Biology JAMB Past Questions and Answers 2018

The vascular bundles in the maize leaf are arranged in two circles. The outer circle is called the xylem ring and the inner circle is called the phloem ring.

If solution Y is more concentrated than solution X, water will move from X to Y by osmosis. This will cause the level of X to rise and the level of Y to rise.

Fertilization is the process of fusion of the male and female gametes to form a zygote. In humans, the male gamete is the sperm cell and the female gamete is the egg cell.

The contractile vacuole is a specialized organelle in Paramecium that is responsible for osmoregulation. It pumps out excess water from the cell to maintain the cell's water balance.

Etiolation is the process of plant growth in the absence of light. Plants that are etiolated have long, thin stems and pale leaves.

Commensalism is a type of symbiotic relationship in which one organism benefits from the other without harming it. For example, some bacteria live on the skin of humans and help to protect us from harmful bacteria.

When the diaphragm contracts, it moves down and increases the volume of the thoracic cavity. This causes the air pressure in the lungs to decrease, which allows air to flow into the lungs.

The tapeworm larvae are found in the muscles of an infected pig. When a person eats undercooked pork, the larvae can develop into adult tapeworms in their intestine.

Man can be infected with the tapeworm by eating undercooked meat that contains tapeworm larvae. The larvae develop into adult tapeworms in the intestine.

Hair is a distinguishing feature of mammals. It is made up of keratin, a protein that is also found in nails and claws. Hair helps to insulate the body and protect it from the elements.

Glycogen is a storage form of carbohydrates that is found in animals and fungi. It is stored in the liver and muscles. Rattus is the genus name for rats and mice.

The xylem is a plant tissue that carries water and minerals from the roots to the rest of the plant. It is made up of dead cells with thick walls that are strengthened by lignin.

Tissues 3 and 4 are the xylem and phloem, respectively. The xylem is responsible for the transport of water and minerals from the roots to the rest of the plant. The phloem is responsible for the transport of food from the leaves to the rest of the plant.

Trichocysts are rod-shaped organelles that are found in the cytoplasm of Paramecium. They are used for defense. When Paramecium is threatened, it can discharge trichocysts, which form a sticky net that traps predators.

An organ is a group of tissues that work together to perform a specific function. The liver is an organ that is responsible for many different functions, including detoxification of the blood, metabolism of nutrients, and production of bile.

The yolk and the albumen provide food for the developing chick. The yolk is a food source that is rich in proteins, fats, and vitamins. The albumen is a protective layer of protein that also contains some nutrients.

The young chick is formed from the blastodisc, the yolk, and the albumen. The blastodisc is the fertilized egg cell. The yolk is a food source for the developing chick. The albumen is a protective layer of protein.

The hormone secreted at IV is adrenaline. Adrenaline is a hormone that is released in response to stress or danger. It prepares the body for the "fight-or-flight" response.

The long neck of the giraffe is an example of natural selection. Giraffes with longer necks were able to reach leaves on higher branches, which gave them a survival advantage. Over time, the long neck trait became more common in the population.

Katsina is a state in northern Nigeria that is located on the edge of the Sahara Desert. It is one of the states that is most susceptible to desert encroachment.

Meat has the highest energy content of the four options.

Poikilothermic animals are cold-blooded animals, meaning that their body temperature depends on the temperature of their environment.

The malpighian tubule is the excretory organ in insects. It is a long, slender tube that is located in the insect's abdomen. The malpighian tubule removes waste products from the insect's blood and excretes them into the gut.

Nitrogen(IV) oxide is a pollutant that is mostly associated with acid rain. When nitrogen(IV) oxide reacts with water in the atmosphere, it forms nitric acid. Nitric acid is a strong acid that contributes to acid rain.

A community is a group of organisms of different species living in a particular area.

Xeromorphism is a physiological adaptation to very dry conditions in animals. Examples of xeromorphism include having a thick skin to prevent water loss, having concentrated urine, and having the ability to store water in the body.

Hydra is a radially symmetrical organism, meaning that it has a body plan that is arranged around a central axis. All parts of the body are the same distance from the central axis.

Lizards are cold-blooded animals, which means that their body temperature changes with the temperature of their environment. Cats, whales, and birds are warm-blooded animals, which means that they maintain a constant body temperature regardless of the temperature of their environment.

If a child can receive blood from all donors, he belongs to the blood group AB. People with blood group AB have no antibodies against the A or B antigens, so they can receive blood from all four blood groups (A, B, O, and AB).

The movement of the whole organism to an external stimulus is termed a taxis. Tropisms are directional movements of plant parts in response to stimuli such as light, gravity, and touch. Nastic movements are non-directional movements of plants in response to stimuli such as touch and temperature. Phototropic movements are directional movements of plant parts in response to light.

A bean seed is an example of an endospermous seed. Endosperm is a nutrient-rich tissue that is stored in the seed and provides food for the embryo during germination.

The stele is the central part of the root vascular system, and it is directly surrounded by the pericycle. The cortex is the outer layer of the root, and the endodermis is the layer of cells that separates the cortex from the stele. The parenchyma is the type of tissue that makes up most of the plant body.

The embryo of a bird is located in the embryo disc, which is a small white disc at the top of the yolk. The chalaza are the two spiraled strands of albumin that anchor the yolk in the center of the egg. The yolk is the food source for the embryo, and the albumen is the protective layer that surrounds the yolk.

Mineral salts can be absorbed into plant roots by both diffusion (for ions like oxygen and carbon dioxide) and active transport (for ions against a concentration gradient).

Mammals have a double circulation system, which means that blood passes through the heart twice in a complete circuit. One circulation is pulmonary (to the lungs) for oxygenation, and the other is systemic (to the rest of the body).

The hepatic portal vein carries blood from the digestive organs (where nutrients are absorbed) to the liver for processing. It is unique because it begins with capillaries in the digestive system and ends with capillaries in the liver.

Rhizopus is a fungus and is known to exhibit extracellular digestion. It secretes enzymes outside its cells to break down organic matter, which is then absorbed by the fungus.

Double fertilization is a characteristic feature of angiosperms (flowering plants). It involves the formation of both a zygote and a triploid endosperm nucleus during the process of fertilization.

A hygrometer is an instrument used to measure the relative humidity of the air.

Vitamin A is essential for the formation of the visual pigment rhodopsin in the retina. Rhodopsin is involved in low-light vision, and its deficiency can lead to night blindness.