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Form 4 Term 3 2023 Biology Paper 2 Exam [PDF]

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Question 1

The diagram shown below is a plant cell as seen when observed under an electron microscope at high power. Study it carefully and use it to answer the questions that follow.

  1. Name the parts labeled A, C and H
    A
    C
    H
  2. State the function of the parts labeled D and G
    D
    G
  3. Give two differences between the structures labeled D and G.
  4. Based on observable features, suggest the main function the cell shown.
Answer
  1. A - Cell wall
    C - Nucleus
    H - Rough endoplasmic reticulum
  2. D - site for photosynthesis
    G - site for respiration
  3. D G
    Has stroma Has matrix
    Greatly flded into granum Greatly folded into cristae
  4. Photosynthesis
Question 2

Study the table below and then answer the questions that follow.

  1. What part of the human body is affected by the virus that causes poliomyelitis?
  2. Give a reason why some doses of vaccine are given more than once.
  3. Suggest a reason for delay in vaccinating against measles until the 9th month.
  4. Describe immune response.
  5. What is a vaccine?
  6. What is the role of vaccination in providing immunity?
  7. What triggers an allergic reaction?
Answer
  1. Joint/muscles
  2. To boost previous vaccinations.
  3. Some immunity is naturally passed from mother through colostrum/placenta.
  4. Reaction of the body as aresult of antigens/pathogen, it involves production of antibodies/leucocytes which combines with antigens.
  5. Vaccine - A substance rich in weakened antigens.
  6. Stimulates the body system to produce antibodies in response to pathogens.
  7. Allergens. e.g pollen grains, dust, fur
Question 3

State three limitations of using a quadrat to estimate the population of organisms.
Answer
1. Quadrats cover a small, fixed area, which may not represent the entire habitat, leading to inaccurate estimates if the population is unevenly distributed.
2. The placement of quadrats may introduce bias, especially if not placed randomly, resulting in over- or underestimation of population sizes.
3. Quadrats are less effective for mobile organisms that can move in and out of the sampled area, causing inaccurate population estimates.
Question 4

In an attempt to estimate the number of grasshoppers in the field, a student captured 435 marked and released. Three days later, 620 were captured 75 of which were marked.
  1. What is the name of the sampling method describe above?
  2. Calculate the approximate population size of the grasshoppers in the field.
  3. What are the disadvantages of this method?
Answer
  1. Capture-Recapture method
  2. Calculate the approximate population size of the grasshoppers in the field.
  3. - Some grasshoppers may die during capture.
    - The mark may fade off.
    - Mark may expose grasshoppers to predation.
    - Migration
Question 5

Study the photograph below and answer the questions that follow.

  1. Name the parts labelled A and B and state its functions.
  2. Identify the mode of feeding of the organism.
  3. i. Name the tooth labelled S.
    ii. State how the tooth named in (c) (i) above is adapted to its function
Answer
  1. A - Diastema
    Function - Provides space for manipulation of food by the tongue so as to separate the newly cut vegetation from that which is being chewed.
    B - Horny pad
    Function - This is where grass is pressed against and cut by the lower incisors.
  2. Herbivorous
  3. i. S - Molar
    ii. 1. Has wider crown for crushing and grinding of food.
     2. Has cusps for grinding food
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- Form 4 Term 3 2023 Biology Paper 2 Exam [PDF]