Biology Paper 1 Questions and Answers - Cekenas Mock Exams 2022

QUESTIONS

1. Explain why ferns are considered to be more advanced than mosses. (2mks)
2. A student estimating a cell size of an onion epidermal cell observed the following on the microscope field of view using a transparent ruler.
   
   The student identified 20 cells across the field of view. Calculate the size of the cell in micrometers. (Show your working). (3mks)
3. What role do the following play in the movement a Tilapia fish? (2mks)
   1. Myotomes
   2. Swim bladder
4. Name the tissues whose cells are thickened with;
   1. Cellulose and pectin (1mk)
   2. Lignin (1mk)
5. The diagram below shows the position of an image formed in a defective eye.
   
   
   1. Name the defect. (1mk)
   2. Explain how the defect named in (a) above can be corrected. (2mks)
6. The paddles of whales and the fins of fish adapt these organisms to aquatic habitat.
   1. Name the evolutionary process that may have given rise to the structures. (1mk)
   2. What is the name given to such structures? (1mk)
   3. Give two examples of vestigial organs in man. (2mks)
7.    
   1. Define the term mutation. (1mk)
   2. State two disorders due to gene mutation. (2mks)
8. An experiment was set to investigate a certain aspect of response. A seedling was put on a horizontal position as shown in figure M below. After 24 hours, the set up was shown in figure N.
   
   
   1. Name the response exhibited by the shoot. (1mk)
   2. Explain the curvature of the shoot upwards. (3mks)
9.      
   1. A student visiting a game park observed an adult elephant flapping its ears twice as much as its calf in order to cool its body when it is hot. Explain. (2mks)
   2. Explain why some desert animals excrete uric acid rather than ammonia. (2mks)
10. The table below shows the concentration of important plant nutrients.
    

    Ion	Concentration in pond water (ppm)	Concentration in cell sap (ppm)
    Potassium	1	15
    Chloride	200	50

    Name the process by which the above ions could have been taken up by the plants.
    1. Potassium (1mk)
    2. Chloride (1mk)
11. Name two hormones produced by the duodenal cells in response to the presence of acidic chyme from the stomach. (2mks)
12. Name the disease causing microorganism in the following respiratory diseases. (2mks)
    1. Pneumonia
    2. Pulmonary tuberculosis
13. State the role of the following hormones during menstruation. (3mks)
    1. Oestrogen
    2. Luteinising hormone
    3. Progesterone
14. Give one aspect of dichogamy in flowers. (1mk)
15. The equation below shows an oxidation reaction of a food substance.
    5C₅₁H₉₈O₆ + 145O₂ → 102CO₂ + 98H₂O + Energy
    1. Determine respiratory quotient of the oxidation of the food substance above. (2mks)
    2. Identify the food substance. (1mk)
16. State two pollution effects of radioactive emissions. (2mks)
17. A blood group A mother gave birth to a blood group O child with a blood group B husband.
    1. State the genotype of the parents. (2mks)
    2. What is the genotype of the child? (1mk)
    3. State other blood groups likely to occur in the children of the couple. (1mk)
18. Name the organelle that would be most abundant in:
    1. White blood cell (1mk)
    2. Salivary glands (1mk)
19. Name three mechanisms through which plants excrete. (3mks)
20.    
    1. Nitrogen in the atmosphere cannot be directly utilized by plants. State two ways through which Nitrogen is made available for plant use. (2mks)
    2. State the importance of saprophytic bacteria in the environment. (1mk)
21. The diagram below shows regions of a root tip.
    
    
    1. What is the function of the part labelled K. (1mk)
    2. Name the region labelled L. (1mk)
    3. Give two characteristics of the cell in the part labelled Q. (2mks)
22. Name the hormones that control the following activities;
    1. Metamorphosis in young insect (1mk)
    2. Formation of abscission layer in leaves and fruits. (1mk)
23. Give the formula for calculating magnification of a specimen using: (2mks)
    1. Light microscope
    2. Hand lens
24. A student met a lion as he walked along a forest path.
    1. Name the hormone that was secreted in his blood stream and state its source. (2mks)
       Name…………………………………………………………………………………………………………………...
       Source…………………………………………………………………………………………………………………...
    2. What is the effect of the hormone in his? (2mks)
       1. Circulatory system
       2. Respiratory system
25. State the function of the following structures found in the walk of the trachea. (3mks)
    1. Cilia
    2. Mucus
    3. Rings of cartilage
26. Explain the basis for the ever changing drugs for malaria. (3mks)
27. During an accident a victim suffered injuries in the head. After the accident he lost his memory and was passing excessive amount of dilute urine. Suggest the part of the brain that was damaged in relation to:(2mks)
    1. Memory
    2. Passing large amounts of dilute urine
28. State two structural differences between bicep muscles and muscles of the gut. (2mks)
29. The diagram below represents an experimental set up to investigate a certain scientific concept. The potted plant was first destarched by keeping it in the dark for four days.
    
    The setup was then placed in sunlight for five hours and leaves were tested for starch.
    1. What scientific concept was being investigated? (1mk)
    2. Give the results likely to be obtained after starch test for A and B.
    3. Why was leaf C included in the set-up? (1mk)

MARKING SCHEME

1. Ferns – have clearly defined vascular systems; show clearly defined sexual reproduction independent of water;
2. Field of view = 4mm
   Field of view = 4x1000 = 4000µm;
   Size of cells =   Field of view  
                          Number of cells
   = 4000 = 200µm;
        20
3.    
   1. Myotomes – The muscle blocks of myotomes contract and relax bringing about movement;
   2. Swim bladder – provides fish with buoyancy by adjusting its vertical position in relation to depth of water;
4.    
   1. Collenchyma;
   2. Sclerenchyma/ xylem tissues;
5.      
   1. Short sightedness/ myopia; reject short sighted
   2. Wearing glasses with concave (diverging) lenses; this bend light rays outward before they reach the eyes enabling them to be focused on the retina;
      (Accept a diagram showing correction of the problem)
6.      
   1. Convergent evolution;
   2. Analogous structures;
   3. Coccyx;appendix; ear muscles;
7.      
   1. Mutation is the spontaneous change in the genetic make-up of an individual;
   2. Colour blindness; Albinism; Haemophilia; Sickle cell anaemia
8.      
   1. Negative geotropism;
   2. Gravity causes high concentration of auxins on the lower part of the shoot; this causes faster elongation of cells on the lower part compared to the upper part; making the shoot to curve upwards;
9.    
   1. Calf has a large surface area to volume ratio than the adult; hence the calf loses more heat than adult;
   2. Elimination of uric acid requires less water than ammonia; hence more water is conserved; uric acid is less toxic than ammonia hence safer to excrete where there is less water;
10.      
    1. Active transport;
    2. Diffusion;
11.        
    1. Secretin;
    2. Cholecystokinin;
12.      
    1. Streptococcus pneumoniae;
    2. Mycobacterium tuberculosis;
       (Binomial nomenclature rules must be followed)
13.        
    1. Oestrogen – repair and healing of the endometrium;
    2. Luitenising hormone – stimulates maturation of graafian follicle/ stimulates corpus luteum to produce progesterone;
    3. Progesterone – stimulates thickening and increased blood supply;
14. Protandry;
    Protogyny;
15.         
    1. Respiratory quotient – Volume of CO₂ produced
                                                 Oxygen used up
       =¹⁰⁸/₁₄₅
       = 0.7;
    2. Fat/lipid;
16. Causes cancers such as bone tumours and Leukemia; increased mutations leading to abnormalities, some inheritable;
17.      
    1. Father – BO;
       Mother – AO
    2. OO;
    3. A, B, AB; (All three must be mentioned)
18.    
    1. Lysosomes ;
    2. Golgi apparatus/ body ;
19. Diffusion; Exudation; Guttation; storage
20.       
    • Nitrogen fixation by lightning;
    • Nitrogen fixation by free nitrogen fixing bacteria;
    • Nitrogen fixation by symbiotic fixing bacteria;
21.    
    1. Protect the apical meristems; (of the root)
    2. Zone/ region of cell differentiation;
    3. Dense cytoplasm; thin cell walls; no vacuoles; prominent nucleus; numerous mitochondria;
22.    
    1. Juvenile hormone;
    2. Abscisic acid;
23.    
    1. Magnification = eye piece lens magnification x objective lens magnification;
    2. Magnification = Drawing length
                                 Actual length
24.      
    1.        
       1. Adrenaline;
       2. Source – adrenal glands;
    2.        
       1. Circulatory system – increases the rate of heartbeat;
       2. Respiratory system – increases the breathing rate;
25.        
    1. Cilia – moves mucus upward into the pharynx; reject traps dust
    2. Mucus – traps and filters the microorganism and dust particles;
    3. Rings of cartilage – makes the trachea open/ prevent it from collapsing;
26. This is because of the ability of the plasmodia to rapidly change its coat surface antigens; resisting drugs meant to kill them; and pass this characteristics to its off springs;
27.        
    1. Cerebrum;
    2. Pituitary gland;
       

       Bicep muscles	Muscles of the gut
       Are striated They are voluntary muscles Contract and fatigue rapidly	Lack striations; They are involuntary muscles; Contract and fatigue slowly

28.      
    1. Photosynthesis;
    2. A- negative test/ starch absent;
       B – Positive test/ starch present;
    3. To act as a control experiment;