2023 - JAMB Biology Past Questions and Answers - page 7

The characteristic of cells related to irritability is the ability to respond to stimuli. Irritability, also known as responsiveness or excitability, is the ability of cells to detect and respond to changes in their internal or external environment. This allows cells to adjust their activities in response to specific stimuli.

The tissue responsible for transporting water and minerals from the roots to the rest of the plant is xylem. Xylem vessels and tracheids form a network that facilitates the upward movement of water and nutrients through the plant.

The epidermis is the outermost layer of cells providing protection, the parenchyma is a type of ground tissue with various functions, and the phloem is responsible for transporting sugars and other organic nutrients within the plant.

Arteries carry oxygenated blood away from the heart. The heart pumps oxygenated blood into the arteries, which branch out to transport the oxygenated blood to various tissues and organs throughout the body.

An evolutionary trend commonly observed in organisms is increased genetic diversity within populations. This diversity arises through mechanisms such as genetic mutation, recombination, and other processes, contributing to the adaptability and survival of populations over time. Increased genetic diversity allows populations to respond to changing environmental conditions and challenges.

Migration is an example of a behavioural adaptation for survival in animals. Migration is a regular, often seasonal, movement of animals from one region to another and is a behaviour that enhances survival by optimizing access to resources or avoiding unfavourable conditions.

Sharp teeth and wings are structural adaptations, while camouflage is a morphological adaptation. Behavioural adaptations involve actions or patterns of behaviour that enhance an organism's chances of survival and reproduction in its environment.

The mosquito transmitting malaria is an example of a microorganism in action as a disease vector. Mosquitoes can carry and transmit the Plasmodium parasite, which causes malaria when it infects humans.

Red blood cells are responsible for carrying oxygen to the body tissues. Hemoglobin, a protein present in red blood cells, binds with oxygen in the lungs and transports it to various tissues and organs throughout the body, ensuring oxygen delivery for cellular respiration.

Physiological variation in organisms refers to variations in the physiological processes and functions of organisms. Variation in blood pressure among individuals is an example of physiological variation, as it involves variations in a physiological parameter. 

Variation in beak shape among finches, differences in fur colour in rabbits, and variation in leaf shape in plants are examples of morphological or structural variations rather than physiological ones.

Mutation is the primary source of genetic variation in a population. Mutations are random changes in the DNA sequence of an organism's genes, and they can introduce new alleles or traits into a population.

Gene flow involves the exchange of genetic material between populations, natural selection acts on existing variations, and genetic drift refers to random changes in allele frequencies in a population due to chance events.

High muscle tone is not typically associated with Down syndrome. Individuals with Down syndrome often exhibit hypotonia, which is characterized by low muscle tone. The other traits mentioned (short neck, small stature, slant eyes) are physical features that may be associated with Down syndrome.