(a)(i) What is placentation? (ii) Name two organs associated with the human placenta. (b) State...

Explanation

(a)(i)Placentation: This is the arrangement of ovules, within the ovary.

(b) (i) Organs Associated with human

placenta: Umbilical cord, Uterus

(b)(ii) Functions of Placenta:

• Establishes connection between the embryo and the mother.
• Carries oxygen/water/food/ nutrients from mother's blood to foetus.
• Removes waste/urea/salt/carbon dioxide from foetus blood to mother's blood for elimination.
• Produces progesterone/hormone for maintenance of uterine wall/ endometrium/pregnancy.
• Carries antibodies from mother's blood to foetus.

(c) Viviparity:This is a type of reproduction in which the young develops inside the mother's body. Obtaining nutrients directly from the parent. When fully developed, the young are born alive.

(ii) Territoriality:In many animal species individuals, usually males mark out areas/territories where they can live and breed.

• They guard these territories fiercely.
• Chasing away other members of the species.
• Only vigorous individuals are able to establish large territories, secure suitable mates and produce many offspring.
• Territoriality limits overcrowding.
• Animals that carry out this phenomenon are lizards, lions, etc.

(iii) Seasonal migration:

• In many habitats food supply is affected by seasonal changes. Food is abundant in rainy seasons but scarce in dry seasons.
• Animals overcome these seasonal food shortages by moving to other habitats during unfavourable seasons.
• Such large scale seasonal movements of animals between habitats are called migrations.
• Other causes of migrations are temperature changes and breeding seasons.