Biology Paper 3 Questions and Answers - Form 4 End Term 1 Exams 2021

BIOLOGY
FORM 4
END TERM EXAMS
TERM 1 2021
PAPER 3
(PRACTICAL)
TIME 2¼ hrs

INSTRUCTIONS

Answer all questions in this paper.

The photographs below show specimens of different types of fruits. Examine them.
1. State four differences between specimens P and R. (4mks)
2. State the types of gynoecium and placentation of specimens P, S and V. (3mks)
  
  Specimen Gynoecium Placentation
  
  P
  
  S
  
  V
3. In the table below name the mode of dispersal for each specimen and the features that adapt the specimen its mode of dispersal. (6mks)
  
  Specimen Mode of dispersal Adaptive features
  
  P
  
  Q
  
  R
  
  S
  
  T
  
  V
4. Draw and label a plan diagram of specimen V. (2mks)
Below are photographs of specimens labeled E and F which were obtained from the same animal. Examine them.
1. With reasons, identify E and F. (2mks)
  1. Specimen E
    Identity
    Reason
  2. Specimen F
    Identity
    Reason
2. On photograph E, label any four parts of the specimen. (4mks)
3. Examine the following diagrams labeled L and M.
  1. Suggest the diet of each of the animals whose skulls are shown in the diagram. Give reasons for your answer. (4mks)
    1. Skull L
      Diet
      Reason
    2. Skull M
      Diet
      Reason
  2. Label the incisor tooth in diagram L. (1mk)
  3. Write the dental formula of the animals whose skulls are shown in diagrams L and M. (2mks)
  4. Identify the photograph of the skull from which specimens labeled E and F could have been obtained. (1mk)
    Specimen E
    Specimen F
  5. On the appropriate photograph, label the position where the horny pad would be found in a living animal. (1mk)
You are provided with the following:
- Food substance labeled Q
- Iodine solution
- Sodium Hydroxide solution.
- Benedicts solution.
- 4 test tubes
- A dropper
- Source of heat.
  1. Using the reagents provided, carry out various food tests on substance Q and record your observation in the table below.
    
    Food substance Procedure Observation Conclusion
    
    (4 ½ mks)
  2. 1. With reasons, identify the organ of a plant in specimen H photograph. (1mk)
      Identity
      Reasons: (3mks)
    2. After peeling off the epidermis of lower surface and the upper surface, the number of stomata was determined using a microscope at a high power and recorded in the table below.
      
      Average number of stomata in the field of view.
      
      Lower epidermis Upper epidermis
      
      30 10
    3. Account for the average number of stomata on upper and lower side of specimen H.
      1. Upper epidermis. (1mk)
      2. Lower epidermis. (1 mk)

CONFIDENTIAL

Solution Q (Glucose, egg)
Iodine solution
Sodium Hydroxide solution
Copper sulphate solution.
Benedicts solutions
4 test tubes
A dropper
Source of heat.

MARKING SCHEME

The photographs below show specimens of different types of fruits. Examine them.

State four differences between specimens P and R. (4mks)
- P has one seed while R has several seeds.
- P has a thick pericarp while R has a thin pericarp.
- P has a distinct epicarp, mesocarp, and endocarp while in R the three layers are distinct.
- P has no suture lines while R has suture lines.
- P has a hollow seed while the seeds of R are not hollow.
State the types of gynoecium and placentation of specimens P, S and V. (3mks)

Specimen Gynoecium Placentation

P monocarpous basal.

S syncarpous pariental

V syncarpous axile/central

In the table below name the mode of dispersal for each specimen and the features that adapt the specimen its mode of dispersal. (6mks)

Specimen	Mode of dispersal	Adaptive features
P	Water	Mesocarp has fibres/airspaces for buoyancy
Q	Wind	Has a wing-like membranous structure/membranous extension.
R	Self dispersal by explosive mechanism	Has lines of weakness/sutures on the wall
S	Animals	Is fleshy/succulent
T	Wind	Has hair-like projections/parachute of hairs.
V	Animals	Is fleshy/succulent

Draw and label a plan diagram of specimen V. (2mks)

Below are photographs of specimens labeled E and F which were obtained from the same animal. Examine them.
1. With reasons, identify E and F. (2mks)
  1. Specimen E
    Identity - molar tooth
    Reason - Has two roots/ has cusps
  2. Specimen F
    Identity - canine
    Reason - Sharp/ has one root
2. On photograph E, label any four parts of the specimen. (4mks)
  Ans
3. Examine the following diagrams labeled L and M.
  
  Ans
  1. Suggest the diet of each of the animals whose skulls are shown in the diagram. Give reasons for your answer. (4mks)
    1. Skull L
      Diet - Vegetation/grass/herbs/plants
      Reason - Presence of diastema/ Presence of horny pad/Pronounced cusps/ridges in the molars for grinding vegetation.
      (no canines and incisors is incorrect: Reason –negative answer.)
    2. Skull M
      Diet - Flesh/meat/bones/feeds on flesh/carnivore
      Reason - Pronounced long curved sharp/pointed canines for grasping/gripping/tearing prey.
      Carnassials teeth for cutting and crushing bone.
  2. Label the incisor tooth in diagram L. (1mk)
  3. Write the dental formula of the animals whose skulls are shown in diagrams L and M. (2mks)
    L (2) I 0 C 0 PM 3 M 3 = 32
    . 3 1 3 3
    M (2) I 3 C 1 PM 4 M 2 = 42
    . 3 1 3 3
    (Demarcating line must be shown in I,C, PM,M.)
  4. Identify the photograph of the skull from which specimens labeled E and F could have been obtained. (1mk)
    Specimen E
    Specimen F
  5. On the appropriate photograph, label the position where the horny pad would be found in a living animal. (1mk)

You are provided with the following:

Food substance labeled Q
Iodine solution
Sodium Hydroxide solution.
Benedicts solution.
4 test tubes
A dropper

Source of heat.

Using the reagents provided, carry out various food tests on substance Q and record your observation in the table below.

Food substance	Procedure	Observation	Conclusion
Starch	To 1cm³ of solution M3 on a white tile, add 2 drops of iodine solution.	Yellow-brown colour of iodine remains	Starch absent
Proteins	To 2cm³ of solution M3 add 3cm3 dulute NaOH solution, shake and add CuSO4 solution drop wise.	Violet – purple colour observed	Proteins present
Reducing sugars	To 2cm³ of solution M3 add an equal amount of Benedict’s solution and boil the mixture	Green-yellow-orange-brown-red colour precipitate formed	Reducing sugar present.

(4 ½ mks)

1. With reasons, identify the organ of a plant in specimen H photograph. (1mk)
  Identity - Leaf
  Reasons: (3mks)
  - Broad leaf blade/lamina
  - Presence of leaf petiole
  - Mid rib and veins present.
2. After peeling off the epidermis of lower surface and the upper surface, the number of stomata was determined using a microscope at a high power and recorded in the table below.
  
  Average number of stomata in the field of view.
  
  Lower epidermis Upper epidermis
  
  30 10
3. Account for the average number of stomata on upper and lower side of specimen H.
  1. Upper epidermis. (1mk)
    - Fewer/less stomata to reduce water loss/transpiration/evaporation because they are exposed to direct sunlight.
  2. Lower epidermis. (1 mk)
    - More stomata to increase rate of gaseous exchange or more stomata away from direct sunlight reduce rate of transpiration.