What is the key difference between spermatogenesis and oogenesis in terms of gamete production?

A. Spermatogenesis produces one viable sperm, while oogenesis produces four viable ova.

B. Spermatogenesis produces four viable sperm, while oogenesis produces one viable ovum.

C. Both processes produce an equal number of viable gametes.

D. Both processes result in gametes with the same amount of cytoplasm.

Which mechanism prevents polyspermy during fertilisation?

A. Release of digestive enzymes

B. Cortical reaction and zona reaction

C. Mitotic division of the zygote

D. Formation of the blastocyst

Why is the implantation of the blastocyst in the endometrium crucial for the continuation of pregnancy?

A. It facilitates external fertilisation.

B. It allows for the exchange of materials between mother and fetus.

C. It ensures the secretion of HCG to maintain progesterone levels.

D. It triggers the onset of meiosis in the fetus.

How does the placenta facilitate the exchange of materials between the mother and fetus?

A. By secreting estrogen and progesterone

B. By allowing diffusion of nutrients, gases, and waste products

C. By preventing the mixing of maternal and fetal blood

D. Both B and C

Which hormone is primarily responsible for stimulating the ovary to secrete progesterone during early pregnancy?

A. Estrogen

B. Oxytocin

C. HCG (Human Chorionic Gonadotropin)

D. FSH (Follicle-Stimulating Hormone)

a) Discuss the processes of spermatogenesis and oogenesis, highlighting the roles of mitosis, cell growth, meiosis, and differentiation in each. [4]

b) Explain how these processes result in different numbers of gametes with different amounts of cytoplasm. [3]

a) Discuss the concepts of internal and external fertilisation in animals, providing examples of each. [3]

b) Explain the mechanisms that prevent polyspermy during fertilisation. [4]

a) Discuss the importance of the implantation of the blastocyst in the endometrium for the continuation of pregnancy. [4]

b) Explain the role of HCG in stimulating the ovary to secrete progesterone during early pregnancy. [3]

a) Describe the ultrastructure of the glomerulus and Bowman's capsule and explain their role in ultrafiltration. [4]

b) Discuss the role of the proximal convoluted tubule in the selective reabsorption of useful substances. [3]

c) Explain how the loop of Henle maintains hypertonic conditions in the medulla. [3]

a) Discuss the correlation between the length of the loop of Henle and the need for water conservation in animals. [3]

b) Explain how ADH plays a role in the reabsorption of water in the collecting duct. [3]

c) Discuss how the placenta facilitates the exchange of materials between the mother and foetus. [4]