Biology Paper 1 Questions and Answers - MECS Cluster Joint Pre Mock Exams 2021/2022

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BIOLOGY
PAPER 1 

INSTRUCTIONS

  • Answer all the questions in the spaces provided
  1. State the advantages of internal fertilization in mammals (2mks)
  2.          
    1. State the ideas proposed by Lamarck in his theory of evolution (2mks)
    2. Why is Lamarck’s theory not acceptable? (1mks)
  3. What is meant by the term irritability? (1mk)
  4. State three aspects that can be used to estimate growth in seedlings (3mks)
  5. Name the organelle that is involved in each of the following
    1. Manufacture of lipid (1mk)
    2. Formation of lysosomes (1mk)
  6. State the importance in living organisms
    1. Nutrition (1mk)
    2. Excretion (1 mk)
  7. Explain the meaning of the following
    1. Flaccid cell (1mk)
    2. Crenated cell (1mk)
  8. Explain the following
    1. Ovaries can be removed from a human female after the fourth month of pregnancy without terminating the pregnancy (2mks)
    2. Human testes are located to hang outside (2mks)
  9.        
    1. Explain how a human stomach is adapted to;
      1. Protein digestion (2mks)
      2. Churning (2mks)
  10. State three characteristics of class crustacea (3mks)
  11.      
    1. Describe the condition known as varicose veins (2mks)
    2. What is the role of blood platelets in the blood clotting process (2mks)
      1. What would be the expected results of a test cross? (2mks)
  12.      
    1. Name the products of anaerobic respiration in;
      1. Plants (1mk)
      2. Animals (1mk)
    2. What is oxygen debt? (1mk)
  13.           
    1. Explain how the following occur during gene mutation
      1. Deletion (1mk)
      2. Inversion (1mk)
    2. What is mean by the term allele? (1mk)
  14.             
    1. Name the compound that stores energy released during oxidation of glucose (1mk)
    2. Explain what happens to excess amino acids in the body (3mks)
  15. Explain the role of the following hormones in plants
    1. Florigen (1mk)
    2. Ethene (1mk)
  16. An individual is blood group B positive
    1. Name the antigens in the individuals blood (2mks)
    2. Give the reason why the individual cannot receive blood from a blood group A donor (2mks)
  17.        
    1. What is meant by each of the following
      1. Pyramid of numbers (1mk)
      2. Pyramid of numbers (1mk)
    2. During an ecological visit to Savannah grassland, students were able to see lions, antelopes, vultures and pastoralists grazing their cattle. Construct a food chain with four consumer levels to illustrate the energy flow in the ecosystem. (2mks)
  18. A group of students placed some bean seeds on moist cotton wool in a retort flask as shown below
    MECBiop1q18
    1. Explain the expected observation after three days (3mks)
    2. State the control experiment for the observation above (1mk)
  19.          
    1. Name the surface involved in gaseous exchange in a locust (1mk)
    2. How is the surface named above adapted for gaseous exchange (4mks)
  20. What would happen to a cell if its nucleus was removed? Explain. (2mks)
  21. A student set up an experiment to investigate a certain process
    MECBiop1q21
    1. Identify the physiological process being instigated (1mk)
    2. What observation would the student make on the visking tubing after 30 minutes (1mk)
    3. Explain your observation in (b) above (2mks)
  22. When testing for starch a leaf from a plant that had been kept in the sun for six hours was put in boiling water for 10 minutes. It was then put in a test tube full of ethanol. The test tube containing ethanol was put in a hot water bath. The leaf was then removed and dipped in a beaker of cold water. The leaf was then tested for starch.
    1. Why was the plant kept in the sun for six hours (1mk)
    2. Why was the test tube containing ethanol not heated directly (1mk)
    3. Why was the leaf boiled in ethanol (2mks)
  23. A certain plant was found to have the following features
    - Parallel venation in leaves
    - Sheath like petiole
    - Flower parts in multiples of three
    1. Name the class to which the plants belongs (1mk)
    2. Describe how the following characteristics would appear in the plant
      1. Vascular bundles in the stem (1mk)
      2. Root system (1mk)
  24. The heart of a chicken continued beating minutes after the lead was cut off. Explain (2mks)
  25.            
    1. Distinguish between homologous and analogous structure (2mks)
    2. Explain the term continental drift as used in evolution (2mks)

MARKING SCHEME

  1. Higher chances of fertilization
    Embryo / gamete / foetus is protected from external environment conditions
  2.        
    1. Use and dis use
      Acquired traits can be passed on to offspring

    2. Acquired traits cannot be inherited
      No evidence to support the theory

  3. Irritability is the ability of an organism to detect (interdict) and respond to changes in the environment / stimulus.

  4. Height / length
    Weight / mass
    Surface area
  5.      
    1. Smooth endoplasmic reticulum
    2. Golgi bodies / golgi apparatus / accept golgi bodies
  6.      
    1. Nutrition – acquisition and utilisation of nutrients / accept assimulations
    2. Excretion – Elimination of metabolic wastes to prevent accumulation to toxic level
  7.         
    1. Flaccid cell – a flubby / shrunk plant cell that has lost water by osmosis
    2. Crenated cell – A shrunk animal cell / Red blood cell that has lost water by Osmosis
  8.           
    1. A progesterone hormone is secreted by the placenta to maintain the pregnancy
    2. Testes located outside the body to provide a cool environment that is conducive for good quality sperm formation.

  9.        
    1. Has gastric glands; that secret gastric juice; accept a component of gastric juice . Hel / pepsin / Rennin / Rj renin
    2. Thick muscular wall that contract and relax

  10. Fused head and thorax / cephalothorax (often) projected by a carapace
    Gaseous exchange through gills
    Two pairs of antennae
    Five or more pairs of limbs / 5 -20 pairs of limbs
    A pair of compound eyes
    Three pairs of mouth parts
  11.         
    1. Weakened / defective valves in veins causing blood / tissue fluid to accumulate; leading to swelling
    2. When exposed to air they disintergrate / rapture/ burst; releasing thromboplastic/ thrombokanase

  12. All the offsprings shows the dorminant characteristics ; of half the offspring show the recessive while the other half show dominant characteristics
  13.             
    1.          
      1. Ethanol, carbon(iv)oxide, energy / 2ATP/ 210Kjo,
      2. Lactic acid, energy / 2ATP/ 150Kj;
    2. Oxygen required to get rid of lactic acid during anaerobic respiration / oxygen required to convert accumulated lactic acid to water, carbon (iv) oxide and energy
  14.                 
    1.            
      1. Deletion – soma bases / nucleotides of a gene are removed
      2. Order of some bases / nucleotides of a gene is reversed
    2. Alternate form of a gene

  15.               
    1. Adenosine triphosphate /ATP
    2. Deaminated
      Resulting information of ammonia
      Ammonia combines with carbon(iv) oxide to form urea and water
      Urea is passed out through urine;
      Carbohydrate group is oxidised STORED AS GLYCOGEN
  16.               
    1. Promotes flowering
    2. ethene
    3.            
      1. Causes uniform ripening of fruits
      2. Induces thickening of stems / inhibits stem elongation
      3. Promotes flower morphogenesis
      4. Causes abscission of leaves / leaf fall fruits
  17.              
    1. Antigen B
      Rhesus factor / antigen
    2. Has antibody a in the blood plasma of the recipient and will correspond with antigen A in the donors blood hence there will be antigen antibody reaction / agglutination.
  18.             
    1.              
      1. Pyramid of numbers – Represents the (total) number of organisms at each trophic level
      2. Grass – cattle / antelope – man / pastoralists – Lion – Vulture
  19.             
    1. Level of potassium hydroxide vides in the flask; oxygen is yused in respiration during germination while carbon(iv) oxide is absorbed by potassium hydroxide; the rise is due to reduction in pressure in the flask;
    2. Use dry cotton wool instead of moist cotton wool / use water instead of potassium hydroxide
  20.            
    1. Tracheoles
    2. Adaptations of tracheoles to their functions
      • Always moist for gases to dissolve and diffuse in solution form
      • Highly branched to serve every cell
      • Consist of numerous tubules to increase surface area for gaseous exchange
      • Has thin epithelium to reduce distance for diffusing molecules for easier gaseous exchange
  21. The cell would die; because all cell activities would cease due to removal of nucleus which controls all cell activities
  22.             
    1. Osmosis
    2. Visking tubing would swell
    3. 0.8m sodium chloride solution in the visking tubing is hypertonic to 0.5m sodium chloride solution in the beaker; water moves from the beaker to the visking tubing by osmosis
  23.        
    1. for starch to be formed in the leaves
    2. Ethanol is highly inflammable
    3. To kill living tissues in the leaf thus stopping further chemical reaction
      To rupture and open the starch grain
  24.          
    1. Monocotyledonae
    2.          
      1. Scattered vascular bundles
      2. Fibrous root system
  25. Heart muscles are myogenic hence able to initiate their contraction without nervous stimulation.
  26.          
    1. Homologous structures are structures that have a common embryonic origin but have been modified to perform different functions ;while analogous structures have different embryonic origin but have evolved to perform different functions.
    2. the breaking up ,drifting and separation; of the big land mass to form the present day different continents;

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