KCSE 2017 Biology Paper 1 with Marking Scheme

Instructions to candidates

• Answer all the questions in this question paper.
• Candidates should answer the questions in English.

Answer all the questions in the spaces provided.

1. Below is an illustration of a piece of apparatus strategically positioned to trap some organisms.
            
   
   1. Name the apparatus.   (1 mark)
   2. State the function of the part labelled E.    (1 mark)
2. Below are diagrams of a cell organelle obtained from different organs of an animal.
          
   
   1.  
      1. For each organelle state an organ in the urinary system where it is likely to be found.     (2 marks)
         F ..............
         G .............
      2. Give a reason for your answers in (a) (i) on page 2    (2 marks)
   2. Name the part of the chloroplast where the following reactions occur:
      
      1. Carbon(IV) oxide fixation   (1 mark)
      2. Photolysis    (1 mark)
3. During a practical investigation on food tests, students were provided with the following reagents.
   Benedict's solution
   Sodium hydrogen carbonate
   Dilute hydrochloric acid.
   
   1. Identify the food substance the students were to test.    (1 mark)
   2. State the role of dilute hydrochloric acid and sodium hydrogen carbonate during the experiment.
      1. Dilute hydrochloric acid   (1 mark)
      2. Sodium hydrogen carbonate    (1 mark)
4. In an experiment on respiration, a mouse was observed to have inhaled 200 cm³ of oxygen and exhaled 199.75 cm³ of carbon(IV) oxide in ten minutes.
   
   1. Calculate the respiratory quotient for the activity in the experiment.   (2 marks)
   2. Identify the possible food substance consumed by the mouse.      (1 mark)
   3. State the fate of the excess food named in (b) above in the human body.      (2 marks)
5. The photograph illustrates a housefly at various stages of its development.
             
   
   1.  
      1. On the photograph, name the stages of the life cycle.   (1 mark)
      2. Using arrows, link the stages of the life cycle in the correct order.    (1 mark)
   2.  
      1. State two differences between the life cycles of a housefly and that of a cockroach.      (2 marks)
      2. State one advantage of the life cycle of a cockroach to itself.    (1 mark)
6. Name two enzymes in the human digestive system which are secreted in an inactive form.    (2 marks)
7. The diagram below represents a stage in the division of a cell.
   
   With a reason, identify the organism from which the cell was obtained.   (2 marks)
8. Explain why short distance runners breathe quickly and deeply at the end of a race.    (2 marks)
9.  
   1. State the function of a mirror in a light microscope.  (1 mark)
   2. Give one reason why the coarse adjustment knob should not be used to lower the high power objective.
      (1 mark)
10.  
    1. State the effect of movement of the diaphragm muscles during inhalation in mammals.  (3 marks)
    2. State two structural adaptations of leaves that maximise efficiency in gaseous exchange.   (2 marks)
11. The set up below illustrates a certain physiological process.
    
    1.  
       1. Name the physiological process.   (1 mark)
       2. Give two examples of the process named in (a) (i) above in plants.    (2 marks)
    2. State two ways by which the movement of dye molecules in the set up would be slowed down.    (2 marks)
12. Explain the survival values of the following tropic responses to plants.
    
    1. Geotropism   (2 marks)
    2. Phototropism.     (1 mark)
13. Name the causative agent for Tuberculosis.   (1 mark)
14. The photograph below illustrates a germinating seedling.
             
    
    1. Name the type of germination illustrated in the photograph.   (1 mark)
    2. Explain the function of each of the parts labelled G and H.   (2 mark)
15. Explain the physiological process responsible for keeping young seedlings upright.    (3 marks)
16. The following are text messages on a cellphone that represent gene mutation.
    

    	Intended message	Actual message
    I	I hate meat	I ate meat
    II	This is my team	This is my mate

    1. Identify the type of gene mutation represented in each case
       I            (1 mark)
       II                (1 mark)
    2. State Mendel's First Law.   (1 mark)
    3. State two disadvantages of genetically modified plant products.   (2 marks)
17. How is the surface area increased in the mammalian small intestines?    (2 marks)
18. Below are diagrams representino developmental stages of three different vertebrates.
              
    1. State the evidence of evolution illustrated by the vertebrates in the diagram.  (1 mark)
    2. Suggest why the structure labelled J has been retained throughout the evolution of fish.   (2 marks)
    3. State two major advantages evolution has given humans over most of the other animals.   (2 marks)
19. The table below shows the percentage concentration of certain substances in blood plasma glomerular filtrate and urine in a human being at a particular time.
    

    Percentage Concentration
    Substance	Blood Plasma	Glomerular filtrate	Urine
    Glucose	0.023	0.02	0.0
    Water	92.70	92.70	96.08
    Protein	5.69	0.0	0.0
    Urea	0.087	0.098	2.6

    
    
    1. Explain the likely impact on the composition of urine in case of the following:
       1. Vigorous physical exercises   (2 marks)
       2. a meal rich in proteins     (2 marks)
    2. Name the processes responsible for:
       1. Presence of glucose in the glomerular filtrate   (1 mark)
       2. absence of glucose in urine   (1 mark)
20. State three methods of fossil formation,     (3 marks)
21. The photograph below represents a leaf obtained from a certain plant.
      
    Account for the observations made if the leaf was tested for starch.   (3 marks)
22. State two ways by which plants manage their solid wastes.   (2 marks)
23. The diagram below represents a set up during an experiment.
              
    1.  
       1. What was, the experiment investigating?   (1 mark)
       2. State the likely identity for substance K   (1 mark)
       3. Explain your answer in (a) (ii) above   (1 mark)
    2. Account for the observations made in flask 2.   (2 marks)

MARKING SCHEME

1.  
   1. Pooter/Aspirator;    (1 mark)
   2.  To prevent dirt/insects from entering the suction tube/into the mouth;   (1 mark)
2.  
   1.  
      1. F - Kidney;   (1 mark)
         G - Bladder/Ureter/Urethra;    (1 mark)
      2. Kidney - active re-absorption of solutes requires more energy; organelle F has more cristae for attachment of more respiratory enzymes producing more energy;
         Bladder/ureter/urethra does not require as much energy organelle G has less number of cristae hence fewer respiratory enzymes attached/less energy produced;    (2 marks)
   2.  
      1. Stroma;      (1 mark)
      2. Grana/granum;          (1 mark)
3.  
   1. Non reducing sugar;   (1 mark)
   2.  
      1. Hydrolyze/break down sucrose/ non reducing sugars to  reducing sugars/glucose/fructose;   (1 mark)
      2. neutralize the acid; 
4.  
   1. R.Q = CO2 produced   
                O2 consumed;
            = 199.75
                   200
            = 0.99875;   (2 marks)
   2. Carbohydrates/glucose;    (1 mark)
   3.  
      • Stored in the body as fat/subcutaneous deposit/adipose tissue;
      • Stored as glycogen (in the liver / muscle cells);
      • (Increase) oxidation; any 2   (2 marks)
5.  
   1.  
      1.  
           (1 mark)
      2.    
             (1 mark)
   2.  
      • 
        

        Housefly	Cockroach
        -Undergo complete metamorphosis/Egg. Larva, Pupa,Adult/has 4 steps; -Eggs have no egg case/ootheca - Many/numerous eggs	-Undergoes incomplete metamorphosis Egg, Nymph,Adult/has 3 steps; -Eggs in egg case/ootheca -Fewer eggs

        2 x 1     (2 marks)
      • Absence of larva and pupa shortens the life cycle of the organism; (avoiding adverse/extreme environmental conditions that would affect its growth/general life processes); (1 mark)
6. Pepsin (secreted as pepsinogen);
   Trypsin (secreted as trypsinogen);
   Rennin/chymosin (Secreted as Prorennin/Prochymosin; max-2   (2 marks)
7.  
   • Animal - accept correct examples (of organisms) amoeba plasmodium;
   • Constriction of the cell membrane presence of centrioles ;     (2 marks)
8. To increase the supply of oxygen (in the tissues); to offset the "oxygen debt"/halt/manage the accumulation of lactic acid in the muscles);   (2 marks)
9.  
   1. Reflects light (through the condenser) to the object;
   2. • Can break the objective lens/cover slip/slide;     (1 mark)
      • Can destroy the specimen (making the microscope dirty);      (1 mark)
        Any one correct
10.  
    1. The diaphragm contracts and flattens, leading to increase in volume of the thoracic cavity; decreasing the pressure inside it, (forcing in the air); 
    2.  
       • Thin leaf lining/epidermis for faster diffusion of respiratory gases/ to reduce diffusion distance for respiratory gases;
       • Numerous stoma to increase surface area for gaseous exchange;
       • loosely packed cells in the spongy mesophyll region intercellular air spaces (lower layer) to allow for free   movement of respiratory gases; 
         Any 2(2 marks)
11.  
    1.  
       1. Diffusion;  (1 mark)
       2.  
          • Gaseous exchange/excretion of carbon (IV) oxide and oxygen;
          • Translocation of materials;
          • Absorption/uptake of mineral ions/salts;
            Any 2 (2 marks)
    2.  
       • Lowering the temperature of the medium;
       • Increasing thickness of the membrane; 
       • Use less dye/add more water/reducing the concentration gradient;    (2 marks)
12.  
    1. Geotropism 
       • enables plants a ccess water/mineral salts;
       •  Anchorage;  (2 marks)
    2. Phototropism-Exposes plant leaves to light for photosynthesis/for formation of chlorophyl; (1 mark)
13. Mycobacterium tuberculosis/Mycobacterium bovis; (1 mark)
14.  
    1. Epigeal;  (1 mark)
    2. G-Elongates to expose the foliage leaves to light photosynthesis  (1 mark)
       H-Stores food (for growth); .
         -For photosynthesis (it is green);
         -Protects plumule during germination;
       Any one (1 mark)
15. Osmosis; water moves into the cells becoming turgid; attaining mechanical support ; OWTTE   (3 marks)
16.  
    1. I-Deletion;   (1 mark)
       II- Inversion;  (1 mark)
    2. The characteristics /traits of an organism are determined by internal factors/genes (which occur in pairs). Only one of the genes can be carried in a gamete passed onto the next generation; (1 mark)
    3.  
       • Most have lost most of the original (desirable) qualities eg taste;
       • Poor/undesirable qualities are perpetuated through subsequent generations;
       • Products' qualities are irreversible-can't get original species/qualities;
         Any 2 (2 marks)
17.  
    • Presence of numerous villi/microvilli;
    • Being long;
    • Being highly coiled;
      Any 2 (2 marks)
18.  
    1. Comparative embryology;   (1 mark)
    2.  
       • Fish remained in the aqueous media/ aquatic habitat; well developed tail/fin for propulsion/movement;
       • Ability to rationalize/higher thinking capacity/higher brain activity/advanced brain; 
       • Ability to walk on two's/ bipedal modification of the limbs/ opposable thumbs/upright posture; 
       • Communicate through speech; 
       • Have binocular/stereoscope vision;
         (4 marks)
19.  
    1.  
       1. Less water and urea; since some is excreted eliminated through the skin as sweat); (2 marks)
       2. increased amount of urea in the urine; due to deamination of amino acids (from proteins):  (2 marks)
    2.  
       1. ultra filtration;  (1 mark)
       2. Selective reabsorption; (1 mark)
20.  
    1. Petrification change into rock;
    2. Entire organism or parts preserved; 
    3. Impressions (eg casts/moulds);
       (3 marks)
21. Differences in distribution of chlorophyll/leaf is variegated; green patches would photosynthesize forming starch; giving blue-black colour with iodine solution unlike the regions without chlorophyll;   (3 marks)
22.  
    • Storage in tissues in non-toxic forms;
    • Deposited in plant tissues/organs- which age and fall off; (eg leaves, bark, fruits, flowers)
      (2 marks)
23.  
    1.  
       1. To investigate how ants respond to moisture/water/ hydrotaxis (varied environments with/without moisture water);   (1 mark)
       2. Silica gel/anhydrous calcium chloride pellets/pyrogallic acid/dehydrating/ drying agent; (1 mark)
       3. The colour of cobalt (II) chloride paper remained blue/all the moisture/ water vapour was absorbed/There was no water/moisture in the flask to change the colour of cobalt (II) chloride paper,  (1 mark)
    2. (More) ants were attracted moved into the flask; due to the presence of moisture/water vapour, (evidenced by the change of cobalt(II) chloride paper to pink)    (2 marks)