SECTION B: BIOLOGY ESSAY QUESTIONS
Answer FOUR questions in ALL; ONE from each Course.
BIO 001: GENERAL BIOLOGY
- (a) State FOUR functions of protein as macro molecules. [4 Marks]
(b) i. Name the bond that exist between the pentose sugar and the phosphate group in nucleotide; glucose molecules in starch; amino acids in proteins [3 Marks]
ii. State the cell theories. [2 Marks]
(c) Define trophic level. [1 Mark]
- (a) i. Differentiate between the Anaphase of mitosis and meiosis I. [1 Mark]
ii. Define the following terms
- Genotype
- Autosome
- Homozygote
- Test cross [4 Marks]
(b) i. List the last four sub stages of Prophase I of Meiosis [1 Mark]
ii. Name the sub stage that is responsible for variation and what the process involved [2 Marks]
iii. List the events that occur during the first phase of the mitotic cell division. [2 Marks]
BIO 002: MICROBIOLOGY
- (a) Draw a well labelled diagram of a bacteriophage. [4 Marks]
(b) State THREE importance of cell wall to a bacterium [3 Marks]
(c) State ONE function each of the following
i. flagella
ii. pili
iii. Capsules [3 Marks]
- (a) Write brief notes on the following infectious diseases: Cholera and AIDS [5 Marks]
(b) Differentiate between immunization and vaccination. [1 Mark]
(c) Enumerate FOUR control measures of food spoilage [2 Marks]
(d) Give ONE causative agent of
i. Botulism
ii. Syphilis [2 Marks]
BIO 003: BOTANY
- (a) Draw and label the internal structure of the mitochondrion. [5 Marks]
(b) Describe the process of cyclic photophosphorylation in plants during photosynthesis [5 Marks]
- (a) i. Define the term pollination. [1 Mark]
ii. State FOUR characteristics of wind pollinated flowers. [2 Marks]
(b) List FOUR modification in plant stem. [2 Marks]
(c) i. Define the term Plant regulators and name any TWO [2 Marks]
ii. Describe hypogeal germination in plants [3 Marks]
BIO 004: ZOOLOGY
- (a) State FIVE differences between chodrichythe and osteichythe [5 marks]
(b) State the location where glycolysis takes place in the cell and net gain of ATPs? [2 Marks]
(c) Which steps in the glyolytic pathway are irreversible? [3 Marks]
- (a) List FIVE hormones secreted by the pituary gland and state their functions. [5 Marks]
(b) Describe spermatogenesis. [5 Marks]
Solutions
BIO 001: GENERAL BIOLOGY
1(a) Four functions of proteins:
- Structural (e.g., collagen, keratin)
- Enzymatic (catalyze biochemical reactions)
- Transport (e.g., haemoglobin carries oxygen)
- Defence (antibodies fight infection); others: hormonal (insulin), contractile (actin/myosin)
(b)(i) Bonds:
- Pentose sugar–phosphate: phosphodiester bond
- Glucose molecules in starch: glycosidic bond
- Amino acids in proteins: peptide bond
(ii) Cell theories:
- All living things are composed of cells
- The cell is the basic structural and functional unit of life
- All cells arise from pre-existing cells
(c) Trophic level: The position an organism occupies in a food chain, based on its feeding relationship (e.g., producer, primary consumer, secondary consumer).
2(a)(i) Anaphase mitosis vs meiosis I:
In mitosis anaphase, sister chromatids separate and move to opposite poles; in meiosis I anaphase, homologous chromosomes (each still with two chromatids) separate, while sister chromatids remain joined.
(ii) Definitions:
- Genotype: The genetic constitution of an organism
- Autosome: Any chromosome that is not a sex chromosome
- Homozygote: An organism having two identical alleles for a gene
- Test cross: A cross between an individual of unknown genotype and a homozygous recessive individual, used to determine the unknown genotype
(b)(i) Last four substages of Prophase I: Zygotene, Pachytene, Diplotene, Diakinesis
(ii) Pachytene is responsible for variation; the process involved is crossing over (exchange of genetic material between non-sister chromatids of homologous chromosomes).
(iii) Events in early mitotic prophase:
- Chromatin condenses into visible chromosomes
- Nucleolus disappears
- Spindle fibres begin to form
- Nuclear envelope begins to break down
BIO 002: MICROBIOLOGY
3(a) Bacteriophage diagram: Label: head (capsid containing DNA/RNA), collar, tail sheath, tail fibres, base plate, tail pins.
(b) Importance of cell wall to bacterium:
- Maintains/gives shape to the cell
- Protects against osmotic lysis (prevents bursting in hypotonic media)
- Provides rigidity and mechanical support
- Site of attachment for flagella
(c) Functions:
i. Flagella – locomotion/movement
ii. Pili – attachment to surfaces/host cells and conjugation (transfer of genetic material)
iii. Capsules – protection against phagocytosis and desiccation; aids attachment
4(a) Brief notes:
- Cholera: Acute intestinal infection caused by Vibrio cholerae, transmitted via contaminated water/food, characterized by severe watery diarrhoea ("rice-water stools") and dehydration.
- AIDS: Acquired Immune Deficiency Syndrome, caused by HIV, which attacks T-helper (CD4) cells, weakening the immune system; transmitted through body fluids (blood, semen), leading to opportunistic infections.
(b) Immunization vs vaccination:
Vaccination is the act of administering a vaccine (antigen) into the body, while immunization is the broader process by which a person becomes protected/immune against a disease (can occur naturally or through vaccination).
(c) Control measures of food spoilage (any four):
- Refrigeration/freezing
- Drying
- Canning
- Use of chemical preservatives/salting/smoking
(d) Causative agents:
i. Botulism: Clostridium botulinum
ii. Syphilis: Treponema pallidum
BIO 003: BOTANY
5(a) Mitochondrion structure: Label: outer membrane, inner membrane, cristae, matrix, intermembrane space, ribosomes/mitochondrial DNA.
(b) Cyclic photophosphorylation:
Occurs in Photosystem I only. Light excites electrons in chlorophyll (P700), which are ejected and pass through an electron transport chain (ferredoxin → cytochrome complex → plastocyanin) and return to PS I, releasing energy used to pump protons and generate ATP via ATP synthase. No NADPH or O₂ is produced, and water is not split; only ATP is generated.
6(a)(i) Pollination: The transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower.
(ii) Characteristics of wind-pollinated flowers:
- Small, dull-coloured petals (often no petals)
- Produce large amounts of light, powdery pollen
- Large, feathery/exposed stigma to trap pollen
- No nectar or scent produced; anthers loosely attached and dangling outside the flower
(b) Modifications of plant stem (any four):
- Rhizome (e.g., ginger)
- Tuber (e.g., potato)
- Corm (e.g., cocoyam)
- Bulb (e.g., onion); also stem tendrils, thorns/spines
(c)(i) Plant regulators (growth hormones): Organic substances produced in small amounts by plants that regulate growth and development. Examples: Auxins and Gibberellins (also: cytokinins, ethylene, abscisic acid).
(ii) Hypogeal germination: A type of germination in which the cotyledons remain below the soil surface, while the epicotyl elongates and pushes the plumule up through the soil (e.g., maize, pea).
BIO 004: ZOOLOGY
7(a) Five differences between Chondrichthyes and Osteichthyes:
- Chondrichthyes have a cartilaginous skeleton, while Osteichthyes have a bony skeleton
- Chondrichthyes lack a swim/air bladder, while Osteichthyes possess one
- Chondrichthyes' gills lack an operculum (covering), while Osteichthyes' gills are covered by an operculum
- Chondrichthyes have placoid scales, while Osteichthyes have cycloid/ctenoid scales
- Chondrichthyes mostly undergo internal fertilization, while Osteichthyes mostly undergo external fertilization
(b) Glycolysis:
- Location: Cytoplasm (cytosol) of the cell
- Net gain: 2 ATP molecules (and 2 NADH + 2 pyruvate) per glucose molecule
(c) Irreversible steps in glycolysis:
- Glucose → Glucose-6-phosphate (catalyzed by hexokinase)
- Fructose-6-phosphate → Fructose-1,6-bisphosphate (catalyzed by phosphofructokinase)
- Phosphoenolpyruvate → Pyruvate (catalyzed by pyruvate kinase)
8(a) Five pituitary hormones and their functions:
- Growth Hormone (GH): Stimulates growth of bones and tissues
- Follicle Stimulating Hormone (FSH): Stimulates development of ovarian follicles/spermatogenesis
- Luteinizing Hormone (LH): Triggers ovulation and stimulates testosterone production
- Prolactin: Stimulates milk production in mammary glands
- Antidiuretic Hormone (ADH): Promotes water reabsorption in the kidneys (others: Oxytocin – stimulates uterine contraction/milk ejection; TSH – stimulates the thyroid gland)
(b) Spermatogenesis:
The process of sperm formation in the testes. A diploid spermatogonium undergoes mitosis to form primary spermatocytes, which undergo meiosis I to form two secondary spermatocytes (haploid), each of which undergoes meiosis II to produce two spermatids (a total of 4 spermatids per primary spermatocyte). The spermatids then undergo spermiogenesis (differentiation) — developing a tail, acrosome, and losing most cytoplasm — to become mature spermatozoa.