Biology Questions and Answers - Form 2 Mid Term 2 2022

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QUESTIONS

  1.                                      
    1. What is meant by resolving power of a microscope? (1mk)
    2. State the reason behind the addition of iodine solution, to an onion epidermis on a slide while being observed on a light microscope. (1mk)
  2.                            
    1. It is necessary for large organisms to have an elaborate transport system. Explain why. (2mks)
    2. Explain why an Amoeba does not require a transport system. (1mk)
  3. State where the light stage of photosynthesis process occurs in a chloroplast. (1mk)
  4. Give two importance’s of the light stage in photosynthesis. (2mks)
  5. State two characteristics of the alveoli of the mammalian lungs. (2mks)
  6. Define counter current flow system as used in gaseous exchange in a fish. (2mks)
  7. Explain why an individual with blood group O cannot receive blood from a person of blood group AB. (2mks)
  8.                                
    1. Name the instrument used to measure the rate of transpiration. (1mk)
    2. State three importances of transpiration in plants. (3mrks)
    3. Give two reasons why fats are not a preferred respiratory substrate in organelles.  (2mks)
  9. Define the term respiratory quotient.  (1mrk)
  10. How is the mitochondrion adapted to carry out its function? (2mks)
  11. The oxidation of a certain substrate is represented by the chemical equation shown below.
    C57H104O6  + 80 O2 → 57co2 + 52H2O + Energy
    Calculate the respiratory quotient. (2mrks)
  12. Identify the food substrate being oxidized (1mrk)
  13. How does the process of respiration depend on photosynthesis? (2mks)
  14. Give two industrial applications of anaerobic respiration (2mrks)

MARKING SCHEME

  1.                                      
    1. What is meant by resolving power of a microscope? (1mk)
      The resolving power of an objective lens is measured by its ability to differentiate two lines or points in an object. The greater the resolving power, the smaller the minimum distance between two lines or points that can still be distinguished. The larger the N.A., the higher the resolving power.
    2. State the reason behind the addition of iodine solution, to an onion epidermis on a slide while being observed on a light microscope. (1mk)
      Although onions may not have as much starch as potato and other plants, the stain (iodine) allows for the little starch molecules to be visible under the microscope.
  2.                            
    1. It is necessary for large organisms to have an elaborate transport system. Explain why. (2mks)
      Because the body is made of many cells which are connected to each other, there are many cells which are not in contact with the outer environment, so they cannot get their needs or get rid of their waste directly to the environment. This means there must be a way for these cells to do so in order to function properly.
    2. Explain why an Amoeba does not require a transport system. (1mk)
      It is single-celled and lives in water. It exchanges nutrients and wastes directly through its outer cell membrane to the surrounding fresh water. These substances move by diffusion, from areas of high concentration to areas of lower concentration.
  3. State where the light stage of photosynthesis process occurs in a chloroplast. (1mk)
    The chloroplast is involved in both stages of photosynthesis. The light reactions take place in the thylakoid. There, water (H2O) is oxidized, and oxygen (O2) is released. The electrons that freed from the water are transferred to ATP and NADPH.
  4. Give two importance’s of the light stage in photosynthesis. (2mks)
    The light-dependent reactions of photosynthesis convert solar energy into chemical energy, producing ATP and NADPH or NADH to temporarily store this energy. In oxygenic photosynthesis, H2O serves as the electron donor to replace the reaction center electron, and oxygen is formed as a byproduc
  5. State two characteristics of the alveoli of the mammalian lungs. (2mks)
    Each alveolus is cup-shaped with very thin walls. It's surrounded by networks of blood vessels called capillaries that also have thin walls. The oxygen you breathe in diffuses through the alveoli and the capillaries into the blood.
  6. Define counter current flow system as used in gaseous exchange in a fish. (2mks)
    A countercurrent system places the water with the highest oxygen content in contact with the blood with the highest oxygen content and as blood and water flow through lamellae exchange occurs over the entire respiratory surface.
  7. Explain why an individual with blood group O cannot receive blood from a person of blood group AB. (2mks)
    Type B blood cells carry B antigens. Type AB blood has both A and B antigens, and type O blood has neither A nor B antigens. Your immune system will produce antibodies against any blood antigens you don't have in your own blood.
  8.                                
    1. Name the instrument used to measure the rate of transpiration. (1mk)
      The instrument used for measuring the rate of transpiration is called potometer.
    2. State three importances of transpiration in plants. (3mrks)
      Cools the surface of the leaves. Helps in growth and development. It controls the temperature of the plants. Allows the movement of minerals from the soil to different parts of the plant.
    3. Give two reasons why fats are not a preferred respiratory substrate in organelles.  (2mks)

      Proteins and fats have to undergo a series of chemical reactions to form simple compound and then only they can enter Krebs Cycle( it is a cycle where our cells during aerobic respiration generate energy). After forming simple compounds only then they can enter the cycle and help to produce energy which takes a lot of time. Glucose on the other hand can be easily oxidised without any complex or time consuming reactions and also it present in a quite large quantity. Due to above reasons fats and proteins are not used as respiratory substrate and glucose is used.

  9. Define the term respiratory quotient.  (1mrk)
    the ratio of the volume of carbon dioxide evolved to that of oxygen consumed by an organism, tissue, or cell in a given time.
  10. How is the mitochondrion adapted to carry out its function? (2mks)
    Mitochondria have a double membrane structure, with an inner layer with many folds to create a high surface area. This provides more space for more metabolising proteins and therefor they are able to create more energy at one time.
  11. The oxidation of a certain substrate is represented by the chemical equation shown below.
    C57H104O6  + 80 O2 → 57co2 + 52H2O + Energy
    Calculate the respiratory quotient. (2mrks)
    The oxidation of a certain substrate is represented by the chemical equation shown below.
    C57H104O6  + 80 O2 → 57co2 + 52H2O + Energy
    Calculate the respiratory quotient. (2mrks)
    RQ = CO2 eliminated/O2 consumed
    57:80
    = 0.7125
  12. Identify the food substrate being oxidized (1mrk)
    Triolein
  13. How does the process of respiration depend on photosynthesis? (2mks)
    Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. While water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.
  14. Give two industrial applications of anaerobic respiration (2mrks)
    Anaerobic fermentation has been applied to many important industrial fermentations, such as ethanol production by yeasts, lactic acid preservation of foods, anaerobic digestion of organic matters in ruminant cultivation and waste treatment.

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