JAMB Biology 1998

A: contains the genetic material

The nucleus contains genetic information used to direct protein production and many cellular activities. Its regulatory role comes from that information and its expression, rather than simply its position or enclosing membrane.

D: mantle

The mantle secretes the shell material of a snail, including its calcium-containing mineral layers and organic components. The shell protects the soft body while remaining associated with the mantle tissue.

D: dorso-ventrally flattened body

A cockroach’s flattened body allows it to fit into narrow spaces with little vertical clearance. This helps it hide and move through cracks and crevices that a deeper-bodied animal could not enter.

B: worker

Termite workers are generally pale and soft-bodied compared with the more strongly pigmented reproductive adults and the hardened heads of soldiers. They perform much of the colony’s feeding, care and construction work.

C: rakers

Gill rakers are projections along the gill arches that help retain food particles and protect the delicate gill surfaces. They differ from the filaments and lamellae, which provide large surfaces for gas exchange.

D: Cambium

Cambium is a meristematic tissue whose cells divide to produce new tissues. Vascular cambium can form additional xylem and phloem, contributing to increasing stem thickness.

C: chlorophyll-containing parts

Photosynthetic carbohydrate production requires photosynthetic tissues containing chlorophyll and the associated machinery. Such tissues may occur in leaves and green stems, so it is not restricted to one organ or to flowering plants.

B: a large surface-area-to-volume ratio

A small unicellular organism has much surface area relative to its volume and short internal diffusion distances. These features help substances cross its surface and reach the cell interior without a large transport system.

D: one ventricle and two auricles

The adult frog heart has two atria, also called auricles, and one ventricle. The atria receive blood from different circuits, while the single ventricle pumps blood into the outflow pathways.

B: inferior

The flower parts arise above the swollen ovary in this section. This arrangement places the ovary below their attachment level, so the ovary is described as inferior.

A: I

The corolla is the collective term for the petals. I points to a broad petal in the flower section; the smaller outer lobe and narrow reproductive structures are not the corolla.

D: dry weight

Dry mass estimates the amount of material remaining after water is removed. It therefore avoids temporary changes in water content that can alter fresh size, volume or mass without an equivalent increase in biomass.

B: chorion

The chorion is the outermost extraembryonic membrane in the mammalian conceptus. The amnion encloses the embryo and amniotic fluid, while the yolk sac and allantois have other developmental roles.

C: ganglia

Ganglia are clusters of neurone cell bodies in the peripheral nervous system. Each cell body contains a nucleus. Nerve roots are bundles of processes, while synapses are communication junctions.

A: low soil oxygen

Low oxygen favours denitrification by organisms that use nitrate in anaerobic respiration. This can convert nitrogen compounds into gaseous forms that leave the soil, especially in waterlogged conditions.

C: cycling of nutrients

Soil microorganisms break down organic material and transform nutrient compounds. Their activities help recycle elements into forms that other organisms, including plants, can use.

D: antibodies bind to their corresponding antigens on red blood cells

Agglutination can occur when antibodies bind to their corresponding antigens on red blood cells and link cells together. Compatibility matters because an antibody reacts with its specific target rather than with any different antigen.

C: variation

The chicks have different body masses despite sharing several stated conditions. Differences among individuals of the same species are variation. A single set of masses does not establish their growth rates or the genetic cause of the differences.

A: totality of the expressed traits

Phenotype includes expressed characteristics, such as visible appearance, physiology and biochemical traits. It reflects the interaction of genetic information with environmental influences and is broader than external appearance alone.

C: blood-feeding female mosquitoes, tsetse flies and aphids

Blood-feeding female mosquitoes, tsetse flies and aphids use piercing and sucking mouthparts to obtain liquid food. The other groups include insects with chewing, sponging or siphoning mouthparts.

D: reducing transpiration

Reducing leaves to small scales limits exposed leaf area and can reduce water loss. Green branchlets continue photosynthesis, allowing the plant to obtain carbon while retaining the reduced-leaf form.

B: chromosomes

Mutations change genetic material. Among the listed choices, chromosomes contain that material and can undergo sequence or structural changes. A phenotype may change as a consequence, rather than being the molecular target.