Biology 2024 Jamb Examination

Individuals with blood group AB have both A and B antigens on their red blood cells and do not have anti-A or anti-B antibodies. This allows them to safely receive blood from any blood group, making them universal recipients.

Counter-shading is a form of camouflage where the dorsal (upper) side is darker and the ventral (lower) side is lighter, helping animals like fish avoid predators by blending with the environment from above and below.

Countershading is an adaptive coloration strategy that conceals animals from predators by making them less visible, using contrasting dorsal and ventral coloration. Hibernation and aestivation are dormancy strategies, while migration is movement.

In the diagram of an insect, the part labelled III corresponds to the thorax, which is the middle segment of the body where the legs and wings are attached. The head and abdomen are the other two major body segments, and maxillae are mouthparts.

Lamarck proposed that organisms can pass on traits acquired during their lifetime to their offspring. For example, a giraffe stretching its neck to reach leaves would produce offspring with longer necks. This is different from Darwin's natural selection theory.

Gametes are formed through meiosis and contain half the number of chromosomes as the somatic cells. If a somatic cell has 8 chromosomes, the gamete will have 4 chromosomes.

The genotypic ratio of offspring in the F1 generation can be determined using a Punnett square. From the diagram, the resulting genotypes are 1 homozygous dominant, 2 heterozygous, and 1 homozygous recessive, giving a 1:2:1 ratio.

The hypothalamus is a part of the brain that regulates homeostatic functions such as body temperature, thirst, hunger, and other autonomic activities. The thalamus processes sensory information, medulla oblongata controls vital involuntary functions, and the spinal cord transmits nerve signals.

Mitosis is the type of cell division responsible for growth, tissue repair, and replacement of worn-out cells. Meiosis is for sexual reproduction, biosynthesis refers to molecule production, and synthesis is a general term for building compounds.

In the diagram of the plant, the part labelled III represents the flower. Flowers are reproductive structures responsible for sexual reproduction in plants.