2017 - JAMB Biology Past Questions and Answers - page 4

Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube.

The result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development.

Its long been recognized that birds and reptiles share many characteristics:

Both have skulls that abut the first neck vertebra with a single ball-and-socket joint.

Both birds and reptiles excrete nitrogenous wastes as uric acid; mammals excrete urea, fish ammonia.

Both lay similar highly yolked eggs
Bird feather is homologous to the reptile scale. Both develop from an epidermal elevation over a nourishing dermal core. Scales flatten, feather buds roll into a cylinder shaped tube

Lungfish are best known for retaining the ability to breathe air, to survive drought

Although sodium ions are small, their charge prevents them from moving across the cell membrane through simple diffusion. They must be transported using active transport.

Amphibians display some interesting and changing characteristics as they metamorphose through various forms on their way to adulthood. The frog, for instance, begins life underwater as a larva with gills and becomes and air-breather with lungs as an adult.
&therefore4; in case of draught, frog can amphibians can use lungs to breathe on land

A red blood cell(erthyrocytes), which (in humans) is typically a biconcave disc without a nucleus.

Erythrocytes contain the pigment haemoglobin, which imparts the red colour to blood, and transport oxygen and carbon dioxide to and from the tissues.

Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance.

He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits.

Protozoa do not have any organellae for the process of respiration. The limiting permeable membrane (body surface) acts as a respiratory surface.

The free molecular oxy¬gen from the surrounding media enters into the body by diffusion. Presence of a cyto¬chrome system has been demonstrated in protozoa.

Plant build of of organic compounds such as oil, coal and gas is a great source of emission of carbon dioxide into the atmosphere
Human activities such as the burning of oil, coal and gas, as well as deforestation are the primary cause of the increased carbon dioxide concentrations in the atmosphere.
Other source such has respiration by animals, thunderstorm release carbon dioxide in smaller quantities compare to 87% of carbon dioxide emission from plants build-up organic compounds through human activities