JAMB UTME - Biology - 1998

The nucleus is considered the central organelle of a cell because it

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The nucleus is considered the central organelle of a cell because it contains the genetic material of the cell, including DNA, which directs cellular activities and determines the characteristics of the organism. It is surrounded by a nuclear membrane that separates it from the cytoplasm of the cell, which contains other organelles and structures. The nuclear sap is the fluid-like substance within the nucleus that helps support and organize the genetic material. While the nucleus is often located near the center of the cell, its position can vary depending on the type of cell and its functions.

The biological association that contributes directly to succession in a community is

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The biological association that contributes directly to succession in a community is "competition". Competition occurs when organisms of the same or different species compete for the same resources such as food, space, or mates. In a community, when one species outcompetes another for these resources, it can lead to a shift in the balance of the community and ultimately contribute to succession. For example, if one species of plant is more efficient at using resources like sunlight and nutrients, it may outcompete other plants and become dominant in the community, altering the composition of the community over time. Therefore, competition is an important factor that drives succession in a community.

A fresh water plant such as water lily can solve the problem of buoyancy by the possession of

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A fresh water plant such as a water lily can solve the problem of buoyancy by the possession of aerenchymatous tissues. Aerenchyma is a spongy tissue that forms air channels in certain aquatic plants. The air pockets provide buoyancy to the plant and also allow for the exchange of gases such as oxygen and carbon dioxide. This adaptation helps the plant to stay afloat on the surface of the water and absorb the necessary sunlight for photosynthesis, while also ensuring that the roots and other submerged parts of the plant receive sufficient oxygen for respiration. The other options (dissected leaves,

The caste of termites that lacks pigmentation is the

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The caste of termites that lacks pigmentation is the "worker". Workers are the caste of termites responsible for carrying out most of the work in the colony such as foraging, nest-building, and taking care of the young. They are generally small, pale, and have soft bodies with no wings. Since workers spend most of their time underground, they do not require pigmentation. On the other hand, soldiers have well-developed jaws for defense, and the king and queen have wings for mating and founding new colonies.

The outermost embryonic membrane in the mammal is the

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The outermost embryonic membrane in mammals is the chorion. The chorion is the membrane that develops around the embryo, and it is responsible for the exchange of gases between the embryo and the mother's bloodstream. In placental mammals, the chorion also plays a crucial role in the formation of the placenta, which nourishes the developing embryo. The other embryonic membranes include the amnion, which surrounds the embryo and contains the amniotic fluid, the allantois, which helps with waste disposal and contributes to the formation of the umbilical cord, and the yolk sac, which provides some nutrition to the embryo in some animals.

The basic point of impact by changes which produce mutation is the

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Mutations occur in the DNA, which is present in the chromosomes. Gametes (sperm and egg) contain half of the genetic information needed to form a zygote (fertilized egg) which will eventually develop into an organism. Therefore, mutations in the gametes or in the chromosomes of any other cell can be passed on to offspring and may result in a change in the phenotype (physical appearance) of the organism. Thus, the basic point of impact by changes which produce mutation is the chromosomes.

In adult mammalian blood, the cells which lack nuclei are the

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In adult mammalian blood, the cells which lack nuclei are the erythrocytes, also known as red blood cells. Erythrocytes are responsible for carrying oxygen from the lungs to the body tissues and carbon dioxide from the tissues to the lungs. The absence of a nucleus in erythrocytes allows more space for the oxygen-carrying molecule hemoglobin, which enables them to transport more oxygen. Without a nucleus, erythrocytes are not able to divide, repair themselves, or synthesize new proteins.

Which of the following is not a function of the mammalian skeleton?

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The corolla is partly represented by

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The line that represents efficient recycling combined with stringent conservation is

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Efficient recycling combined with stringent conservation is best represented by the line IV. This is because efficient recycling involves reducing waste by reusing and recycling materials, while stringent conservation involves reducing the use of resources in the first place. Line IV shows a high level of resource use efficiency, with low input and output levels, indicating a combination of efficient recycling and stringent conservation.

The condition that encourages denitrification is

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Denitrification is the process by which certain bacteria convert nitrate (NO3-) in the soil to nitrogen gas (N2), which is released into the atmosphere. The condition that encourages denitrification is a low soil oxygen level. This is because the bacteria that carry out denitrification require an oxygen-free environment to function. When there is not enough oxygen in the soil, the bacteria will turn to using nitrate as an alternative electron acceptor, leading to the conversion of nitrate to nitrogen gas. Therefore, option A - low soil oxygen - is the correct answer. The other options are not related to the process of denitrification.

The structure labelled I is formed as a result of the fusion of

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In the whistling pine, leaves are reduced to brown scales and young stems are green. This is an adaptation for

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The adaptation in whistling pine where leaves are reduced to brown scales and young stems are green is for reducing transpiration. Transpiration is the process by which water is lost from the surface of leaves and stems in the form of water vapor. In dry and arid regions, water is a scarce resource, and plants need to conserve it. The brown scales in whistling pine protect the stem from excessive water loss through transpiration. The green stems of the plant carry out photosynthesis and produce food, and the brown scales protect the plant from excessive water loss, ensuring that the plant can survive in dry conditions. Thus, the adaptation is primarily for reducing transpiration and conserving water.

In a water culture experiment, a plant showed poor growth and yellowing of the leaves. These may be due to deficiency in

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Toes of the feet ending in sharp, curved hook suitable for holding and tearing are most likely to belong to the bird with the bill in

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In snails, the hard calcareous shells are secreted by the

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The hard calcareous shells in snails are secreted by the mantle. The mantle is a tissue layer that covers the internal organs of the snail and produces the shell by secreting calcium carbonate. As the snail grows, the mantle continues to secrete more calcium carbonate, which gradually builds up to form the spiraled shell that we see.

The special name of the part labelled II is

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A group of organisms of different species living in a particular area is described as a

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A group of organisms of different species living in a particular area is described as a community. A community consists of all the living things (plants, animals, and microorganisms) in a given area and their interactions with each other and their environment. This can include predators and prey, competitors, and symbiotic relationships. In contrast, a population refers to all the individuals of a single species that live in a particular area, while a colony refers to a group of organisms of the same species living together. Niche refers to the role that an organism plays in an ecosystem, including its habitat, behavior, and the resources it uses.

The manufacture of carbohydrates by plants takes place only in

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Carbohydrates are manufactured by plants through a process called photosynthesis. During photosynthesis, plants use energy from the sun, water from the soil, and carbon dioxide from the air to produce glucose and oxygen. This process occurs in specialized structures called chloroplasts, which are found in the chlorophyllous parts of the plant, including the leaves and green stems. Therefore, the correct option is "chlorophyllous parts".

Regulation of blood sugar level takes place in the

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In blood transfusion, agglutination occurs when

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Which of following movements occur during exhalation?

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During exhalation, the diaphragm and intercostal muscles relax. As a result, the thoracic cavity decreases in volume, causing a decrease in lung volume and an increase in pressure within the lungs. This increased pressure forces air out of the lungs, allowing for exhalation. Therefore, the correct option is "The diaphragm and intercostal muscles relax."

The bird's bill adapted for fishing is labelled

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The ability of the cockroach to live in cracks and crevices is enhanced by the possession of

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The dorso-ventrally flattened body of the cockroach enhances its ability to live in cracks and crevices. The flattened body allows the cockroach to easily squeeze through narrow openings and find shelter in tight spaces, making it difficult for predators to catch them. The wings and segmented body are important for their mobility and agility, but do not specifically contribute to their ability to live in crevices. The compound eyes and claws on the leg are adaptations for their feeding and sensory functions, respectively.

Which of the following groups of diseases are associated with water? I Onchocerciasis II Schistosomiasis III Dracunculiasis IV Elephantiasis V Taeniasis

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A dry fruit formed from two or more carpels containing several seeds is a

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A dry fruit that is formed from two or more carpels and contains multiple seeds is called a schizocarp. The schizocarp fruit splits into segments, each containing a single seed, at maturity, and these segments can disperse separately. Examples of plants that produce schizocarp fruits include parsley and carrot.

Soil micro-organisms are beneficial because of their involvement in

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Soil micro-organisms are beneficial because of their involvement in the cycling of nutrients. These micro-organisms break down organic matter in the soil, such as dead plants and animals, into smaller molecules that can be taken up by plants as nutrients. They also convert nitrogen gas from the atmosphere into a form that plants can use, a process called nitrogen fixation. Additionally, soil micro-organisms can help to control plant diseases by attacking harmful organisms that could harm the plant. Overall, soil micro-organisms play a critical role in maintaining soil fertility and supporting plant growth.

A distinguished feature of mammals is the possession of

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Mammals are characterized by having hair, which is a unique feature of this group of animals. Hair provides insulation, protection, and sensory functions for mammals, and it also plays a role in communication and social behavior in some species. Therefore, the correct answer to this question is hair.

Unicellular organisms transport essential nutrients directly to all parts of their bodies by the process of diffusion because, they have

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Unicellular organisms are single-celled organisms, meaning that their entire body is in direct contact with the external environment. Because of their small size, they have a large surface area to volume ratio, which allows for efficient diffusion of essential nutrients directly to all parts of their body. This means that nutrients can simply move through the cell membrane by the process of diffusion without the need for a specialized circulatory system. Therefore, the correct answer is: "a large surface area to volume ratio".

In which of the following groups of animals is the malpighian tubule found?

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The Malpighian tubule is a type of excretory organ that is responsible for removing metabolic waste from an animal's body. In this case, the animal group in which the Malpighian tubule is found is being asked. The correct answer is option B, which includes insects such as crickets, houseflies, and grasshoppers. The Malpighian tubule is a unique structure that is found in insects and some other arthropods, and it functions to remove metabolic wastes from the body and regulate water balance.

The ovary represented is

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The group of insects that have mouth parts adapted for both piercing and sucking is

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The correct answer is: mosquitoes, tse-tse flies and aphids. These three types of insects have specialized mouthparts called proboscis that are adapted for both piercing and sucking. The proboscis is a long, tubular structure that is used to pierce the skin of a plant or animal and then suck up the fluids inside. Mosquitoes use their proboscis to feed on the blood of animals, while tse-tse flies use theirs to feed on the blood of mammals. Aphids use their proboscis to feed on plant sap.

The heart of the adult frog consist of

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The heart of the adult frog consists of one ventricle and two auricles. The ventricle pumps oxygen-poor blood to the lungs and skin for gas exchange, while the two auricles receive oxygen-rich blood from the lungs and skin and pump it to the rest of the body. The single ventricle is divided into two chambers by a partial septum, which helps to partially separate oxygen-poor blood from oxygen-rich blood.

The structure that prevents food particle from escaping through the fish gills are called gill

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The structure that prevents food particles from escaping through the fish gills are called gill rakers. Gill rakers are bony or cartilaginous processes that project from the gill arches and form a mesh-like structure. They help to filter out large food particles and other debris, preventing them from entering the fish's respiratory system.

The natural tendency of organisms as they evolve is to

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The natural tendency of organisms as they evolve is to develop specialized structures. This means that over time, organisms tend to develop specific adaptations that allow them to better survive and reproduce in their environment. These adaptations can include specialized organs, behaviors, or physical characteristics that improve the organism's ability to obtain food, avoid predators, find mates, or adapt to changes in their environment. Specialization is an important aspect of evolution, as it allows organisms to become better adapted to their environment and to fill specific niches within their ecosystem.

The sequence of the biomes in Nigeria from port Harcourt to Damaturu is

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The correct sequence of biomes in Nigeria from Port Harcourt to Damaturu is estuarine → rain forest → Guinea Savannah → Sahel Savannah. This means that if we were to travel from Port Harcourt to Damaturu, we would first encounter the estuarine biome, followed by the rainforest, then the Guinea Savannah, and finally the Sahel Savannah. This sequence is determined by the changes in climate, vegetation, and geography as one moves inland from the coastal region to the northern part of Nigeria.

After one week of life, the weight of five chicks of the same sex hatched simultaneously from the eggs of the same hen and fed on the same diet were 45g, 40g, 35g, 33g and 30g. This is an example of

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This is an example of variation. Variation refers to the differences that exist among individuals of the same species. In this case, the chicks are of the same sex, hatched from the eggs of the same hen, and fed on the same diet, yet they have different weights. This is because of genetic and environmental factors that influence their growth and development. These differences in weight can lead to differences in survival and reproductive success, which are important factors in the process of natural selection. However, in this case, the observation is simply an example of variation.

The procaryotic cell type is characterized by a

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The phenotype of an individual can be summed up as the

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In million's test, when the reagent is added to a protein food item, a white precipitate is produced which turns

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In the honey bee colony, the drones are

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In the honey bee colony, the drones are fertile males with well-developed mouth parts. The drones are larger than the workers and have eyes that are twice the size of the worker bees' eyes. They are produced by the queen specifically for mating purposes and have the sole function of mating with the queen. They do not have any other tasks within the colony and are eventually expelled from the hive at the end of the mating season.

One of the ways which body cells differ from gamete cells is in the

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Body cells and gamete cells differ in the number of chromosomes they contain. Body cells (also called somatic cells) are diploid cells, which means they contain two sets of chromosomes (one from each parent), whereas gamete cells (sperm and egg cells) are haploid cells, which means they contain only one set of chromosomes. This is important because during fertilization, the haploid gamete cells combine to form a diploid zygote that contains two sets of chromosomes, one from each parent. The other options listed do not accurately describe the difference between body cells and gamete cells.

Which of the following structures is capable of producing more tissues in the stem of a herbaceous flowering plant?

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Out of the given options, only the Cambium is capable of producing more tissues in the stem of a herbaceous flowering plant. The cambium is a layer of meristem cells in the stem of a plant, and it is responsible for the production of new xylem and phloem tissues. This process is called secondary growth, and it is the reason why woody plants such as trees and shrubs can grow wider over time. In contrast, herbaceous plants do not undergo secondary growth and do not have a cambium layer. Therefore, only the cambium structure is capable of producing more tissues in the stem of a herbaceous flowering plant.

The best explanation for the theories of natural selection is that

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The theory of natural selection proposes that organisms with favorable variations that enable them to better adapt to their environment have a greater chance of survival and passing on their advantageous traits to their offspring. This means that not all organisms have equal capacity for survival in their habitats. Instead, organisms have varying capacities for survival based on their ability to compete for resources and adapt to their environment. Better competitors are more likely to survive and thrive, leading to the evolution of more fit and adapted organisms. Therefore, the best explanation for the theories of natural selection is that organisms have varying capacities for survival in their habitats and that organisms compete for resources, with better competitors being more likely to survive and thrive.

The most reliable estimate of growth is by measuring changes in

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The most reliable estimate of growth is by measuring changes in dry weight. When an organism grows, its cells increase in size and/or number, leading to an overall increase in mass. Measuring dry weight is a way to determine the actual amount of organic matter gained by the organism, without including any extraneous water or other substances. This method is widely used in the study of microbial growth and also in plants and animals.

The unrestricted pattern is represented by

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A sex-linked character cannot be passed on directly from

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A sex-linked character is a trait that is carried on the sex chromosomes (X and Y). In humans, females have two X chromosomes, while males have one X and one Y chromosome. Since a father can only pass the Y chromosome to his son, he cannot pass on an X-linked trait to him. Therefore, a sex-linked character cannot be passed on directly from father to son.

Which of the following is the direct consequence of transferring energy from one trophic level to another?

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The correct increasing order of size for the cell components responsible for heredity is

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Heredity is the passing of traits from parents to their offspring, and it involves the transmission of genetic information from one generation to the next. The components responsible for heredity are the ones that carry and transfer the genetic information from parent to offspring. DNA is the molecule that carries the genetic information in all living organisms, and it is organized into structures called chromosomes. A gene is a segment of DNA that codes for a specific trait, and it is located on a chromosome. The nucleus is the part of the cell that contains the chromosomes. Therefore, the correct increasing order of size for the cell components responsible for heredity is DNA → gene → chromosome → nucleus.

The small masses of nervous tissues in which many neurones have their nuclei are called

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The small masses of nervous tissues in which many neurons have their nuclei are called ganglia. Ganglia are clusters of nerve cell bodies located outside the central nervous system (brain and spinal cord). They are composed of a number of neurons, usually between a few and several thousand, that are responsible for relaying signals to and from different parts of the body. Ganglia are found in both the peripheral nervous system and the enteric nervous system, which controls the digestive system.