Biology Paper 3, WASSCE (PC 1ST)2019

Question 2

 

The diagrams below are illustrations of types of leaves from two different plants.Study them and answer questions 2(a) to 2(f).

(a) Identify Y and Z. [2 marks]

(b) (i) What is the main biological importance of Y? [1 mark]

(ii) State two features of biological importance in Z. [2 marks]

(c) (i) Identify the parts labelled I to VI. [3 marks]

(ii) State one function each of the parts labelled II, IV, V and VI. [4 marks]

(d)(i) Name the mineral element that is deficient in the soil where plant Z is found. [1 mark]

(ii) Name two feeding habits of plant Z. [2 marks]

(e) Explain how gaseous exchange takes place in the leaf of plant Y. [4 marks]

(f) In the table below, state three leaf modifications in plants other than that shown in plant Z and give one example of each of the modifications.

Leaf modification

One example

Observation

 

In this question, many candidates were unable to answer the questions correctly. Hence, they lost a lot of marks.

The few questions where they scored averagely were in (a) and (b).

The expected answers are:

(a) Identification of Plants Y - Hibiscus plant
Z - Venus flytrap

(b) (i) Biological importance of Y
- Has leaves for photosynthesis;
- Has flowers for pollination.

(ii) Features of biological importance of Z
- It has (green) leaf that carries out photosynthesis
- It has modified leaves for trapping insects
- Has flowers for pollination.

(c) (i) Labelled parts
I - Leaf margin/apex
II - Lamina/leaf blade
III - Vein
IV - Vein/leaf margin
V - Petiole/leaf stalk
VI - Axillary bud

(ii) Functions of labelled parts
- II/leaf blade/lamina: for absorption of sunlight/for photosynthesis/gaseous exchange/transpiration.
- IV/ vein/leaf margin: for transportation/translocation of food/conduction of water/nutrient/ leaf margin gives shape to the leaf.
- V/Petiole: holds leaves in position/attach leaf to stem.
- VI/Axillary bud: develops into branch.

(d) (i) Mineral element deficient in the soil of Z
Nitrogen

ii) Feeding habits of Z
- Insectivorous/carnivorous
- Photosynthetic /Photosynthesis/Autotrophic

(e) Gaseous exchange in the leaves of plant Y
- when the stomata open;
- oxygen diffuses into the intercellular air spaces;
- carbon dioxide diffuses out during respiration;
- carbon dioxide diffuses in during photosynthesis;
- oxygen diffuses out during photosynthesis.

(f) Modifications of the leaf

Leaf Modification

Example

Succulent/fleshy leaves

Kalanchoe/Bryophyllum/Life plant/Everlasting leaf, Onion leaf; Aloe

Tendrils of petiole/leaf tips modified into tendrils

Yam; Melons; Pumpkin/Gloriosa uperb.

Leaves reduced to spines

Cactus/Euphorbia/Opuntia

Leaf with lateral buds

Bryophyllum

Leaves modified into pitchers

fuPitcher plant/Nepenthes

Leaf covered with sticky glands

Sundew/Drosera

Scale leaves

Onion, Ginger, Imperata, Canna lily

Reduced into small size

Casuarina/Whistling pine

1 mark for leaf modification, 1 mark for corresponding example