Biology Paper 2 Questions and Answers - Kakamega Evaluation Mock Exams 2022

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QUESTIONS
SECTION A [40Marks]
Answer all questions in the spaces provided

  1. The photograph below shows an organism undergoing a certain process. Examine the external features of the organism and answer the following questions.
    1
    1.      
      1. Identify the class to which the organism above belongs
      2. Give two reasons for your answer in (a)i. above.
    2.      
      1. Identify the type of metamorphosis illustrated above.
      2. Give a reason for your answer in {d}i. above. 
    3. Name the stages P and Q.
  2. Below is an illustration showing the mechanism of blood sugar regulation in the body. Use it to answer the following questions. 
    2
    1. State the process that can lead to an increase in glucose level.
    2. What type of feedback mechanism is represented by H? 
    3. State three corrective mechanisms carried out at G. 
    4. Name the condition that may result from further excess.
    5. Name the hormone that would be responsible for correcting the deficiency.
    6. What is the disadvantage of low blood glucose level in blood
  3. The pedigree chart below illustrates the inheritance of haemophilia in a given a given family.
    3
    1. Suggest the possible genotype of: ( 2 Marks)
      Individual ……………………
      Individual 4 ………………….
    2. Using a punnet square, work out the possible phenotypes of offspring’s, if individual 4 married a haemophiliac male. (4 Marks)
    3. Explain why there are no carrier males. (1Mark)
    4. Name a condition in man that is due to chromosomal mutation. (1Mark)
  4. Carbohydrates used during respiration and those formed during photosynthesis by a certain plant was measured over a period  of 24 hours at an interval of 3 hours
    Time of day 12AM 3AM 6AM 9AM 12PM 3PM 6PM 9PM 11PM
    Carbohydrates formed during photosynthesis (mg) 0 0 5 30 60 30 5 0 0
    Carbohydrates used during respiration  (mg) 10 10 10 10 10 10 10 10 10
    1. Account for the levels of carbohydrates.
      1. Between 12.00a.m and 3a.m.
      2. Between 3.00a.m to 12.00noon.
    2. How could foggy weather influence the net amount of carbohydrates formed over the 24 hour period?
    3. Give other external factors apart from temperature and light intensity that influence the rate of photosynthesis.
    4. In which form are carbohydrates stored in Fungi.
  5.          
    1. Active yeast cells were added to dilute sugar solutions in a container. The mixture was kept in a warm room. After a few hours bubbles of a gas were observe escaping from the mixture
      1. Write down the word equation to represent the reaction
      2. Give two economic importance of the chemical reaction in industry?
    2. State two application of the above process in agriculture. (2 Mark)
    3. What is oxygen debt?
    4. Give two stages of aerobic respiration?

SECTION B [40Marks]
Answer question 6 (Compulsory) and either question 7 or 8.

  1. In a study on immunity, two groups of mice were immunized with sheep blood. One of the groups was given 5 doses of a drug Tinocordine prior to immunization. The second group was not treated with Tinocordine. Blood was collected from each group every third day for one month. The results were shown in the table below.
    Number of days after immunization Antibodies produced after immunization
      Tinocordine treated mice Non-Tinocordine treated mice
    3 15 5
    6 20 5
    9 30 15
    12 60 25
    15 122 30
    18 250 30
    21 122 30
    24 60 30
    27 37 22
    30 27 5
    1. Plot graphs using the same axes of antibodies produced after immunization against number of days after immunization.  (8 Marks)
    2. Determine the rate of antibody production between day 13 and 17 in Tinocordine treated mice.(2 Marks)
    3. What type of immunity will be developed by the mice?  (1 Mark)
    4. Name three diseases whose spread is controlled by vaccination in human beings(3 Marks)
    5. State two other was of controlling highly infectious diseases apart from vaccination. (2 Marks)
    6.    
      1. Give a reason why AIDS can’t be easily detected by normal blood test.(1 Mark)
      2. State three ways of controlling AIDS. (3 Marks)
  2.      
    1. State how each of the following food substances are assimilated in the body (6 Marks)
      1. Glucose
      2. Amino acids
      3. Fatty acids and glycerol
    2. Descibe the adaptation of the ileum to its functions. (14 Marks)
  3. Explain how desert plants are adapted to their habitat. (20 Marks)


MARKING SCHEME

  1.      
    1.    
      1. Insecta
      2. Two pairs of wings;
        3 pairs of legs;
        3 body parts: head, thorax and abdomen;  
    2.    
      1. Incomplete (metamorphosis);
      2. Egg hatches to nymph which develops to adult; 
    3. P: Nymph;
      Q: Adult;
  2.    
    1. Absorption of glucose from the ileum
    2. Positive feedback;
    3. Excess glucose converted to glycogen and stored in the liver
      Increased oxidation of glucose
      Coversion of excess glucose to fat for storage
      Inhibition of conversion of glycogen to glucose
    4. Hyperglycemia
    5. Glucagon
    6. Less respiration, less energy available to the tissues
  3. Individual 1 XhY
    Individual 4 XHXh;
    1. XhY X XHXh;
        Xh Y
      XH XHXh X
      Xh XhXh XhY
    2. Males only have one X chromosome 
    3. Klinefelter’s syndrome
      Turner’s syndrome 
      Down’s syndrome
  4.    
    1.      
      1. No carbohydrates formed; due to lack of sunlight;
      2. Gradual increase in carbohydrates formed;  due to increasing light intensity
    2. Reduced light available; hence carbohydrates formed becomes low;
    3. carbon (IV) oxide;
      Moisture/ water;
    4. Glycogen;
  5.      
    1.    
      1. Sugar Enzymes → Carbon (IV)Oxide+Ethanol+Energy
      2. Baking bread
        Manufacture of organic acids
    2. Silage making
      Compost manure making
    3. The extra amount of oxygen needed to oxidise the accumulated lactic acid in the tissues after anaerobic respiration;
    4. Glycolysis
      Kreb’s cycle
  6.    
    1.       
    2. 175-137.5 Antibodies
           17-13 days
      9.375 Antibodies/day
    3. Acquired immunity
    4. Covid-19
      Measles
      Tuberculosis
      Whooping cough
      Polio 
    5. Quarantine
      Isolation 
    6.    
      1. It is caused by a virus;
      2. Avoid unprotected sex (with infected individuals)
        Stop sharing of hypodermic needles 
        Faithfulness to one partner / Avoid indiscriminate sexual activities.
  7.    
    1.    
      1. Oxidised to release energy in the tissues
        Excess converted and stored as glycogen 
      2. Synthesis of proteins for general body growth & repair of worn out tissues
        In absence of fats and glucose, oxidised to release energy
      3. Oxidised to release energy
        Stored in the adipose tissues
    2.    
      • Has secretory glands / crypts of lieberkuln which secretes enzymes (maltase / sucrose / peptidase / lipase to complete digestion of lipids / sugar / proteins.
      • has mucus secreting cells/Goblet cells which secrete mucus which allows for smooth movement of food / protect wall of ileum from action of digestive enzymes.
      • long to provide large surface area for absorption
      • Highly folded / coiled to slow movement of food to allow more time for digestion / absorption / increase surface area for absorption.
      • Has numerous villi which increase surface area for absorption / microvillus which further increase surface area for absorption.
      • Ileum wall / villi have thin epithelium which is only one cell thick to reduce distance over which digested food has to diffuse.
      • Villi are highly vascularised / have a rich network of blood capillaries for rapid transport from small intestines / maintain a steep concentration gradient.
      • Villi have lacteals for absorption of fatty acids and glycerol
      • Cells of ileum wall have a large count of mitochondria to release energy that aid in active transport across the epithelium.
  8.      
    • some have thick/fleshy/succulent stems to store water thick waxy cuticle that reduces water loss by transpiration;
    • leaves reduced to spines to reduce surface area through which water is lost;
    • stems and branches are green/ have chloroplast for photosynthesis;
    • some have superficial roots to provide large surface area for absorbing maximum amount of water after a short shower;
    • Have deep penetrating roots that absorb underground water far below the surface;
    • Most have spines/thorns which discourage herbivores from feeding on their succulent parts
    • Some have leaves covered with hair or scales; to trap a layer of still moist air close to the leafy surface thus reducing transpiration;
    • Some roll their leaves in dry weather to reduce surface area expose to external environment to reduce transpiration
    • Some have needle like leaves; and stomata are reduced in number; and located in cavitiest /sunken stomata;
    • Some have reversed stomata rhythm to minimize loss of water by transpiration;
    • Short life cycles; to maximize use of the rainy season which is short
    • Shallow extensive fibrous root system to absorb water during light showers;
    • Seeds are resistant to desiccation and remain dormant yet viable for several years;
    • Some have perennating underground organs like bulbs/corms which store food/water  

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