Biology Paper 2 Questions and Answers - Form 4 Opener Term 1 Exams 2022

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Answer all the questions in this section in the spaces provided.

    1. The diagram below represents a plant in the division Bryophyta.
      1. Name the parts labeled B and D. (2marks)
      2. State one function for each of the parts labeled A and C. (2marks)
    2. The diagram below represents a member of the kingdom Animalia.
      1. Name the phylum to which the organism belongs. (1mark)
      2. Using observable features in the diagram, give three reasons for the answer in b(i). (3marks)
  2. The set up below illustrates a procedure that was carried out in the laboratory with a leaf plucked from a green plant that had been growing in sunlight.
    1. What was the purpose of the above procedure. (1mark)
    2. Give reasons for carrying out steps A,B and C in this procedure. (3marks)
    3. Name the reagent that was used at the step labeled D. (1 mark)
    4. State the expected result on the leaf after adding the reagent named in (iii0 above. (1mark)
  3. The chart below represents the result of successive crosses, starting with red flowered plants and white flowered plants and in which both plants are pure breeding.
    1. What were parental genotypes? Use letter R to represent the gene for red colour and r for white colour. (2marks)
      1. What was the colour of the flowers in the first filial generation? (1mark)
      2. Give a reason for your answer in (b)(i) above. (2marks)
    3. 480 red flowered plants were obtained in the second filial generation, how many F2 plants were white coloured plants? Show your working. (3marks)
  4. The diagram below represents a mammalian nephrone.
    1. Name the:
      1. Structure labeled P. (1mark)
      2. Portion of the nephrone between point X and Y. (1mark)
    2. Name the process that takes place at point Q. (1mark)
    3. Name one substance present at point R but absent at point S in a healthy human. (1mark)
    4. The appearance of the substance you have named in (c above is a symptom of a certain disease caused by a hormone deficiency.
      Name the :
      1. Disease (1mark)
      2. Hormone (1mark)
    5. State the structure modifications of nephrones found in desert mammals. (2marks)
    6. State two advantages terrestrial animals have in excreting urea as their main nitrogenous waste product. (2marks)
  5. In an experiment on respiration ,a mouse was observed to have inhaled 200cm3 of oxygen and exhaled 199.75cm3 of carbon (IV)Oxide in ten minutes.
    1. Calculate the respiratory quotient for the activity in the experiment. (2marks)
    2. Identify the possible food substance consumed by the mouse.
    3. State the fate of the excess food named in (b)above in the human body. (2marks)
    4. Name the three end products of anaerobic respiration in plants.

Answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8

  1. A scientist carried out an investigation to find out the population growth of mice under laboratory conditions. Twenty young mice were placed in a cage. The results obtained from the investigation were as shown in the table below.
    Time in months 0 2 4 6 7 10 12 16 18
    Number of mice 20 20 65 115 310 455 450 145 160

    1. On the grid provided, draw a graph of the number of mice against time. (6marks)
    2. Account for the changes in mice population between.
      1. 0 to 2 months. (2marks)
      2. 2 to 6 months (2marks)
      3. 6 to 10 months (2marks)
      4. 10 to 12 months (2 marks)
      1. Between which two months was the population change greatest? (1mark)
      2. Calculate the rate of population change over the period in (c) (i) above. (2marks)
    4. What change in population was continued to the 19th month?
    5. To obtain the observed results state two variables that were kept constant during the investigation.

Marking Scheme 

      1. B - Seta
        D - Rhizoid
      2.  A - Contains spore bearing structures that bear spores
        C - Contains chlorophyll for photosynthesis
      1. Arthropoda
        • Has jointed appendages
        • Presence of exoskeleton
        • Body is divided into head, thorax and abdomen hence segmented
        • Has spiracles hence gaseous exchange is through trachea system
    1. Testing (a leaf) for the presence of starch
      • Step A: Kill the leaf/cells/ protoplasm/stop enzymatic activity/ denature enzymes
      • Step B: Removal of chlorophyll/ dissolve chlorophyll decolourise the leaf
      • Step C: Soften leaf/ makes leaf less brittle
      • Iodine solution
      • Reject iodine alone
    4. Stain dark blue/ blue-black
    1. RR and rr
      1. Red
      2. Red is completely dominant over white colour i.e, Red is dominant while white is recessive
    3. Ratio of F2 generation = 3:1 (i.e in every 4 flowers 3 are red, 1 is white)
      Therefore 480 red flowers means 3/4 of the total number i.e 3/4 = 480
      Total numbers of flowers = 480 x 4 = 640
      White flowers in F2 plants = 1/4 x 640 = 160
      = 160 white flowered.
      1. Efferent arteriole
      2. Loop of henle
    2. Ultrafiltration
      • Glucose
      • Amino acids
      1. Diabetes mellitus
      2. Insulin
      • Small Bowman's capsule/ glomerulus
      • Long loop of henle
      • Urea is less toxic and soluble in water thus easy to excrete
      • Requires less water to eliminate hence prevents loss of water maintaining normal blood osmotic pressure.
      • Respiratory quotient = volume of carbon (IV) oxide produced
                                               volume of oxygen consumed
        = 199.75cm3
        = 0.999
        ≈ 1.0
    2. Carbohydrates
      • Excess glucose (a form of carbohydrate) is converted to glucogen fro storage in the liver and muscle cells
      • Glucose is oxidised to releases energy
      • Further excess carbohydrate in form of glucose is converted to fat for storage as a dispose tissue.
      • Ethanol/ alcohol
      • Energy/ Adenosine triphosphate
      • Carbon (IV)oxide
        • Population growth of mice is constant due to:
        • The mice are still immature for reproduction
        • Mice are still adjusting to their new environment
        • Population growth of mice rose steadily/ had a slow growth due to
        • Few number of mice have reached maturity
        • Plenty of food for the mice
        • Mice are already adjusted to their new environment.
        • Rapid population growth due to
        • There are many rats that were healthy thus able to reproduce, leading to massive growth in num bers
      4.  The population was decreasing because of reduced resources as the number of rats became more        
      1. 12 - 16    
    4.   Increase in population.
      • Food & water( nutritional) supply
      • Size of habitat.
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