentrated solution (d) very concentrated solution Page | XXVIII  FULL LENGTH PRACTICE EXAMS NO. 3 20. Plants always take their food: (a) in organic form (b) in inorganic form (c) in solid form (d) in soluble form 21. The first step in photosynthesis is: (a) photolysis of water (b) formation of ATP (c) excitement of an electron of chlorophyll by a photon of light (d) formation of NADPH 22. In which of following process the light energy is converted into chemical energy: (a) digestion (b) respiration (c) fermentation (d) photosynthesis 23. In light phase of photosynthesis there is formation of: (a) ATP and NADPH2 (b) NADPTB (c) ATP (d) carbohydrates 24. What is the source of oxygen liberated in photo-synthesis? (a) CO2 (b) H2O (c) carbohydrates (d) photosynthetic enzymes 25. During dark reaction of photosynthesis: (a) water splits (b) Co2 is reduced to organic compounds (c) chlorophyll is activated Page | XXIX  FULL LENGTH PRACTICE EXAMS NO. 3 (d) 6 carbon sugar is broken down into 3 carbon sugar 26. Ptyalin of saliva acts in: (a) slightly alkaline medium (b) slightly acidic medium (c) neutral medium (d) all type of media 27. Bile juice assists in digestion of fats by: (a) emulsifying the fats (b) contributing a lipolytic enzyme (c) stimulating secretion of lipase (d) increasing the alkalinity of digestive medium 28. Liver cells secrete: (a) amylopsin (b) trypsin (c) bile juice and no enzymes (d) digestive enzymes 29. Protein digestion requires: (a) proteases (b) peptides (c) proteolytic enzymes (d) all of these 30. Some proteolytic enzymes are: (a) trypsin, erepsin, pepsin (b) amylase, lipase, zymase (c) amylase, steapsin, ptyalin (d) all of these 31. Whichof these is a group of end products of carbohydrate digestion? (a) glucose, galactose, fructose (b) sucrose, galactose, maltose (c) galactose, glucose, maltose (d) lactose, maltose, glucose Page | XXX  FULL LENGTH PRACTICE EXAMS NO. 3 32. Pancreatic juice takes part in digestion of: (a) proteins carbohydrates (b) proteins, fat, carbohydrates (c) proteins only (d) proteins and fats 33. Conversion of glucose into glycogen in liver is called: (a) glycogenolysis (b) glycogenesis (c) glycolysis (d) gluconeogenesis 34. Oxygen carrier or the respiratory pigment in blood of frog and other vertebrates is: (a) haernocyanin (b) haemoglobin (c) cytochrome (d) haernolyrnph 35. A frog must swallow air if the lungs are to be expanded, because frog: (a) has no diaphragm (b) normally breathes through its skin (c) has no vagus nerve (d) is relatively low form of life 36. Anaerobic respiration is likely to occur in: (a) ants (b) earthworms (c) Echinoderms (d) tapeworms 37. What is the end product of glcolysis? (a) pyuvic acid (b) acetyl Co-A (c) citric acid (d) lactic acid 38. Out of there, the end product of anaerobic respiration is: (a) Co2 + H2O (b) fumaric acid (c) pyruvic acid (d) lactic acid Page | XXXI  FULL LENGTH PRACTICE EXAMS NO. 3 39. In glycolysis, ultimately: (a) protein is converted to glucose (b) glucose is converted to fructose (c) glucose is converted to pyruvic acid (d) starch is converted to glucose 40. A person with blood group O can receive blood transfusion from persons with blood group: (a) O and AB (b) O, A and B (c) O only (d) AB only 41. Universal recipient in blood transfusion belongs to the group: (a) A (b) O (c) AB (d) B 42. Haemophilia is a disease caused by deficiency of: (a) water in plasma (b) RBCS (c) WBCS (d) thromboplastin 43. Mangolism or Down's syndrome is the result of: (a) 47 chromosomes instead of 46 (b) 45 chromosomes instead of 46 (c) 23rd pair of chromosomes in three doses (d) 21 st pair of chromosomes having a single dose 44. Eugenics pertains to: (a) improvement of mankind by improving his heredity (b) prescribing human sperms for artificial insemination (c) study of human genetics Page | XXXII  FULL LENGTH PRACTICE EXAMS NO. 3 (d) controlling size of human family 45. Sickle-cell anaemia is due to: (a) hormones (b) viruses (c) genes (d) bacteria 46. Sex linked inheritance was discovered by: (a) Mendel (b) Landsteiner (c) Morgan (d) Mc Clung 47. Chromosomal pattern of Turner's syndrome: (a) 22 A + XXV (b) 22 A + XXX (c) 22 A + X (d) 22 A + Y 48. Chromosomes of Klkinefelter's syndromes usually have: (a) one X (b) XXV (c) 2 X only (d) no Y 49. Autotrophic component of ecosystem is: (a) sunlight (b) green plants (c) herbivorous (d) bacteria and fungi 50. Which of the following is the main factor of water pollution? (a) smoke (b) ammonia (c) getergents (d) industrial wastes 51. The main air pollutant is: (a) Co (b) Co2 (c) N2 (d) sulphur Page | XXXIII  FULL LENGTH PRACTICE EXAMS NO. 3 52. Which of the following-is non-renewable source of energy? (a) coal (b) forest (c) H2O (d) wild life 53. Loss of air exchange capacity by deterioration of alveoli in lung tissues called: (a) emphysema (b) necrosis (c) effluent (d) eutrophication 54. Majorfood crop of the world belongs to: (a) leguminosae (b) solanaceae (c) gramineae/poaceae (d) cruciferae 55. the most important foods are derived from: (a) roots (b) fruits (c) leaves (d) stem 56. A cell became turgid when placed in: (a) isotonic solution (b) hypertonic solution (c) hyportonic solution (d) any acrated water 57. When the contents of a cell are in the shrinkage state the process is called: (a) hypotonic (b) plasmolysis (c) endosmosis (d) osmosis 58. Which of the following statements is true? (a) the plasma is the liquid part of blood (b) RBC is smaller than WBC (c) haemoglobin is stored in RBC (d) all are true Page | XXXIV  FULL LENGTH PRACTICE EXAMS NO. 3 59. The blood coming from the heart is carried to liver by: (a) aorta (b) renal artery (c) renal vein (d) hepatic artery 60. Ammonia is the chief nitrogenous excretory material in: (a) cartilaginous fishes (b) fowl (c) freshwater fishes (d) mosquitoes 61. Urea is produced from 'ammonia in the body of rabbit or man in: (a) liver (b) kidneys (c) spleen (d) heart 62. Kidney of a mammal resembles contractile vacuole of amoeba in expelling out: (a) salt (b) glucose (c) excess water (d) urea and uric acid 63. Which of these will completely be reabsorbed under normal condition in the nephrons? (a) glucose (b) urea (c) salts (d) uric acid 64. Aquatic animal are mostly ammonotelic because: (a) ammonia helps in checking inflow of water into body (b) excretion of ammonia requires large amount of water which is available to these animals (c) water contains less nitrogen (d) they get less light Page | XXXV  FULL LENGTH PRACTICE EXAMS NO. 3 65. Which part of mammalian brain controls the muscular co-ordination? (a) cerebellum (b) cerebrum (c) corpus callosum (d) medulla 66. The central nervous system consists of: (a) brain and the spinal cord (b) spinal cord and spinal nerves (c) brain, spinal nerves and cranial nerves (d) brain and the cranial nerves 67. Acetylcholine is responsible for transmission of nerve impulses through: (a) soma (b) dendrites (c) axons (d) synapses 68. Cerebellum of brain is concerned with: (a) static balance (b) regulation of body posture and equilibrium (c) initiation of muscular contraction (d) co-ordination of muscular movements 69. Which part of the brain is responsible for sensation, memory and emotions? (a) thaiamus (b) medulla oblongata (c) cerebrum (d) cerebellum 70. Which of the following statements is incorrect? (a) a gynoecium is the female part of the flower (b) the style receives pollens (c) stamens collectively are named as androecium (d) in marchantia, eggs develop inside archegonium Page | XXXVI  FULL LENGTH PRACTICE EXAMS NO. 3 ANSWER FULL LENGTH PRACTICE EXAM NO. 3 1. A 11. B 21. C 31. A 41. C 51. A 61. A 2. A 12. D 22. D 32. B 42. D 52. A 62. C 3. C 13. A 23. A 33. B 43. A 53. A 63. A 4. A 14. C 24. B 34. B 44. A 54. C 64. B 5. B 15. D 25. B 35. A 45. C 55. B 65. A 6. A 16. A 26. B 36. D 46. C 56. C 66. A 7. A 17. B 27. A 37. A 47. C 57. B 67. D 8. C 18. C 28. C 38. D 48. B 58. D 68. D 9. A 19. A 29. C 39. C 49. B 59. D 69. C 10. D 20. D 30. A 40. C 50. D 60. C 70. B Page | XXXVII  FULL LENGTH PRACTICE EXAMS NO. 4 FULL LENGTH PRACTICE EXAMS NO.4 1. During the process of fertilization, it is usually found that of the two male gametes. One fuses with the egg and the second with the secondary nucleus this is known as: (a) simple fertilization (b) double fertilization (c) fusion (d) zygospore formation 2. The nutritive status of slime mould is: (a) producer (b) consumer (c) decomposer (d) consumer/decomposer 3. Sexual reproduction is uncommon in: (a) deuteromycota (b) zygornycota (c) ascomycota (d) basidiomycota 4. Fertilization of ovum takes place in man and other placental mammals in: (a) ovary (b) uterus (c) fallopian tubes (d) vagina 5. Corpus luteum in mammals occurs in: (a) brain and connects the two cerebral hemispheres (b) ovaries and produces progesterone hormone (c) heart and initiates atrial contraction (d) skin and acts as a pain receptor 6. Bread moldis used to manufacture: (a) lactic acid (b) acetic acid (c) fumaric acid (d) all of these Page | XXXVIII  FULL LENGTH PRACTICE EXAMS NO. 4 7. Which one of the following substances is released into the blood stream of a normal individual to increase the concentration of blood sugar? (a) vitamins (b) insulin (c) glucagon (d) enzyme 8. A plant cell has the potential to develop into an entire plant. This property of the plant cells is known as: (a) totipotency (b) nucleopotency (c) tissue culture (d) gene cloning 9. Outer covering of cartilage is known as: (a) endostium (b) perichondrium (c) periostium (d) serous coat 10. Germs cells in the vertebrate gonads form by: (a) mitosis (b) meiosis (c) both meiosis and mitosis (d) maturation without cell division 11. Which one is called the king of genetics due to the excessive use for genetic research? (a) neurospora (b) penicillium (c) saccharomyces (d) aspergillus 12. Smallest insect is: (a) house fly (b) fairy fly (c) cockroach (d) small beetle 13. After ovulation in female rabbit, the collapsed ovarian follicle shrinks and becomes filled with cells to from: (a) corpus luteum (b) endothelium (c) epittelium (d) follicle Page | XXXIX  FULL LENGTH PRACTICE EXAMS NO. 4 14. Medicines from fungi are used extensively: (a) exogenously (b) endogenously (c) exogenously and endogenously (d) on animals only 15. Polar bodies are formed during: (a) oogenousis (b) spermatogenousis (c) gematogenousis (d) sporogenousis 16. Natural parthenogenesis occurs in: (a) earthworms (b) all insects (c) honey bee (d) protozoans 17. Main function of corpus lutcum is to: (a) facilitate fertilization (b) facilitate ovulation (c) secrete progesterone (d) facilitate passage of ova a in oviducts 18. In a spontaneous reaction the free energy of a system: (a) decreases (b) increases (c) becomes equal to zero (d) remain unchanged 19. Placenta acts like a: (a) semi permeable membrane (b) fully" permeable (c) impermeable membrane (d) none of these 20. Which of the following structure are protective in function? (a) amnion and yolk sac (b) amnion and allantois (c) amnion and chorion (d) chorion and allantois Page | XL  FULL LENGTH PRACTICE EXAMS NO. 4 21. Which types of division occurs in cleavage? (a) amitotic (b) mitotic (c) meiotic (d) mitotic and meiotic 22. What is site of the fertilization in human being? (a) vazina (b) uterus (c) fallopian tube (d) ovary 23. Which layer forms liver, pancreas thymus and thyroid? (a) endodenn (b) mesoderm (c) lctoderm (d) epiblast 24. Sedimentation coefficient is: (a) svedberg unit (b) centrifugation (c) ultracentrifugation (d) density gradient centrifugation 25. Which group exclusively consists of polysaccharides? (a) starch, glycogen lactose (b) lactose, cellulose, starch (c) glycogen, maltose, starch (d) glycogen, cellulose, starch 26. The most diverse molecules in a cell are: (a) mineral salts (b) lipids (c) proteins (d) carbohydrates 27. Which one is correctly matched? (a) vitamin A-thiamine (b) vitamin B-calciferol (c) vitamin E-riboflavin (d) vitamin E-tocopherol Page | XLI  FULL LENGTH PRACTICE EXAMS NO. 4 28. Which of the following is not function of liver? (a) detoxification (b) glycogen storage (c) production of insulin (d) production of bile 29. Vitamin k is required for: (a) formation of prothrombin (b) conversion of prothrombins (c) synthesis of prothrombin (d) formation of thromboplastin 30. Vitamin D is synthesized in skin by the action of sunlight on: (a) 7-dehydrocholesterol (b) cephalocholes (c) cholesterol (d) all of these 31. Which of the following trace element is significant for maintenance of teeth? (a) manganese (b) copper (c) line (d) fluoride 32. Feeding on dead and decaying organism represent what type of nutrition: (a) autotrophic (b) parasitic (c) saprotrophic (d) holozoic 33. We take food rich in lime juice then: (a) action of ptyalin on starch stops (b) action of ptyalin on starch is unaffected (c) action of ptyalin on starch is reduced (d) action of ptyalin on starch is enhanced 34. Which part of the body secretes the hormone secretin? (a) oesophagus (b) stomach (c) duodenum (d) ileum Page | XLII  FULL LENGTH PRACTICE EXAMS NO. 4 35. Enterokinase converts: (a) starch → maltose (b) proteins → dipeptides → amino acids (c) trypsinogen → trypsin (d) fats → glycerol 36. Which one of the following vitamins can be synthesized by bacteria inside the gut? (a) K (b) D (c) B (d) C 37. Which of the following are absorbed in the elementary canal as such? (a) proteins (b) fat soluble vitamins (c) polysaccharides (d) albumen of egg 38. Strongest part in the body is: (a) muscle (b) enamel (c) bone (d) cartilage 39. Gall bladder of a man is stimulated by: (a) enterokinase (b) cholecystokinin (c) secretin (d) enterogastrone 40. When gall bladder of a man is removed: (a) effect of pancreatic juice upon food is impaired (b) acidity continues in duodenum (c) fat digestion is not possible (d) all of these Page | XLIII  FULL LENGTH PRACTICE EXAMS NO. 4 41. Taste buds of bitter taste are located in our tongue: (a) on upper surface in posterior (b) on lower surface (c) on lower sides (d) at tip 42. Maximum absorption takes places in: (a) rectum (b) colon (c) stomach (d) ileum 43. Which of the following is unpaired bone of face? (a) maxilla (b) lacrimal (c) palatine (d) vomer 44. Seed coat and nut shells only contain ___________ type of sclerenchyma cells. (a) fibers (b) sclereides (c) tracheids (d) vessels 45. Rectal glands remove the excessive salt to outside by: (a) diffusion (b) active transport (c) facilitated (d) both (a) and (b) 46. In marine environment, internal salt concentration will be lower in the cast of: (a) most cartilaginous fishes (b) hag fishes (c) most marine invertebrates (d) all of these 47. The covalent bound between two amino acids is called as: (a) amide (b) protein (c) protoamide (d) peptide Page | XLIV  FULL LENGTH PRACTICE EXAMS NO. 4 48. The two families of nitrogenous bases of nucleotides are: (a) adinine and guanine (b) thymine and cytosine (c)purine and pyrimidine (d) uracil and purine 49. Endoplasmic reticulum is not found in: (a) mammalian WBC (b) mammalian RBC (c) adipose cells (d) cardiac dells 50. The science of improving physical and mental qualities of humans, through control of the factors influencing heredity, is called: (a) genetics (b) genetic engineering (c) gene therapy (d) phycology 51. Study of the external character of organisms is called: (a) history (b) biogeography (c) paleontology (d) morphology 52. Hypothesis is: (a) a reasoned explanation (b) an educated guess (c) idea given on the basis of previous Knowledge (d) all of these 53. Nanometer (nm) is other name of: (a) mill micron (mµ) (b) micron (µ) (c) micrometer (µm) (d) angstrom (Ao) Page | XLV  FULL LENGTH PRACTICE EXAMS NO. 4 54. Which of the following cannot be grown on artificial culture medium? (a) E.coil (b) T.M.V (c) yeast (d) aspergillus 55. Secretion of the sweat glands of mammals are primarily meant for: (a) regulation of body temperature (b) removal of excess salt (c) removal of excess water (d) killing of bacteria on skin 56. According to fluid-mosaic model, plasma membrane is made of: (a) cellulose and hemicellulose (b) phospholipids and hemicellulose (c) phospholipids and intrinsic proteins (d) phospholipids, intrinsic proteins and extrinsic proteins 57. Osmosis through semipermeable membrane is a flow of: (a) solutes from low concentration to higher concentration (b) phospholipids and gemicellulose (c) phospholipids and intrinsic proteins (d) phospholipids, intrinsic proteins and extrinsic proteins 58. How many molecules of oxygen gas (O2) are used during the glycolysis of one glycolysis of one glucose molecule? (a) 0 (b) 1 (c) 16 (d) 38 59. Which of the following substances donot pass across membranes by simple diffusion? (a) O2 (b) CO2 (c) H2O (d) H+ Page | XLVI  FULL LENGTH PRACTICE EXAMS NO. 4 60. In the conversion of pyruvic acid to acetyl coenzyme A, pyruvic acid is: (a) oxidized (b) reduced (c) isomerized (d) broken into one carbon fragments 61. Which of the following structure is not found in prokaryotic cell? (a) plasma membrane (b) nuclear envelop (c) ribosome (d) cell wall 62. Which of the following is a testcross? (a) AABB × AABB (b) AABD × AABB (c) AABB × AABB (d) AABB × AABB 63. Which of the following taxonomic categories contain organisms least similar to ea. h other? (a) class (b) genus (c) family (d) species 64. Maximum mitochondria in the cells of: (a) human liver (b) bird's wing (c) human kidney (d) air bladder of a fish 65. Which one is false nucleus? (a) nucleoid (b) nucleolus (c) chromosome (d) coenocytic condition 66. Identification + nomenclature + classification + interrelationship = ? (a) systematics (b) organic evolution (c) phonetics (d) taxonomy Page | XLVII  FULL LENGTH PRACTICE EXAMS NO. 4 67. Which of the following molecules moves regularly from the nucleus to the cytoplasm? (a) glycogen (b) RNA (c) DNA (d) cholesterol 68. Of all the texa, the only one that exists in nature as a biologically cohesive unit is the: (a) species (b) genus (c) phylum or division (d) kingdom 69. Bacteria that get their energy by fermentation and for whom oxygen is lethal are called: (a) obligate anaerobs (b) obligate aerobs (c) facultative aerobs (d) facultative anaerobs 70. When the fluid outside a cell has a greater concentration of a given molecule than the fluid inside the cell, the external fluid is: (a) isotonic (b) hypertonic (c) hypotonic (d) ultratonic Page | XLVIII  FULL LENGTH PRACTICE EXAMS NO. 4 ANSWER FULL LENGTH PRACTICE EXAM NO. 4 1. B 11. C 21. B 31. D 41. A 51. D 61. B 2. D 12. B 22. C 32. C 42. D 52. D 62. D 3. A 13. A 23. A 33. C 43. D 53. A 63. A 4. C 14. C 24. A 34. C 44. B 54. B 64. B 5. B 15. A 25. D 35. C 45. B 55. A 65. A 6. B 16. C 26. C 36. A 46. A 56. D 66. A 7. C 17. C 27. D 37. B 47. D 57. B 67. B 8. A 18. A 28. C 38. B 48. C 58. A 68. A 9. B 19. A 29. C 39. B 49. B 59. D 69. A 10. B 20. C 30. A 40. D 50. C 60. A 70. B Page | XLIX  UNIT NO. 1 CELL CYCLE THE CELL Major Contents Content → Cell Structure → Structure and Function of Cellular Organelles → Cell Division → Additional / Related Readings Learning Outcomes i. Compare the structure of typical animal and plant cell. ii. Compare and contrast the structure of prokaryotic cell with Eukaryotic cells. iii. Fluid mosaic model of cell membrane and transportation (diffusion, facilitated diffusion, active and passive transport), endocytosis and exocytosis. iv. Outline the structure and function of the following organelles. a. Nucleus b. endoplasmic reticulum, c. Golgi apparatus, d. mitochondria, e. centrioles f. ribosome v. Explain mitosis, what us tits significance? vi. What is meiosis, describe it in detail? vii. Discuss the terms karyokinesis and cytokinesis. viii. Discuss and explain: a. Uncontrolled cell division (cancer) b. Programmed cell death (appotosis) c. Necrosis Page | 50  UNIT NO. 1 CELL CYCLE Did you know? We have explained this entire Module (with practice questions) in just 14 video lectures at www.nearpeer.org ANIMAL AND PLANT CELLS HAVE SOME COMMON FEATURES:  In animals and plants each cell is surrounded by a very thin plasma (cell surface) membrane, which is too thin to be seen a light microscope.  Cell has a nucleus which is a relatively large structure. The deeply staining material in the nucleus is called chromatin and is mass of loosely coiled threads. This material collects together to form visible separate chromosomes during nuclear division. It contains DNA which controls the activities of nucleus.  The material between the nucleus and the plasma membrane is known as cytoplasm. Organelles themselves are often surrounded by membrane so that their activities can be separated from the surrounding cytoplasm. This is called compartmentalization. Since each type of organelles has its own function the cell is said to show division of labour.  The most numerous organelles seen with the light microscope are usually mitochondria. Page | 51  UNIT NO. 1 CELL CYCLE DIFFERENCES BETWEEN ANIMAL AND PLANT CELLS:  The only structure commonly found in animal cells which us absent from plant cells in the centriole. Under the light microscope it is a small structure close to the nucleus. It is involved in nuclear division.  Individual plant cells are  More easily seen with a light microscope than animal cells are because they are usually larger and surrounded by a relatively rigid cell wall outside the plasma membrane (singular plasmodesma) which pass through pore like structures in the walls of these neighbouring cells.  Mature plant cells differ from animal cells in having a large central vacuole and chloroplast in case of photosynthetic cell.  The vacuole is surrounded by a membrane, the tonoplast which controls exchange between the vacuole and the cytoplasm. The fluid in the vacuole is a solution of mineral salts, sugars, oxygen, carbon dioxide, pigments, enzymes and organic compounds including some waste products.  Vacuoles also help to regulate the osmotic properties of cells.  A large proportion of the inside of the cell is taken up with a fluid-filled compartment known as the vacuole. Together the wall and vacuole maintain the shape of the whole cell.  Plant cells have specialized organelles, the chloroplasts, which enable them to make their own food by photosynthesis ANIMAL CELL PLANT CELL (i) Usually smaller in size. (i) Comparatively larger in size. (ii) Enclosed by plasma membrane (ii) In addition to plasma membrane mostly only. surrounded by a thick cell wall. (iii) Plastids absent. (iii) Palstides (chloroplast and chromoplast) are very common. (iv) Cytoplasm consists largely of (iv) Cytoplasm peripheral, central space smaller vacuole. occupied by a large vacuole. (v) Prominent and highly complex (v) Contain several subunits of Golgi bodies Golgi bodies. called dictyosomes. (vi) Possess centrosome with one of (vi) No centrioles present, instead two small two centrioles. clear area called polar caps are present. Page | 52 UNIT NO. 1 CELL CYCLE TABLE: COMPARING PLANT AND ANIMAL CELLS FEATURE ANIMAL CELL PLANT CELL Nucleus √ √ Plasma membrane √ √ Mitochondria √ √ Rough ER √ √ Golgi bodies √ √ Lysosomes √ √ Cell wall × √ Plastids, e.g. chloroplasts × √ Vacuoles Small Large Centrioles √ × Did you know that you can watch this comparison in full detail in the video lecture 1.01 Intro to Cell Biology at www.nearpeer.org Page | 53 UNIT NO. 1 CELL CYCLE Fig. (a) Ultra structure of a typical cell of a higher plant Fig. (b) Ultra structure of a typical animal cell TABLE: MAJOR DIFFERENCES BETWEEN PROKARYOTES AND EUKARYOTES PROPERTY PROKARYOTIC CELLS EUKARYOTIC CELLS Nuclear Since there is no nuclear membrane Present membrane therefore no distinct nucleus Chromatin The genetic material (DNA) is without A nucleus is present in which nuclear material any nuclear membrane and freely material (chromosomes) is enclosed present in the cytoplasm. in double nuclear membrane. Chromosome Chromosome is formed of DNA only Chromosome is formed of DNA and protein. Organelles Few organelles Many organelles envelop-bound None are surrounded by an envelope organelles present e.g. nucleus, (two membranes) internal membrane mitochondria, and chloroplasts. Great Page | 54 UNIT NO. 1 CELL CYCLE scarce if present usually associated with diversity of organelles bounded by respiration or photosynthesis. single membrane e.g. lysosomes, vacuoles, micro bodies, endoplasmic, reticulum etc. Ribosomes Ribosomes are 70 S smaller subunit is Ribosomes are 80 S smaller subunit is 30S while larger subunit is 50 S. 40 S while larger subunit is 60 S. Cell wall Cell wall is composed of peptidoglycan The cell wall if present is formed of or murein. When polysaccharide chains cellulose is most of the plant cells and are bound covalently to shorter chains is formed of chitin in fungi. of amino acids. Peptidoglycan is formed. The entire cell wall is considered as a single complex molecule called sacculus. Cell division In prokaryotes mitosis is missing and Cell division by mitosis. the cell divided by binary fission. Organelles Organisms possessing prokaryotic cells Organism possessing eukaryotic cells are called prokaryotes. is called eukaryotes. Origin / Prokaryotes present primitive stage of Eukaryotes probably evolved from Evaluation evaluation. prokaryotes. Flagella Simple, lacking microtubules Complex, with 9 + 2 arrangement of extracellular (not enclosed by cell microtubules intracellular surface membrane) 20 nm diameter. (surrounded by cell surface membrane) 200 nm diameter Respiration Mesosomes in bacteria except Mitochondria for aerobic respiration. cytoplasmic membrane un blue green algae. Photosynthesis No chloroplasts no membrane stacking Chloroplasts containing membranes which are usually stacked into lamellae or grana. Nitrogen Mainly unicellular Mainly have the ability fixation Form Mainly unicellular Mainly multi-cellular (except prototista, many of which are unicellular) Cell size Average diameter 0.5 – 20 µm 10-100 µm diameter common commonly 1000-10000 times volume of prokaryotic cells. Examples Prokaryotes include bacteria and blue Eukaryotes include all other green algae (cyanobacteria) unicellular or multi-cellular organisms such as animals, plants fungi and Protista. Page | 55  UNIT NO. 1 CELL CYCLE CELL MEMBRANE Plasma membrane or cell membrane is the outer most boundary of the cell. However, in most plant cells, it is covered by a cell wall. Structure: Under electron microscope it is a bilayered structure, this structure is delicate and elastic it has some ability to repair itself. Models of Cell Membrane Structure: There are two models of cell membrane structure: i. Unit Membrane Model: According to this model the cell membrane is composed of lipid bilayer and sandwiched between two protein layers. This structure is present in all cell organelles (e.g. mitochondria, chloroplast etc.) ii. Fluid Mosaic Model: According to the fluid mosaic model the cell membrane consists of a double layer of phospholipid molecules, known as a lipid bilyers. It has proteins and other molecules. The name fluid mosaic is used because the bilyer is a very fluid structure and it contains a mosaic of protein molecules. Chemical Composition:  Cell membrane contains phospholipids 20-40 % proteins 60-80 % cholesterol and polysaccharides.  IT is about 7 nm thick  The basic structure is a phospholipid bilayer.  The hydrophilic phosphate heads of the phospholipids face outwards. The result is the aqueous environment inside and outside the cell.  The hydrocarbon tails face inwards and create a hydrophobic interior.  Most protein molecules float about in the phospholipid bilayer forming a fluid mosaic pattern. Page | 56  UNIT NO. 1 CELL CYCLE  The proteins stay in the membrane because they have regions of hydrophobic amino acids which interact with the fatty acid tails to exclude water.  Some proteins and lipids have short branching carbohydrate chains like antennae forming glycoproteins and glycolipids respectively.  Membrane also contains cholesterol. Like unsaturated fatty acids cholesterol disturbs the close packing of phospholipids and keeps them more fluid. This can be important for organisms living at low temperatures when membranes can solidify. Cholesterol also increases flexibility and stability of membranes,without it membrane break up.  The two sides of a membrane differ in composition and function. Functions of Membrane:  The phospholipid bilayer provides the basic structure of membrane. It also restrict entry and exit of polar molecules and ions.  Channel protein and carrier proteins are involved in the selective transport of polar molecules and ions across the membrane.  Some proteins act as enzymes for example the epithelial cells on some parts of the gu contain digestive enzymes.  Some proteins act as receptor molecules foe chemical signaling between cells.  Some proteins act a antigens these act as cell identity markers.  Glycolipids and glycoproteins help cells to recognize each other – allowing the immune system to tell the difference between body cells and invading bacteria.  Energy transfer ion photosynthesis and respiration proteins take part in the energy transfer system. TRANSPORT ACROSS THE CELL SURFACE MEMBRANE Diffusion and Facilitated Diffusion: Diffusion is the movement of molecules or ions from a region of their high concentration to a region of their low concentration. The process is passive (does not require energy and happens spontaneously). Two factors affect the rate of diffusion. Page | 57  UNIT NO. 1 CELL CYCLE 1. Difference in concentration between point A and point B,the steeper the gradient, the faster the rate of diffusion. 2. The greater the surface area of a membrane through which diffusion is taking place the greater the rate of diffusion. Facilitated Diffusion:  Some substances enter and leave cells much faster than you would expect it only diffusion occurred. We now know that some membrane proteins facilitate the diffusion of some substances across the cell membrane. Two types protein are responsible for facilitated diffusion.  Specific carrier protein takes particular substance from the membrane to the other.  Ion channels are proteins that open and close to control the passage of selected charged articles.  Channel proteins have a fixed shape. Osmosis: Osmosis is a passage of water molecules from a region of their high concentration to a region of their low concentration through a partially permeable membrane. We can say that it is a form of diffusion in which only water molecules move. Active Transport: Active transport is the energy-consuming transport of molecules or ions across a membrane against a concentration gradient. Movement are usually in one direction only. Unlike diffusion which is reversible. The energy is supplied in the form of ATP made in respiration. Without respiration, active transport is therefore impossible. Endocytosis and Endocytosis:  Endocytosis and exocytosis are active processes involving the bulk transport of materials through membrane, either into cells (endocytosis) or out of cells (exocytosis).  Endocytosis occurs by an enfolding or extension of the cell membrane to form a vesicle it is of two types. Page | 58  UNIT NO. 1 CELL CYCLE o Phagocytosis (cell eating) material taken up is in solid form. Cells specializing in the process are called phagocytes and are said to be phagocytic. For example, some white blood cells take up bacteria by phagocytosis. The sea formed during uptake is called a phagocytosis vacuole. o Pinocytosis (cell drinking) material taken up is in liquid form. The vesicles formed are often extremely small, in which case the process is known as micropinocytosis and the vesicles as micropincytosis vesicles.  Exocytosis is the reverse process of endocytosis. Waste materials may be removed from cells, such as solid, undigested remain from the pancreas is achieved in this way. Plant cells use exocytosis to export the material needed to form cell walls. Understand entire cell membrane in less than 10 minutes and watch practice questions in video 1.02b Structure of Cell Membrane at www.nearpeer.org THE NUCLEUS Page | 59  UNIT NO. 1 CELL CYCLE The Nucleus  The nucleus is the largest and most prominent organelles in the animal cell.  Almost all eukaryote cells have a nucleus – red blood cells in mammals and phloem cells in plants are a exception.  Every nucleus is surrounded by a nuclear envelope. This consists of two membranes that are separated by gap of 20 to 40 nm.  Nucleus may be irregular in shape and about 10 µm in diameter. It contains the cell’s DNA, which carries information that allows the cell to divide and carry out all its cellular processes.  Nucleus controls the life and activities of the cell.  In animal cells nucleus is generally present in the central part. In plant cells nucleus is pushed towards periphery due to a large central vacuole.  DNA/RNA and proteins (including enzymes) forms the chemical composition of coleus.  Nucleus consists of nuclear membrane, nucleoli, nucleoplasm and chromosomes.  The number of nuclear pores is highly variable. For example the undifferentiated cells (e.g. eggs) have many pores (about 30000 per nucleus) while the differentiated cells (e.g. erythrocytes)have only 3 or 4 pores/nucleus. Each pore has a definite structure.  Nucleus is a darkly stained structure within the nucleus. Nucleolus has no membrane. There are two regions of a nucleolus. (i) The Peripheral Granular Area: It contains the materials from which ribosomal subunits are formed. (ii) The Central FibrillarArea: It has large molecular weight RNA and rDNA. Page | 60  UNIT NO. 1 CELL CYCLE  The heredity material is in the form of chromosomes,which controls all the activities of the cell. Chromosome is formed of DNA and proteins.  Nucleus is visible when the cell is in non-dividing stage. It contains chromatin network and soluble sap called nucleoplasm. Dark staining chromatin, consisting of tightly packed DNA, is known as Heterochromatin. The lighter, more loosely packed material is called Euchromatin contains the DNA that is being actively read to produce proteins. In heterochromatin, the DNA is packed together and is not being read. Nucleus is stained with basic dyes because of the chromatin material. During cell division chromatin material is converted into darkly stained thread like structures called chromosomes  Chromosome is made of arms and centromeres. Centromere is the place on the chromosome where spindle fibres are attached during cell division. Each chromosome consists of two identical chromads at the beginning of cell division which are heldtogether at centromere. A chromatid is exact replica of the chromosome. Fig. Ultra structure of interphase nucleus The information to control cell activities is present on the chromosomes in the form of genes. The chromosome number varies which may be 2n = 2 to 2n = 1200 (Pteridophytes). Page | 61  UNIT NO. 1 CELL CYCLE The number of chromosomes in all individuals of the same species remains constant generation after generation. Some examples of chromosome No. are: Frog = 26, Chimpanzee = 48. Fruit fly (Drosophila melanogaster) = 8, Wheat = 42, Onion = 16, Potato. = 48. Garden pea = 14. Penicillium(a fungus) has two chromosomes (one pair), corn 20, wheat 42, sugarcane 80, some ferns have more than 500 pairs, mosquito 6, fruit fly 8, frog 26, honey bee 32, mouse 40 and human cells have 46 chromosomes (23 pairs). The number of chromosomes in normal body cells is diploid (2n) while the gem cells (sperms and eggs) have haploid chromosome number (11). Examples: Human germ cells (eggs and sperms) = 23 chromosomes. Drosophila germ cells = 4 chromosomes. ENDOPLASMIC RETICULUM (ER) The nuclear envelope joins with the membrane of the endoplasmic reticulum (ER). It is a system of complex network spreaded throughout the cell. These are present in Eukaryotic cells & are of two types: RER & SER. On the outside surface of the RER are ribosomes. The main function of RER is to keep together and transport the proteins made on the ribosomes. Instead of simply diffusing away into the cytoplasm, newly made proteins enter into RER. Here they fold into three-dimensional shape. A mature cell that makes and secretes large amounts of protein – suchas one that makes digestive enzymes – has RER that occupies as much as 90 per cent of the total volume of the cytoplasm. PER is also a storage unit for enzymes and other proteins. Page | 62  UNIT NO. 1 CELL CYCLE Small vesicles containing newly synthesized proteins pinch off from (he ends of the RER and either fuse with the Golgi complex or pass directly to the cell surface membrane. ER with no ribosomes attached is known as SER. Smooth ER is not involved in protein synthesis but is the site of steroid (lipid hormone) production. It also contains enzymes that detoxify, or make harmless, a wide variety of organic molecules, and it acts as a storage site for calcium in skeletal muscle cells. The channels having material present in them which is separated from the cytoplasmic materials by the spherical or tubular membranes is called cisternae. E.R provides mechanical support to the cell. In some cells SER transmit impulses. For example nerve and muscle cells. Both RER and SER are involved in the transportation of materials from one part of the cell to the other. Difference between two type of ER: Smooth (Agranular) and rough (granular) Smooth Endoplasmic Reticulum (SER) Rough Endoplasmic Reticulum (PER) (i) It does not bear ribosomes over the surface (i) It possesses ribosomes attached to its of its membranes. membranes. (ii) It is mainly formed of, vesicles and tubules. (ii) It is mainly formed of cisternae and a few tubules. (iii) It is engaged in 'the synthesis of glycogen, (iii) It takes part in the synthesis of lipids and steroids. proteins and enzymes RIBOSOMES Ribosomes were discovered by Palade in 1955. Ribosomes are small dense organelles, about 20 nm in diameter present in great numbers in the cell. Most are attached to the surface of RER but they can occur free in the cytoplasm. Page | 63  UNIT NO. 1 CELL CYCLE Ribosomes are made from a combination of rRNA and protein. Eukaryotic ribosomes are compose-I of an equal quantity of RNA and protein. Therefore they are also called asribonucleo proteins. Ribosomes are involved in protein synthesis. They assemble amino acids in the rightorder to produce new proteins. The ribosome uses the code on' messenger RNA (mRNA) to put amino acid together in chains to form specific proteins. Generally proteins that are to be used inside the cell are made on free ribosome while those that are to be secreted out of the cell are made on ribosomes that are bound to ER membranes. New ribosomes are formed in the nucleolus. Eukaryotic ribosome is 80 S (60 S + 40 S). Mg++ controls this attachment. A group of ribosomes attached to the same mRNA are called polysomes. Nucleolus is a factory of ribosomes while ribosomes are the factory of protein synthesis. Fig. 80 S and 70 S Ribosome Page | 64  UNIT NO. 1 CELL CYCLE THE GOLGI COMPLEX The Golgi apparatus/Golgi complex was discovered by Comillo Golgi in 1898. It is found in eukaryotic cells. Golgi apparatus consists of stacks of flattened membrane bound sacs or flattened cavities or vesicles called Cisternae (5 – 8). The whole organelle is a shifting, flexible structure; vesicles are constantly being added at one side and lost from the other. Generally, vesicles fuse with the forming face (the one nearest to the nucleus) and leave from the maturing face (the one nearest to the cell surface membrane). Golgi complex has proteins, carbohydrates, glycoproteins and some enzymes. The (Golgi complex appears to be involved with the synthesis and modification of proteins. lipids and carbohydrates. Major functions of Golgi complex are formation of conjugated molecules and Secretions. Proteins made on the ribosomes attached to ER are packaged into the vesicles by the ER.Some of the vesicles join with the Golgi complex and the proteins they contain are modified before they are secreted out of the cell. Golgi apparatus + Golgi vesicles = Golgi complex Secretions are products formed in the cells on ribosomes and then pass to the outside through endoplasmic reticulum and Golgi apparatus. In plants Golgi apparatus is involved in the synthesis of cell wall. Page | 65  UNIT NO. 1 CELL CYCLE MITOCHONDRIA Watch Video 1.05 of 2nd Module at www.nearpeer.org for the practice question of Golgi Complex MITOCHONDRIA Mitochondria are important organelles of eukaryotic cells. They manufacture and supply energy to the cell. Therefore they are also called powerhouse of the cell. Mitochondria are particularly abundant in metabolically active cells, tissues such (is muscle and tissues involved in active transport. The size (0.5 – 1.5 µn wide) and number of mitochondria varies and depend upon the physiological activity of the cell. Page | 66  UNIT NO. 1 CELL CYCLE Under compound microscope mitochondria may be rod shaped, vesicles or filaments. In Electron Microscope, Mitochondria have two membranes, outer smooth and inner with aristae. The inner surface of aristae in the mitochondrial matrix has small knob like structures called F1 particles. These are involved in ATP formation. Mitochondrial matrix contains enzymes, coenzymes and organic and inorganic salts. Mitochondria also contain DNA and ribosomes. Mitochondrial matrix helps in metabolic processes like Kerb's cycle, aerobic respiration and fatty acid metabolism etc. Their main function is to make ATP via the process of aerobic respiration. ATP diffuses into the cell and provides instant chemical energy. Mitochondria have a double membrane; the outer membrane is smooth while the inner one is folded. This arrangement gives as large internal surface area on which the complex reactions of aerobic respiration can take place. Mitochondrion is a self-replicating organelle. Fig. Structure of a Mitochondrion Page | 67  UNIT NO. 1 CELL CYCLE CENTRIOLES Centrioles are present in animal cells, some microorganisms and lower plants. They are absent in higher plants. Centrioles are short bundles of filaments, set at right angles to each other. They are found in a clear area of cytoplasm known as the centrosome. In a cross section, each centriole consists of a cylindrical array of 9 microtubules,each microtubule has 3 tubules. The tubules are composed of special protein caned tubulin. The chemical composition and structure is similar to that of cilia and flagella. Their function is the formation of spindle (that guides the chromosomes during cell division). In addition to spindle formation, the centrioles act as the centre of