Biology Paper 1 Questions and Answers - Form 3 Term 2 Opener Exams 2023

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QUESTIONS
  1. State two functions of lipids      (2 marks)
  2. The gill of a tilapia fish is composed of many outgrowths called gill filaments. Explain the significance of this observation     
    (2 marks)
  3. A process that occurs in plants is represented by the reaction below
    C6H12O6  arrow   C2H5OH + CO2 + Energy
    1. Identify the process     (1 mark)
    2. Name the substance that accumulates in muscles when the food is broken down with insufficient oxygen  (1 mark)
    3. State the side effect of accumulation of the substance named in (ii) above.  (1 mark)
  4. Name the disease in humans that is caused by lack of each of the following.(3 marks)
    1. Vitamin C
    2. Vitamin D
  5. State four ways by which the mammalian skin responds to low temperature in the environment.  (4 marks)
  6. Explain how sunken stomata lower the rate of transpiration  (2 marks)   
  7. Distinguish between haemolysis and crenation   (2 marks)
  8. Why should respiratory surfaces be      (2 marks)
    1. Moist
    2. Thin
  9. State two functions of the cell sap (2 marks)
  10. What Osmoregulatory changes would take place in a marine amoeba if it was transferred to fresh water environment    (3 marks)
  11. State two functions of the plasma membrane        (2 marks)
  12. State the economic importance of anaerobic respiration  (3 marks)
  13. Name the branch of Biology that involves the study of: (2 marks)
    1. Organisms for the sake of classifying them.
    2. Microscopic organisms.
  14. The diagram below represents a plant
    BioF32023ET2OP1Q14
    1. Name the division to which the plant belongs. (1 mark)
    2. Give three reasons for your answer in (a) above. (3 marks)
  15. The diagram below represents a transverse section of a plant part. Study it and answer the Questions that follow.
    BioF32023ET2OP1Q15
    1. Name the class in which the plant belongs.  ( 1 mark)
    2. Give a reason for answer (a) above  ( 1 mark)
    3. State one adaptation for the structures labeled X to their functions. (1 mark)
  16. The diagram below represents a set up that was used to investigate a certain process in a plant.
    BioF32023ET2OP1Q16
    1. State the process that was being investigated. (1 mark)
    2. Other than the factors shown, state two factors that would affect the process named in (a) above. ( 2 marks)
  17.  
    1. Name the causal organism for amoebic dysentery. (1 mark)
    2. State three preventive measures of schistosomiasis in human beings  (3 marks)
    3. Name the organism that causes cholera and state two precautionary measures to prevent cholera outbreak. (3 marks)
      1. Organism-
      2. Measures-
  18. Describe capture - recapture method of estimating population. (3 marks)
  19. The diagram below shows a simplified nitrogen cycle
    BioF32023ET2OP1Q19
    1. Name the processes labeled P,Q and R (3 marks)
    2. List down three adaptations of the preys against being predated upon by predators. (3 marks)
  20. Give two reasons why primary productivity decreases with increase in depth in an aquatic ecosystem. (2 marks)
  21.  
    1. Give two ways by which the skins prevent entry of microorganisms into the body.   (2 marks)
    2. What is the importance of deamination in excretion and homeostasis? (1 mark)     
  22.  
    1. What type of circulatory system is found in members of class insecta? (1 mark)
    2. Name the blood vessel that transports blood from:
      1. Small intestine to liver. (1 mark)
      2. Lungs to heart  (1 mark)
  23. Distinguish between natural and acquired immunity. (2 marks)
  24.  
    1. Describe the condition known as varicose veins (2mks)
    2. What is the role of blood platelets in the blood clotting process?  (2mks)
  25. What is meant by the following terms? (2 marks)
    1. Habitat:
    2. Ecosystem
  26. Differentiate between the following pairs of terms:
    1. Guttation and transpiration. (2mark) 
    2. Morphology and anatomy. (2mark)
  27. The diagram below represents the structure of a nephron. Study it and answer the questions that follow.
    BioF32023ET2OP1Q27
    1. State the roles of the part labelled B and C. (2 marks)
    2. Which hormone is involved in the function of the part labelled D? (1 mark)
    3. Name the part labelled X. (1 mark)

MARKING SCHEME

  1. State two functions of lipids      (2 marks)
    • Metabolic regulators
    • Sources of energy
    • Sources of metabolic water
  2. The gill of a tilapia fish is composed of many outgrowths called gill filaments. Explain the significance of this observation   
    (2 marks)
    • They are numerous to increase the surface area for rapid gaseous exchange
  3. A process that occurs in plants is represented by the reaction below
    C6H12O6  arrow   C2H5OH + CO2 + Energy
    1. Identify the process     (1 mark)
      • Fermentation/anaerobic respiration
    2. Name the substance that accumulates in muscles when the food is broken down with insufficient oxygen  (1 mark)
      • Lactic acid
    3. State the side effect of accumulation of the substance named in (ii) above.   (1 mark)
      • Causes muscle crumps
  4. Name the disease in humans that is caused by lack of each of the following.(3 marks)
    1. Vitamin C
      • Scurvy
    2. Vitamin D
      • Rickets/Osteoporosis
  5. State four ways by which the mammalian skin responds to low temperature in the environment.  (4 marks)
    • Raising of hair or fur
    • Vasoconstriction
    • Decreased sweating
    • Thickening of the subcutaneous fat layer
  6. Explain how sunken stomata lower the rate of transpiration  (2 marks)   
    • Water vapor accumulates in the depression where sunken stomata is lacated; saturation deficit in the leaf and outside the leaf is reduced thus lowering transpiration
  7. Distinguish between haemolysis and crenation   (2 marks)
    • Haemolysis is bursting of the red blood cells when placed in water/hypotonic solution while crenation is wrinkling of red blood cells after losing water when placed in a hypertonic solution
  8. Why should respiratory surfaces be      (2 marks)
    1. Moist. To dissolve respiratory gases since they diffuse faster in solution form
    2. Thin.  For rapid diffusion of gases
  9. State two functions of the cell sap (2 marks)
    • Stores sugars and salts in solution
    • Mechanical strength
  10. What Osmoregulatory changes would take place in a marine amoeba if it was transferred to fresh water environment  (3 marks)
    • More water will enter the amoeba by osmosis
    • Rate of discharge by contractile vacuoles will increase
    • More contractile vacuoles will be formed to cope with increased amount of water entering
  11. State two functions of the plasma membrane   (2 marks)
    • Encloses cell contents
    • Regulates movement of substances selectively in and out of the cell
  12. State the economic importance of anaerobic respiration  (3 marks)
    • Brewing of alcohol
    • Baking of bread
    • Biogas production
  13. Name the branch of Biology that involves the study of: (2 marks)
    1. Organisms for the sake of classifying them.
      • taxonomy
    2. Microscopic organisms.
      • microbiology
  14. The diagram below represents a plant
    1. Name the division to which the plant belongs. (1 mark)
      • pteridophyta
    2. Give three reasons for your answer in (a) above. (3 marks)
      • presence of sori
      • presence of rhizome
      • presents of fronds
  15. The diagram below represents a transverse section of a plant part. Study it and answer the Questions that follow
    1. Name the class in which the plant belongs.  ( 1 mark)
      • Dicotyledonae
    2. Give a reason for answer (a) above  ( 1 mark)
      • Centrally placed star shaped Xylem with phloem (alternatively) between the arms of the Xylem
    3. State one adaptation for the structures labeled X to their functions. (1 mark)
      • Numerous/Elongated to increase surface area for absorption of water/minerals/both;
      • Thin walled for faster absorption of water/mineral salts/or both;
      • Numerous mitochondria to provide energy for absorption of mineral salts;
      • Large sap vacuole to create high osmotic pressure;
  16. The diagram below represents a set up that was used to investigate a certain process in a plant.
    1. State the process that was being investigated. (1 mark)
      • photosynthesis
    2. Other than the factors shown, state two factors that would affect the process named in (a) above. ( 2 marks)
      • Carbon (IV) oxide concentration;     
      • Temperature;
      • Amount of chlorophyll;           
  17.  
    1. Name the causal organism for amoebic dysentery. (1 mark)
      • Entamoeba histolytica;      (rules of Binomial nomeclacture followed)
    2. State three preventive measures of schistosomiasis in human beings  (3 marks)
      • Proper (sanitary) disposal of faeces and urine/use of deep pit latrines/flash toilets for disposal of faeces and Urine;
      • All drinking water boiled/chemically treated to kill the eggs/miracidia/cercariae;
      • People should not bath/swim in water infested with snails;
      • People should wear protective shoes/water proof shoes/gumboots when walking in waters infested with snails/swampy areas;
      • Spray water infested with snails with molluscicides;
  18. Describe capture - recapture method of estimating population. (3 marks)
    • Capture the organism using appropriate means ;
    • mark with water proof paint, count and releases;
    • capture again after 48hrs count all, use the formula to estimate the population
  19. The diagram below shows a simplified nitrogen cycle
    1. Name the processes labeled P,Q and R (3 marks)
      • P-nitrogen fixation
      • Q-decomposition / Decay
      • R-absorption
    2. List down three adaptations of the preys against being predated upon by predators. (3 marks)
      • Camouflaged skin to skip notice by predator; prey mimicry/ assuming taste of another organism non-palatable to the predator;  prey showing confrontational behaviour  against the predator; prey running very fast and in zigzag movement  to avoid being caught by predator;
  20. Give two reasons why primary productivity decreases with increase in depth in an aquatic ecosystem. (2 marks)
    • Decrease in light intensity hence low photosynthesis.
    • Decrease in oxygen for respiration.
  21.  
    1. Give two ways by which the skins prevent entry of microorganisms into the body.    (2 marks)
      • Cornified layer which act as a barrier to the pathogen.
      • Sebum which is antiseptic secreted by sebaceous gland.
    2. What is the importance of deamination in excretion and homeostasis? (1 mark)
      • remove excess amino acid   
  22.  
    1. What type of circulatory system is found in members of class insecta? (1 mark)
      • Open circulatory system
    2. Name the blood vessel that transports blood from:
      1. Small intestine to liver. (1 mark)
        • Hepatic portal vein
      2. Lungs to heart  (1 mark)
        • pulmonary vein
  23. Distinguish between natural and acquired immunity. (2 marks)
    • Acquired immunity is immunity developed after suffering from a disease or following immunization whereas natural immunity is inborn/inherited.
  24.  
    1. Describe the condition known as varicose veins (2mks) 
      • Weakened/defective valves in veins; causing blood/body fluids/ tissue fluid to accumulate  (leading to swelling)
    2. What is the role of blood platelets in the blood clotting process?  (2mks)
      • When exposed to air, they disintergrate/rupture/burst; realizing thromboplastin /thrombokinase
  25. What is meant by the following terms? (4marks)
    1. Habitat: Place/ Environment in which (specified) organism lives;                                       
    2. Ecosystem:  A natural unit with  a biotic and biotic factors
  26. Differentiate between the following pairs of terms:
    1. Guttation and transpiration. (2mark) 
      • Guttation is the process by which plants lose excess water to the atmosphere in liquid form through hydathodes in the leaves while transpiration is the process by which plants lose excess water to the atmosphere in gaseous/ vapour form;
    2. Morphology and anatomy. (2mark)
      • Morphology  is the scientific study of external structures of living organisms while anatomy is the scientific study of internal structures of living organisms;
  27. The diagram below represents the structure of a nephron. Study it and answer the questions that follow.                         
    1. State the roles of the part labelled B and C. (2 marks)
      • B- Selective reabsorption of glucose and amino acid;
      • C- Reabsorption of water; 
    2. Which hormone is involved in the function of the part labelled D? (1 mark)
      • Aldosterone hormone
    3. Name the part labelled X. (1 mark)
      • Bowman’s capsule
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