BIOLOGY
ESSAY
QUESTIONS
AND ANSWERS
(Secondary school course)
,1. DISCUSS THE VARIOUS WAYS IN WHICH ANAEROBIC RESPIRATION IS
UTILIZED IN INDUSTRIES AND HOMES
Bread making; yeast is used to ferment sugar in wheat flour into carbon (IV)
oxide and energy; the carbon (IV) oxide is produced in form of bubbles that
causes the dough to rise and become porous; Beer making; yeast is used to
ferment sugars in malt/grapes/fruits; to form beer, wines and spirits; Sewage
treatment; anaerobes break down raw sewage and harmful industrial effluents;
to harmless products of water, energy/heat and carbon (IV) oxide; Silage
formation; vegetation is fermented by bacteria to produce nutritious and good-
scented/flavoured animal feed that increases production/yields; Production of
acids and strong liquors; special bacteria and fungi ferment food products; to
produce acids such as citric acid, oxalic acid and vinegar; the products are
used as food preservatives and flavouring agents; Manufacture of dairy
products; under controlled environments; anaerobes help in fermentation
hence manufacture of milk products such as butter, cheese, ghee and yorghurt;
Production of fuels such as biogas; and gasohol; cane sugar is fermented by
yeast; to produce gasohol for running engines or operating machinery; animal
wastes such as guano and cow dung; can be used to produce a mixture of
methane and carbon (IV) oxide gas; by exposing it to fermentation agents;
methane is used to run simple machines such as water pumps and for cooking;
Production of fermented porridge and milk; maize or wheat flour and milk is
exposed to microbes in the air which ferment it; to produce sour and sweet
tasting porridge or milk; Max. 20 mks
2. EXPLAIN HOW THE VARIOUS SPECIALIZED CELLS ARE MODIFIED TO CARRY OUT
THEIR FUNCTIONS IN PLANTS AND ANIMALS Animal cells: Sperm cell; has
acrosome containing lytic enzymes; that digest the egg membranes for
penetration during fertilization; has a long tail; containing numerous
mitochondria; to generate maximum energy for propulsion/swimming in the
vaginal fluid after ejaculation; Red blood cells; are flattened, circular/spherical
biconcave in shape; to increase the surface area for packaging of
haemoglobin; has hemoglobin; that combines with respiratory gases; for
transport to and from body tissues; White blood cells; are amoeboid in shape
hence able to change shape; to engulf pathogens through phagocytosis;
lymphocytes produce antibodies to fight pathogens; Nerve cell; has
extensions/dendrites; to receive and send information for sensation; Ciliated
epithelial cells; have cilia for propulsion of mucus that traps dust and micro-
organisms in the respiratory tract; Muscle cells; elongated, striated and
, contractile; to bring about movement; Plant cells: Guard cells; bean-shaped; to
regulate the size of the stomata allowing gaseous exchange; and control water
loss; has chloroplasts with chlorophyll; for photosynthesis; Root hair cell;
elongated; thin-walled; with dense cytoplasm for absorption of water and
mineral salts; Epidermal cell; thin; for protection of inner tissues from
mechanical and micro-organism attack; Palisade cell; contains numerous
chloroplasts with chlorophyll; for photosynthesis; elongated; to increase
surface area for trapping maximum amounts of light energy; Meristem tic cell;
thin-walled; with dense cytoplasm; for primary and secondary growth; Max.
20 mks
3. DESCRIBE HOW THE MAMMALIAN BODY PROTECTS ITSELF AGAINST INFECTIONS –
Pathogenic microbes are found on the skin, respiratory tract, mouth, vagina
and the intestinal tract; the skin; has a keratinized and waterproof cornified
outer layer; that provides a mechanical barrier to microbes/prevents entry of
microbes; sebaceous gland; produces sebum; which has antiseptic properties;
the respiratory tract; produce mucus secretions that trap dust; cilia
sweep/waft/propel the microbes to the pharynx for swallowing or to be
coughed out; reflex actions of coughing/sneezing/vomiting help remove
foreign materials from the respiratory tract/digestive tract;
lysozymes/enzymes in saliva/nasal secretions/tears; digest walls of bacteria
destroying them; gastric secretions such as hydrochloric acid lowers the pH in
the stomach killing micro-organisms; clotting of blood; prevents entry of
microbes after damage of blood vessels; phagocytosis; by phagocytes engulf
and destroy microbes and other foreign bodies; lymphocytes are stimulated to
produce antibodies; by proteins present in microbes protecting the body;
antibodies destroy/kill micro-organisms through various ways: agglutinins;
bind to pathogens making them clump together; killing them; Lysins; bind to
pathogens and make them burst or disintegrate; opsonins; bind to pathogens
making them easily recognized hence be engulfed/destroyed by other
lymphocytes; anti-toxins; bind and neutralize toxins produced by micro-
organisms; vagina is acidic; hence making it not conducive for growth and
reproduction of micro-organisms;
Max: 20 mks
,
ESSAY
QUESTIONS
AND ANSWERS
(Secondary school course)
,1. DISCUSS THE VARIOUS WAYS IN WHICH ANAEROBIC RESPIRATION IS
UTILIZED IN INDUSTRIES AND HOMES
Bread making; yeast is used to ferment sugar in wheat flour into carbon (IV)
oxide and energy; the carbon (IV) oxide is produced in form of bubbles that
causes the dough to rise and become porous; Beer making; yeast is used to
ferment sugars in malt/grapes/fruits; to form beer, wines and spirits; Sewage
treatment; anaerobes break down raw sewage and harmful industrial effluents;
to harmless products of water, energy/heat and carbon (IV) oxide; Silage
formation; vegetation is fermented by bacteria to produce nutritious and good-
scented/flavoured animal feed that increases production/yields; Production of
acids and strong liquors; special bacteria and fungi ferment food products; to
produce acids such as citric acid, oxalic acid and vinegar; the products are
used as food preservatives and flavouring agents; Manufacture of dairy
products; under controlled environments; anaerobes help in fermentation
hence manufacture of milk products such as butter, cheese, ghee and yorghurt;
Production of fuels such as biogas; and gasohol; cane sugar is fermented by
yeast; to produce gasohol for running engines or operating machinery; animal
wastes such as guano and cow dung; can be used to produce a mixture of
methane and carbon (IV) oxide gas; by exposing it to fermentation agents;
methane is used to run simple machines such as water pumps and for cooking;
Production of fermented porridge and milk; maize or wheat flour and milk is
exposed to microbes in the air which ferment it; to produce sour and sweet
tasting porridge or milk; Max. 20 mks
2. EXPLAIN HOW THE VARIOUS SPECIALIZED CELLS ARE MODIFIED TO CARRY OUT
THEIR FUNCTIONS IN PLANTS AND ANIMALS Animal cells: Sperm cell; has
acrosome containing lytic enzymes; that digest the egg membranes for
penetration during fertilization; has a long tail; containing numerous
mitochondria; to generate maximum energy for propulsion/swimming in the
vaginal fluid after ejaculation; Red blood cells; are flattened, circular/spherical
biconcave in shape; to increase the surface area for packaging of
haemoglobin; has hemoglobin; that combines with respiratory gases; for
transport to and from body tissues; White blood cells; are amoeboid in shape
hence able to change shape; to engulf pathogens through phagocytosis;
lymphocytes produce antibodies to fight pathogens; Nerve cell; has
extensions/dendrites; to receive and send information for sensation; Ciliated
epithelial cells; have cilia for propulsion of mucus that traps dust and micro-
organisms in the respiratory tract; Muscle cells; elongated, striated and
, contractile; to bring about movement; Plant cells: Guard cells; bean-shaped; to
regulate the size of the stomata allowing gaseous exchange; and control water
loss; has chloroplasts with chlorophyll; for photosynthesis; Root hair cell;
elongated; thin-walled; with dense cytoplasm for absorption of water and
mineral salts; Epidermal cell; thin; for protection of inner tissues from
mechanical and micro-organism attack; Palisade cell; contains numerous
chloroplasts with chlorophyll; for photosynthesis; elongated; to increase
surface area for trapping maximum amounts of light energy; Meristem tic cell;
thin-walled; with dense cytoplasm; for primary and secondary growth; Max.
20 mks
3. DESCRIBE HOW THE MAMMALIAN BODY PROTECTS ITSELF AGAINST INFECTIONS –
Pathogenic microbes are found on the skin, respiratory tract, mouth, vagina
and the intestinal tract; the skin; has a keratinized and waterproof cornified
outer layer; that provides a mechanical barrier to microbes/prevents entry of
microbes; sebaceous gland; produces sebum; which has antiseptic properties;
the respiratory tract; produce mucus secretions that trap dust; cilia
sweep/waft/propel the microbes to the pharynx for swallowing or to be
coughed out; reflex actions of coughing/sneezing/vomiting help remove
foreign materials from the respiratory tract/digestive tract;
lysozymes/enzymes in saliva/nasal secretions/tears; digest walls of bacteria
destroying them; gastric secretions such as hydrochloric acid lowers the pH in
the stomach killing micro-organisms; clotting of blood; prevents entry of
microbes after damage of blood vessels; phagocytosis; by phagocytes engulf
and destroy microbes and other foreign bodies; lymphocytes are stimulated to
produce antibodies; by proteins present in microbes protecting the body;
antibodies destroy/kill micro-organisms through various ways: agglutinins;
bind to pathogens making them clump together; killing them; Lysins; bind to
pathogens and make them burst or disintegrate; opsonins; bind to pathogens
making them easily recognized hence be engulfed/destroyed by other
lymphocytes; anti-toxins; bind and neutralize toxins produced by micro-
organisms; vagina is acidic; hence making it not conducive for growth and
reproduction of micro-organisms;
Max: 20 mks
,
