Biology Paper 1 Questions and Answers - Achievers Joint Mock Exams 2023

INSTRUCTIONS 

• Answer ALL the questions

QUESTIONS

1. State the functions of the following points of a light microscope.
   1. Diaphragm (1mk)
   2. Condenser (1mk)
2. State the functions of the following organelles.
   1. Nucleolus (1mk)
   2. Ribosomes (1mk)
3. The reaction represented by the equation below occurs in the body.
   
   
   1. Name enzyme Y. (1mk)
   2. Name an organ in the body where the reaction occurs. (1mk)
   3. What is the significance of the reaction (1mk)
4.  
   1. Name two disorders in man that occur through gene substitution (2mks)
   2. Give two advantages of polyploidy in plants. (2mks)
5. The diagram below shows the human ear.
   
   
   1. Name the structures labeled 3, 4 (2mrks)
   2. State the function of the parts labeled 5 and 7. (2mrks)
6. The diagram below represents a maize seedling
   
   
   1. 1. Name the type of germination exhibited by maize. (1mk)
      2. Give a reason for your answer in (a) (i) above. (1mk)
   2. State the functions of the parts labelled A and B. (2mk)
      A
      B
7.  /
   1. Explain how the following factors control population.
      1. Predation (1mk)
      2. Competition (1mk)
      3. Parasitism (1mk)
   2. A cat was used to control the population of rats.
      1. What term is used to refer to this method. (1mk)
      2. State one advantage of using the method you named in (i) above. (1mk)
8. State the role played by the following substance in digestion.
   1. Hydrochloric acid (2mks)
   2. Bile salts (2mks)
9. The chemical equation below represent a reaction that occurs in cells.
   
   
   1. Calculate the respiratory quotient (RQ) (2mks)
   2. Identify the substrate used in the reaction. (1mk)
   3.  Give two reasons why the substrate you have identified in 9. (ii) above is not the main respiratory substrate. (2mks)
10. Explain what happens in humans when the concentration of glucose in the blood decreases below normal level. (4mks)
11. State two adaptations of the alveolus to its functions. (2mks)
12.  
    1. Explain the role of oxygen in Active transport (1mk)
    2. Name two processes that depend on Active transport in animals (2mks)
13. Name support tissues in plants thickened with:
    1. Cellulose (1mk)
    2. Lignin (1mk)
14. Give the survival value of the following tropic responses
    1. Geotropism (1mrk)
    2. Haptotropism (1mrk)
    3. Chemotropism (1mrk)
15.  
    1. What are Analogous structures? (1mk)
    2. Give two examples of Homologous structures (2mks)
16. State three limitations of fossil records as an evidence of organic evolution (3mks)
17. Study the diagram below and answer questions that follow
    
    
    1. State the division the organism belongs (1mk)
    2.  Name the parts labelled K and L (1mk)
       K
       L
    3. What is the function of the part labelled M. (1mk)
       M
18. Explain the role of the following hormones in reproduction.
    1. Progesterone (2mks)
    2. Oestrogen (2mks)
19. State two factors that hinder self-pollination and fertilization. (2mks)
20. A mango tree is known as mangifera Indica
    1. Identify two mistakes made in the writing of the name (2mks)
    2. What is the scientific naming called? (1mk)
21. State three methods that could be used to determine the diet of wild animals in an ecosystem (3mks)
22. State two ways in which chloroplasts are adapted for photosynthesis (2mks)
23. Name joints formed between the:
    1. Humerus and scapula (1mk)
    2. Cranial bones (1mk)
24. State the role of the following chemicals in a test for non-reducing sugar.
    1. Hydrochloric acid (1mk)
    2. Sodium hydrogen carbonate (1mk)
25. Name two chemical compounds that are protein in nature that regulate metabolic activities in the body (2mks)
26. State three environmental factors that increase the rate of transpiration. (3mks)
27. Carbon (II) oxide is a respiratory poison. Explain (3mks)

MARKING SCHEME

1.  
   1. Regulates the amount of light passing through the condenser; (1mk)
   2. Concentrates light on the object on the stage; (1mk)
2.  
   1. Manufacture ribosomes; (1mk)
   2. Synthesis protein; (1mk)
3.  
   1. Catalase; (1mk)
   2. Liver; (1mk)
   3. Detoxify hydrogen peroxide; (1mk)
4.  
   1. Haemophilia;sickle-cell anaemia; Albinism; (2mks)
      (any two)
   2. Early maturity;
      Resistance to pests/ diseases/ drought;
      High yield; (any two) 2mks
5.  
   1. (3) Incus ; rej-ear ossicless
      (4) Auditory nerve;
   2. (5) Dispates/ cancels/ cushions excessive vibrations;
      (7) Contains sensory cells when stimulated generates nerve impulses to the brain for
      interpretation/ integration;
6.  
   1.  
      1. Hypogeal; (1mk)
      2. Cotyledon remain underground; (1mk)
   2.  Acoleoptile – protects the plumule; (1mk)
      B – Stores food for germination; (1mk)
7.  
   1.  
      1. Kills animals reducing their numbers (1mk)
      2. Better adaptated organisms survive and reproduce increasing in number/ poorly adapted organisms die hence reduce in number; (1mk)
      3. Some parasites transmit pathogens that kill host/ parasites weaken hosts that are killed by predators; (1mk)
   2.  
      1. Biological control; (1mk)
      2. Does not pollute the environment; (1mk)
8.  
   1. Provide optimum pH for enzyme activities; kills micro-organisms in food; (2mks)
   2.  
      • Emulsification of fat;
      • Neutralize acid chyme;
      • Provide optimum pH (alkaline medium) (2mks) any 2 points
9.  
   1. (2mks)
      
   2. Lipid; acc fat/oil (1mk)
   3. Not soluble in water hence difficult to transport to respiring cells;
      Requires more oxygen to be oxidised compared to carbohydrates; (2mks)
10. Pancrease release glucogon; to stimulate the liver cells to convert stored glycogen to glucose; fat
    converted to glucose; reduces rate of respiration.
    Rej if source of glycogen is the liver
11. Thin membraned for easy diffusion of gases;
    Highly vascularised to transport gases;
    Moist surface to dissolve gases; (2mks)
12.  
    1. Oxidize food to produce energy required in active transport
    2. Reabsorption of sugar and some salts by kidney;
       Absorption of digested food from alimentary canal;
       Excretion of waste products from body cell;
13.  
    1.  Collenchyma;
    2. Sclerenchyma; xylem; trachieds;
14.  
    1. enables plant roots to grow deep into the soil thus offering (firm) anchorage to the
       plants/absorption of water;
    2. enables pollen tubes to grow towards the embryo-sac to effect fertilization/sperms moving towards the ovum//anthropoids towards archegonia in ferns to; effect fertilization
15. Structures with different embryonic origin but have evolved to perform similar functions
    (due to exploitation of similar niche)
16. Not all organisms were fossilised;
    • Distortion of pevits during sedimentation produce wrong impression of the structure;
    • Destruction of fossils by geological activities;
17.  
    1. Bryophyta; (amk)
    2. A - capsule; B – seta; (2mks)
    3. Anchorage; Absorb water and mineral salts;
18.  
    1.  Progesterone
       • Stimulates thickening of endomentruim;
       • Stimulates increased blood supply to endomentrium;
       • Inhibits follicle stimulating hormone from stimulating maturation of Graafian follicle;
         (2mks)
    2. Oestrogen
       • Healing and repair of endomentrium;
       • Stimulates pituitary gland to secrete Luteinising hormone; (2mks)
19.  
    • Protandry/ protogyny; OWTTE
    •  Self-sterility;
    • Heterostyly/ incompatibility;
    • Dioeciousness; (2mks)
      Mark 1st 2
20.  
    1. The genus name should start with a capital letter while the specific name should start with a small letter;
       Both names should be underlined separately; (2mks)
    2. Bonomial system;
21.  
    • Direct observation of food eaten;
    • Analysing gut contents;
    • Observing faeces; (3mks)
22.  
    • Have chlorophyll that absorb light for photosynthesis;
    • Have grana that increase surface area for package of chlorophyll;
    • Have stroma that contain enzymes that catalyse the process of photosynthesis; (2mks)
23.  
    1. Ball and socket joint
    2. Fixed joint;
24.  
    1. Hydrolyse non-reducing sugar to reducing sugar/ Hydrolyse dissacharides to
       monossacharides;
    2. Neutralise the hydrochloric acid;
25.  Hormones;
    Enzymes; (2mks)
    NB If specific hormones or enzymes are named they should be at least 3
26. High light intensity; increased/ High temp.
    Strong wind; Low humidity; Low atmospheric pressure; (2mks)
    Mark 1st 2
27. Carbon (IV) oxide combines with haemoglobin to carboxyhaemoglobin; carboxyhaemoglobin does not dissociate easily; hence reduce the capacity of haemoglobin to transport oxygen leading to suffocation;