Biology 2023 Jamb Examination

Bones form the rigid framework of the skeleton and joints connect bones allowing movement. Together they provide structural support, protection for internal organs, leverage for muscles, and enable locomotion. Cartilage, ligaments and tendons are associated tissues but the core skeletal components are bones and joints.

Establishing marine protected areas is a conservation strategy that preserves habitats and biodiversity through legal protection and managed use. Such areas support replenishment of fish stocks, protect breeding grounds, and maintain ecological associations that sustain marine food webs and ecosystem services over the long term.

Robert Hooke coined the term 'cell' in 1665 after observing thin slices of cork under a microscope and noting box-like compartments. His observations initiated cell theory development, later expanded by other scientists describing cellular structure and function across living organisms.

The lungs are the main organs where oxygen and carbon dioxide are exchanged. Millions of alveoli within the lungs provide an enormous surface area and thin diffusion distances, allowing efficient gas transfer between air and blood via the pulmonary capillary network.

The pancreas contains endocrine islets (islets of Langerhans) whose beta cells synthesize and secrete insulin. Insulin regulates blood glucose by promoting cellular glucose uptake and storage, playing a central role in metabolic homeostasis and preventing hyperglycemia.

Buoyancy in most bony fishes is maintained by a swim bladder (also called an air bladder), which can be inflated or deflated to adjust depth. Since swim bladder and air bladder are essentially the same structure, the correct combination (I and II) explains why fishes maintain buoyancy without sinking.

An individual carrying two different alleles (for example Aa) at a given genetic locus is described as heterozygous. Heterozygosity allows interactions between dominant and recessive alleles, and can influence phenotype depending on dominance relationships between the alleles.

Xylem is the vascular tissue specialized for long-distance transport of water and dissolved mineral nutrients from roots upward through stems to leaves. Its tracheids and vessel elements form continuous conduits that facilitate transpiration-driven flow and supply water for photosynthesis and cooling.

Abiotic factors are non-living physical or chemical elements of the environment. Temperature is a fundamental abiotic variable that affects metabolic rates, species distributions, and ecosystem processes, whereas competition, predation and symbiosis are biotic interactions between living organisms.

Fertilization is the fusion of male and female gametes to form a zygote, initiating development of a new organism. It is the central reproductive process in sexual reproduction, enabling genetic recombination and the start of embryogenesis in many multicellular organisms.