Biology Paper 2 Questions and Answers - Maranda Mock Examinations 2022

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Instructions to candidates

  1. This paper consists of two sections; A and B Answer all the questions in section A in the spaces provided
  2. In section B answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8

QUESTIONS

  1. The diagram below represents a plant tissue
    1 adada
    1. Name the structures L and O (2 marks)
      L
      O
    2. State the function of structure N and cell labelled M (2marks)
      N
      M
    3. Give two structural differences between phloem tissue and xylem tissue (2marks)
    4. Distinguish between active and passive immunity (2marks)
  2. The following figures represent the forelimb of a certain animal species Study them and answer the questions that follow
    2 adadad
    1. Name the bones labelled E and G (2marks)
      E
      G
    2. State the type of skeleton represented by figure 1 (1mark)
    3. Name the type of joint at point Q (1mark)
    4. Which two figures represent analogous structures? (1mark)
    5. Give adaptational differences between structures in figure 1 and 3 (3 marks)
  3. Colour blindness is a disorder caused by gene mutation and it is controlled by a recessive gene A man with normal colour vision marries a carrier woman:
    1. Using letter B to represent the gene for normal color vision, what is the chance that their son will be colour blind? Show your working (4marks)
    2. Name another trait in humans inherited in the same way as colour blindness (1mark)
    3. Briefly describe inversion in gene mutation (1mark)
    4. Distinguish between back cross and testcross (2marks)
  4.                  
    1. Nitrogen in the atmosphere cannot be directly utilized by plants State two ways by which this nitrogen is made available for plant use (2marks)
    2. State the importance of saprophytic bacteria in the environment (1mark)
    3. Briefly explain the how excessive use of fertilizers affects the large water bodies (3marks)
    4. Explain how competition regulates the animal population in a habitat (2marks)
  5. The figure below shows the parts of the human digestive system Study it and answer the questions that follow
    5 adadad
    1. Name the organs labelled A, B and D (3marks)
      A
      B
      D
    2. State the role of part labelled C (1mark)
    3. Name the two salivary glands in human beings (2marks)
    4. Give two adaptations of part labelled D to its function (2marks)
  6. An experiment was carried out to investigate transpiration and absorption of water in sunflower plants in their natural environment with adequate supply of water The amount of water was determined in a two hour intervals The results are as shown in the table below

    TIME OF THE DAY

    AMOUNT OF WATER IN GRAMMES

     

    Transpiration

    Absorption

    11:00-13:00

    33

    20

    13:00-15:00

    45

    30

    15:00-17:00

    52

    42

    17:00-19:00

    46

    46

    19:00-21:00

    25

    32

    21:00-23:00

    16

    20

    23:00-01:00

    8

    15

    01:00-03:00

    4

    11

    1. Using the same axes, plot graphs to show transpiration and absorption of water in grammes against time of the day (7marks)
      graph paper adaaa
    2. At time of the day was the amount of water the same for transpiration and absorption? (1 mark)
    3. Account for the shape of the graph of :
      1. transpiration (3marks)
      2. absorption (3marks)
    4. What would happen to transpiration and absorption of water if the experiment was continued till 0500 hours? (2marks)
    5. Name two environmental factors that may affect rate of transpiration and absorption at any given time  (2marks)
    6. Explain how the factors you named in (e) above affect transpiration (2marks)
  7.                
    1. Explain how blood sugar is regulated in the human body (12marks)
    2. Explain the adaptation of the mammalian skin to thermoregulation (8marks)
  8.                  
    1. Describe the factors that make the leaf of a terrestrial plant to absorb maximum light for photosynthesis (12marks)
    2. Describe how support is achieved in herbaceous plants and shrubs (8marks)

MARKING SCHEME

  1. The diagram below represents a plant tissue
    1 adada
    1. Name the structures L and O (2 marks)
      L sieve plate
      O plasmodema; rej plural - plasmodesmata
    2. State the function of structure N and cell labelled M (2marks)
      N allows for continuous movement of manufactured food substances along them
      M provide energy for translocation; 
      regulate activities of the sieve tube cells
    3. Give two structural differences between phloem tissue and xylem tissue (2marks)
       Phloem  xylem
       made of living cells  made of dead cells
       has cross walls that form sieve plates  lack cross walls
    4. Distinguish between active and passive immunity (2marks)
      passive immunity is a type of immunity that results from transfer of antibodies from one animal to the other while active immunity is a type of immunity where the animal's body produces its own antibodies
  2. The following figures represent the forelimb of a certain animal species Study them and answer the questions that follow
    2 adadad
    1. Name the bones labelled E and G (2marks)
      E humerus
      G carpal; rej plural
    2. State the type of skeleton represented by figure 1 (1mark)
      endoskeleton
    3. Name the type of joint at point Q (1mark)
      Hinge
    4. Which two figures represent analogous structures? (1mark)
      fig 2 and fig 3;
    5. Give adaptational differences between structures in figure 1 and 3 (3 marks)
      human hand has 5 digits separated into four fingers and an opposable thumb; for hrasping or manipulation; while bat wing has 5 digits which are long and spread out; to support a large membranous wing for flight
  3. Colour blindness is a disorder caused by gene mutation and it is controlled by a recessive gene A man with normal colour vision marries a carrier woman:
    1. Using letter B to represent the gene for normal color vision, what is the chance that their son will be colour blind? Show your working (4marks)
      3 ans adadd
    2. Name another trait in humans inherited in the same way as colour blindness (1mark)
      haemophilia; Duchane muscular dystrophy
    3. Briefly describe inversion in gene mutation (1mark)
      portion DNA strand breaks at two points, rotates through 180º and thus rejoins in an inverted manner
    4. Distinguish between back cross and testcross (2marks)
      back cross is a cross between an offspring with unknown parental geotype while test cross is a cross between an individual of unknown genotype with a homozygous recessive individuals
  4.                  
    1. Nitrogen in the atmosphere cannot be directly utilized by plants State two ways by which this nitrogen is made available for plant use (2marks)
      fixation by lighting
      fixation by micro-organisms eg. nitrogen fixing bacteria/algae
    2. State the importance of saprophytic bacteria in the environment (1mark)
      decomposition of dead organic matter releasing nutrients in the soil
    3. Briefly explain the how excessive use of fertilizers affects the large water bodies (3marks)
      causes rapid growth of photo planktons / small water plants; leading to low light intensity in water hence decreasing primary productivity
    4. Explain how competition regulates the animal population in a habitat (2marks)
      organisms with advantagious variations survive and continue with the generation; while those with disadvantagious varions migrate or die;
  5. The figure below shows the parts of the human digestive system Study it and answer the questions that follow
    5 adadad
    1. Name the organs labelled A, B and D (3marks)
      A gall bladder
      B liver
      D illeum
    2. State the role of part labelled C (1mark)
      secretion of hormones insulin and glycogen
      secretion of pancreatic juice/digestive enzymes e.g. pancreatic lipase/ amylase
    3. Name the two salivary glands in human beings (2marks)
      sublingual
      submandibulars
      parotid
    4. Give two adaptations of part labelled D to its function (2marks)
      long to increase the surface area for absorbtion / digestion of food
      highly coiled to reduce the movement of digested fod allowing more time for absorption
      inner walls have villi / microvilli to increase  surface area for absorptions
      lacteals for absorption of fatty acids and glycerol
      thin epithelium to reduce distance for absorption
  6. An experiment was carried out to investigate transpiration and absorption of water in sunflower plants in their natural environment with adequate supply of water The amount of water was determined in a two hour intervals The results are as shown in the table below

    TIME OF THE DAY

    AMOUNT OF WATER IN GRAMMES

     

    Transpiration

    Absorption

    11:00-13:00

    33

    20

    13:00-15:00

    45

    30

    15:00-17:00

    52

    42

    17:00-19:00

    46

    46

    19:00-21:00

    25

    32

    21:00-23:00

    16

    20

    23:00-01:00

    8

    15

    01:00-03:00

    4

    11

    1. Using the same axes, plot graphs to show transpiration and absorption of water in grammes against time of the day (7marks)
      graph filled ad
    2. At time of the day was the amount of water the same for transpiration and absorption? (1 mark)
      1700 - 1900 hrs
    3. Account for the shape of the graph of :
      1. transpiration (3marks)
        1100 - 1700 hrs: increase in the rate of transpiration due to high light intensity / high temperature
        1700 - 0300 hrs : decrease in rate of transportation due to low light intensity / absence of light / low temp
      2. absorption (3marks)
        1100- 1900 hrs: increase in rate of absorption of water; to replace water lost through transpiration 
        1900 - 0300 hrs: decrease in rate of absorption of water ; due to decline in transpiration rate
    4. What would happen to transpiration and absorption of water if the experiment was continued till 0500 hours? (2marks)
      both transpiration and absorption would decrease
    5. Name two environmental factors that may affect rate of transpiration and absorption at any given time  (2marks)
      • wind
      • humidity
      • atmospheric pressure
      • light intensity
      • temperature
    6. Explain how the factors you named in (e) above affect transpiration (2marks)
      • wind - rate of transpiration is faster in windy conditions / lower when air is still
      • humidity - low humidity causes high rate of transpiration due to high saturation deficit / conc gradient / high humidity leads to low rate of transpiration due to low saturation deficit 
      • Atmospheric pressure - low atmospheric pressure causes high rate of transpiration / high atmospheric pressure causes low rate of transpiration
      • Light intensity - high light intensity leads to high rate of transpiration and vice versa
      • temperature - high temperature leads to high rates of transiration and vice versa
  7.                
    1. Explain how blood sugar is regulated in the human body (12marks)
      normal blood sugar level is about 90mg/100cm3 ;increase  in blood sugar above normal is detected by the hypothalamus; which then send nerve impulses to pancreatic cells/ islets of langerhans; that are stimulated to secret insulin hormone ; insulin stimulates liver cells; to convert excess glucose to glycogen / fats, excess glucose is also oxidised to release energy; this reduces glucose level back to normal;
      Decrease in blood sugar level below optimum is detected by the hypothalamus that send impulses to the pancreatic cells/ islets of langerhans, which OR stimulated to secret glucagon hormone; glycogen stimulates liver cells to convert glycogen to glucose ; fats and amino acids are converted to glucose; reduced oxidation of glucose ; this increases the level of glucose in blood to normal
    2. Explain the adaptation of the mammalian skin to thermoregulation (8marks)
      • sweat glands secret more sweat ; when temperatures are high water in sweat evaporates absorbing latent heat of vapourisation; hence cooling the body
      • when temperatures are low, hairs stand upright; when erector pili muscles contract ; trapping air to insulate / reduce heat loss, hairs lie flat; to allow heat loss when temperatures are high
      • vasodilation; when temperatures are high to enhance heat loss; vasoconstriction when temperatures are low to minimise heat loss;
      • subcutaneous layer; insulates the body against heat loss
  8.                  
    1. Describe the factors that make the leaf of a terrestrial plant to absorb maximum light for photosynthesis (12marks)
      • thinnes; the leaf to reduce distance ; for maximum absorption of light
      • broad lamina; to provide large surface area; for maximum light absorption
      • numerous chloroplasts in the palisade mesophyll; with more chlorophyll pigment for maximum trapping light
      • leaf mosaic; to minimise overlapping and overshadowing
      • transparent cuticle ; to allow light to pass through
      • palisade mesophyll found beneath the upper epidermis ; to receive maximum light for photosynthesis
    2. Describe how support is achieved in herbaceous plants and shrubs (8marks)
      • turgidity of parenchyma cells; the cells take in water by osmosis; become turgid and closely packed ; hence providing mechanical support
      • twinning around other plants; in some plants
      • use of tendrils; in some plants
      • use of hooks; in some plants
      • some herbaceous plants use collenchyma cells ; where walls are thickeneed with cellulose ; to provide mechanical support
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