Biology Paper 1 Questions and Answers - Form 3 Term 3 Opener Exams 2021

INSTRUCTIONS TO CANDIDATES

• Answer ALL the questions in the spaces provided

QUESTIONS

1.  
   1. State two characteristics that are specific to plants (2mks)
   2. Name three mechanisms that ensure cross pollination takes place in flowering plants. (3mks)
2.  
   1. State two differences between complete and incomplete metamorphosis. (2mks)
   2. State the importance of moulting to an insect. (2mks)
3. A student collected an organism and observed the following features: simple eyes, four pairs of legs and two body parts.
   1. State the class to which the organism belongs. (1 mark)
   2. Give an example of an organism in this class. (1 mark)
   3. Name the kingdom to which plasmodium belongs (1 mark)
4. Name the three end products of anaerobic respiration in plants. (3 marks)
5. State two reasons why accumulation of lactic acid leads to an increase in heart beat. (2 marks)
6. Name the flower parts that produces gametes. (2 marks)
7. What is meant by the following terms? (2 marks)
   1. Ecology
   2. Carrying capacity
8. How is the human sperm cell structurally adapted? (2 marks)
9. The figure below is a fine structure of a generalized animal cell as seen under an electron microscope.
               
   
   1. Name the parts labeled A and B. (2 marks)
      A………………………………………………………………………
      B………………………………………………………………………
   2. How is the structure labeled B adapted to its function? (2 marks)
10. What name is given to a group of hormones that controls the development of secondary sexual characteristics in a human male? (1 mark)
11. Name two substances that leave the foetal blood through the placenta (2 marks)
12. Name two nutrients that are absorbed without being digested by enzymes in humans.(2 marks)
13. State one use for each of the following apparatus in the study of living organisms. (2 marks)
    1. Pooter
    2. Pitfall trap
14. The figure below illustrates a food web in a certain ecosystem.
                        
    From the food web:
    1. Draw the shortest food chain; (2 marks)
    2. Identify the organisms with the highest
       1. Number of predators (1 mark)
       2. Biomass (1 mark)
15. State two functions of the following parts of a light microscope.
    1. Fine adjustment knob (2 marks)
    2. Stage (2 marks)
16. The diagram below represents a certain plant.
                
    
    1. What is the likely habitant of the plant? (1 mark)
    2. Give two reasons for your answer in (a) above. (2 marks)
17. The number of stomata on the lower and upper surface of two leaves from plant X and Y were counted under the field of view of a light microscope. The results were as shown in the table below.
    
    

    Leaf	Number of stomata
    	Upper surface	Lower surface
    X	4	12
    Y	20	23

    
    
    1. Which of the leaves would be expected to have a lower rate of transpiration? (1 mark)
    2. Given a reason for your answer in (a) above (2 marks)
18. The diagram below represents a transverse section of an ovary from a certain flower.
                           
    
    1.  
       1. Name the structure labeled W (1 mark)
       2. Name the type of placentation illustrated in this diagram. (1 mark)
    2. Give an example of a fruit that show the type of placentation illustrated in this diagram. (1 mark)
19. The diagram below illustrates the structure of bread mould.
            
    
    1. Name the part labeled J (1 mark)
    2. State the function of the structure labeled K (2 marks)
20.  What is meant by the following term?
    1. Habitat; (1 mark)
    2. Ecosystem (1 mark)
21. State two ways by which acquired Immune deficiency syndrome (A.I.D.S) Virus is transmitted. ( 2 mks)
22. Figures 1 and 2 below represent reproductive organ of plants and an animal respectively.
                   
    
    1. Which letters in figures 1 and 2 represents the organs that produce female gametes? (2mks)
                  Figure 1…………………………………………….
                  Figure 2…………………………………………………
    2. What is the function of the structure labeled S? (2mks)
    3. Name the structure labeled W (1mk)
    4. Which letters in figures 1 and 2 represents the structures where fertilization takes place (2mks)
    5. Which letter in figure 1 represents the structure where male gametes are produced (1mk)
23. What is the function of the following structures in the human reproductive organ?
    1. Fallopian tubes. (2 mark)
    2. Epididymis (1 mark)
    3. Scrotal sac (2 mark)
24. State any three fruit and seed dispersal mechanisms (3mks)
25. A student observing a leg of an insect under a hand lens made a drawing of the leg whose length was 4cm a width magnification of X2.what was the actual length of the leg? (3mks)
26. Give two reasons why mitosis is important to organisms. (2mks)

MARKING SCHEME

1.   
   1. Autotrophic nutrition; show alternation of generation; Limited movement; Limited excretory products/unspecialized respiratory structures; Localized growth;
   2. having brightly coloured flowers; scented flowers; protandry;protagyny;self sterility; heterostyly;
2.  
   1. Complete metamorphosis - eggs hatch into larvae while in incomplete metamorphosis hatch into nymphs which resemble the adult;
      Complete metamorphosis has four stages; egg, larvae, pupa and adult while in incomplete metamorphosis has three stages; egg, nymph and adult.
   2. To allow for growth of the insect;
3.  
   1. Arachnida;
   2. Spider/scorpion/tick/mite;
   3. Protoctista /protista;
4. Alcohol/ethanol; Carbon (IV) oxide; Energy/Adenosine Triphosphate;
5. -To increase supply of oxygen to the tissues;
   -The oxygen is used to oxidize lactic acid (to carbon (IV) oxide, water and energy);
6. Ovary /Anther;
7.  
   1. This is the study of the interrelationship between organisms and their environment
   2. The maximum population of a species/Total number of organisms that a population habitat/area/region/ecosystem can support or Total number of population of a species a given habitat/area/region/ ecosystem can support without depleting available resources. Rej. If different species
8. Acrosome /Lysosome contain enzyme to digest membrane of the ovum;
   - Numerous mitochondria to provide energy for movement;
   - Long tail for faster movement;
9.  
   1. A    nuclear pore
      B    Rough endoplasmic reticulum
   2. Surface area covered with ribosome’s; for protein synthesis/ channels for transport of protein
10. Androgens
    Acc-androgen
11. Carbon (IV) oxide, nitrogenous waste
12. water; mineral ions/salts, vitamins
13.  
    1. Sacking small insects/small animals
    2. A trap into which (small) animals fall and get trapped; acc. Examples of small animals e.g. insect/reptiles. Arachnids
14.  
    1. Grass → Grasshopper → Lizards
    2.  
       1. Chicken
       2. Grass
15.  
    1. Fine adjustment knob
       Moves the body tube through smaller distances to bring image/specimen/object into sharper/sharp focus
    2. Stage
       Platform where specimen (on slide) is placed
16.  
    1. Dry/arid/semi-arid/desert
    2. Succulent/freshly stem; reduced leaves/leaves reduced into thorns/spines. Acc. Thick stem for storage of water
17.  
    1. X
    2. X has fewer stomata; most stomata in leaf X are concentrated on the lower side
18.  
    1.  
       1. Ovule; rej; ovules
       2. Axile
    2. Orange or any other citrus fruit; lemon, tangerine, grape, lime, tomato, Sodom apple, Irish potato, egg plant, thorn apple, banana
19.  
    1. J – sporangium
    2. - Absorption of soluble substances/ digested food
       - Secretion of digestive enzymes;
       - Anchorage(of mould on substrate); anchorage must be in the right context
20.  
    1. Place/environment in which (specified)organism lives
    2. A natural unit with abiotic and biotic factors
21. Aids causes
    • Sexual intercourse
    • Blood transfusion
    • Pregnant HIV positive mother to child
22.  
    1. Figure 1 R:
       Figure 2 T: Accept growth
    2. Development of the foetus /zygote/fertilized/ova/egg/embryo
    3. Style
    4. R;P;
    5. X
23.  
    1. Passage of ova/ site of fertilization
    2. Storage of sperms
    3. Hold the testis/ protect the testis
24. Explosive; water; wind; animal
25. Actual length= drawing length divided by magnification;
    4/2=2cm;
26. Leads to growth of the organism;
    -Production of new cells;