1. (a) State two advantages of classification of living things to Biology.

[2 marks]

(b) State four ways each by which the following groups of organisms are of economic importance in their habitats:

(i) animals;

(ii) plants.

[8 marks]

(c) Complete the table below by stating five major phyla of the Kingdom Animalia and give one example of each.

[10 marks]

Answers to Question 1a - c

1. (a) Two advantages of classification of living things to Biology.

1. It helps scientists to organize and study the immense diversity of living organisms more effectively.

2. It enables easy identification and comparison of organisms based on shared characteristics.

(b) Four ways in which the following groups of organisms are of economic importance in their habitats:

(i) Animals:

1. They serve as a source of food (meat, milk, eggs).

2. They aid in pollination and seed dispersal.

3. Some are used for transportation (e.g., horses, donkeys).

4. They provide raw materials (wool, leather, silk).

(ii) Plants:

1. They provide food (fruits, vegetables, grains).

2. They serve as raw materials for medicine and pharmaceuticals.

3. They help in maintaining atmospheric oxygen through photosynthesis.

4. They are used for building and construction (timber, bamboo).

(c) Completed table of five major phyla of the Kingdom Animalia with one example each.

2. (a) Complete the table below.

[8 marks]

(b) Explain briefly the term balanced diet

[4 marks]

(c) State two roles each of the following structures of the digestive system in humans:

(i) colon;

(ii) mouth.

[4 marks]

(d) Explain briefly the following terms:

(i) micronutrients;

(ii) macronutrients.

[4 marks]

Answers to Question 2a - d(ii)

2. (a) Completed Table

(b) Balanced Diet:

A balanced diet is a meal that contains the correct proportions of carbohydrates, proteins, fats, vitamins, minerals, water, and fiber required for proper growth, energy, and maintenance of the body.

(c)(i) Two roles of the colon:

1. Absorbs water and electrolytes from undigested food.

2. Forms and stores feces for excretion.

(ii) Two roles of the mouth:

1. Begins the mechanical digestion of food through chewing.

2. Mixes food with saliva which contains enzymes like amylase for chemical digestion.

(d)(i) Micronutrients:

Micronutrients are nutrients required by the body in small quantities for proper functioning.

Examples include vitamins and minerals.

(ii) Macronutrients:

Macronutrients are nutrients needed by the body in large amounts.

These include carbohydrates, proteins, and fats, which provide energy and materials for growth and repair.

3. Relationships I, II, III, IV and V exist among some organisms in an ecosystem.

Use them to answer questions 3(a) to 3(e).

• I: Organism A feeds on organism B, causing organism B a disease.


• II: Organism C provides shelter for organism D while organism D transports organism C towards food.


• III: Organism E kills organism F for food.


• IV: Organism G feeds on the remnants of food left by organism H without affecting organism H negatively or positively.


• V: Organism J grows on dead organism F.

(a) Name the type of relationship in:

I:

II:

III:

IV:

V:

[5 marks]

(b) In relationship III, what is the biological term for each of organisms E and F?

(i) E:

(ii) F:

[2 marks]

(c) Name one example each of organisms A to H:

A:

B:

C:

D:

E:

F:

G:

H:

[8 marks]

(d) (i) Name the relationship that is most beneficial to the ecosystem:

(ii) Give one reason for the answer in 3(d)(i):

[2 marks]

(e)(i) Give two examples of organism J:

(ii) Name the group to which organism J belongs:

[3 marks]

Answers to Question 3a - e(ii)

3. (a) Type of relationship in:

I: Parasitism – a relationship where one organism benefits while the other is harmed.

II: Mutualism – both organisms benefit from the relationship.

III: Predation – one organism kills and eats another for food.

IV: Commensalism – one organism benefits while the other is unaffected.

V: Saprophytism – one organism feeds on dead organic matter.

(b) In relationship III, the biological term for organisms E and F are:

(i) E: Predator – an organism that hunts and feeds on another.

(ii) F: Prey – the organism that is hunted and eaten.

(c) Example of organisms A to H are:

A: Plasmodium – a parasite that causes malaria in humans.

B: Human – the host affected by Plasmodium.

C: Alga – provides food in a mutualistic relationship like in lichens.

D: Fungus (lichen) – offers protection and structure to the alga.

E: Lion – a predator that hunts other animals.

F: Zebra – a prey animal that can be hunted by predators.

G: Vulture – feeds on leftover food or carcasses.

H: Lion – leaves food remnants that vultures can feed on.

(d) (i) The relationship that is most beneficial to the ecosystem is:

Mutualism – promotes cooperation and survival of both species.

(ii) The reason for the answer in 3(d)(i) is:

It ensures survival and cooperation between organisms, benefiting both parties involved.

(e)(i) Two examples of organism J are:

Mucor & Rhizopus – fungi that decompose dead organic material.

(ii) The group to which organism J belongs to is:

Fungi – organisms that feed on decaying matter.

4. (a) Complete the following Punnett squares of a dihybrid cross between two monkeys. One has brown eyes (EE) and short tail (tt), the other has blue eyes (bb) and long tail (TT).

[12 marks]

(b) How many of the offspring will have:

(i) brown eyes and short tail;

(ii) brown eyes and long tail;

(iii) blue eyes and long tail;

(iv) blue eyes and short tail?

[4 marks]

(c) If there were ten (10) chromosomes in the pollen grains of a plant, how many chromosomes would be in each of the following cells of the plant?

(i) guard cell

(ii) leaf cell

(iii) root cell

(iv) ovule

[4 marks]

Answers to Question 4a - c

4. (a) Completed Punnett square:

(b) Number of offspring:

(i) brown eyes and short tail: 4

(ii) brown eyes and long tail: 12

(iii) blue eyes and long tail: 8

(iv) blue eyes and short tail: 4

(c) Chromosome numbers:

(i) guard cell: 20 chromosomes

Guard cells are diploid, so 2n = 2 × 10 = 20

(ii) leaf cell: 20 chromosomes

Leaf cells are diploid, so 2n = 2 × 10 = 20

(iii) root cell: 20 chromosomes

Root cells are diploid, so 2n = 2 × 10 = 20

(iv) ovule: 20 chromosomes

Ovule cells before fertilization are diploid, so 2n = 2 × 10 = 20

5. (a)(i) What are sense organs?

[3 marks]

(ii) Name three sense organs that respond to the stimulus of chemicals.

[3 marks]

(b) List three animals each that exhibit the following courtship behaviours:

(i) territoriality

(ii) pairing

[6 marks]

(c)(i) State one similarity between the eggs of toads and the eggs of birds.

[1 mark]

(ii) State three differences between the eggs of birds and the eggs of toads.

[3 marks]

(d) Complete the table below by listing four organisms involved in the nitrogen cycle and state one role each of the organisms.

[8 marks]

(e) Complete the table below by naming two types of heterotrophic modes of nutrition in animals and give two examples each of the organisms that carry out the modes of nutrition.

[6 marks]

Answers to Question 5a - e

5. (a)(i) Sense organs are specialized organs composed of sensory cells that detect and respond to specific stimuli from the environment such as light, sound, touch, taste, and smell.

(ii) Three sense organs that respond to the stimulus of chemicals are:

• Tongue (taste)
• Nose (smell)
• Skin (in response to chemical irritants)

(b)(i) Animals that exhibit territoriality:

• Lion
• Eagle
• Dog

(ii) Animals that exhibit pairing:

• Dove
• Penguin
• Parrot

(c)(i) One similarity between the eggs of toads and birds is: both are reproductive cells laid to give rise to new individuals.

(ii) Differences between eggs of birds and eggs of toads:

(d) Four organisms involved in the nitrogen cycle and their roles:

(e) Two types of heterotrophic nutrition and two examples each: