Biology Questions and Answers - Form 2 End Term 1 Exams 2021

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INSTRUCTIONS TO CANDIDATES:

  • Answer ALL the questions
  • Answers should be written in the spaces provided
  1. Define the following terms. (2mks)
    1. Taxon
    2. Taxonomy
  2. A donkey and a horse can breed and produce a young one called a mule. Explain why they do not belong to the same species. (2mks)
  3. Give one reason for each of the following operations in microscopy work. (3mks)
    1. Adding a drop of iodine solution
    2. Covering the specimen with a cover slip.
    3. Cutting the specimen using a sharp blade.
  4. The table below shows the concentration of mineral A and B in sea water and in the cell sap of a certain sea weed.
     Mineral   Concentration in sea water in (ppm)  Concentration in the cell sap in (ppm) 
      A
      B
                        16
                        39
                         108
                          11

    1. Suggest the physiological process by which mineral A and B were absorbed by the sea weed.    (2mks)
    2. State and explain the mineral that would fail to be absorbed if the sea weed was treated with respiratory poison. (2mks)
  5. Differentiate between fats and oils. (2mks)
  6. Name the element contained in all proteins. (1mk)
  7. The diagram below shows the dentition of an animal.
             F2ET1BioQ7
    1. Identify the mode of feeding of the animal with the dentition above. (1mk)
    2. Give two reasons for your answer in (i) above. (1mk)
  8. State two functions of mucous produced in the gastro-intestinal tract. (2mks)
  9. The diagram below shows a set-up used to investigate a certain process in plants.
             F2ET1BioQ9
    1. Identify the process being investigated. (1mk)
    2. Name the equipment represented by the diagram above. (1mk)
    3. Give two precaution that should be taken when setting up this experiment. (2mks)
  10. Explain the following concepts:
    1. Some plants fold their leaves in dry weather. (2mks)
    2. Leaves of plants from arid areas have fewer stomata on the upper leaf surface. (2mks)
  11. A lady had her veins swollen at the back of the legs. The swellings are painful.
    1. Name this condition.   (1mk)
    2. What causes the condition?    (1mk)
    3. How can the condition be corrected?      (1mk)
  12. State three differences between open and closed circulatory system. (3mks)
  13. In what chemical form is oxygen transported in the blood. (1mk)
  14. Give two protective roles of mammalian blood. (2mks)
  15. Name:
    1. A vitamin that is needed in blood clotting    (1mk)
    2. A metal ion needed in blood clotting.    (1mk)
    3. An anti-clotting factor found in mammalian blood that prevents blood from clotting before an injury. (1mk)
    4. Two enzymes needed in blood clotting. (2mks)
  16. State two ways in which blood clotting is beneficial to humans. (2mks)
  17. State one:-
    1. Advantage of people having blood group O. (1mk)
    2. Disadvantage of people having blood group O. (1mk)
  18. What is gaseous exchange? (2mks)
  19. Give two reasons why gaseous exchange is important in human beings. (2mks)
  20. The diagram below shows the structure of a gill of a bony fish.
              F2ET1BioQ20
    1. Name the structure labeled Q, R and S. (3mks)
    2. State the function of structure Q, R and S. (3mks)
    3. Give four ways in which structure Q is adapted to its functions. (4mks)
  21. State two theories that explain the mechanisms of opening and closing of the stomata. (2mks)
  22. Name the structure or surfaces involved in the gaseous exchange in the following organisms. (4mks)
    1. Fish 
    2. Insects
    3. Plant
    4. Amoeba
  23. State three factors that affect the rate of breathing in human beings. (3mks)
  24. Describe what happens during the light stage of photosynthesis. (3mks)


Marking Scheme

  1. Define the following terms. (2mks)
    1. Taxon – A group of organisms with similar characteristics.
    2. Taxonomy – Science of classification.
  2. A donkey and a horse can breed and produce a young one called a mule. Explain why they do not belong to the same species. (2mks)
    • Because their offspring mule is infertile.
  3. Give one reason for each of the following operations in microscopy work. (3mks)
    1. Adding a drop of iodine solution
      • To make cell structures distinguishable/distinct/clearer
    2. Covering the specimen with a cover slip.
      • To prevent dirt from contaminating the specimen
      • Prevent entry of air bubbles.
    3. Cutting the specimen using a sharp blade.
      • To prevent distortion of the cells/tissues
  4. The table below shows the concentration of mineral A and B in sea water and in the cell sap of a certain sea weed.
    1. Suggest the physiological process by which mineral A and B were absorbed by the sea weed. (2mks)
      • A – Active transport
      • B – Diffusion.
    2. State and explain the mineral that would fail to be absorbed if the sea weed was treated with respiratory poison. (2mks)
      • Mineral A because treatment of sea weed with respiratory poison prevents synthesis of energy thus stopping the absorption since the process of Active transport requires energy.
  5. Differentiate between fats and oils. (2mks)
    • Fats are solid at room temperature while oils are liquid at room temperature.
    • Oils are found in plants while fats are found in plants.
  6. Name the element contained in all proteins. (1mk)
    • Nitrogen.
  7. The diagram below shows the dentition of an animal.
    1. Identify the mode of feeding of the animal with the dentitron above. (1mk)
      • Carnivorous
    2. Give two reasons for your answer in (i) above. (1mk)
      • Presence of chisel shaped incisors which are fitted closely to grasp and strip flesh close to the bones.
      • Presence of long curved and pointed canines for piercing prey and killing it.
  8. State two functions of mucous produced in the gastro-intestinal tract. (2mks)
    • Lubricates food.
    • Protects the stomach and intestinal lining from being digested by enzymes pepsin and trypsin.
  9. The diagram below shows a set-up used to investigate a certain process in plants.
    1. Identify the process being investigated. (1mk)
      • Transpiration
    2. Name the equipment represented by the diagram above. (1mk)
      • Potometer
    3. Give two precaution that should be taken when setting up this experiment. (2mks)
      • All air bubbles in the capillary tube should be expelled before the experiment.
      • Cut off the last few centimeters of the stem under water.
      • Some jelly should be applied around the stem and rubber bung.
      • The end of the capillary tube should rest in water in the beaker.
      • The leafy shoot should be from a herbaceous plant.
  10. Explain the following concepts:
    1. Some plants fold their leaves in dry weather. (2mks)
      • Reduce the surface area of leaves thus reducing the rate of transpiration.
    2. Leaves of plants from arid areas have fewer stomata on the upper leaf surface. (2mks)
      • Reduce exposure of stomata to direct sun thus reducing the rate of transpiration.
  11. A lady had her veins swollen at the back of the legs. The swellings are painful.
    1. Name this condition. (1mk)
      • Varicose veins
    2. What causes the condition? (1mk)
      • Failure of some valves to function properly
    3. How can the condition be corrected? (1mk)
      • Carry out physical exercise of the body.
  12. State three differences between open and closed circulatory system.
     Open   Closed 
    Transport of fluid is conveyed in general body cavity. Transport of fluid is conveyed in blood vessels
    Transport of fluid is in direct contact with tissues. Transport of fluid/blood is not in direct with the tissues.
    Fluid flow is under low pressure hence slow Blood flow is under high pressure hence faster.
    Organisms are more active. Organisms are less active
  13. In what chemical form is oxygen transported in the blood. (1mk)
    • Oxyhaemoglobin
  14. Give two protective roles of mammalian blood. (2mks)
    • Contains platelets which help blood clotting to prevent entry of pathogens and excessive loss of blood.
    • Has lymphocytes that produce antibodies that protect the body from infections.
    • Has phagocytes that engulf and digest pathogens through the process of phagocytosis.
  15. Name:
    1. A vitamin that is needed in blood clotting. (1mk)
      • Vitamin K
    2. A metal ion needed in blood clotting. (1mk)
      • Calcium ions
    3. An anti-clotting factor found in mammalian blood that prevents blood from clotting before an injury. (1mk)
      • Heparin.
    4. Two enzymes needed in blood clotting. (2mks)
      • Thrombokinase/ Thromboplastin
      • Thrombin
  16. State two ways in which blood clotting is beneficial to humans.(2mks)
    • Prevents excessive loss of blood after an injury.
    • Prevents entry of pathogens into the body after an injury.
  17. State one:-
    1. Advantage of people having blood group O. (1mk)
      • Can donate blood to all other blood groups
    2. Disadvantage of people having blood group O. (1mk)
      • Can only receive blood from a person with blood group O.
  18. What is gaseous exchange? (2mks)
    • Is the process by which respiratory gases are passed across respiratory surfaces.
  19. Give two reasons why gaseous exchange is important in human beings. (2mks)
    • To allow intake of oxygen needed for respiration.
    • Facilitate removal of carbon (IV) oxide which is a waste product of metabolism from the body.
  20. The diagram below shows the structure of a gill of a bony fish.
    1. Name the structure labeled Q, R and S. (3mks)
      • Q – Gill filaments
      • R – Gill rakers
      • S – Gill bar
    2. State the function of structure Q, R and S. (3mks)
      • Q ;- Gill filament – provide large surface are for gaseous exchange.
      • R ;- Gill rakers – Trap food and solid particles to prevent them from damaging delicate gill filament.
      • S ;- Gill bar – for attachment of gill filaments and gill rakers.
    3. Give four ways in which structure Q is adapted to its functions. (4mks)
      • Numerous to provide large surface area for gaseous exchange.
      • Thin epithelium to provide a short distance for diffusion of molecules.
      • Highly vascularised to create a steep concentration gradient for gaseous exchange.
      • Moist to dissolve gaseous for easier diffusion in solution form.
  21. State two theories that explain the mechanisms of opening and closing of the stomata.
    • Photosynthetic theory.
    • Starch sugar interconversion theory.
    • Potassium ion theory.
  22. Name the structure or surfaces involved in the gaseous exchange in the following organisms. (4mks)
    1. Fish – Gill filaments
    2. Insects – Tracheole
    3. Plant – Stomata/lenticels/cuticle
    4. Amoeba – Cell membrane
  23. State three factors that affect the rate of breathing in human beings. (3mks)
    • Age
    • Exercise
    • Temperature
    • Emotions
    • Health
  24. Describe what happens during the light stage of photosynthesis.
    • light energy is absorbed by chlorophyll; The light energy splits water molecules/photolysis to form hydrogen ions/atoms and oxygen gas; Light converted to ATP;

 

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