Biology Paper 2 Questions and Answers - Bondo Joint Mocks Exams 2022

Share via Whatsapp

Questions

Instructions to candidates

  • This paper consists of two sections; A and B. Answer all the questions in section A in the spaces provided.
  • In section B answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8.

SECTION A (40 marks)
Answer all the questions in this section in the spaces provided

  1.      
    1. Name two disorders in humans caused by gene mutation. (2 marks)
    2. Describe the following chromosomal mutations. (2 marks)
      1. Inversion
      2. Translocation
    3. In mice the allele for black fur is dominant to the allele for brown fur. What percentage of offspring would have brown fur from a cross between heterozygous black mice and brown mice? (Show your working)
      Use letter B to represent the allele for black colour. (4 marks)
  2. The diagram below represents a vertical section through a mammalian skin.
    Biop2q02
    1. Name the structures labelled P,Q,R and U (4 marks)
    2. What is the function of S and T (2marks)
    3. State the physiological changes that would occur in the following structures if the environmental temperature was raised gradually from 22 to 40 (2 marks)
  3. An experiment was set up with seedlings as shown in the diagram below.
    Biop2q03
    1. What observation would be made? (2 marks)
    2. Account for the observation made in (a) above (5 marks)
    3. Why were the seedlings labeled B and C included in the experiment (1 mark)
  4. In an experiment to investigate an aspect of digestion, two test tubes A and B were set up as shown in the figure below. The test tubes were left in the bath for 30minutes. The content of each test tube was then tested for starch using iodine solution.
    Biop2q04
    1. What was the aim of the experiment? (1 mark)
    2. What were the observations expected in test tube A and B? (2 marks)
    3. Account for the observation made in (b) above (2 marks)
    4. Why was the set up left at 37 (1mark)
    5. How is the mouth adapted to digestion (2marks)
  5. Ojwang’ Hatari is confronted by a hyena while walking in the forest. His adrenal glands secreted adrenaline to prepare him to run away.
    1. What was the effect of adrenaline in his circulatory system? (4marks)
    2. Explain why the skin temperature rises shortly after drinking iced Coca-Cola. (4marks)

SECTION B (40marks)
Answer question 6(compulsory) and either 7 or 8 in the spaces provided after question 8.

  1.  A culture of bacteria was incubated in nutrients agar at 35. Samples were taken at intervals in order to estimate the number of bacteria in the population.
    The data obtained is as shown below.
     Time(hours) 10  15  20  25  30 35 40 45
     No. of living cells(millions) 20 30  950  1000  1000  1000  800  500 250 50
    Draw a graph of number of living cells(millions) against time(hours) (6 marks)
    1. When was the population of bacteria 750 million? (1 mark)
    2. Account for the shape of the graph between:
      1. 0-5 hours (2 marks)
      2. 5-10 hours (2 marks)
      3. 15-25 hours (2 marks)
    3. Give 3 reasons for the shape of the curve between 25 hours -45 hours. (3 marks)
    4.    
      1. Suggest what would happen to the population of the bacteria if the temperature was lowered to 0 after incubation for 12 hours. (1 mark)
      2. Give a reason for your answer in (e)(i) above (1 mark)
    5. Define the following; (2mks)
      1. Biological control
      2. Carrying capacity
  2. Describe the structure and functions of the various parts of the human ear. (20 marks)
  3. Explain the various ways in which seeds and fruits are adapted to dispersal. (20 marks)

Marking Scheme

  1.    
    1. Name two disorders in humans caused by gene mutation. (2marks)
      • Albinism
      • Sickle cell anaemia
      • Haemophilia
      • Phenylketommia
      • Achordo plazia
      • Colour blindness
    2. Describe the following chromosomal mutations. (2marks)
      1. Inversion
        • Occurs when chromatid breaks at 2 places and when rejoining it rotates and joins in an inverted position
      2. Translocation
        • Occurs when a section of a chromatid breaks off and becomes attached to another chromatid of another non homologous chromosome.
      3. In mice the allele for black fur is dominant to the allele for brown fur. What percentage of offspring would have brown fur from a cross between heterozygous black mice and brown mice? (Show your working)
        Use letter B to represent the allele for black colour. (4marks)
        Biop1qa01c
  2. The diagram below represents a vertical section through a mammalian skin.
    Biop1qa02
    1. Name the structures labelled P,Q,R and U (4marks)
      • P Epidermis
      • Q Blood capillaries
      • R Sweat glands
      • U Erector Pilli
    2. What is the function of S and T (2marks)
      • S Protection against mechanical injury/bacteria/fungal infection
      • T Produce sebum/oily substance which keeps epidermis sapo/stops drying/anticeptics
    3. State the physiological changes that would occur in the following structures if the environmental temperature was raised gradually from 22 to 40 (2marks)
      • R Will produce more sweat
      • Q Will dilate for more blood to flow near the skin surface
  3. An experiment was set up with seedlings as shown in the diagram below.
    1. What observation would be made? (2marks)
      • A curves towards light
      • B and C remains straight
    2. Account for the observation made in (a) above (5marks)
      • A- Light causes Auxins to diffuse towards away from light. Auxins causes faster growth of the dark side; shoots curves towards light
      • B- Aluminium foil prevents light from shoot hence Auxins evenly distributed
      • C- Source of Auxins removed
    3. Why were the seedlings labeled B and C included in the experiment (1mark)
      • Control experiment
  4. In an experiment to investigate an aspect of digestion, two test tubes A and B were set up as shown in the figure below. The test tubes were left in the bath for 30minutes. The content of each test tube was then tested for starch using iodine solution.
    Biop1qa04
    1. What was the aim of the experiment? (1mark)
      • Effects of heat on enzymes
    2. What were the observations expected in test tube A and B? (2marks)
      • A- Brown solution turns brown//colour if iodine
      • B -Brown solution turns blue black
    3. Account for the observation made in (b) above (2marks)
      • A- Enzyme salivary amylase digests starch
      • B- Boiling has denatured salivary amylase
    4. Why was the set up left at 37 (1mark)
      • Optimum temperature
    5. How is the mouth adapted to digestion (2marks)
      • Teeth breaks down food to provide large surface area for enzyme action
      • Salivary gland secrets salivary amylase which digests starch
      • Tongue rolls food into bolus and pushes it to the back of the mouth
  5. Ojwang’ Hatari is confronted by a hyena while walking in the forest. His adrenal glands secreted adrenaline to prepare him to run away.
    1. What was the effect of adrenaline in his circulatory system? (4marks)
      • Heart beat increases
      • Blood vessels dilate
      • More blood to tissues
      • To deliver more oxygen //nutrients// glucose
      • And remove metabolic waste
    2. Explain why the skin temperature rises shortly after drinking iced Coca-Cola. (4marks)
      • Temperature of blood around gut is lowered;
      • (Cold blood) stimulates hypothalamus
      • Nerve impulses transmitted along efferent nerves to;
        1. Arterioles constrict
        2. Hairs stands
        3. Sweat glands stimulated less//less sweat produced
      • Heat is thus retained
  6. A culture of bacteria was incubated in nutrients agar at 35. Samples were taken at intervals in order to estimate the number of bacteria in the population.
    The data obtained is as shown below.
    Draw a graph of number of living cells (millions) against time(hours) (6marks)
    Biop1qa06
    1. When was the population of bacteria 750 million? (1mark)
      • 5hrs and 32hours
    2. Account for the shape of the graph between:
      1. 0-5 hours (2marks)
        • Gradual increase; few dividing cells//not used to the environment
      2. 5-10 hours (2marks)
        • Exponential increase; dividing cells have increased //enough food//oxygen
      3. 15-25 hours (2hours)
        • Constant; environmental resistance// death rate equals to birth rate.
    3. Give 3 reasons for the shape of the curve between 25 hours -45 hours (3marks)
      • Death rate greater than birth rate
      • Increase in metabolic waste
      • Decrease in food//oxygen
    4.  
      1. Suggest what would happen to the population of the bacteria if the temperature was lowered to 0 after incubation for 12 hours. (1mark)
        • Population remain constant
      2. Give a reason for your answer in (e)(i) above (1mark)
        • Enzymes inactive
    5. Define the following; (2mks)
      1. Biological control
        • Introducing another organism to control population of another
      2. Carrying capacity
        • Number of organisms in an area which would not deplete the available resources.
  7. Describe the structure and functions of the various parts of the human ear. (20marks)
    • Pinna collects/channels sound waves to auditory canal
    • Auditory canal concentrates/directs sound waves to tympanic membrane/eardrum which vibrates //converts sound waves into vibrations to the ear Ossicles/malleus incus and stapes; that amplify sound waves. Vibrations are then transmitted to the oval window
    • Oval window amplify / transmittes vibrations to the fluids/perilymph and endolymph then cochlea
    • The sensory hairs/cells are set into vibrations/stimulated producing nerve impulses in the auditory nerve
    • Auditory nerve transmites nerve impulses to the brain for hearing.
    • In the inner ear are semi-circular canals/utricules/sacules/ vestibulary apparatus
    • Due to movement of fluid/endolymph; the sensory impulses are generated.
    • The auditory nerve to the brain for interpretation of position of body/posture//balanc
    • Eustachian tube connect middle ear to back of throat and equalizes air pressure
    • Fenestra rotunda/round window discharges vibrations from inner to outer ear.
  8. Explain the various ways in which seeds and fruits are adapted to dispersal. (20marks)
    1. Water dispersal fruits /seeds
      • Mesocarp/ seeds has airspaces thus light/ buoyant to float thus carried away by water
      • The fruits/seeds are protected from soaking by water proof pericarp/ testa
    2. Animal dispersal fruits/seeds
      • Presence of hooks for attachment to the animals, thus carried to other places
      • Fruits are brightly coloured ;succulent; scented to attract the animals
      • The seed coat/hard seeds are resistant to digestive enzymes thus remains unaffected. The seeds are dropped away from the parent plant in faeces/ droppings
    3. Self-dispersed fruits/seeds/explosive mechanism
      • Dry pods split
      • Scattering seeds away from parent plant
    4. Wind dispersed fruits/seeds
      • censer mechanism; open capsule is usually loosely attached to stalk which is swayed by wind scattering seeds
      • Presence of hairs/ wing-like structure /floss/extensions which increases surface area for buoyancy/float; making it easy for fruits /seeds to be blown away
      • Fruits/ seeds are light due to small size therefore easily carried away by wind

Download Biology Paper 2 Questions and Answers - Bondo Joint Mocks Exams 2022.


Tap Here to Download for 50/-




Why download?

  • ✔ To read offline at any time.
  • ✔ To Print at your convenience
  • ✔ Share Easily with Friends / Students


Join our whatsapp group for latest updates
Get on WhatsApp Download as PDF
.
Subscribe now

access all the content at an affordable rate
or
Buy any individual paper or notes as a pdf via MPESA
and get it sent to you via WhatsApp

 

What does our community say about us?