Biology Paper 2 Questions and Answers - Cekenas Mock Exams 2022

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QUESTIONS

SECTION A (40 MARKS)

  1. The diagram below represents two plant cells A and B placed in two different solutions. Study the diagrams and answer the questions that follow:
    1
    1. Identify the nature of solution into which each cell was placed. (2mks)
    2. Name the physiological process responsible for the observed results. (1mk)
    3. Give the correct biological term used to describe cell A. (1mk)
    4. Describe what happen if red blood cell was placed in the solution in which cell B was placed. (2mks)
    5. Explain why freshwater amoeba do not burst when placed in distilled water. (2mks)
  2.      
    1. Under certain conditions, carbon (IV) oxide concentration in the blood of mammals rises above the normal levels. State two physiological change that occur to bring carbon (IV) oxide level back to normal. (2mks)
    2. Why does a fresh wound bleed more in a hot weather than in cold weather? (2mks)
    3. A certain organ R was surgically removed from a rat. Later a drastic increase in glucose level was observed in blood. Substance S was injected into the animal’s blood. The whole process was reversed. Identify:
      Organ R………… (1mk)
      Substance S………… (1mk)
    4. State two functions of blood plasma. (2mks)
  3.        
    1. Explain why people with sickle-cell trait have an advantage of surviving malarial attack than those with normal red blood cells. (2mks)
    2. Colour blindness is a sex linked trait caused by a recessive gene carried on the X chromosome. A carrier woman marries a man with normal colour vision. Using letter N to represent the gene for normal colour vision, workout the probability of the couple getting a colour blind son. (5mks)
    3. State one advantage of polyploidy in plants. (1mk)
  4. The diagram below represents a living organism.
    2
    1. Name the division to which the organism belongs to. (1mk)
    2. Name part labelled Q. (1mk)
    3. State two functions of part T. (2mks)
    4. During a practical activity, Form three students of Bora Boys collected a specimen whose drawing is as shown below. State the class that the organism belongs to giving a reason.
      3
      Class ……(1mk)
      Reason ……... (1mk)
    5. State the economic importance of a named fungus. (2mks)
  5.      
    1. Distinguish between population and community. (2mks)
    2. What is the importance of the following in an ecosystem? (2mks)
      Decomposers………...
      Predation……...
    3. Give a reason why two species in an ecosystem cannot occupy the same niche. (2mks)
    4.      
      1. Name the bacteria found in root nodules of leguminous plants. (1mk)
      2. Identify the relationship between the bacteria named in d(i) above. (1mk)

SECTION B (40MARKS)
Answer Question 6 (compulsory) and either question 7 or 8 in the spaces provided.

  1. The table below shows how quantities of sweat and urine produced by a healthy adult human vary with external temperature.
    External Temperature 0 5 10 15 20 25 30 35
    Urine produced cm3/hr 100 90 80 70 60 50 40 30
    Sweat produced in cm\3/ hr 5 6 01 15 30 60 120 200
    1. Using the same axes, draw graphs of quantities of urine and sweat against external temperature. (8mks)
    2. Account for the amount of sweat produced as the external temperature rises. (3mks)
    3. At what temperature was the amount of urine equal to amount of sweat produced. (1mk)
    4. Explain the effects of temperature on the amount of urine produced. (4mks)
    5. Explain how the following structures reduce body heat loss when external temperatures are low.
      1. Skin hairs (2mks)
      2. Blood vessels (2mks)
  2.       
    1. Describe the adaptations of mammalian male reproductive system to its function. (10mks)
    2. Explain how the vertebrae below are adapted to their functions. (10mks)
      1. Cervical vertebrae
      2. Thoracic vertebrae
  3. Explain how the leaves of mesophytes are suited to their functions. (20mks)


MARKING SCHEME

  1.      
    1.      
      1. Hypertonic solution/ highly concentrated solution
      2. Hypotonic solution/ lowly concentrated solution
    2. Osmosis
    3. Plasmolysis;
    4. It will gain water by osmosis; swell and eventually burst;
    5. Form contractile vacuoles; which get rid of excess water to the surrounding.
  2.      
    1. Increased rate of heart beat/ increased rate of blood circulation
      Increased rate of breathing/ deep inspiration and expiration
    2. During hot weather surficial blood vessels dilate; (thus) more blood flows through the skin;
    3. Organ R – Pancreas
      Substance S – Insulin
    4. Transport of hormones
      Transport of nitrogenous waste Mark first 2
      Transport of dissolved nutrients
  3.      
    1. People with sickle cell trait have less than half of their red blood cells being sickle shaped; plasmodium do not survive in sickle shaped red blood cells.

    2. 4
      Probability = ½
    3. Early maturity; rej. Faster maturity.
      High yields;
      Resistance to pests and diseases; Mark first 1
      Resistance to drought
  4.      
    1. Bryophyta; Rej. Bryophyte Should start with a capital letter.
    2. Q- Capsule;
    3. Absorption of water/ mineral salts;
      Anchorage; OWTTE.
    4. Arachnida; should start with a capital letter
      Reason – 4 pairs of legs; OWTTE
      2 body parts (cephalo thorax and abdomen)
      Reason and class tied
    5. Source of food;
      Production of antibiotics; Mark any 2
      Cause diseases;
      Causes decomposition
      Any 2
  5.      
    1. Population is the number of organisms of the same species occupying a particular habitat at a given time; community is the total number of different species;
    2. Recycle nutrients
      Predators – regulation of prey;
    3. Lead to (stiff) competition for available resources; leading to elimination of one of them;
    4. Rhizobium
      Symbiosis
  6.      
    1.   
      5
    2. Amount of sweat increases with increase in temperature; high temperature stimulates the sweat glands; to secrete sweat;
    3. 24ºC ± 0.5
    4. An increase in temperature leads to a decrease in the amount of urine produced; high temperature stimulates sweating leading to water loss; this leads to increase in osmotic pressure of the body fluids; thus release of ADH; which increases reabsorption of water;
      Total 5 mks max 4
    5. Hair (stand) erect/ upright; trapping a layer of air insulating the body against heat loss;
      Vasoconstriction; reducing the amount of blood flowing through the skin surface thus heat loss;
  7.    
    1. Position of scrotal sac out of abdominal cavity provide cooler temperature for sperm development/ spermatogenesis; Has seminiferous tubules, highly coiled whose lining consist of actively dividing cells; between them are interstitial cells which produce androgens; Seminiferous tubules unite to form epididymis; a coiled tube; which provide surface for sperm storage; Seminal vesicles provide alkaline fluid which nourishes spermatozoa; prostate gland secretes alkaline fluid to neutralize the vaginal fluids; it also activates sperms; Cowper’ s gland secretes an alkaline fluid that neutralize acidity along the urethra; penis which projects from the body, made of spongy tissue, muscle and blood vessel; erects by having spaces in its spongy tissue filled with blood enabling it to penetrate vagina during coitus, to deposit sperms in the female reproductive tract;
      (Total 12 marks; max 10 marks)
    2.      
      1. Cervical Vertebra.
        • Has vertebraterial canal for passage of vertebral artery and nerves;
        • It has branched and broad transverse process to provide surface for attachment of neck muscles;
        • Short neutral spine for attachment of neck muscles;
        • Wide neural canal for passage of spinal cord;
        • Centrum and a neural arch for protection of the spinal cord;
        • Prezygapophysis and postzygapophysis for articulation with the vertebrae in front and behind;
        • Atlas has broad surface for articulation with condyles of the skull and this allows the nodding movement of the heard;
        • Axis has a projection of the centrum, the odontoid process that fits into atlas and allows for the rotatory / turning movement of the head;
          (Total 8marks; max 5 marks)
      2. Thoracic Vertebra.
        • Long neural spine for muscles attachment;
        • Short transverse process for muscle attachment and for articulation with the ribs;
        • Neural arch and centrum protect the spinal cord;
        • Large centrum to support the body weight;
        • Facets for articulation with other vertebrae adjacent to it:
        • Turbercular and capitular demi facets for articulation with the rib:
          (Total 6 marks; max 5 marks)
          NB. Structure and function 1 mark. `
  8.    
    • Broad leaves; to increase the surface area; for maximum trapping of sunlight; for photosynthesis;
    • Thin; to reduce diffusion distance of carbon (IV) oxide; (for photosynthesis)
    • Transparent cuticle; and epidermis; for easy penetration of light;
    • Extensive veins; with vascular bundles; for transport of water and mineral salts; and translocation of food;
    • Numerous stomata; for gaseous exchange; and transpiration;
    • Leaf mosaic arrangement; prevent overlapping; for maximum absorption of light;--
    • Numerous chloroplasts; for maximum trapping of light; for photosynthesis

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