Biology Paper 1 Questions and Answers - Samia Joint Mock Examination 2023

Instructions

• Answer all the questions

1.  
   1. Students at Ikumbi high school observed that when sodium chloride was poured onto grass, the grass dried up. Explain this observation. (2mks)
   2. Study the experimental setup below and answer the questions that follow:
                                                              
      1. Name the process that is being investigated (1mk)
      2. State and explain what would be observed if the setup was left for 12 hours (3mks)
2.  
   1. Name the blood vessel that connects arteries to vein. (1mark)
   2. Explain two ways in which the vessel named in (a) above are adapted to carry out their functions (2 marks)
3. How does hot water of about 35°C act as a pollutant when it is discharged from industries into rivers? (2mks)
4. Name the causative agents of the following diseases in humans. (2mks)
   1. Amoebic dysentery.
   2. Candidiasis.
5.  
   1. Define the term immunity. (1mk)
   2. Distinguish between natural immunity and acquired immunity. (1mk)
   3. Identify one immunizable disease in Kenya. (1mk)
6. Give two advantages of polyploidy in plants. (2mks).
7. The diagram below illustrates part of a nephron from a mammalian kidney.
                                                             
   1. Name the fluid found in the part labeled Q. (1mk)
   2. Identify the process responsible for the formation of the fluid named in (a) above. (1mk)
   3. Which two hormones exert their effect in the nephron? (2mks)
8. Explain how blood sugar level is maintained constant in human blood (3mks)
9. State three unique characteristics of members of the class Crustacea. (3mks)
10. How is mammalian skin adapted for excretion (3mks)
11. The paddles of whales and the fins of fish adapt these organisms to aquatic habitats.
    1. Name the evolutionary process that may have given rise to these structures. (1mk)
    2. What is the name given to such structures? (1mk)
12. The diagram below show part of a food relationship in an ecosystem
                                                                            
    1. Name the food relationship shown in the diagram (1mk)
    2. Name the trophic level occupied by organism A (1mk)
    3. What is the main source of energy in the ecosystem shown in the diagram above (1mk)
13.  
    1. Name a protein and vitamin involved in blood clotting.
       1. Protein. (1mk)
       2. Vitamin (1mk)
    2. Explain why blood from a donor whose blood group is A cannot be transfused into the recipient whose blood group is B. (2mks)
14.  
    1. State two effects of Gibberellins on shoots of plants. (2mks)
    2. Account for loss in dry weight of cotyledons in a germinating bean seed. (1mk).
15. Explain why a pregnant woman excretes less urea compared to a woman who is non pregnant. (2mks)
16. Study the reaction below and answer the questions that follow.
                                            
    1. What biological processes are represented by A and B? (2mks)
       
       1.  
    2. Identify the product Y. (1mk)
    3. State the bond represented by X. (1mk)
17. Explain what happens during the light stage of photosynthesis. (3mks)
18. State two characteristics of aerenchyma tissue. (2mks).
19.  
    1. Name the substance that accumulates in muscles when respiration occurs with insufficient oxygen. (1mk)
    2. Give the end products of anaerobic respiration in plants. (2mks).
20. What is the importance of carrying out the following procedures when preparing temporary slides in the laboratory? (3mks).
    1. Adding water to the specimen.
    2. Staining the specimen.
    3. State two functions of the body tube of a light microscope (2marks)
21. In an experiment the shoot tip of a young tomato plant was decapitated as shown in the diagram below
                                                                  
    1. State the expected results after 2 weeks (1mk)
    2. Give a reason for your answer in (a) above (2mks)
22. Name two internal factors that are necessary for seed germination. (2mks)
23. Certain animals have the following dental formula
    A; i 3/3, c 1/1, pm 4/4, m 2/3 B. i 0/3 , c 0/1 , pm 2/2 , m 3/3
    1. What is the most likely mode of feeding for animals A and B.? (2mks)
    2. Give a reason for your answer in (i) above. (1mk)
24. Name the components of a DNA molecule. (3mks)
25. Name the characteristics of living organisms shown by each of the following;
    1. Budding in yeast (1mark)
    2. Enlargement of the eye pupil in dim light (1mark)
26. The diagram below shows an organism in a certain kingdom
                                                                                
    1. Name kingdom to which the organism belongs (1mk)
    2. State the mode of nutrition for the organism (1mk)
    3. Name the part labeled E and state two of its functions (3mk)
       Name……………………
       Functions:

MARKING SCHEME

1.  
   1. Students at Ikumbi high school observed that when sodium chloride was poured onto grass ,the grass dried up. Explain this this observation. (2mks)
      • The external environment becomes hypertonic compared to the internal tissues of the leaves ;the leaves looses water by osmosis making them unable to carry out vital biological processes such as photosynthesis(hence dry up)
   2. osmosis
   3. Level of the liquid in the cavity of the potato while that in the petri dish will drop b ecause cells adjacent to the sugar solution will loose water into the solution by osmosis
2.  
   1. Name the blood vessel that connects arteries to vein. (1mk)
      • Cappilaries
   2. Explain three ways in which the vessel named in (a) above are adapted to carry out their functions. (3mks)
      • Numerous to increase the surface area over which diffusion and active transport of substances occur
      • Thin walled/one cell thick to reduce distance over which exchange of substances occur
      • Narrow lumen to enhance ultra-filtration
      • Have small pores for the passage of materials
        (TIED TO PART (a)
3. How does hot water of about 35°C act as a pollutant when it is discharged from industries into rivers? (2mks)
   • It reduces the solubility of gases in water/reduces amount of dissolved gases.
4. Name the causative agents of the following diseases in humans. (2mks)
   1. Amoebic dysentery.
      • Entamoba histolitica;
   2. Candidiasis.
      • Candida albicans
5.  
   1. Define the term immunity. (1mk)
      • Ability of the body to identify /recognize foreign antigens and develop mechanisms of destroying them/ability to resist infection;
   2. Distinguish between natural immunity and acquired immunity. (1mk)
      • Natural immunity is inborn/inherited/passed from parents to offspring while acquired immunity is obtained in life
   3. Identify one immunizable disease in Kenya. (1mk)
      • Tuberculosis;poliomyelitis;diphtheria;whooping cough;measles;
6. What happens to glucose synthesized during photosynthesis. (2mks).
   • Used in respiration /produce energy
   • Converted to starch/lipids/sucrose/proteins and stored
7. The diagram below illustrates part of a nephron from a mammalian kidney.
   1. Name the fluid found in the part labeled Q. (1mk)
      • Glomerular filtrate;
   2. Identify the process responsible for the formation of the fluid named in (a) above. (1mk)
      • Ultra- filtration/pressure filtration
   3. Which two hormones exert their effect in the nephron? (2mks)
      • Antidiuretic hormone/vasopressin;
      • Aldosterone;
8. Explain how blood sugar level is maintained constant in human blood (3mks)
   • When in excess, insulin,is produced to make liver cells convert the excess to glycogen
   • When less,glucagon,is produced to make liver cells convert stored glycogen to glucose
9. State 3 unique characteristics of members of the class crustacea . (2mks)
   • Two pairs of antennae
   • Body covered with carapace
10. How is mammalian skin adapted for excretion (3mks)
    • Has sweat glands which collects water and salts;
    • Has sweat pores through which water,salts and urea pass out;
11. The paddles of whales and the fins of fish adapt these organisms to aquatic habitats
    1. Name the evolutionary process that may have given rise to these structures. (1mk)
       • Convergent evolution
    2. What is the name given to such structures? (1mk)
       • Analogous structures
12. The diagram below show part of a food relationship in an ecosystem
    1. Name the food relationship shown in the diagram (1mk)
       • Food chain
    2. Name the trophic level occupied by organism A (1mk)
       • Primary consumer
    3. What is the main source of energy in the ecosystem shown in the diagram above (1mk)
       • The sun/sunlight
13.  
    1. Name a protein and vitamin involved in blood clotting.
       1. Protein. (1mk)
          • Fibrinogen
       2. Vitamin (1mk)
          • Vitamin K
    2. Explain why blood from a donor whose blood group is A cannot be transfused into the recipient whose blood group is B. (2mks)
       • Recipient has antibody a in the blood plasma and will correspond with antigen A in the donors;hence there will be antigen –antibody reaction/agglutination;
14.  
    1. State two effects of Gibberellins on shoots of plants. (2mks)
       • Promotes cell division;
       • Promotes cell elongation;
       • Promotes parthenocarpy
    2. Account for loss in dry weight of cotyledons in a germinating bean seed. (1mk).
       • Food stored is used for respiration /growth;
15. Explain why a pregnant woman excretes less urea compared to a woman who is non pregnant. (2mks)
    • Amino acids are used in the formation of foetal tissues;thus has less excess to be eliminated;
16. Study the reaction below and answer the questions that follow.
    1. What biological processes are represented by A and B? (2mks)
       • A - Condensation
       • B - Hydrolysis
    2. Identify the product Y. (1mk)
       • Sucrose;
    3. State the bond represented by X. (1mk)
       • Glycosidic;
17. Explain what happens during the light stage of photosynthesis. (3mks)
    • Light energy is absorbed by chlorophyll molecules ;used to split water molecules into oxygen and hydrogen atoms/ions ;light energy is converted into chemical energy(ATP) and stored;
18. State two characteristics of aerenchyma tissue. (2mks).
    • Has thin cell wall;
    • Has large air spaces;
19.  
    1. Name the substance that accumulates in muscles when respiration occurs with insufficient oxygen. (1mk).
       • Lactic acid;
    2. Give the end products of anaerobic respiration in plants. (2mks).
       • Ethanol; rej Alcohol
       • Carbon (IV) Oxide;
       • Energy;
20.  What is the importance of carrying out the following procedures when preparing temporary slides in the laboratory? (3mks).
    1. Adding water to the specimen.
       • To make the specimen turgid;/prevent dehydration
    2. Staining the specimen.
       • To make cell dinstinct/more clearer
    3. It holds the eyepiece lens and the revolving nosepiece.
21. In an experiment the shoot tip of a young tomato plant was decapitated as shown in the diagram below
    1. State the expected results after 2 weeks (1mk)
       • Auxillary/lateral buds sprot/branches will be formed
    2. Give a reason for your answer in (a) above (2mks)
       • Decapitation removes the hormone /auxins/IAA which is produced in the terminal bud/the stem tip;remove of the auxin/hormone/IAA promote branch/development of auxillary lateral buds.
22. Name two internal factors that necessary for seed germination. (2mks)
    • Enzymes;
    • Hormones;
    • Viability
23. Certain animals have the following dental formula
    A; i 3/3, c 1/1, pm 4/4, m 2/3 B. i 0/3 , c 0/1 , pm 2/2 , m 3/3
    1. What is the most likely mode of feeding for animals A and B. (2mks)
       • A  - Carnivorous; reject carnivore
       • B  - Herbivorous;rej,herbivore
    2. Give a reason for your answer in (i) above. (1mk)
       • Absence of upper insisors
24. Name the components of a DNA molecule. (3mks)
    • A five carbon sugar/Deoxyribose sugar
    • A phosphate molecule
    • A nitrogenous base
25.  
    1. reproduction
    2. irritability
26.  
    1. fungi
    2. saprophytism
    3. Name- hypha
       Function;
       • secrete digestive enzymes
       • anchor the organism onto the substrate
       • absorb digested food materials/absorb water and mineral salts