Biology Paper 1 Questions and Answers - Form 4 End Term 1 Exams 2023

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INSTRUCTIONS TO CANDIDATES:

Answer ALL the questions

Answers should be written in the spaces provided

Name the disease in humans that is caused by lack of vitamin C. (1mk)
State three characteristics that cause cross- pollination to take place in flowering plants. (3mks)
Name two structures used for gaseous exchange in plants. (2mks)
When are two organisms considered to belong to the same species? (2mks)
State the functions of the following cell organelles (2mks)
1. Golgi apparatus..
2. Ribosomes
State three ways in which xylem vessels are adapted to their functions. (3mks
A person who found to pass out large volumes of dilute urine frequently.
1. Name the disease the person was suffering from (1mk)
2. Name the hormone that was deficient. (1mk)
State any three pieces of evidence that support the theory of evolution. (3mks)
Why are people with blood group O universal donors. (2mks)
Which organelle would be abundant in
1. Skeletal muscle cell(1mk)
2. Palisade cell(1mk)
In an experiment, it was found that when maggots are exposed to light, they move to dark areas. Name
1. The type of response exhibited by maggots.(1mks)
2. The advantages of the response to the maggots(1mk)
State two ways by which the human immune deficiency (H.I.V) is transmitted other than through sexual intercourse. (2mks
Suggest three reasons why green plants are included in a fish aquarium. (3mks)
State three ways in which some fungi are beneficial to human. (3mks)
Why is oxygen important in the process of active transport in cells. (2mks)
State two disadvantages of metamorphosis to the life of insects. (2mks)
A person whose blood group is AB requires a blood transfusion. Name the blood groups of the donors. (1mk)
State two functions of muscles found in the alimentary canal of mammals. (2mks)
Name three types of chrosomal mutations. (3mks)
The diagram below shows a specialized plant cell
.
1. Name the cell.(1mk)
2. Name the parts labeled D and E. (2mks)
3. State the function of the part labeled C. (1mk)
Distinguish between haemolysis and plasmolysis. (2mks)
Explain why it is not advisable to be in poorly ventilated room with a burning charcoal stove. (3mks)
What is the role of bile salts in digestion in human’s. (2mks)
1. The following is the dental formula of a certain mammal. i ⁰/₃ c ⁰/₁ pm /₃m³/₃
  1. State the likely mode of feeding for the mammal(1mk)
  2. Give a reason for your answer in (a) above (1mk)
2. State the changes that occur in arterioles in the human skin during thermoregulation (2mks)
3. Name the site of anaerobic respiration in a cell(1mk)
1. What is meant by convergent evolution? (1mk)
2. State two limitations of fossils as an evidence of evolution. (2mks)
3. Apart from the lungs, name two gaseous exchange surfaces in a frog. (2mks)
1. The diagram below represents a certain plant.
  1. What is the likely habitat for the plant. (1mk)
  2. Give two reasons for your answer in (a) above (2mks)
2. What would be the expected results from a test cross. (2mks)
1. State one economic importance of each of the following plant excretory products. (3mks)
  1. Tannin
  2. Quinine
  3. Caffeine
2. Name three salivary glands in humans. (3mks)
3. Name two dental diseases (2mks)
The diagram below represents a certain organism

State the phylum and class to which it belongs (2mks
What is meant by the flowing terms. (2mks)
1. Ecology.
2. Carrying capacity

MARKING SCHEME

Name the disease in humans that is caused by lack of vitamin C. (1mk)
- Scurvy
State three characteristics that cause cross- pollination takes place in flowering plants. (3mks)
- Protandry
- Protogyny
- Self-sterility
- Monoecious plants
Name two structures used for gaseous exchange in plants. (2mks)
- Stomata
- Cuticle
- lenticels
When are two organisms considered to belong to the same species? (2mks)
- When they freely interbreed , to produce a viable off spring
State the functions of the following cell organelles (2mks)
1. Golgi apparatus
  - Packing of synthesized materials/ glycoproteins
2. Ribosomes
  - Transport of packed materials
  - Manufacture of proteins
State three ways in which xylem vessels are adapted to their functions. (3mks)
- Lignified to prevent collapse
- Narrow to facilitate capillarity
- Hollow for continuous flow of water
- Bordered pit for lateral movement of water
A person who found to pass out large volumes of dilute urine frequently.
1. Name the disease the person was suffering from (1mk)
  - Diabetes insipidus/diuresis/water diabetes
2. Name the hormone that was deficient. (1mk)
  - Antidiuretic hormone/vasopresin
State any three pieces of evidence that support the theory of evolution. (3mks)
- Fossil records
- Geographical distribution of organisms
- Comparative anatomy
- Cell biology
- Comparative serology
- Comparative embryology
Why are people with blood group O universal donors. (2mks)
- Blood has no antigen and does not cause agglutination
Which organelle would be abundant in
1. Skeletal muscle cell. (1mk)
  - mitochondria
2. Palisade cell (1mk)
  - chloroplast
In an experiment, it was found that when maggots are exposed to light, they move to dark areas. Name
1. The type of response exhibited by maggots. (1mks)
  - Photo taxis
2. The advantages of the response to the maggots. (1mk)
  - To avoid desiccation/drying/dehydration
  - To escape from predators
State two ways by which the human immune deficiency (H.I.V) is transmitted other than through sexual intercourse. (2mks)
- Use of unsterilized instrument
- Blood transfusion
- Mother foetus
- Mixing of infected blood through cuts
Suggest three reasons why green plants are included in a fish aquarium. (3mks)
- Food, shelter, breeding sites; removal of CO₂; for oxygen
State three ways in which some fungi are beneficial to human. (3mks)
- Brewing; baking; manufacture medicine; some edible
Why is oxygen important in the process of active transport in cells. (2mks)
- Oxygen is required for respiration that produces energy necessary for active transport
State two disadvantages of metamorphosis to the life of insects. (2mks)
- No competition for food
- Enable survival in adverse conditions
A person whose blood group is AB requires a blood transfusion. Name the blood groups of the donors. (1mk)
- A,B,AB, O (rej if the four not given)
State two functions of muscles found in the alimentary canal of mammals. (2mks)
- Act as values to regulate food movement
- Churning food
Name three types of chrosomal mutations. (3mks)
- Inversion; duplication; deletion; translocation; non - disjunction
The diagram below shows a specialized plant cell.
1. Name the cell. (1mk)
  - Root hair cell
2. Name the parts labeled D and E. (2mks)
  - D – cell wall
  - E- sap vacuole
3. State the function of the part labeled C. (1mk)
  - Control activities’ of the cell
Distinguish between haemolysis and plasmolysis. (2mks)
- Haemolysis- bursting of an animal cell when placed in a hypotonic solution.
- Plasmolysis- loss of water by a plant cell when placed in a hypertonic solution.
Explain why it is not advisable to be in poorly ventilated room with a burning charcoal stove. (3mks)
- In a poorly ventilated room the charcoal burns producing carbon (ii) oxide; it combines with haemoglobin forming a stable compound carboxyhaemoglobin which which does not easily dissociate ; it prevents oxygen from combining with haemoglobin leading to suffocation. (3mks)
What is the role of bile salts in digestion in human’s. (2mks)
- Emulsification
- Creates alkaline conditions ( for enxyme action)
1. The following is the dental formula of a certain mammal
  .i ⁰/₃ c ⁰/₁ pm ³/₃ m ³/₃
  1. State the likely mode of feeding for the mammal. (1mk)
    - herbivorous
  2. Give a reason for your answer in (a) above (1mk)
    - Absent of upper incisors/presence of horny pad
    - Lack of canines on upper jaw/diastema present
2. State the changes that occur in arterioles in the human skin during thermoregulation (2mks)
  - Vasoconstriction in cold conditions
  - Vasodilation in hot conditions
3. Name the site of anaerobic respiration in a cell (1mk)
  - Cell's Cytoplasm
1. What is meant by convergent evolution? (1mk)
  - A type of evolution where structures of different origin and modified to perform similar functions
2. State two limitations of fossils as an evidence of evolution. (2mks)
  - Missing links
  - Partial fossilization
  - Destruction by geological activities
3. Apart from the lungs, name two gaseous exchange surfaces in a frog. (2mks)
  - Mouth/buccal cavity
  - skin
1. The diagram below represents a certain plant
  1. What is the likely habitat for the plant. (1mk)
    - Arid/semi arid
  2. Give two reasons for your answer in (a) above (2mks)
    - Leaves modified into spines/thorn
    - swollen stems to store water
2. What would be the expected results from a test cross. (2mks)
  - If unknown phenotype is heterozygous, the off- spring are a mixture of dominant and recessive 1:1, if phenotype is homozygous; all off spring display the dominant trait.
1. State one economic importance of each of the following plant excretory products. (3mks)
  1. Tannin
    - Treating leather
  2. Quinine
    - Anti- material drug
  3. Caffeine
    - Stimulant in beverage
2. Name three salivary glands in humans. (3mks)
  - Sub maxillary salivary gland
  - Subliqual gland
  - parotid
3. Name two dental diseases (2mks)
  - Periodontal
  - Dental caries
The diagram below represents a certain organism
State the phylum and class to which it belongs (2mks)
- Phylum- chordata
- Class- aves
What is meant by the flowing terms. (2mks)
1. Ecology
  - study of inter-relationship of organisms and their environment
2. Carrying capacity
  - maximum number of organisms of the same species on area can support without depleting available resources