Biology Paper 1 Form 3 Questions and Answers - End Term 2 Exams 2021

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Biology Paper 1 Form 3 End Term 2 Exams 2021 with Marking Schemes


Answer all the questions in the spaces provided

  1. The diagram below is that of a gill of a fish.
    1. Name the parts labeled A and B. (2mks)
    2. State the function of part labeled C. (1mk)
    3. Explain how structure labeled A is adapted to its function. (2mks)
    1. Give the products of aerobic respiration in plants and animals. (3mks)
    2. Name two factors that affect the rate of respiration. (2mks)
  3. Explain why red blood cells burst when placed in distilled water while plant cells remain intact. (3mks)
  4. Distinguish between diffusion and osmosis. (2mks)
  5. A form three student came across two different types of fruits which are described as follows:

    Fruit A
    Has free central placentation, hard epicarp and fibres air-filled mesocarp.

    Fruit B
    Has axile placentation, fleshy mesocarp and brightly coloured epicarp

    Suggest the possible agent of dispersal of each type of fruit. (2mks)
  6. A student examining pond water came across a certain living organisms which he drew as shown below.
    1. Identify the organism shown above. (1mk)
    2. State the kingdom of the above organism. (1mk)
    3. Name the structure labeled A. (1mk)
    4. State the function of the part labeled B. (1mk)
  7. Give the role of the following hormones during menstrual cycle. (3mks)
    1. Follicle stimulating hormone.
    2. Oestrogen.
    3. Luteinizing hormone.
  8. During a surgical operation, a doctor accidentally cut two blood vessels A and B. Out of blood vessel A, blood was spurting out while through blood vessel B, blood was flowing smoothly.

    Identify blood vessels A and B. (2mks)
  9. What are the disadvantages of sexual reproduction? (3mks)
  10. During cold weather, very small mammals eat more than their own weight of food per day whereas large mammals eat food which is only a small fraction of their weight. Give an explanation for this. (3mks)
  11. State the function of the following cell organelles. (3mks)
    1. Lysosomes.
    2. Ribosomes.
    3. Golgi apparatus.
  12. Pregnancy would persist after the expiry of the fifth month of pregnancy even if the two ovaries are surgically removed from the body of female individual. Give an account for this. (2mks)
  13. List two main branches of biology and for each, give a definition. (2mks)
  14. What is the role of vascular bundles in plant nutrition? (3mks)
  15. What do you understand by the term double fertilization in flowering plants? (2mks)
  16. Define the following terms as used in ecology. (3mks)
    1. Carrying capacity.
    2. Biosphere.
    3. Ecological niche.
  17. Distinguish between intra-specific and inter-specific competition. (2mks)
    1. Name the process through which free atmospheric nitrogen is converted into nitrates. (1mk)
    2. Name the bacteria found in root nodules of leguminous plants. (1mk)
    3. What is the role of bacteria named (a) above. (1mk)
  19. In a capture-recapture exercise to estimate population size of dragon flies on a stretch of rivers, 250flies were first caught and marked. Two days later 500 flies were caught in the second capture and out of this, 50 flies had marks on their bodies. Estimate the population size of the flies. (show your working) (3mks)
  20. The diagram below shows a stage of a certain type of cell division.
    1. Identify the stage and type of the cell division the above cell is undergoing. (2mks)
    2. State two importance of the above type of cell division. (2mks)
    1. What is placentation? (1mk)
    2. Give three types of placentation. (3mks)
  22. Identify four ways through which the HIV/AIDs virus is transmitted. (4mks)
  23. State the mode of asexual reproduction in; (3mks)
    1. Yeast.
    2. Amoeba.
    3. Rhizopus species.
    1. Name one defect of circulatory system in humans. (1mk)
    2. State three functions of blood other than transport. (3mks)
  25. What do you understand by the term oxygen debt? (2mks)
  26. List any two distinguishing features of class arachnida. (2mks)
  27. Give the name used to refer to fruit development without fertilization. (1mk)
  28. During which phase of meiosis does crossing over occur? (1mk)

Marking Scheme

    1. A – Gill filament rej. Gill filaments
      B – Gill bar rej. Gill bars
    2. Traps solid particles in water which would otherwise pass over the surfaces of gill filaments and damage them mechanically / physically.
    3. - Moistened to facilitate diffusion of gases in solution form.
      - Large and extensive to provide a large surface area for gaseous exchange.
      - Carbon (IV) oxide.
      - Water.
      - Energy (ATP)
    2. - Substrate concentration.
      - Oxygen concentration.
      - Hormones.
      - Surface area to volume ratio.
  3. Plant cells are enclosed by a rigid, cellulose cell wall, while the red blood cells are enclosed by a fragile (delicate) cell membrane which makes the red blood cells to burst when placed in distilled water.
  4. Diffusion is the process by which molecules move from a region of high concentration to a region of low concentration while osmosis is the process that involves the movement of water molecules from a region of high water concentration to a region of low water concentration across a semi-permeable membrane.
  5. Fruit A – Water
    Fruit B – Animal.
    1. Paramecium
    2. Protoctista
    3. Oral groove
    4. Removes excess water form the animal body.
    1. It causes Graafian follicles to develop in the ovary
      It stimulates the tissues of the ovary to secrete another hormone called oestrogen.
    2. Brings about repair and healing of the endometrium which is destroyed during menstruation.
    3. Stimulates the maturity of Graafian follicle.
  8. Blood vessel A – Artery.
    Blood vessel B – Vein.
  9. - Takes a longer time to reproduce.
    - Few offsprings are produced at a time.
    - Involves two different sexes for mating to occur.
    - Undesirable characteristics from the parents may be passed on the offspring.
  10. Small mammals have a relatively large surface area to volume ratio as compared to large mammals. Because of this, small mammals lose heat to the external environment very fast. In order to maintain their body temperature relatively constant, they have to increase their metabolic rates considerably. This requires that they eat a lot of food.
    1. They contain lytic enzymes that destroy aged and unwanted cell organelles, materials taken in by the cell from its environment.
    2. They form sites for protein synthesis.
    3. Packaging and transportation of glycoprotein as secretions.
      Transport of synthesized materials out of the cell as secretions.
  12. After the expiry of the third month of pregnancy, the placenta takes over the role of ovaries of secreting hormone progesterone, which maintains pregnancy.
  13. Botany – is the study of plants.
    Zoology – is the study of animals.
    Microbiology – is the study of microscopic organisms. 
    Rej. any other branch.
  14. Vascular bundles contain xylem and phloem
    Xylem – conducts water and mineral salts from the roots to the leaves.
    Phloem tissues – translocate manufactured food, soluble and organic products of photosynthesis from the leaves to the rest of the plant parts.
    The student should state the name and the function.
  15. This is whereby, one of the male nuclei fuses with the egg cell nucleus, to form a diploid zygote which develops into an embryo, while the other male nucleus fuses with the polar nucleus to form a triploid nucleus that develops into primary endosperm nucleus.
    1. Maximum number of organisms an area can comfortably support without depletion of the available resources.
    2. Is the part of earth and atmosphere inhabited by living organisms.
    3. Is the position that an organism occupies in a habitat.
  17. Intra-specific competition is a competition between individuals of the same species, while inter-specific competition is between individuals of different species.
    1. Nitrogen fixation
    2. Rhizobium
    3. Convert nitrogen into nitrates or fix Nitrogen gas into nitrate compounds.
  19. Total population= (First number marked × Second capture)
                                              (Marked recapture)
    =(250 × 500)
    = 2500 dragon flies <rej.2500 alone>
    Rej. if the formula is wrong.
    1. Stage – metaphase rej. metaphase I
      Cell division – mitosis
    2. - Forms the basis for asexual reproduction.
      - Formation of new body cells hence growth.
    1. Is the arrangement of the ovules in an ovary.
    2. - marginal placentation.
      - Basal placentation.
      - Parietal placentation.
      - Axile placentation.
      - Free central placentation.
      Give any 3. 
    • Through sexual intercourse.
    • Through blood transfusion, transplant and by use of contaminated surgical instruments.
    • Infected mothers can transmit HIV/AIDs to babies during birth and through breast milk.
    1. Budding
    2. Binary Fission
    3. Spore formation
    1. Thrombosis
    2. - Regulation of pH of body fluids.
      - Regulation of blood temperature.
      - Defense against disease-causing organism.
      - Prevent excessive bleeding by enhancing clotting / prevent excessive loss of blood.
  25. The amount of oxygen required to get rid of accumulated lactic acid in the body when the body produces energy by anaerobic respiration.
  26. - Have two segmented body parts.
    - Have eight jointed legs or appendages.
  27. Parthenocarpy.
  28. Prophase I
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