BIOLOGY PAPER 2 - 2019 LAINAKU JOINT MOCK EVALUATION EXAMINATION

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SECTION A (40 MARKS)

Answer ALL the questions in this section in the spaces provided.

  1. The flow diagram below represents passage of a meal through the human digestive system. Study the diagram and answer the questions that follow.
    BIO2 Q1JKHGFG
    1. Name the physical process that will occur in mouth cavity (1mk)
    2. Name the digestive juices B and C (2mks)
    3. Explain two ways in which the digestive system is protected from corrosive effects of digestive juices. (2mks)
    4. Name the hormone that stimulate secretion of juice B. (1mk)
    5. Identify two contents of digestive juice A (2mks)
  2. Examine the diagram below and answer the questions that follows
    BIO2 Q22KJJUK
    1. Name the parts labeled A-D                                                                    (4mks)
    2. State the type of germination exhibited by the seedling above                         (1mk)
    3. State and explain three environmental conditions necessary for germination.      (3 marks)
  3. A cross between a red flowered plants and white flowered plants produced plants with pink flowers. Using letter R to represent the gene for red color and W for white.
    1. What were the parental genotypes?                                                 (2mks)
    2. Work out the cross between f1 generations                                     (4mks)
    3. State the phenotypic and genotypic ratios of the f2 generations             (2mks)
    1. What is meant by:
      1. Autecology                         (1mk)
      2. Synecology                                                                                       (1mk)
    2. Using the table below, answer the questions that follow
       

      Number of stomata

      Leaf

      Upper epidermis

      Lower epidermis

      A

      300

      0

      B

      150

      200

      C

      02

      13

      Name the parts labeled Y and X                                                                                (2mks)
    3. Suggest the possible habitat of the plants from the leaves were obtained   (3mks)
    4. State the modifications in the stomata of leaf C (3mks)
  4. The diagram below shows a section through the mammalian skin
    BIO2 Q5YUYHJK
    1. State the function of the parts labeled W and Z                                                        (2mks)
    2. Explain the changes that occur on the skin when it is cold                                        (4mks)

SECTION B: (40MKS)
QUESTION 6 is COMPULSARY: Answer either question 7 or 8.

  1. In an experiment, three healthy rabbits were fed with equal amounts of carbohydrates. After 1 hour their blood sugar glucose concentration was measured at 30 minutes intervals for 3 hour. The results are as shown in the table below.

    Glucose conce Mg/ml Rabbit

    Initial time(minutes)

    30 Minutes

    60Minutes

    90 Minutes

    120 Minutes

    150 Minutes

    180 Minutes

    P

    1.6

    1.55

    1.43

    1.36

    1.3

    1.19

    1.11

    Q

    1.49

    1.39

    1.34

    1.32

    1.27

    1.2

    1.09

    R

    1.59

    1.39

    1.33

    1.27

    1.18

    1.1

    0.99

    Mean

    1.56

    1.44

     

    1.32

    1.25

    1.16

    -

    Calculate the mean glucose concentration 1mg/ml of blood at 60 and 180 minutes.                             (2mks)
      1. On the grid provided plot a graph of mean glucose concentration against time. (6mk)
      2. What was the mean concentration in the blood after 75minutes?                                 (1mks)
      3. Why was it necessary to use 3 rabbits in the experiment?                                           (1mks)
      4. Account for differences in mean glucose concentration between initial time and 180 minutes                                                                                 
    1. Name three products of digestion other than glucose                                                     (3mks)
    2. What is the fate of excess glucose in:
      1. Plants?                                                                                                                             (2mks)                
      2. Animals ?                                                                                                                       (2mks)
  2. Describe how the male reproductive system is adapted to its functions.(20mks)
    1. How are structures of the human eye adapted to their functions                            (14 marks)
    2. State three defects of the eye and how each can be corrected                            ( 6 marks)


MARKING SCHEME

    1. Mastication;/chewing;/grinding; any one (1mk)
    2. B – Gastric juice;                                                  (1mk)
      C – Intestinal juice;/succusentericus;              (1mk) reject wrong spelling
    3. produces mucus;                                       
      - Enzymes produced in inactive from that is pepsinogen and trypsinogen (2mks)
    4. Gastrin;                             (1mk)
    5. – Enzyme salivary amylase.Ptyalin;
      - Mucin/Mucus;
       - Water;                                         (any two) (2mks)
    1. A- Foliage leave,     C-Hypocotyl
      B –Cotyledon,                 D-Roots
    2. --Epigeal germination
      1. Optimum temperature----To activate the germination enzyme
      2. Oxygen –Oxidising the food material to release energy necessary for germination
      3. Water----solvent to dissolve substance weaken testa to enable germination to place and hydrolysis enzyme
    1. RR;           WW; (2mks)
    2. Phenotypes Pink                      Pink                         (1mk)
    3. Phenotypic ratio; 1 Red flowered: 2 Pink flowered: 1 white flowered;   Rej: 1:2:1 (1mk)
      Genotypic ratio     1RR: 2RW:1WW;        Rej: 1:2:1 (1mk)
  1. Autecology-study of a single species;
    Synecology-study of many species;
    A- aquatic/ fresh water;
    B-terestrial/ forest;
    C-arid/ semi-arid/ desert;
    -Sunken stomata;
    -Reversed stomatal rhythm;
    -Mid-day closure;
    - Small stomatal pore
    1. Y-sweat pore;
      X-Eractor pili muscles; (2mks)
    2. W- produces sebum which keeps the skin supple/ antiseptic
      Z- Secrets sweat which evaporates to bring about cooling/sweat also removes excretory products/excess salts/water (2mks)
    3. vasoconstriction; hence less blood flows to the skin surface;reducing heat loss;no sweating;heat produced throught metabolisms/shievering;heat is retained in the body; ( 4 marks)
      1. 60 minutes – 1.37;
        180 minutes- 1.06;
      2. On grid provided;
        BIO2 GRAPH
      3. 1.35+ 0.001mg/ml;
      4. To get more reliable results;
      5. initial glucose concentration was high because of absoption into the blood stream.
        Glucose concentration decreased due to oxidation to release energy; excess converted to glycogen; under Influence of insulin;
    1. Amino acids; fatty acids; glycerol;
      1. Trans located; to storage organs; and converted into starch;
      2. translocated to the liver( 1mk); and converted to glycogen;
  2. Consist of testes; that lie outside the abdominal/location outside the body to provide cooler environment/ lower temperatures; suitable for sperm production/ spermatogenesis;
    inside the testes there are seminiferous tubules; that are highly coiled and have actively dividing germinal epithelial cells; that form sperms;
    Interstitial cells that produce male sex hormones/ Androgens/testosterone; that promotes development of secondary sexual characteristics; and maintain masculinity;
    Epididymis form ducts that convey sperms out of the testes; testes they are highly coiled to increase surface area for the (temporary) storage of sperms;
    Sperm duct/vas deferens has thick muscular walls that contracts to propel sperms to the urethra (during ejaculation)
    Seminal vesicle; is a blind ending sac that produces alkali fluid; with nutrients for the spermatozoa/sperms; to provide energy for the sperms;
    Prostate glands; secrete alkaline; fluid that neutralizes the acidic vaginal fluids; and activates the sperms;
    Cowper’s gland; secrets alkaline fluid that neutralizes the acidity of urine in the urethra; :urethra is along tube along the penis; for conduction and expulsion of urine; and passage of sperms during copulation;
    penis is made up of spongy erectile muscular tissue; consisting of numerous spaces that are filled with blood; making the penis to become erect during sexual stimulating/activity; to enable it penetrate the vagina; to deposit sperms;
    tip of penis has gland; that is highly innervated for stimulation during sexual activity;
    Scrotum/scrotal sac; is a sac like structure made of skin and it encloses testes protects the testes; (Total 20)
  3. Adaptation

    Function

    Conjunctiva - An epithelium colourless

    Protects eyeball

    Cornea: Transparent/curved

    Allow light/ refract light entering the eye

    Aqueous/vitreous: clear

    Allow light to pass through/ refract light.

    Maintain the shape of the eye

    Iris. Opaque and contractile

    Controls light intensity/amount of light entering the eye.

    Ciliary muscle/ body contractile

    Control curvature of lens, secretes humour

    Suspensory ligaments: are fibrous

    Hold lens in position

    Lens is transparent; lens is biconvex

    To allow light to go though/to refract light/ to focus light.

    Retina- contain light sensitive cells

    Where an image is formed which perceive light.

    Cones: contain pigments

    For colour vision/ bright light/ light of high intensity

    Rods contain pigments

    For dim light vision

    Foreacentralis: High concentration of cones

    For accurate vision

    Choroid: Layer has blood vessels

    For nutrition and pigments.

    Reduce light reflection and absorb stray light

    Sclera- Tough/ non elastic or fibrous

    Gives eye shape and protects

    Optic nerve

    Contain sensory neurones for transmitting impulses from retina to brain.


    Defect

    Correct

    Myopia/ short sightedness

    Biconcave/diverging lenses

    Hypermetropia/long sightedness

    Biconvex/ converging lenses

    Astigmation

    Use of cylindrical lenses with   combined curvature

        

 

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