Biology Paper 1 Questions and Answers - Mang'u Mock 2020 Exam

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BIOLOGY
PAPER 1
TIME: 2 HOURS.

Instructions to candidates

  • Answer ALL the questions

 

  1. During initial stages of respiration one molecule of glucose is split into two molecules eách a 3 carbon compound. State;
    1. The name given to this initial stage.(1mk)
    2. The name of the 3-carbon compound formed.(1mk)
    3. Where the initial stages occur in cells. (1mk)
    4. The total number of ATP molecules formed during this initial stage.(1mk)
  2. Describe the events that lead to inhalation in fish.(4mks)
  3. What is meant by the following term?
    1. Crenated cell.(1mk)
    2. Flaccid cell.(1mk)
  4. An individual is of blood group A positive.
    1. Name the antigens in the individual's blood.(2mks)
    2. Give the reason why the individual cannot receive blood from a blood group B donor.(2mks)
  5. How is the human stomach adapted to;
    1. Protein digestion?(2mks)
    2. Churning?(2mks)
  6. The diagram below shows one of the nerve cells. Use it to answer the question that follow.
    p1q6
    1. Identify the cell.(1mk)
    2. Name the cell that transmit impulse to part A.(1mk)
    3. State one structural difference between motor and sensory neurone.(1mk)
  7.    
    1. During germination and early growth, dry weight of endosperm decreases while that of the embryo decreases. Explain.(2mks)
    2. State three internal conditions with seeds that are necessary for germination.(3mks)
  8. State three physiological mechanism of controlling the human body temperature during a hot day.(3mks)
  9. Air is forced into the lungs when the pressure in the thoracic cavity is lowered below the atmosphere pressure. How is the pressure in the thoracic cavity lowered?(3mks)
  10.    
    1. Name a genetic mutation disorder that illustrates a case of incomplete dominance in human beings. (1mk)
    2. State the survival advantage associated with the trait named above.(1mk)
  11. Name two structures in a mammalian body with ciliated epithelial tissue.(2mks)
  12. The diagrams below represent results of an animal cell that has undergone meiosis I.
    p1q12
    1. Name the stage of meiosis II represented by the above diagram.(1mk)
    2. Describe the next stage of meiosis II.(2mks)
    3. Describe events that occurred in meiosis I that lead to the reduction in the number of chromosomes by half.(3mks)
  13. The paddles of whales and fins for fish adapt these organisms to aquatic habitat.
    1. Name the evolutionary process that may have given rise to these structures. (1mk
    2. What is the name given to such structure?(1mk)
    3. Give two examples of vestigial organs in man.(2mks)
  14. The diagram below illustrates germinated pollen grains.
    p1q14
    1. Name the part labeled B.(1mk)
    2. Explain the role of part labeled A during fertilization.(2mks)
    3. State the structural difference between pollen grains produced by insect and wind pollinated flowers.(2mks)
  15. Using a simple but well labeled diagram illustrate the reflux arch during a knee jerk reflex which occurs when the knee is tapped below the knee. (6 mks)
  16. State four structural differences between class arachnida and insect. (4 mks)
  17. The chart is a summary of a certain process in plants. Study it and answer the questions that follow.
    p1q17
    1. Identify the process and organelle in which it takes place
      Process___________________Organelle______________________(2 mks)
    2. Identify the process X and Y
      X___________________Y______________________(2 mks)
    3. Identify the gases C and P
      C___________________P______________________(2 mks)
    4. What is the role of substance D in the process (1 mk) 
    5. Name the products E and process Z(2 mks)
  18.  Name the fins in a bony fish which the following functions
    1. Changing direction(1 mk)
    2. Control pitching(1 mk)
    3. Control yawing.(1 mk)
  19. State three structural differences between DNA and RNA (3 mks)
  20. The graph below shows relative levels of hormones during human menstrual cycle.
    p1q20
    1. By labeling P and Y identify the curve that represents oestrogen and progesterone respectively (2 mks)
    2. What is the role of the above named hormones during menstrual cycle?
      1. Progesterone (1mk)
      2. Oestrogen(2 mks) 
    3. On the graph draw a curve to show relative changes in the level of luteinizing hormone. (1 mk)

MARKING SCHEME

  1. During initial stages of respiration one molecule of glucose is split into two molecules eách a 3 carbon compound. State;
    1. The name given to this initial stage.(1mk)
      • Glycolysis

    2. The name of the 3-carbon compound formed.(1mk)
      • Pyruvic acid, pyruvate

    3. Where the initial stages occur in cells. (1mk)
      • Cytoplasm

    4. The total number of ATP molecules formed during this initial stage.(1mk)
      • Four

  2. Describe the events that lead to inhalation in fish.(4mks)
    • Muscles during the buccal cavity contract: lowering the floor of the mouth; decreasing pressure but increasing volume; fish opens the mouth; and water flows into the mouth; operculum bulges outwards; while operculum slows pressure against the body, this lowers pressure in gill chambers and water in the mouth flows to the gills.

  3. What is meant by the following term?
    1. Crenated cell.(1mk)
      • An animal cell that has shrunk due to loss of water by osmosis.

    2. Flaccid cell.(1mk)
      • A plant cell that is flabby shrunk due to loss of water by osmosis.

  4. An individual is of blood group A positive.
    1. Name the antigens in the individual's blood.(2mks)
      • Antigen A - Rhesus antigen/ rhesus factor

    2. Give the reason why the individual cannot receive blood from a blood group B donor.(2mks)
      • He/she have bantibodies that will correspond with B antigen from the donor, causing agglutination.

  5. How is the human stomach adapted to;
    1. Protein digestion?(2mks) - Has gastric glands that secret gastric juice/ pepsin/renin.

    2. Churning?(2mks) - Has thick muscular wall that contract and relax (to mix food with digestive enzymes/ enhance mechanical digestion.

  6. The diagram below shows one of the nerve cells. Use it to answer the question that follow.
    p1q6
    1. Identify the cell.(1mk) 
      Relay/intermediate interneuron

    2. Name the cell that transmit impulse to part A.(1mk)
      Sensory neurone

    3. State one structural difference between motor and sensory neurone.(1mk)
      Motor neurone has one nerve fibre while sensory has two.

  7.    
    1. During germination and early growth, dry weight of endosperm decreases while that of the embryo decreases. Explain.(2mks)
      • Food stored in the endosperm is hydrolysed andoxidized to provide energy, thus decrease in weight while embryo undergoes mutation cell division leading to growth;

    2. State three internal conditions with seeds that are necessary for germination.(3mks)
      • Enzymes
      • Hormones germination promoters
      • Viability of the seed.

  8. State three physiological mechanism of controlling the human body temperature during a hot day.(3mks)
    • Vasodilation of blood capillaries;.
    • Increased sweat production
    • Erector pilli muscles relax
    • Decreased metabolism

  9. Air is forced into the lungs when the pressure in the thoracic cavity is lowered below the atmosphere pressure. How is the pressure in the thoracic cavity lowered?(3mks)
    • Contraction of external intercostal muscles and relaxation of internal intercostal muscles; thus raising rib cage upwards and outwards; while diaphragm muscles relax flattening the diaphragm; thus lowering pressure.
  10.    
    1. Name a genetic mutation disorder that illustrates a case of incomplete dominance in human beings. (1mk)
      • Sickle cell trait

    2. State the survival advantage associated with the trait named above.(1mk)
      • Individual have increased resistance to malaria 

  11. Name two structures in a mammalian body with ciliated epithelial tissue.(2mks)
    • Fallopian tube;
    • Trachea -

  12. The diagrams below represent results of an animal cell that has undergone meiosis I.
    p1q12
    1. Name the stage of meiosis II represented by the above diagram.(1mk)
      • Metaphase II

    2. Describe the next stage of meiosis II.(2mks)
      • Chromatids separate at centromere point; and migrate to opposite poles:

    3. Describe events that occurred in meiosis I that lead to the reduction in the number of chromosomes by half.(3mks)
      • Synapsis - pairing of homologous chromosomes,
      • Arrangement of homologous chromosomncs at the equator o the spindle and during metaphase I.
      • Separation of homologous chromosomes and migration of individual homologous chromosomes to opposite poles.

  13. The paddles of whales and fins for fish adapt these organisms to aquatic habitat.
    1. Name the evolutionary process that may have given rise to these structures. (1mk)
      • Divergent evolution

    2. What is the name given to such structure?(1mk)
      • Homologous structures

    3. Give two examples of vestigial organs in man.(2mks)
      • Coccyx Appendix Nictating membrane
      • Body hair Muscles that move the car.

  14. The diagram below illustrates germinated pollen grains.
    p1q14
    1. Name the part labeled B.(1mk)
      • Pollen tube nucleus

    2. Explain the role of part labeled A during fertilization.(2mks)
      • One male nucleus fuse with egg cell to form a zygote while the other with polar nuclei to form tripod nucleus primary endosperm nucleus.

    3. State the structural difference between pollen grains produced by insect and wind pollinated flowers.(2mks)
      • Pollen grains produced by insect pollinated flowers are large/ heavy and smooth/ stick; polar grains while from wind pollinated flowers are small, smooth and light.

  15. Using a simple but well labeled diagram illustrate the reflux arch during a knee jerk reflex which occurs when the knee is tapped below the knee. (6 mks)
    biop1qa15
  16. State four structural differences between class arachnida and insect. (4 mks)
    Arachnida Insects
    Has two body parts/ cephalothorax and abdomen  Has three body parts, head, thorax and abdomen 
    Have no antennae Has a pair of antennae
    Have four two pairs of walking legs Has three pairs of walking legs
    Has eight simple eyes on cephalothorax As a pair of compound and several simple eyes on its head
    Has two chelicerae on ventral side of cephalothorax Has no chelicerae on its ventral side
     
  17. The chart is a summary of a certain process in plants. Study it and answer the questions that follow.
    p1q17
    1. Identify the process and organelle in which it takes place
      Process - Photosynthesis  Organelle - Chloroplast    (2 mks)
    2. Identify the process X and Y
      Process X   Photolysis      Y - Carbon IV Oxide fixation(2 mks)
    3. Identify the gases C and P
      Gas C - Oxygen  P - Carbon (IV) oxide (2 mks)
    4. What is the role of substance D in the process (1 mk) 
      • Reacts/ reduces carbon (IV) oxide leading to formation of sugar;

    5. Name the products E and process Z(2 mks)
      • C-Glucose
      • Z-Condensation

  18.  Name the fins in a bony fish which the following functions
    1. Changing direction(1 mk) - Pectoral fins
    2. Control pitching(1 mk) - Pelvic and pectoral fins
    3. Control yawing.(1 mk) - Dorsal and anal fins

  19. State three structural differences between DNA and RNA (3 mks)
    DNA RNA
    Double stranded/ double helix Single stranded
    Has rhythm Has uracil instead of rhythm
    Has deoxyribose sugar Has ribose sugar
  20. The graph below shows relative levels of hormones during human menstrual cycle.
    p1q20
    1. By labeling P and Y identify the curve that represents oestrogen and progesterone respectively (2 mks)
      biop1qa20
    2. What is the role of the above named hormones during menstrual cycle?
      1. Progesterone (1mk) - to promote stimulate thickening of the uterine walis:
      2. Oestrogen(2 mks) - Stimulate repair of uierine wall endometrium; stimulate pituitary glands to secrete luteinizing hormone
    3. On the graph draw a curve to show relative changes in the level of luteinizing hormone. (1 mk)

 


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