Biology Paper 3 Questions and Answers with Confidentials - Asumbi Girls High School KCSE Mock 2021

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Instructions to candidates:

  • Answer all the questions in section A and B
  • You are required to spend the first 15 minutes of the 1 ¾ hours allowed for this paper reading the whole paper carefully.


    1. Place 2ml of bicarbonate indicator in a clean test tube. Add dilute hydrochloric acid drop by drop and shake after each drop till there is a permanent color change.
      1. State the resulting color 1mk
      2. To the mixture obtained above, now add sodium hydroxide solution dropwise until there is a permanent color change. Record your observations 1mk
      3. From your observations in a) i) and a) ii) above, what is the nature of the bicarbonate indicator 1mk
    2. Place 10ml of a fresh bicarbonate indicator in boiling tube. Using a drinking straw, bubble air through the bicarbonate indicator until there is color change
      1. Record your observation 1mk
      2. What does the color obtained in b) i) above suggest about the nature of the gas breathed out 1mk
    3. Rinse the measuring cylinder and use it to place 2ml of lime water solution in a clean test tube. Rinse the drinking straw in (b) above and use it to bubble air through lime water solution
      1. Record your observation 1mk
      2. Suggest the identity of the gas that give rise to the observations above 1mk
      1. Name the physiological process in cells that leads to formation of gas named in (c)( ii) above 1mk
      2. Write down a word equation for the process named in (d) (i) above 1mk
      3. What is the importance of the identified process in cells of living organisms 1mk
  2. Below are photographs of two seedlings labeled K and L. Examine them.
    1. Given that the two plants belongs to the same class, name the class and give a reason based on the observable features in any of the two seedlings or both. 2mks
      1. State giving a reason, the type of germination that occurs in each of the two seedlings 4mks
      2. Explain how the two types of germination you have stated in (b) (i) above occur 2mks
    3. Name the parts labelled H and G on the seedling 2mks
    4. As germination progresses, both seedlings straightens. Explain how this occurs. 4mks
    5. Name the type(s) of root system that will develop in the two seedlings 1mk
    6. State another observation that will be made as seedling L straightens 1mk
  3. The photographs below are specimens from the same animal of two different bones each shown in two views. Examine them.
    1. Identify the two specimens 2mks
      Specimen V……………………………………………………………………………………….
      Specimen W………………………………………………………………………………………
    2. Give four observable differences between bones V and W 4mks
      Bone V  Bone W
    3. Name the structure that articulates with part labeled A 1mk
    4. State two roles of opening labeled B 2mks
    5. Name the part labelled E and state its role 2mks
    6. Which of the labelled part(s) are used for articulation with adjacent vertebra 1mk
    7. State a common role of the parts labelled H and J 1mk
    8. Which of the labeled part(s) is(are) used for muscle attachment 1mk


Each student should be provided with the following

  • 25ml bicarbonate indicator
  • Lime water
  • A drinking straw
  • 2 test tubes
  • 10ml measuring cylinder
  • A boiling tube
  • Dilute hydrochloric acid
  • Dilute sodium hydroxide

Marking Scheme

      1. yellow
      2. red
      3. acid-base indicator
      1. color change from red to yellow
      2. the gas is acidic
      1. white precipitate formed
      2. carbon iv oxide
      1. respiration(aerobic)
      2. Glucose + oxygen carbon iv oxide + water + energy
      3. for provision of energy
    1. class- Dichotyledonae
      1. presence of two cotyledons in specimen L
      2. Net venation on plumule/leaves of specimen L(reticulate)
      1. K- hypogeal; cotyledon remains in the ground
        L- epigeal ; cotyledons brought above the ground
      2. K- epicotyl elongates pulling the plumule leaves and the shoot tip out of the cotyledons and out of the ground leaving the cotyledons in the soil.
        L- Hypocotyl elongates pulling the cotyledons enclosing the plumule above the ground
    3. H –Epicotyl
      G- hypocotyls
    4. As the bent parts exposed to sunlight, more light on the upper side causes auxins to migrate to the lower side; the increased auxin concentration on the lower side , stimulates faster elongation of cells; on the lower side leading to straightening og the seedling
    5. Both will develop a taproot system
    6. the cotyledons will part and the leaves will expand and spread out
    1. V- Atlas
      W- Axis
      Bone V  Bone W
      Has a wider neural canal  Narrower neural canal
      Has a very small centrum Prominent centrum
      Has a greatly reduced neural spine Has a broad neural spine
      Lack odontoid process Has an odontoid process
    3. occipital condyles of the skull
    4. passage of the spinal cord and fitting of odontoid process of the axis
    5. name- odontoid process
      role- it fits into the canal of the atlas and allows for rotational movements of the head
    6. C,F and K ( mark any one)
    7. protection of the spinal cord
    8. D and G ( mark any one)

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