Answers to Questions 1a - c

1. (a) Completed Table

(b) Four parts of the nephron of a kidney:

1. Bowman's capsule: A cup-shaped structure that surrounds the glomerulus and is involved in the filtration of blood to form urine.

2. Proximal convoluted tubule: The first part of the renal tubule that reabsorbs water, ions, and nutrients from the filtrate back into the blood.

3. Loop of Henle: A U-shaped tube that concentrates urine by reabsorbing water and salts in the kidney.

4. Distal convoluted tubule: The part of the nephron where further absorption and secretion occur, regulating the balance of electrolytes and pH in the urine.

(c) completed Table.

2. An individual ate a hot and large meal of cassava with salty groundnut soup. The individual was sweating profusely but did not drink water after the meal.

(a) Name four food nutrients contained in the food

[4 marks]

(b)(i) State one role each played by the following organs involved in the activity above.

[8 marks]

(ii) Name three of the organs listed that contain enzymes needed to break down the food.

[3 marks]

(iii) Name three digestive enzymes that would be involved in the digestion of the meal.

[3 marks]

(iv) Name two end products of the meal after digestion.

[2 marks]

Answers to Question 2a - b(iv)

2. (a) Four food nutrients contained in the meal:

1. Carbohydrates – Found in cassava; provide the body with energy.

2. Proteins – Present in groundnut; help in body building and repair of tissues.

3. Fats and oils – Present in the groundnut soup; serve as a source of long-term energy and support vitamin absorption.

4. Minerals (e.g., sodium) – Found in the salty soup; help regulate body fluids and nerve functions.

(b)(i) Completed Table of the Roles of the following organs:

(ii) Three organs that contain enzymes needed to break down the food:

1. Mouth – Contains salivary glands that produce amylase to begin digestion of starch.

2. Stomach – Produces gastric juices including pepsin that start protein digestion.

3. Small intestine – Releases enzymes from the pancreas and intestinal lining to complete digestion of carbohydrates, proteins, and fats.

(iii) Three digestive enzymes involved in digestion of the meal:

1. Amylase – Breaks down starch into simple sugars like maltose or glucose.

2. Protease (e.g., pepsin) – Breaks down proteins into smaller peptides and amino acids.

3. Lipase – Breaks down fats into fatty acids and glycerol.

(iv) Two end products of the meal after digestion:

1. Glucose – A simple sugar that provides energy to the body; derived from carbohydrates like cassava.

2. Amino acids – Building blocks of proteins; derived from groundnut protein digestion.

Answers to Question 3a - b(iv)

3. (a) Completed Table of Food Preservation Methods and Their Mechanisms:

(b)(i) Four likely changes that would be observed on the fish:

1. Bad odour – The fish emits a strong, foul smell due to decomposition.

2. Discoloration – The skin and flesh of the fish change color, often turning dull or grey.

3. Soft or slimy texture – The fish becomes soft and develops a slimy surface.

4. Presence of maggots or mold – Insects and fungi may begin growing on the decaying fish.

(ii) Two methods that would have been used to preserve the fish:

1. Smoking – Uses heat and smoke to dry and preserve the fish.

2. Freezing – Keeps fish at low temperatures to prevent microbial activity.

(iii) Principle involved in each of the methods listed in 3(b)(ii):

1. Smoking: Reduces moisture content and uses heat to kill microorganisms.

2. Freezing: Slows down microbial growth by lowering the temperature.

(iv) Two likely causes of the observation in 3(b)(i):

1. Bacterial decomposition – Microorganisms break down fish tissues, causing spoilage.

2. Exposure to air and poor storage – Leads to contamination and rapid decay.

4. (a) One of the parents of four offspring belongs to blood group O. If the blood group of the offspring are different from those of their biological parents, what would be the:

(i) Blood group of the other parent?

[1 marks]

(ii) Likely blood groups of the four offspring?

[4 marks]

(b) Explain briefly how genes are involved in the process of evolution.

[3 marks]

(c)(i) Complete the table below by stating the type of cell division and the type of set of chromosomes for the listed cells.

(ii) What is meiosis?

[2 marks]

Answers to Question 4a - c(ii)

4. (a)(i) Blood group of the other parent:

The other parent must belong to blood group AB.

This is because group O can only contribute the O allele, so to produce offspring with different blood groups (A, B, AB, O), the other parent must carry both A and B alleles.

(ii) Likely blood groups of the four offspring:

1. Blood group A

2. Blood group B

3. Blood group AB

4. Blood group O

(b) How genes are involved in the process of evolution:

Genes carry the hereditary information that determines traits.

During reproduction, mutations can occur, introducing new variations.

Natural selection acts on these variations, favoring traits that provide survival or reproductive advantages.

Over time, these genetic changes accumulate, leading to the evolution of species.

(c)(i) Completed table of cell division and chromosome sets:

(ii) Meiosis

Meiosis is a type of cell division that occurs in reproductive cells and results in four daughter cells, each with half the number of chromosomes of the original cell.

It is essential for sexual reproduction and genetic diversity.

5. (a)(i) What is competition?

[3 marks]

(ii) List two types of competition.

[2 marks]

(iii) List four factors that organisms compete for in a habitat.

[4 marks]

(iv) Explain briefly the relationship between competition and succession.

[2 marks]

(b)(i) What is structural adaptation?

[2 marks]

(ii) State four types of structural adaptations in animals.

[4 marks]

(c) List four features of variation in humans that are used in crime detection.

[4 marks]

(d) Complete the table below by listing three types of adaptive colouration in animals and give one example each of animals that show the colourations.

[6 marks]

(e) Give three examples of plants found in a tropical rainforest.

[3 marks]

Answers to Question 5a - e

5. (a)(i) Competition?

Competition is the interaction between organisms or species in which both are harmed as they attempt to obtain the same resources, such as food, water, or space, that are limited in supply.

(ii) Two types of competition.

1. Intraspecific competition – Competition between individuals of the same species.

2. Interspecific competition – Competition between individuals of different species.

(iii) Four factors that organisms compete for in a habitat.

1. Food – Organisms compete for available food resources in a habitat.

2. Water – Access to water is a vital resource for survival.

3. Space – Organisms need space for nesting, shelter, and territory.

4. Mates – Organisms compete for mates to reproduce and pass on genes.

(iv) The Relationship between competition and succession.

Competition and succession are linked because as species compete for resources in a habitat, the process of ecological succession may occur.

This is the gradual process by which different species replace each other over time, often in response to competition and environmental changes.

(b)(i) Structural adaptation?

Structural adaptation refers to the physical features of an organism that enhance its survival and reproduction in a particular environment.

These features have evolved to help the organism adapt to specific environmental challenges.

(ii) Four types of structural adaptations in animals.

1. Camouflage – Enables animals to blend into their surroundings and avoid predators (e.g., chameleons).

2. Body covering – Protective features such as fur, scales, or shells to shield from environmental factors (e.g., a turtle's shell).

3. Body shape – Helps organisms to move efficiently in their environment (e.g., streamlined bodies in fish for swimming).

4. Specialized limbs – Adaptations for specific functions like grasping, running, or flying (e.g., webbed feet in ducks).

(c) Four features of variation in humans that are used in crime detection.

1. Fingerprints – Unique to each individual and used for identification.

2. DNA – Genetic variation in DNA is used to link individuals to crime scenes.

3. Eye color – Inherited traits that can help describe suspects.

4. Hair type – Variations in hair characteristics can be used for identification.

(d) Three types of adaptive colouration in animals and examples:

(e) Three examples of plants found in a tropical rainforest:

1. Rattan palm – A climbing palm used for making furniture.

2. Cocoa tree – Produces cocoa beans used in chocolate production.

3. Orchids – Known for their beautiful flowers and variety in the rainforest.