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

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BIOLOGY

INSTRUCTIONS.

  • Answer all the questions in the spaces provided.


Questions

  1. State the function of the following organelles. (2mks)
    1. Lysosomes
    2. Ribosomes
  2. A student observed a row of 16 epidermal cells in a microscopic field that was 8mm in diameter. Calculate the average length of one cell in micrometres. Show your working. (3mks)
  3. A student drew a 6cm diagram of a plant flower if the actual length of the flower was 12cm. calculate the magnification of the drawing made by the student. Show your working. (3mks)
  4. State three factors that affect the rate of diffusion. (3mks)
  5. An experiment was set-up in a laboratory as shown below.
    F2ot106BioQ5i
    1. What will happen to visking tubing in M and N after two hours. (2mks)
    2. Explain the observations made in M. (2mks)
    3. What does visking tubing represent in a living organism? (1mk)
  6. Distinguish between autotrophism and heterotrophism modes of nutrition. (2mks)
  7. State three properties of monosaccharides. (3mks)
  8. The equation below shows formation of a disaccharide.
                                      process p
    Glucose + Glucose            →       Q + water
    1. Name process P. (1mk)
    2. Product Q. (1mk)
    3. Other than product Q named above name other two examples of disaccharides. (2mks)
  9. List four factors which affect enzyme controlled reaction. (4mks)
  10. Name two nutrients that are absorbed without being digested by the enzymes in humans. (2mks)
  11. List three types of salivary glands. (3mks)
  12. Give two roles of saliva in the process of digestion. (2mks)
  13. Differentiate between homodonts and heterodonts. (2mks)
  14. The diagram below represents the lower jaw of a mammal.
    F2ot106BioQ14
    1. Name the mode of nutrition of the animal whose jaw is shown above. (1mk)
    2. Mode of feeding. (1mk)
    3. Give a reason for your answer in (b) above. (1mk)
    4. Diet of the animal. (1mk)
    5. Name the toothless gap labeled K. (1mk)
    6. Name the substance that is responsible for hardening of teeth. (1mk)
  15. State the roles of the structures found within a tooth:
    1. Blood vessels. (1mk)
    2. Nerves. (1mk)
  16. List two major types of dental diseases. (2mks)
  17. Give two roles played by bile salts in the process of digestion. (2mks)
  18. Explain five ways in which the illume is adapted to its functions. (5mks)
  19. The following is a dental formula of a certain mammal.
    I0/3 C0/1 Pm3/3 m3/3
    1. Calculate the total number of teeth of the mammal. (2mks)
    2. Give the likely mode of feeding. (1mk)
    3. Give a reason for your answer in (ii) above. (1mk)
  20.            
    1. Name the disease in humans caused by deficiency the following: (5mks)
      1. Vitamin A
      2. Vitamin D
      3. Vitamin C
      4. Iodine
      5. Iron
    2. State one function of water in the diet. (1mk)
    3. State five factors that determine energy requirements in human beings. (5mks)


Marking Scheme

  1. State the function of the following organelles. (2mks)
    1. Lysosomes
      • Contain lytic enzymes that destroy worn out cells.
    2. Ribosomes
      • They are sites for protein synthesis

  2. A student observed a row of 16 epidermal cells in a microscopic field that was 8mm in diameter. Calculate the average length of one cell in micrometres. Show your working. (3mks)
    • Size of one cell =       diameter of field of view       
                                   Number of cells in field of view.
      8mm x 1000μm
           1mm
      = 8000um
      16cells
      =500μm

  3. A student drew a 6cm diagram of a plant flower if the actual length of the flower was 12cm. calculate the magnification of the drawing made by the student. Show your working. (3mks)
    • Magnification of a handlens = Drawing length
      Actual length of the object
       6cm = x0.5
      12cm

  4. State three factors that affect the rate of diffusion. (3mks)
    • Diffusion gradient
    • Thickness of tissues
    • Size of molecules
    • Temperature
    • Type of medium
    • Surface area to volume ratio
  5. An experiment was set-up in a laboratory as shown below.
    1. What will happen to visking tubing in M and N after two hours. (2mks)
      • M – will swell / increase in size
      • N – Will shrink / decrease
    2. Explain the observations made in M. (2mks)
      • Sodium chloride solution is a hypertonic solution while distilled water is a hypotonic solution therefore distilled water molecules will move from the beaker to the visking tubing by osmosis making it to swell.

    3. What does visking tubing represent in a living organism? (1mk)
      • Cell membrane/ plasma membrane/plasmalema.

  6. Distinguish between autotrophism and heterotrophism modes of nutrition. (2mks)
    • Autotrophism is a mode of nutrition in which some plants manufacture their own complex food substances from simpler substances such as carbon (IV) oxide and water while heterotrophism is a mode of nutrition that involves taking complex ready made food materials from plants and other animals.

  7. State three properties of monosaccharides. (3mks)
    • They are soluble in water
    • They form sweet tasting solution
    • They are reducing sugars
    • They are crystalisable.

  8. The equation below shows formation of a disaccharide.
    Glucose + Glucose process p Q + water
    1. Name process P. (1mk)
      • Condensation

    2. Product Q. (1mk)
      • Maltose

    3. Other than product Q named above name other two examples of disaccharides. (2mks)
      • Sucrose
      • Lactose

  9. List four factors which affect enzyme controlled reaction. (4mks)
    • Temperature
    • pH
    • Specificity
    • Enzyme co-factors and co-enzyme
    • Enzyme inhibitors
    • Substrate concentration and enzyme concentration.

  10. Name two nutrients that are absorbed without being digested by the enzymes in humans. (2mks)
    • Water
    • Vitamins
    • Mineral ions/salts

  11. List three types of salivary glands. (3mks)
    • Sublingual
    • Sub-mandibular
    • Parotial sub-maxillary

  12. Give two roles of saliva in the process of digestion. (2mks)
    • Lubricates food
    • Moistens food
    • Softens food
    • Dissolves food
    • Contains salivary amylase hence digests starch to maltose
    • Provides an alkaline medium for action of salivary amylase.

  13. Differentiate between homodonts and heterodonts. (2mks)
    • Homodonts: are animals which have the same types, size and shape of teeth while heterodonts are animals with different types, size and shapes of teeth.

  14. The diagram below represents the lower jaw of a mammal.
    1. Name the mode of nutrition of the animal whose jaw is shown above. (1mk)
      • Heterotrophism
    2. Mode of feeding. (1mk)
      • Herbivorous

    3. Give a reason for your answer in (b) above. (1mk)
      • Presence of a diastema

    4. Diet of the animal. (1mk)
      • Vegetation/ grass/green leaves.

    5. Name the toothless gap labeled K. (1mk)
      • Diastema

    6. Name the substance that is responsible for hardening of teeth. (1mk)
      • Calcium phosphate

  15. State the roles of the structures found within a tooth:
    1. Blood vessels. (1mk)
      • They supply nutrients to living tissues in the dentine.
        Remove waste products from the dentine
    2. Nerves. (1mk)
      • They detect heat, cold and pain in the tooth

  16. List two major types of dental diseases. (2mks)
    • Dental carriers
    • Periodontal disease

  17. Give two roles played by bile salts in the process of digestion. (2mks)
    • They aid in the breakdown of fats into tiny fat droplets to increase their surface area for digestion (emulsification)
    • They provide an alkaline medium which the enzymes work best.
    • They neutralize the acidic chime from the stomach.

  18. Explain five ways in which the illume is adapted to its functions. (5mks)
    • Long and narrow to increase surface area for digestion and bring digested food into close contact with walls of the ileum for easier absorption.
    • Highly coiled to slow down movement of food thus allowing more time for digestion and absorption to take place.
    • Large number of villi and micro-vill to increase surface area.
    • Presence of thinner layer of cells to reduce diffusion distance of digested food.
    • Presence of dense network of capillaries in the villi into which amino acids, sugar and vitamins are absorbed.
    • Presence of lacteals in the villi for the absorption of fatty acids and glycerol.

  19. The following is a dental formula of a certain mammal.
    1. Calculate the total number of teeth of the mammal. (2mks)
      0 + 0 + 3 + 3 x 2 = 12
      3 + 1 + 3 + 3 x 2 = 20
                                    32 teeth

    2. Give the likely mode of feeding. (1mk)
      • Herbivorous

    3. Give a reason for your answer in (ii) above. (1mk)
      • It lacks incisors and canines in the upper jaw to create a horny pad.

  20.            
    1. Name the disease in humans caused by deficiency the following: (5mks)
      1. Vitamin A
        • Night blindness

      2. Vitamin D
        • Rickets

      3. Vitamin C
        • Scurvy

      4. Iodine
        • Goiter

      5. Iron
        • Anemia

    2. State one function of water in the diet. (1mk)
      • it is a solvent of soluble food substances cooling of the body.
      • Provided the medium for transport of dissolved food substances.
      • Facilitates hydrolysis of food substances.

    3. State five factors that determine energy requirements in human beings. (5mks)
      • Basal metabolic rate
      • Occupation/everyday activity
      • Age
      • Body size
      • Sex

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