Biology Paper 1 Questions and Answers - Lainaku II Joint Mock Examination 2023

INSTRUCTIONS TO CANDIDATES

• Answer all questions 

1.  
   1. Name the one chemicals of a life that makes up protoplasm (1mark)
   2. State Two disadvantages of using fats as respiratory substrates (2marks)
2.  
   1. Name the type of gene mutation that results in loss of skin pigment (1mark)
   2. Explain how sunlight contributes to stronger bones and teeth in human beings (2marks)
3. Name the main target organ of the following hormones: (2marks)
   1. Antidiuretic
   2. Glucagon
4.  
   1. What is Binary Fission? (1mark)
   2. Give Two disadvantages of sexual reproduction (2marks)
5. The diagram shown below represents a seedling. Use it to answer questions that follow
   
   1.  
      1. Name Class in which the seedling belong (1mark)
      2. Give reasons for your answer in a (i) above (2marks)
   2. Explain why the biomass of part labelled A will be lower compared to the one found in the seed stage of the same plant (2marks)
6. A solution of sugarcane was boiled with hydrochloric acid. Sodium hydrogen carbonate was added and the mixture heated with Benedict’s solution. An orange precipitate was formed.
   1. Why was the solution boiled with hydrochloric acid? (1mark)
   2. To which class of carbohydrates does sugarcane belong? (1mark)
   3. Name the type of reaction that takes place when:
      Simple sugars combine to form complex sugar. (1mark)
   4. State the form in which carbohydrates are stored in animals (1mark)
7.  
   1. State Two ways in which blood clotting is important to a human being (2marks)
   2. What are the roles of thrombokinase enzyme during blood clotting? (2marks)
8. The diagram shown below represents a flower
   
   1. Name the agent of pollination for the flower shown above (1mark)
   2. Give Two reasons for your answer in a) above (2marks)
9. State the differences between cones and rods in terms of the following (2marks)
   

   Feature	Cone	Rod
   Visual acuity	High
   Photochemical	Low

10. Use the diagram of a nerve cell shown below to answer questions that follow
    
    1. With a reason, give the identity of the nerve cell (2marks)
       Identity 
       Reason
    2. Explain the significance of absence of part labelled H in nerve cells found in the brain.  (1 marks)
11. Give Three features that make modern man to be more adaptable to the environment (3marks)
12. The diagram below represents a living organism
    
    1. State Two economic importance of the above organism in the food industry (2marks)
    2. Why does the rate of respiration reduce under the following conditions? (2marks)
       1. Low temperature 
       2. Metabolic poison
13. State Two reasons why Biotechnology is important in modern science (2marks)
14. Fill in the table shown below to give differences between biceps and gut muscles (3marks)
    

    	Biceps	Gut muscles
    I
    II
    III

15. Explain how variation is important in the process of evolution? (2marks)
16. Explain the term negative feedback (1mark)
17. State Two contributions of Carolus Linnaeus (1708 – 1778) to taxonomy (2marks)
18.  
    1. In an experiment, Venna counted 9 cells along the diameter of field of view of a light microscope measuring 3.0mm. Determine the diameter of one cell in micrometers  (3marks)
    2. Why is electron microscope safer to the eye than light microscope during use? (1mark)
19. The following diagram represents results of an experiment carried out on two sets of germinating seeds.
    
    1. Account for the result shown in test tube X (2marks)
    2. What is the importance of dipping the boiled seeds in a disinfectant in test tube Y? (1mark)
20. The diagram shown below represents a section of the vertebral column
    
    1. Name the part labelled S (1mark)
    2. State TWO ways in which part T is important to movement in human beings (2 marks)
21. The diagram below shows an experiment carried out to investigate photosynthesis in a potted plant which has been kept in the dark for 48 hours.
    
    The setup was left in the sunshine for 6 hours. The leaf was tested for starch using iodine solution at the end of the experiment.
    1. What would be the colours of the regions of the leaf marked L, M and N? (3marks)
    2. What is the function of the sodium hydroxide pellets? (1mark)
22.  
    1. In fruit flies (Drosophila) the gene for red eyes (R) is dominant over the one for white – eye (r). In a true breeding white – eyed male, all the offspring will be red eyed. However, if a true – breeding white-eyed female is mated with a true- breeding red- eyed male, all the female offspring will be red – eyed. Explain this apparent contradiction. (1mark)
    2. Work out the expected FI genotypes if a red- eyed female offspring from the cross- described in (a) above is mated with red- eyed males. (4marks)
23. An experiment was set up to investigate the effect of unilateral/unidirectional light in growth of maize seedlings. The diagram in the table below represents experimental set up at the beginning. The tip of D is covered by an aluminium foil.
    
    Using diagrams, complete the table to show the expected results in experimental set up. (3 marks)
24. Use the figure below to answer the questions that follow.
    
    1. Identify the cardiac cycle represented by the diagram. (1mark)
    2. Identify the valves X and Y (2marks)
       X
       Y
25. How does sunken stomata help in lowering transpiration? ( 3marks)
26.  
    1. Name the hormone that stimulate the maturation of the graafian follicles to release a mature ovum in female reproductive cycle. (1mark)
    2. Explain why menstruation does not take place after fertilization in human beings. (2marks)

MARKING SCHEME

1.  
   1. Protein molecule; lipid molecule; (First correct)
   2. Requires a lot/more oxygen to oxidise; Insoluble in water thus not easy to transport to respiratory site;
2.  
   1. Substitution;
   2. Influences formation of Vitamin D (in the body); Which is required for absorption of phosphates and calcium ions; important in bone and teeth formation
3.  
   1. Kidney;
   2. Liver;
4.  
   1. A form of asexual reproduction whereby a cell split into daughter cells and develop into new offspring;
   2. Slower/takes longer time to obtain off-springs; Rely on unpredictable pollination/fertilization that are easily affected by weather changes; variation may lead to disadvantageous traits; Relies on the presence of both parents that may be possible in some cases e.g when one dies; (first two correct ans)
5.  
   1.  
      1. Class Monocotyledonae; (M must be capital and correctly spelt)
      2.  
         • Parallel leaf venation; Narrow leaf lamina; Fibrous roots;
         • Seed cotyledon remains in soil after growth; (any two correct point)
   2. Stored nutrients are hydrolysed/converted to simpler forms; that are used in cell to produce energy used in division/growth (of the seedling);
6.  
   1. To hydrolyse/break down the disaccharide (non-reducing sugar) to reducing sugars;
   2. Non-reducing sugar/Disaccharides;
   3. Condensation;
   4. Glycogen;
7.  
   1. Prevent excessive loss of blood/anaemia; Prevent entry of pathogens into the body; Initiate healing of wound; (first two correct)
   2. Convert prothrombin to thrombin; Neutralises anti-clotting factor/Heparin; (correct spelling)
8.  
   1. Wind; Reject Wind-pollinated
   2. Has feather-like stigma; Long filament/Androecium hangs outside; Reduced petals/bracts to expose the gynoecium/androecium to wind; (fist two correct)
9.  
   

   Feature	Rod
   Visual acuity	Iodopsin; (correct spelling)
   Photochemical	Rhodopsin; (correct spelling)

10.  
    1.  
       • Identity: Motor; Reject Multipolar
       • Reason: Cell body located at one end axon; Multipolar;
    2. Entirely protected; Slow down movement of impulse; to give adequate time for interpretation of the impulse (by brain/CNS); (Any one correct)
11. High level of intelligence/Reasoning/Brain capacity; Well-developed speech/effective communication abilities; Upright gait to see far/danger easily; Bipedal locomotion frees hands for other uses; pre-hensile hands for handling various tools; non-opposable toe for stability; 1_st 3
12.  
    1. Baking/Manufacture of bread; Brewing Alcoholic beverages; Manufacture of high nutritional value proteins/Single Cell Protein; Manufacture of biofuel/gasohol; Food flavouring; Food conditioning/Preservation; Making vitamin supplements; Ripening of cheese; Food spoilage; Mark 1_st2
    2.  
       1. Respiratory enzymes are inactivated;
       2. Bind to the enzymes/active sites of enzymes permanently or temporarily thus inhibit enzyme action on substrates;
13. Development of new tools/techniques/procedures for biological research; Development of materials for medicine/agriculture/health/industries;
    Accept specific examples e.g Drugs/Medicine/Hormones/Vaccine/Cultivars
14.  
    

    	Biceps	Gut muscles
    I	Striated	Non-striated/Un- striated;
    II	Multinucleated	Un- nucleated;
    III	Long fibre	Short fibred;
    IV	Cylindrical	Spindle shaped;

15. Organisms with disadvantageous variations are eliminated; those with advantageous variations adapt, survive (and reproduce); accumulation of such variations over time may lead to speciation/emergence of a new species; (any correct two)
16. Negative feedback refers to a regulatory mechanism whereby a deviation of the entity being regulated above or below the normal range triggers a sequence of event to bring it back to normal;
17. b) Came up with binomial nomenclature; Pioneered Modern/Natural system of classification/taxonomy;
18.  
    1. 9 cells measure 3.0mm
       Therefore 1cell will measure: (1cell x 3.0mm)/9cells = 0.333mm; 1mm = 1000micrometers
       Thus 0.333mm = (0.333mm x 1000micrometers)/1mm; Diameter of a cell = 333micrometers; (conversion; substitution; answer;)
    2. Viewing of images is indirect/is done on the screen;
19.  
    1. Germinating seeds utilized Oxygen in respiration; the released Carbon (IV) oxide was absorbed by Potassium hydroxide solution; (Thus reduces volume of air in the tube and level of coloured liquid rises)
    2. To preserve/Prevent decomposition/Anaerobic respiration;
20.  
    1. Neural spine; Reject Spine alone
    2. Create vertebral column flexibility; Absorb shock; Reduce friction/rubbing together of the adjacent vertebrae; Mark 1_st 2
21.  
    1.  
       • L - Blue-black;
       • M -Yellow/Brown;
       • N - Yellow/Brown;
    2. Absorb carbon (IV) oxide in the jar;
22.  
    1. These observation show that eye colour in fruit flies is a sex-linked trait; (Since it is well known that the Y chromosomes carries very few genes, we can assume that eye colour in fruit flies is an X-linked trait. - When a true-breeding, red-eyed female is mated with a white-eyed male, all the offspring received an X-chromosome carrying the dominant gene from the female. Because of this, they all develop red eyed.)
    2.  
       
       1 mark for correct genotypes; 1 marks for correctly written gamtes; 1 marks for fusion lines; 1 mark for correct genotypes;
23.  
    
    One mark for each diagram; (total 3 marks)
24.  
    1. Diastole ;rej.filling of heart/relaxation of muscles of ventricle.
    2. Identify the valves X and Y (2mks)
       • X. Semi-lunar valve;
       • Y. Tricuspid valve;
25. Water vapour accumulates in stomatal pits making the environment around the stomata humid; this lowers the saturation deficit;(hence less water is lost into the atmosphere;
26.  
    1. Luteinising hormone; (reject LH/wrong spelling) (1mk)
    2. Increasing progesterone; inhibits follicle stimulating hormone from stimulating the maturation of another graafian follicle;