Biology Paper 1 Questions and Answers - Form 3 Mid Term 3 Exams 2023

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INSTRUCTIONS TO CANDIDATES:

Answer all the questions in this question paper.
Answers must be written in the spaces provided in this booklet.
All answers must be written in English

What do the following branches of Biology deal with? (2marks)
1. Cytology
2. Entomology
State TWO characteristics of kingdom Monera that are not found in other kingdoms. (2marks).
Two species in an ecosystem cannot occupy the same niche. Explain. (1 mark)
State two functions of aerenchyma tissue in hydrophytes. (2marks)
The diagram below shows results of what happens to plant cell when placed in a certain solution.
1. What was the nature of the solution in which the cell was placed? (1 mark)
2. Identify the force represented by the arrow X and explain how it develops. (2 marks)
Which organelle would be numerous in the following cells; (2 marks)
1. Liver cell
2. Palisade cell
The scientific names of three animals leopard, wolf and lion in the family carnivora are; Panthera pardus, Canis lupas and Panthera leo respectively.
1. Why are scientific names given in Latin? (1 mark)
2. What does Canis refer to? (1 mark)
3. Giving a reason, state the organisms that are MOST closely related. (1 mark)
The word equation below shows a biological process.
Water → Hydrogen atom + oxygen
1. Name the process. (1 mark)
2. Where does the process named in a) above take place? (1 mark)
3. State two conditions necessary for the process to occur. (2 marks)
1. What is the importance of heartbeat in blood circulation? (1 mark)
2. If the nerve supply to the heart of a mammal is severed, the rhythmic heart movement will still go on and the heart continues to beat. Explain this observation. (1 mark)
State the difference between habitat and ecological niche. (2 marks)
The diagram below represents a stage during cell division.
1. Name the stage of cell division. (1 mark)
2. Give two reasons for your answer in a) above. (2 marks)
3. State the significance of this stage of cell division in living organisms. (1 mark)
Name the causative agent for the following diseases;
1. Typhoid (1 mark)
2. Amoebic dysentery. (1 mark)
Examine the diagram below and answer the questions that follow.

Name the structures labeled: (3mks)
1. A……………………………………………………………………………………………
2. B...…………………………………….……………………………………………………
3. X..…………………………………….……………………………………………………
1. Name the respiratory surface for gaseous exchange in insects. (1 mark)
2. State two adaptations of the site named in a) above. (2 marks)
The graph below shows the effect of substrate concentration on the rate an enzyme catalyzed reaction.
1. Account for the shape of the graph between region B and C. (2mks)
2. How can the rate of reaction be increased after point B? (2mks)
Explain the meaning of the following terms;
1. Basal Metabolic Rate (1 mark)
2. Oxygen Debt (1 mark)
In an experiment, the concentration of ions in the cell sap of reeds growing in a swampy area and the water in the swamp were determined. The data below was obtained. Study it and answer the questions that follow:

Sample Na²⁺ Mg²⁺ Cl⁻ SO₄²⁻

Cell sap 50 11 101 13

Swamp water 1.2 30 10.2 0.67
1. Name the process by which uptake of the following ions by the reeds occurs. (2 marks)
  1. Na⁺ ions ....................................................
  2. Mg²⁺ ions ......................................................
2. What effect would reduced oxygen supply have on the uptake of sulphate ions? (2 marks)
  Explain your answer.
The diagram below shows a part of a nephron.
1. State TWO differences in composition of blood in parts P and R. (2 marks)
2. State a characteristic feature of blood capillaries in part Q that is not found in other capillarities (1 mark)
State two functional differences between arteries and veins in mammals. (2mks)
A set up was used to investigate a certain process in plants as shown in the diagram below.
1. What process was being investigated? (1 mark)
2. Giving a reason, state one precaution that should be taken when setting up this experiment. (1 mark)
3. How would changes in environment temperature affect the rate of movement of the air bubble? (1 mark)
Julie observed eight onion epidermal cells across the field of view of a light microscope. If the field of view was 4mm in diameter, estimate the average size of the cells in micrometers (1mm= 1000m). (2 marks)
State two ways in which root hairs are adapted to their functions. (2mks)
Explain how high humidity affects the rate of transpiration. (2mks)
Give three differences between aerobic and anaerobic respiration. (3mks)
State one use of each of the following excretory products in plants.
1. Tanin (1mk)
2. Colchicine (1mk)
3. Quinine (1mk)
State THREE adaptations of a leaf to gaseous exchange. (3 marks)
State three types of asexual reproduction. (3mks)
Give three sources of water pollution. (3mks)
Name the antigens that determine human blood groups. (2mks)
1. The action of pepsin stops in the duodenum. Explain. (2 marks)
2. State two functions of the ileum in the alimentary canal of mammals. (2 marks)

MARKING SCHEME

1. Ans. The study of cells in living organism;
2. Ans. The study of insects.
Ans. The genetic material is not surrounded by a nuclear membrane/genetic material lacks a membrane/ not membrane bound/they are prokaryotic;
- Organelles are not enclosed by membrane;
- Lack most organelles e.g. mitochondria Rej. If no example/have few organelles;
  Mark first two.
Ans. A stiff competition for available resources sets in, resulting in the elimination of one species;
reduces density to give buoyancy to the plant –contains air for gaseous exchange
1. Ans. Hypotonic solution;
2. Ans. Turgor pressure; the cell gained water through the process of osmosis and becomes turgid; Rej:
  Absorbed for gained;
1. Ans. Golgi apparatus/body;
2. Ans. Chloroplast; Rej. Plural
1. Ans. Latin language is fairly static/it does not change with time or locality like most other languages;
2. Ans. Generic name of wolf; Rej. Genus name
3. Ans. Lion and leopard, they belong to the same genus Panthera;
1. Ans. Photolysis;
2. Ans. Grana of chloroplast; Rej. Chloroplast
3. Ans. Sunlight; chlorophyll;
1. Ans.
  - It ensures sufficient supply of nutrients and oxygen to the cells;
  - It ensures exchange and removal of waste products of metabolism from the body cells to excretory organs;
  - It ensures that blood flows out of the heart to all parts of the body;
2. Ans. The rhythmic contractions of the heart arises from within special cardiac muscles/the heart muscles are myogenic;
Habitat is a specific locality with a particular set of conditions where an organism lives; Ecological niche is the position that an organism occupies in a habitat in terms of physical state and its role in
Ans.
1. Ans. Anaphase I;
2. Ans. Homologous chromosomes separate at the equator/homologous chromosomes start migrating to the opposite poles; sister chromatids attached at the centromeres;
3. Ans. It is the reduction phase that results in haploid sex cells/gamete cells;
1. Ans. Salmonella typhi;
2. Ans. Treponema palladium;
Ans
- A – stoma; rj. Stomata;
- B – Epidermal cell;
- X – Guard cell;
1. Ans. Tracheole; Rej. Tracheoles
2. Ans. It is moist to dissolve gases/for diffusion of gases in solution;
  - It has thin epithelia to reduce distance for diffusing gases;
  - It has numerous fine tubes to increase surface area for gaseous exchange;
    Mark first two correct answers.
1. All the active sites are occupied; hence rate of reaction is constant;
2. Increase/raise concentration of the enzyme;
1. Ans. The energy produced by an animal when it is resting to maintain its life processes;
2. Ans. The extra oxygen required to breakdown lactic acid that accumulates during exercise when oxygen supply is less than required;
1. Na⁺ ions – Ans. Active transport
  Mg²⁺ ions – Ans. diffusion
2. Ans. Reduces the rate of active transport due to increased rate of respiration/oxidation of glucose, hence less energy;
Ans. P – has more nitrogenous wastes; more water, more mineral salts/ions; more oxygen than R; mark first two correct answers

Arteries	Veins
- Transport blood from the heart to the body	- Transport blood from body tissue to heart.
- Transport oxygenated blood except Pulmonary artery	- Transport deoxygenated blood except pulmonary vein

1. Ans. Transpiration.
2. Ans. Cut shoot under water/assemble entire set up under water; apply petroleum jelly at the stopper –
  Glass – shoot connections; to ensure no air enters the leafy shoot xylem/apparatus causing airlock; to ensure apparatus is airtight;
3. High temperatures increase the transpiration rate, hence the bubble moves faster;
Ans. 1mm = 1000μm
4mm = 4 x 1000μm
= 4000μm;
Average size of cell = 40008 μm
= 500μm;
- Numerous to increase the surface area for absorption of water
- Have numerous mitochondria to supply energy (for active uptake of minerals);
- Have thin walls for faster movement of substances;
- Have large sap vacuole with solutes for steep concentration gradient;
- High humidity reduces concentration gradient of water vapour between the intercellular air

Aerobic	Anaerobic
- Uses oxygen	Doesn’t use oxygen;
- More energy given out;	-Less energy given;
- Occurs in cytoplasm and mitochondria	-Occurs in cytoplasm only;
- Complete breakdown of substrate	-Incomplete breakdown of substrate;

(1st two)

1. Tanning hides and skins (in manufacture of leather)
2. Colchicine
  - Causes polyploidy;
  - Used in treatment of cancer; (any one)
3. Quinine - used as an anti-malaria drug
Ans. It has stomata for efficient diffusion of gases; It is thin to allow gases to diffuse through short distances; It has air spaces for easy circulation of gases; it has broad and flat lamina to provide large surface area for absorption; Mark 1st three
- Binary fission in amoeba
- Spore formation in rhizopus
- Budding in yeast
- Industrial effluents;
- Domestic sewage;
- Hot water from industrial effluents
- Soil erosion
- Agricultural runoff;
- Antigens A;
- Antigens B;
1. Ans. Because it is destroyed / denatured; by alkaline medium / bile salts in the duodenum;
2. - Nutrient absorption
  - Reabsorption of Bile salts