Biology Questions and Answers - Form 2 Mid-term Exams Term 1 2022

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QUESTIONS

Answer all the questions in the spaces provided.

  1.              
    1. State the function for co-factors in cell metabolism. (1 mk)
    2. Give one example of a metallic co-factor. (1 mk)
  2. The diagram below shows all human tooth.
    2 auiygduyad
    1. Identify the tooth . (1 mk)
    2. How is the tooth adapted to its function. (2 mks)
    3. State the role of the following vitamins in the human body. (2 mks)
  3. Name two enzymes in the human digestive system which are secreted in an active form.
  4. Name the part of chloroplast where the following reactions occur. (2 mks)
    1. Carbon (IV) oxide fixation.
    2. Photolysis.
  5. Explain the importance of the following in photosynthesis. (3 mks)
    1. Light –
    2. Carbon (iv) oxide –
  6. The diagram below represents a transverse section of a young stem.
    6 aiuhdua
    1. Name the part labeled A and B. (2 mks)
    2. State the function of the parts labeled C, D and E. (3 mks)
    3. List three differences between the section shown above and one that would be obtained from the root of the same plant. (3 mks)
      ROOT  STEM 
         
         
         
         
  7. State three ways in which xylem vessels are adapted to their functions. (3 mks)
  8. Name two processes that bring about the translocation of manufactured food. (2 mks)
  9. The diagram below shows a section of a plant organ.
    9 aiuyhduiad
    1. Name the part of the plant on which the organ above was obtained (1 mk)
    2.                      
      1. Name the class to which the plant organ was obtained. (1 mk)
      2. Give a reason for your answer in (b) (i) above. (1 mk)
    3. Name the part labeled X. (1 mk)
  10. Distinguish between haemolysis and plasmolysis.
    1. Haemolysis . (1 mk)
    2. Plasmolysis - (1 mk)
  11. State the function of the following cell organelles.
    1. Ribosome - (1 mk)
    2. Lysosome - (1 mk)
  12.                      
    1. What is a single circulatory system. (1 mk)
    2. Name an organism which has single circulatory system. (1 mk)
    3. Name the opening to the chamber of the heart of an insect. (1 mk)
  13.                      
    1. Explain two roles of diffusion in human being. (4 mks)
    2. What is meant by each of the following terms?
      1. Crenated cell. (1 mk)
      2. Flaccid. (1 mk)
  14. A spotted plant was kept in the dark for 48 hours. Two leaves X and Y were treated as shown in the diagram below.
    14 auihuidhad
    The experimental set up was kept in sunlight for six hours after which a starch test was carried out on the two leaves.
    1. What were the results of the starch test on leaves X and Y. (2 mks)
    2. Give reasons for your answer in (a) above. (2 mks)
  15. Name one end product of dark reaction in photosynthesis. (1 mk)

MARKING SCHEME

Answer all the questions in the spaces provided.

  1.              
    1. State the function for co-factors in cell metabolism. (1 mk)
      They activate enzymatic reactions
    2. Give one example of a metallic co-factor. (1 mk)
      Calcium ion (Ca2+)
  2. The diagram below shows all human tooth.
    2 auiygduyad
    1. Identify the tooth . (1 mk)
      Canine
    2. How is the tooth adapted to its function. (2 mks)
      The tooth is –
      Pointed/sharp for piercing/tearing/cutting flesh.
      has a long root to support it into the few bone.
    3. State the role of the following vitamins in the human body. (2 mks)
      1. C – Absorption of iron /prevent scurvy/quick healing of wounds/prevent anaemia.
      2. K – Blood clotting by initiating formation of prothrombin in the liver
  3. Name two enzymes in the human digestive system which are secreted in an active form.
    Pepsin
    Trypsin
  4. Name the part of chloroplast where the following reactions occur. (2 mks)
    1. Carbon (IV) oxide fixation.
      Stroma
    2. Photolysis.
      Grana
  5. Explain the importance of the following in photosynthesis. (3 mks)
    1. Light –
      Light provide energy needed to split water molecules into oxygen gas and hydrogen atoms/ions by process called photolysis
      2H2O → 2H2 + O2
    2. Carbon (iv) oxide –
      Carbon (iv) oxide combine with hydrogen atom to form simple sugars or simple carbohydrates.
  6. The diagram below represents a transverse section of a young stem.
    6 aiuhdua
    1. Name the part labeled A and B. (2 mks)

      A – epidermis
      B – pith

    2. State the function of the parts labeled C, D and E. (3 mks)

      C – Translocate manufactured foods/soluble organic products of photosynthesis.
      D – Divides to give rise to new cells that produces secondary phloem and xylem.
      E – Transports mineral salts and water from the roots to the leaves.

    3. List three differences between the section shown above and one that would be obtained from the root of the same plant. (3 mks)

      ROOT

      STEM

      Xylem is centrally placed and star   

      shaped while the phloem is in between the arms of the xylem

      Vascular bundles are arranged in a ring or cambium ring

      There is presence of root hairs

      There is absence of root hairs

      Has no pith

      Has a pith.

  7. State three ways in which xylem vessels are adapted to their functions. (3 mks)
    - Are lignified or thickened to prevent collapsing
    - Have long and narrow lumen to facilitate capillarity
    - Made of dead cells to ensure passage of water
  8. Name two processes that bring about the translocation of manufactured food. (2 mks)
    - Active transport
    - Diffusion
    - Mass flow
    - Cytoplasmic streaming
  9. The diagram below shows a section of a plant organ.
    9 aiuyhduiad
    1. Name the part of the plant on which the organ above was obtained (1 mk)
      Stem
    2.                      
      1. Name the class to which the plant organ was obtained. (1 mk)
        Monocotyledonae
      2. Give a reason for your answer in (b) (i) above. (1 mk)
        - Vascular bundles are scattered and not arranged in a ring
        - Absence of pith/cambium
    3. Name the part labeled X. (1 mk)
      Epidermis
  10. Distinguish between haemolysis and plasmolysis.
    1. Haemolysis . (1 mk)
      Process by which red blood cells take in water by Osmosis ktill they burst when placed in a hypotonic solution compared to their cytoplasm
    2. Plasmolysis - (1 mk)
      Process where plant cells lose water by Osmosis, become flaccid and the cell membrane detaches from the cell walls when they are placed in a hypertonic solution compared to cell cytoplasm.
  11. State the function of the following cell organelles.
    1. Ribosome - (1 mk)
      Site for proten synthesis
    2. Lysosome - (1 mk)
      - Contain lytic enzyme that break down worn out cells or organelles or food materials or pathogens
      - Destroy micro-organisms or entire cells
  12.                      
    1. What is a single circulatory system. (1 mk)
      - Single circulatory system is a system in which blood passes only once through the heart to complete its circuit in the body.
    2. Name an organism which has single circulatory system. (1 mk)
      Fish, earthworm
    3. Name the opening to the chamber of the heart of an insect. (1 mk)
      Ostium
  13.                      
    1. Explain two roles of diffusion in human being. (4 mks)
      - Absorption of digested foods such as glucose, amino acids in the ileum into the blood stream.
      - Exchange of gases across the alveolus, e .g. CO2/O2 diffuse from capillaries to the blood.
    2. What is meant by each of the following terms?
      1. Crenated cell. (1 mk)
        - It is an animal cell that loses water by osmosis and shrinks when placed in a hypertonic solution to their cytoplasm.
      2. Flaccid. (1 mk)
        - It is a plant cell that loses water by osmosis, become flabby or shrink when placed in a hypertonic solution to their cytoplasm.
  14. A spotted plant was kept in the dark for 48 hours. Two leaves X and Y were treated as shown in the diagram below.
    14 auihuidhad
    The experimental set up was kept in sunlight for six hours after which a starch test was carried out on the two leaves.
    1. What were the results of the starch test on leaves X and Y. (2 mks)

      X – Iodine solution turned blue black hence presence of starch.
      Y – Iodine solution retains its yellow brown colour hence presence of starch.

    2. Give reasons for your answer in (a) above. (2 mks)

      X – Is a control experiment, where all requirements are present.
      Y – Carbon(iv) oxide is absent. It is absorbed by potassium hydroxide pellets, hence the rate of photosynthesis could not take place.

  15. Name one end product of dark reaction in photosynthesis. (1 mk)
    glucose, amino acid
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