Biology Paper 1 Questions and Answers - Form 3 Mid Term 1 Exams 2021

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  1. State two ways in which the rough endoplasmic reticulum is adapted to its function. (2mks)
  2. State three characteristics that are used to divide phylum arthropoda into classes.(3mks) 
  3. Distinguish between diffusion and active transport.(2mks)
  4. An organism was found to have the dental formula:
    I 1  C 0  PM 3  M 4
      1     0       2      4
    1. Calculate the total number of teeth in the organism. (1mk)
    2. Giving a reason, suggest the mode of feeding of the organism. (2mks)
    1. Give a reason for the biconcave shape of the red blood cells. (1mk)
    2. Name the enzyme that speeds up loading of carbon (IV) oxide in the red bloode cells. (1mk)
    1. Name the vitamin, an enzyme and a mineral element that are involved in blood clotting.(1½mks)
      1. Vitamin
      2. Enzyme
      3. Mineral element
    2. Differentiate between heparin and histamine. (2mks)
    1. Name the part of the brain that influences breathing rate. (1mk)
    2. State two advantages of breathing through the nostrils instead of through the mouth in mammmals. (2mks)
  8. The diagram below represents a cell organelle.
             diagram representing cell organelle
    1. Name the main product of the organelle's activity. (½mk)
    2. name the parts labelled A, B, C and D. (2mks)
    1. State the causes of diabetes mellitus. (1mk)
    2. How may the disease in (9)(a) above be tested in a school laboratory? (2mks)
    1. Distinguish between ecological niche and habitat. (2mks)
    2. State the reason why plants are included in a fish pond other than provision of food. (2mks)
  11. State the functions of the following parts of a light microscope.
    1. Diaphragm. (1mk)
    2. Objective lenses. (1mk)
    1. Define the term respiratory quotient. (1mk)
      1. After respiration of a certain substrate 50cm3 of Carbon (IV) Oxide was produced and 70cm3 oxygen was used. Calculate the respiratory quotient of the substrate. (1mk)
      2. Name the substrate in (12)(b) above. (1mk)
    1. If a person who lives at a low altitude moves to a hicher altitude, changes occur in his blood consumption. Name two of these changes. (2mks)
    2. State the importance of these changes. (1mk)
  14. How are leaves or submerged plants adapted for photosynthesis? (2mks)
  15. Name the causative agent of the diseases below:-
    1. Anthrax  (1mk)
    2. Gonorrhea  (1mk)
    3. Whooping cough  (1mk)
  16. Explain why plants in waterlogged soils dry up. (3mks)
    1. Name the antigens that determine the human blood groups. (2mks)
    2. Explain why people who have blood group AB are called universal recipients. (2mks)
  18. Name three processes in the human body in which homeostasis is involved. (3mks)
    1. How are root hairs adapted to their function? (2mks)
    2. Name the processes by which food is transported in plants. (1mk)
  20. State the significance of the following adaptations in a leaf.
    1. Thinness (1mk)
    2. Presence of air spaces (1mk)
    3. Stomata (1mk)
  21. Study the food web below representing a certain ecosystem and use it to answer the questions that follow.
             food web representing certain ecosystem
    1. State the trophic level occupied by the lion in the food web. (1mk)
    2. Write down a food chain in which the vulture is a tertiary consumer.(1mk)
      1. Name the organism with the largest biomass.(1mk)
      2. Give two reasons
  22. Explain how temperature affects an enzyme controlled reaction.(3mks)
  23. The diagram below represents a certain plant.
    diagram representing a certain plant
    1. What is the likely habitat of the plant? (1mk)
    2. Give two reasons for your answer in (a) above. (2mks)
  24. The number of stomata on the lower and upper surfaces of two leaves from plant species x and y were counted under the field of view of a light microscope. The results were as shown below.
     Leaf   Number of stomata   
       Upper surface  Lower surface
      x       4     12
      y       20     23

    1. Which of the two leaves would be expected to have a lower rate of transpiration? (1mk)
    2. Give a reason for your answer in (a) above. (1mk)
  25. Construct a dichotomous key for the animals listed below. Part of the key has already been constructed. Bird, snake, Lizard, hyena. (4mks)
      1. Animal a mammal ....... Hyena.
      2. Animal not a mammal...... go to 2.
  26. Other than transport of substances, state two other functions of the human mammalian blood. (2mks)
  27. Some students set-up the apparatus shown below to demonstrate the breathing mechanism in a mammal.
    set up of breathing mechanism
    What structure in a mammal is represented by each of the following?
    1. The glass tube. (1mk)
    2. The balloons. (1mk)
    3. The bell jar. (1mk)
  28. The diagram below represents part of the nephron. Use it to answer the questions that follow.
    diagran representing part of a nephron
    1.  Name the parts labelled A, B, C and D. (2mks)
    2. Name the fluids found in C and D. (2mks)
    3. Name the process by which the fluid found in D is formed. (1mk)
    4. Mention one difference in the composition 
  29. Apart from having many features in common, state another characteristic of members of a Species. (1 mk)
  30. An experimental set-up shown below was used to investigate a certain process.
    set up investigating certain process
    After 20 minutes, a student tested the sample from the boiling tube for starch and glucose and recorded the results as shown in the table below.
       Star  After 20 minutes 
     Start   Absent   Absent
     Glucose   Absent   Present

    1. Explain the presence of glucose in the water sample. (2mks)
    2. What change occurred in the volume of liquid in:
      1. The boiling tube  (1mk)
      2. The visking tube (1mk)
  31. State and explain how respiratory surfaces are adapted for gaseous exchange. (3mks)
  32. The equation below shows a process that takes place in mammals.
    Amino acids → Organic compound + Urea
    1. Identify the process. (1mk)
    2. State the importance of this process to a mammal. (1mk)
    3. In which organ does this process take place? (1mk)

Marking Scheme

    • Presence of ribosomes for protein synthesis;
    • Presence of channels for transport of proteins and other substances; (1mk)
    • Number of wings
    • number of legs and other appendages;
    • number of body parts;
    • type of eyes (simple or compound) max;1mk each
    • Diffusion is movement of particles(ions ,molecules) from where they are more to where they are few against a diffusion gradient ;(1mk)
    • Active transport is the movement of ions/molecules from where they are few to where they are more using energy against a concentration gradient; (1mk)
    1. Upper jaw = 8x2=16
      Lower jaw=7x2 = 14
      Or (2+5+ 8) x 2 = 30 teeth.
    2. Herbivorous ;(1mk)
      • it has the molar, premolars and incisors except canines ;(1mk)
    1. To increase the surface area over which gases will diffuse;Acc.oxygen or carbon (vi) oxide for gases.(1mk)
    2. Carbonic anhydrase;
      1. Vitamin K;
      2. Thrombokinase /thromboplastin;
      3. Calcium /calcium ions; (1½mk)
      • Heparin is a chemical substance that prevents blood form clotting within the blood vessels;(1mk)
      • Histamine is a chemical substance that is produced by tissue cells after an injury/sting/allergic reaction ;(1mk)
    1. Medulla oblongata;(1mk)
      • the nostrils have a mucus lining that traps dust unlike the mouth;
      • Nostrils have cilia that facilitate the movement of dust particles outwards;
      • Nostrils have chemoreceptorۥs for detecting smells/chemicals unlike the mouth ;(max 2=2mks)
    1. Energy/ATP;(1mk)
      • A-Matrix;
      • B- Cristae;
      • C.Outer membrane;
      • D-Inner membrane; (½mk @ max 2mks)
    1. Little or no insulin in the blood;(1mk)
    2. Boil a little urine sample with Benedictۥs solution; an orange precipitate confirm presence of sugar in the urine;(2mks)
      • Ecological niche-the position an organism occupies and the role it plays in a habitat;(1mk)
      • Habitat – a specific place where an organism lives/adapted to live ;(1mk)
      • Provide breeding site for fish.
      • Provide oxygen for the fish and other aquatic organism
      • Removes carbon (IV) oxide from the pond
    1. Diaphragm – regulates the amount of light passing through the specimen;(1mk)
    2. Objective lenses-for magnification of the specimen;(1mk)
    1. Respiratory quotient-the ratio of the volume of carbon (iv)oxide produced to that of oxygen used in a respiratory process;(1mk)
      1. R.Q =70cm3= 0.7;(1mk)
      2. Lipid;(1mk)
    1. An increase in amount of haemoglobin,an increase in the number of red blood cells;(2mks)
    2. To increase the surface area for transport of oxygen/to increase the volume of oxygen in the body/to trap more oxygen;(1mk)
    • A greater number of chloroplasts that trap light of low intensity;
    • Their leaves are highly dissected /branched to increase the surface area for photosynthesis;
    • Epidermis has chloroplasts; (max 2=2mks)
    1. Bacillus anthracis;(1mk)
    2. Neisseria gonorrheae;(1mk)
    3. Bordetalla pertusis;(1mk)
  16. Due to anaerobic respiration; hence production of ethanol in the roots; which kills them and the whole plant;(3mks)
    1. A and B ;(1mk each)
    2. They may be transfused with all other blood group’s they lack antibodies ‛aۥand‛ bۥ ;max (2mks)
    • thermoregulation/regulation of body temperature;
    • Osmoregulation/regulation of water and salts.
    • Blood sugar regulation ;(3mks)
      • are elongated to increase the surface area of absorption;
      • their hypertonic sap enables osmosis to take place;
      • Presence of a thin cell membrane to quicken diffusion ;(max 2=2mks)
    2. Translocation ;(1mk)
    1. to reduce diffusion distance of carbon (iv) oxide /reduce the penetration distance of light;
    2. for gaseous exchange /store gases;
    3. allows gaseous exchange /allows transpiration to take place;
    1. Secondary consumer;(1mk)
      • Grass → antelopes → lions → vulture;
      • Grass → caterpillars → Guinea fowl → Vulture;(1mk)
      1. Grass;(1mk)
        • Many organism’s depend on it for food/energy, being the primary producer;
        • energy is lost during its transfer to higher levels through respiration, excretion and defecation ;(2mks)
    • Low temperatures inactivate enzymes;
    • increase in temperature up to the optimum increase the reaction rate/turn over;
    • higher temperatures above the optimum denatures enzymes;(3mks)
    1. Desert/semi a desert; acc.arid/semi-arid areas;rej. Dry areas(1mk)
      • Presence of large and succulent leaves.
      • pressure of thorns /prickles ;(2mks)
    1. X; (1mk)
    2. Has fewer stomata on both sides of the leaf than Y;(1mk)
      1. Animal a mammal …………………………………hyena;
      2. Animal not a mammal……………… go to 2;
      1. Animal with body covered with feathers………………. Bird;
      2. Animal with body not covered with feathers……………….. go to 3(1mk)
      1. Animal with legs………………..lizard;(1mk)
      2. Animal without legs……………………………………….snake ; (1mk)
        Acc.any other correct
    • Defense against infections;
    • Distribution of heat;    (1mk each)
    1. Trachea; (1mk)
    2. Lungs (1mk)
    3. Rib cage;(1mk)
      • A- Afferent arteriole;
      • B-Efferent arteriole;
      • C-Glomerulus ;
      • D-Bowman’s capsule;(½mk=2mks)
      • C- Blood;(1mk)
      • D- Glomerulus filtrate ;(1mk)
    3. Ultrafiltration ;(1mk)
    4. The fluid in C contains blood cells and large protein molecules while the fluid in D does not;(1mk)
  29. They interbreed to give rise to fertile offspring;(1mk)
    1. The visking tubing is semi permeable; and allows the small glucose molecules into boiling tube by diffusion;(2mks)
      1. the volume of the liquid in the boiling tube decreased .(1mk)
      2. The volume of the liquid in the visking tubing increased ;( 1mk)
    • are moist to dissolve gases;
    • have a dense network of blood capillaries to transport gases;
    • They have thin membranes/thin epithelium to reduce the diffusion distance;
    • They have a large surface area for transport of more gases;
      1mk each=3mks
    1. Deamination;(1mk)
    2. Helps to regulate the amount of proteins /amino acids in the body;(1mk)
    3. Liver (1mk)

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