INSTRUCTIONS TO CANDIDATES:
- Answer all the questions in the spaces provided.
- Below is a diagram representing a longitudinal section of a human tooth.
- Name the type of tooth.
- Give a reason for your answer in (a) above
- Name structures P, Q, and R and give their functions. (6 marks)
- State four ways of keeping teeth healthy. (4 marks)
- The diagram below shows circulation of blood in a mammal.
- Name the type of circulation represented above (1 mark)
- Give reason for your answer (1 mark)
- Name the blood vessel labeled A, B, C ,D (4 marks)
- State two roles of blood capillaries (2 marks)
- Name other two types of blood vessels beside capillaries (2 marks)
- State two functional differences between the blood vessels you have named above (2 marks)
- State two roles of the red blood cells (2marks)
- Name the three types of immunity (3 marks)
-
- What is gaseous exchange? (1 marks)
- Name the mineral element and vitamin required for blood clotting (2 marks)
- The diagram below represents a transverse section of a plant part
- Identify the class from which it is obtained (1 mark)
- Name parts G and H (2 marks)
- Give one role of J (1 marks)
- Name the three types of transpiration (3 marks)
- Give one difference between xylem vessels and xylem trancheids (2 marks)
- Name the strengthening material in vessels (1 marks)
- The diagram below shows an organelle in plants
- Identify the organelle (1 marks)
- Name the parts E and F (2 marks)
- Give one role of part E (1 marks)
- Name two requirements for photosynthesis (2 marks)
- Explain what happens during the light stage of photosynthesis.
- Discuss the factors that affect rate of enzyme action.
- Discuss the forces involved in the absorption and transport of water and mineral salts. (10 marks)

MARKING SCHEME
- Below is a diagram representing a longitudinal section of a human tooth.
- Name the type of tooth.
- Molar
- Give a reason for your answer in (a) above
- Have two roots
- Broad surface
- Ridged with cusps
- Name structures P, Q, and R and give their functions. (6 marks)
- P - Enamel
protect the inner parts from bacterial infection; provide harrd biting surface - Q - Nerve fibre
Detects heat, cold and pain - R - Blood capillaries
provide nutrients and oxygen to the living tissues; remove waste products
- P - Enamel
- State four ways of keeping teeth healthy. (4 marks)
- Regular brushing/ cleaning
- Avoid eating too much sugary foods
- Eating hard foods like carrots
- Eating diet rich in calcium, phosphorus and regular visit to the dentist for check-up
- Name the type of tooth.
- The diagram below shows circulation of blood in a mammal.
- Name the type of circulation represented above (1 mark)
- Double circulation
- Give reason for your answer (1 mark)
- blood flows into the heart twice for every complete circulation
- Name the blood vessel labeled A, B, C ,D (4 marks)
- A - Pulmonary artery
- B - pulmonary vein
- C - Hepatic portal vein
- D - Renal artery
- State two roles of blood capillaries (2 marks)
- Exchange of nutrients and works between tissue and blood
- formation of tissue fluid
- Name other two types of blood vessels beside capillaries (2 marks)
- Arteries
- Veins
- State two functional differences between the blood vessels you have named above (2 marks)
- Arteries transport oxygenated blood except pulmonary artery while veins transport deoxygenated blood except pulmonary vein.
- In arteries blood flows rapidly under pressure while in veins it flows smoothly and slowly under low pressure.
- State two roles of the red blood cells (2marks)
- Transport of oxygen
- Transport of Carbon (IV) Oxide
- Name the three types of immunity (3 marks)
- Natural immunity/ Inmate immunity
- Naturally acquired immunity
- Artificially acquired immunity
- Name the type of circulation represented above (1 mark)
-
- What is gaseous exchange? (1 marks)
- The process by which the respiratory gases (oxygen and carbon (IV) oxide ) are passed across the respiratory surface
- Name the mineral element and vitamin required for blood clotting (2 marks)
Mineral element - calcium ion ( Ca2+)
Vitamin - k
- What is gaseous exchange? (1 marks)
- The diagram below represents a transverse section of a plant part
- Identify the class from which it is obtained (1 mark)
- Dicotyledonae
- Name parts G and H (2 marks)
- G - xylem
- H - Schlerenchyma
- Give one role of J (1 marks)
- Stores water and food substance
- Name the three types of transpiration (3 marks)
- Stomatal
- Cuticular
- Lenticular
- Give one difference between xylem vessels and xylem trancheids (2 marks)
- Trancheids have tapering/ chisel-shaped ends with perforated cross walls while vessels cross walls disintegrate to form a hallow tube with no tapering.
- Name the strengthening material in vessels (1 marks)
- Lignin
- Identify the class from which it is obtained (1 mark)
- The diagram below shows an organelle in plants
- Identify the organelle (1 marks)
- Chloroplast
- Name the parts E and F (2 marks)
- E - Inner membrane
F - granum
- E - Inner membrane
- Give one role of part E (1 marks)
- Bind the internal pigments and molecules
- Name two requirements for photosynthesis (2 marks)
- Light
- carbon (IV) oxide
- Water
- Explain what happens during the light stage of photosynthesis.
- Cholorophyll molecules absorb light energy, which is used to split water molecules (photolysis); into oxygen and hydrogen atoms; some energy from light is used to from A.T.P, oxygen is released.
- Identify the organelle (1 marks)
- Discuss the factors that affect rate of enzyme action.
- Temperature; enzymes work best within a narrow range of temperatures, high temperatures denature enzymes while low temperature inactivates them;
- PH; enzymes work best at a given PH (ophmum PH), majority work best at a PH close to 7 while some work best in acidic or alkaline medium. i
- Specificity: enzymes are specific in nature i.e. a particular enzyme will only act on a particular substrate;
- Substrate concentration and enzyme concentration; rate of reaction increases with increase in substrate concentration till all the active sites in enzymes become the limiting factor;
- enzyme inhibitors, competitive inhibitors shows down the reaction as they compete for the active sites while non-competitive prevents enzymes from interacting with the substrate i.e. stops the reaction processes.
- Discuss the forces involved in the absorption and transport of water and mineral salts. (10 marks)
- Transpiration pull; as water vaporizes from spongy mesophyll cells into sub-stomach air spaces, osmotic pressure of the spongy mesophyll increases: it then draw water forin surrounding cells which in turn take water form the xylem vessels;
- cohesion and adhesion force; water molecules attract one another thus sticking together, as the same time its attracted to walls of xylem vessels; this maintains a thin but high columns of water in xylem vessels up the plant;
- capillarity; This is the rise of water column n the xylem vessels because the vessels are narrow; and there is attracting force between walls of the xylem and water;
- Root pressure; This is the force in the roots that pushes water up the stem; this is due to active pumping of water across the endodermisto xylem vessels.
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