Nutrition in Plants and Animals Questions and Answers - Form 1 Biology Topical Revision

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  1. An experiment was carried out to investigate the rate of reaction shown below.
    Sucrose → Fructose + Glucose
    For the products; fructose and glucose to be formed, it was found that substance K was to be added and the temperature maintained at 370C. When another substance L was added, the reaction slowed down and eventually stopped.
    1. Suggest the identity of substances K and L. (2mks)
      K ________________________
      L ________________________
    2. Other than temperature state three ways by which the rate of reaction could be increased. (3mks)
    3. Explain how substance L slowed down the reaction. (1mk)
  2. State the role of light in the process of photosynthesis. (2mks)
    Name one product of dark reaction in Photosynthesis (1mk)
  3. State one effect of magnesium deficiency in green plants.
  4. The graph below shows the effect of substrate concentration on the rate of enzyme reaction.
    rate of enzyme reaction graph
    1. Account for the shape of the graph between
      1. A and B (3mks)
      2. B and C (2mks)
    2. How can the rate of reaction be increased after point B? (1mk)
    3. State two factors that affect the rate of enzyme reaction. (2mks)
    1. State the function of co-factors in cell metabolism. (1 mk)
    2. Give one example of a metallic co-factor. (1 mk)
  5. Name two mineral elements that are necessary in the synthesis of chlorophyll. (2mks)
  6. What is the role of the vascular bundles in plants nutrition? (3mks)
  7. Describe what happens during the light stage of photosynthesis. (3mks)
  8. Photosynthesis takes place in two stages.
    1. Name the part of the chloroplast where
      1. Light stage occurs
      2. Dark stage occurs (2mks)
    2. How is dark stage dependant on the light stage of photosynthesis? (2mks)
  9. A solution of sugarcane was boiled with hydrochloric acid; sodium carbonate was heated with Benedict’s solution. An orange precipitate was formed.
    1. Why was the solution boiled with hydrochloric acid? (1mk)
    2. To which class of carbohydrates does sugarcane belong?
    3. Name the type of reaction that takes place when:
      1. Simple sugars combine to form complex sugar. (1mk)
      2. A complex sugar is broken into simple sugar. (1mk)
    4. State the form in which carbohydrates are stored in:
      1. Plants
      2. Animals (2mks)
    1. Name structural units of lipids (1mk)
    2. State three important functions of lipids in living organisms. (3mks)
  11. 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.
    potted plantq12
    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? (3mks)
    2. What is the function of the sodium hydroxide pellets? (1mk)
    1. Name the bacteria found in the root nodules of leguminous plant. (1mk)
    2. State the association of the bacteria named in a) above with the leguminous plants. (1mk)
    1. State the function of co-factors in cell metabolism.
    2. Give one example of metallic co-factor.
  13. Name the disease in humans that is cause by lack of vitamin C. (1mk)
  14. Name a disease caused by lack of each of the following in human diet;
    1. Vitamin D (1mk)
    2. Iodine (1mk)
  15. Explain how birds of prey are adapted to obtaining their food. (2mks)
  16. Explain biological principles behind the preservation of meat by;
    1. Salting
    2. Refrigeration
    3. Canning (3mks)
  17. State one similarity and one difference between parasitic and predatory modes of feeding (3mks)
  18. In an investigation, the pancreatic duct of a mammal was blocked. It was found that the blood sugar regulation remained normal while food digestion was impaired. Explain these observations. (3mks)
  19. Give a reason why lack of roughage in diet often leads to constipation.
    1. What does the term digestion mean? (2mks)
    2. Describe how the mammalian small intestine is adapted to its function. (18mks)
  20. State the role of vitamin C in humans. (2mks)
    1. Distinguish between the terms homodont and heterodont. (1mk)
    2. What is the function of carnasial teeth? (1mk)
    3. A certain animal has no incisors, no canines, 6 premolars and 6 molars in its upper jaw, in the lower jaw there are 6 incisors, 2 canines, 6 premolars and 6 molars. Write its dental formula.
    1. State two functions of bile juice in the digestion of food. (2mks)
    2. How does substrate concentration affects the rate of enzyme action? (1mk)
  22. Name the end-products of the light stage in photosynthesis. (2mks)
  23. The diagram below represents a section through a human tooth.
      1. Name the type of tooth shown.
      2. Give a reason for your answer in (a) (i) above. (1mk)
    2. State a factor that denatures enzymes. (1mk)
    1. Name a fat soluble vitamin manufactured by the human body. (1mk)
    2. State two functions of potassium ions in the human body. (2mks)
    1. The action of ptyalin stops at the stomach. Explain. (1mk)
    2. State a factor that denatures enzymes. (1mk)
    3. Name the features that increase the surface area of small intestines. (2mks)
  26. Define the following terms (5mks)
    1. Ingestion
    2. Digestion
    3. Absorption
    4. Assimilation
    5. Egestion
  27. Explain the role of the following organs in the digestion of food in a mammal.
    1. Salivary glands
    2. Pancrease
    3. Liver (3mks)
  28. State any three functions of the mucus, which is secreted along the wall of the alimentary canal. (3mks)
  29. Explain why the digestion of starch stops after food enters the stomach. (3mks)
  30. Give an account of the adaptation of a named herbivore to its mode of feeding. (3mks)
  31. What are the contents of gastric juice and what is their role in digestion. (6mks)
  32. Liver damage leads to impaired digestion of fats . Explain the statement. (3mks)
  33. For each of the following nutrients give one example of a good source and one example of its role in the body.
    Nutrient Food source Role in the body
    Vitamin A    
    Vitamin D    


    1. K- Enzyme , sucrose, invertase
      L- Inhibitor
    2. Additional of sucrose/substance, Addition of enzyme, Optimum
      PH, Removal of products.
    3. Complete with substrate for active site of the enzyme.
    1. Split water molecules/photolysis
    2. Glucose
  3. Yellowing of leaves/stunted growth/chlorosis/lack of chlorophyll.

      1. A and B -more active sites of enzymes available for a large number of molecules of substrate. There is increase in rates of reaction
      2. B-C
        - Enzyme/substance are in equilibrium. All active sites are occupied hence rate of reaction is constant.
    1. Raising concentration of enzymes
    2. PH, temperature, inhibitors/cofactors.
    1. Substances that activate enzymes
    2. Iron/Magnesium/Zinc/Copper.
  5.  - Magnesium,
    - Nitrogen
    - Iron
  6. Xylem
    - Transport water to photosynthesizing cells from stem
    - Offer support to the lamina for maximum exposure to sun-light.

    - Transport manufactured food away from the leaf to create high concentration gradient.

  7. Takes place in the grana of the chloroplast. Light is absorbed and used to split water molecules into hydrogen ions and oxygen, photolysis. Energy is formed and is stored in form of ATP.
      1. Light stage-grana
      2. Dark stage-stroma
    1. -Uses the energy formed or produced during light stage.
      -Uses the hydrogen ions produced in light stage for carbon dioxide fixation.
    1. Cuticle-Transparent allowing light to penetrate.
    2. Veins –Xylem vessel transport water to the photosynthesizing cells as it is a raw material
      Phloem - Transport manufactured food out of the leaf to create high concentration gradient.

    1. To hydrolyse/break down the disaccharide (non-reducing sugar).
    2. Non-reducing sugar
      1. Condensation,
      2. Hydrolysis
      1. Starch,
      2. Glycogen
    1. Fatty acids and glycerol
    2. Form part of the cell membrane
      - Provide insulation of bodies of animals
      - A source of metabolic water.
      - Provide energy in absence of carbohydrates
    1. L - Blue-black
      M -Yellow
      N - Blue Black
    2. Absorb carbon (IV) oxide in the jar.
    1. Rhizobium
    2. Symbiosis
    1. Activate enzymes
    2. Magnesium/zinc
  15. Scuvy
  16. - Rickets
    - Goitre
  17. Sharp/ hooked/ strong beaks for killing/ripping off flesh from bones, sharp claws for grabbing/holding prey.
    1. Salting -This removes / absorbs water by osmosis from microorganism cell. Which then die due to dehydration. Meat also becomes dehydrated and thus unsuitable for microbial growth.
    2. Refrigeration –Low temperature renders the micro-organism inactive (Enzymes do not work at low temperature).
    3. Canning –Boiling kills all micro-organism in the food. Sealing under pressure excludes all micro-organisms and ensures that growth takes place.
  18. Similarity: Both are heterotrophic.
    Difference: Predators kill to get food while parasites obtain foods without killing the host.
  19. Pancreatic juice containing digestive enzymes is prevented from reaching food.
    Insulin and glycogen hormones which regulate sugar are released directly into the blood stream.
  20. Roughage provide grip needed for peristalsis/lack of roughage results in slow/no movement of food leading to constipation. (Accept: add bulk to peristalsis to take place)
    1. Breakdown of (complex) food substance by enzymes to simpler compounds which can be absorbed.
    2. - Small intestine is long/coiled to offer large surface area for digestion and absorption.
      - The walls are muscular for peristalsis.
      - Inner walls posses mucus glands, goblet cell; that secret mucus for lubrication and protection of the walls from digestive enzymes.
      - The inner walls have digestive glands that secrete digestives enzymes.
      - The inner walls has villi to increase surface area for absorption.
      - The villi have numerous blood vessels for transport of the end products of digestion.
      - The villi also have lacteal vessels, for transport of fats/lipids.
  22. - Quicken healing of wounds
    - Forms connective tissues of the teeth and jaws.
    - Provides resistance to body infections
    1. Homodont-Organism has same number of teeth, type of teeth and the same size.
    2. Slice fish and crush bones
    3. I=0, C = 0, PM = 3, M = 3
         3         3          3         3
    1. -Has alkaline salts that help create alkaline media to neutralize acidic food from stomach.
      -Enhance emulsification of fats into droplets
    2. As the substance concentration decreases the rate of enzyme action decreases.
  25.  -Hydrogen ions, ATP molecules
    -Oxygen gas
      1. - Premolar tooth
      2. - Presence of two roots
        - Presence of cusps on the crown.
    1. Has a blood vessel that provides nourishment to the tooth and remove waste products.
    1. Vitamin D, Vitamin K
    2. - Transmission of nerve impulses.
      - Ionic balance/osmotic balance
      - Contraction of muscles.
    1. In the stomach there is acid medium and ptyalin only acts at slightly alkaline medium.
    2. High temperatures above 400C.
    3. -Villi
      - Microvilli
    1. Ingestion is the taking of food into the body.
    2. Digestion is the breakdown of large and insoluble molecules that can be absorbed.
    3. Absorption is the uptake of soluble food materials from lumen of digestive tract across the epithelial lining of the gut into blood stream.
    4. Assimilation is the utilization of absorbed food molecules by the body to provide energy or the materials necessary for growth, repair and reproduction.
    5. Egestion in the elimination of undigested waste food materials from the body.
    1. They produce saliva. Saliva contains the enzyme salivary amylase (ptyalin) which begins the digestion of starch breaking it to maltose. It also lubricates food making it suitable for swallowing.
    2. It produces pancreatic juice. Contains NaHClwhich neutralizes the acid of chime and creates a PH of 7-8 which is the Optimum PH for the action of pancreatic juice are;-
      • Trypsin which digests protein to peptides.
      • Amylase which digests starch to maltose
      • Lipase which digests fats to fatty acids and glycerol
    3. It produces bile. Bile salts droplets a process called emulsification. This increases the surface area of the fat enhancing the action of pancreatic lipase.
    • It lubricates food
    • It prevents digestion of the gut wall by proteolytic enzymes
    • It makes food particles to adhere to one another during swallowing and during gestation.
  32.  Hydrochloric acid in the stomach denatures salivary amylase stopping its activity.
  33. A sheep has the following herbivorous adaptations.
    - It has a thick horny pad on the upper jaw over which vegetation is pressed by chisel-like incisors and canines on the lower jaw during feedings.
    - If has a diastema which provides space for tongue movements that separate grass which is being chewed by check teeth and grass that is newly gathered by front teeth.
    - Its premolars and molars have large top surface, which is worn out unevenly forming cusps which help in crushing and grinding of vegetation.
    - The joints of the jawbones are loose allowing up and down as well as sideways movement of the lower jaw, which aids in the grinding of vegetation.
    - Its rumen contains microorganisms that ferment cellulose releasing simple fatty acids that are absorbed by the animal.
    1. Pepsin-digests proteins to peptides
    2. Rennin-Coagulation of milk proteins to peptides
    3. - Hcl-converts pepsinogen to pepsin
      - Kills bacteria in food
      - Provides an acidic pH (pH 1.5-2.5) which is the optimum pH for action of Pepsin
      - Unfolds proteins enabling pepsin to work on them.
  35. This leads to lack of bile salts, which emulsify fats.
      Nutrient Food source Role in the body
    a)  Vitamin A  Carrots, Liver, Egg yolk Synthesis of rhodopsin (for proper
    function of retinal).
    b)  Iron Liver Manufacture of hemoglobin
    c)  Iodine Iodized salt, sea food Manufacture thyroxin
    d)  Vitamin D  Fish, liver, plant oil, egg yolk Aids assimilation of calcium phosphate
    for making teeth and bones.
    e)  Protein Meat, milk seed of legumes, fish  Making new cells/growth and repair of
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