Biology 2025 Jamb Examination
Biology 2025 Jamb Examination
Question 111
The zone in an ecosystem that provides habitat for living organism is referred to as
The biosphere is the global sum of all ecosystems; it is the specific 'life zone' of the Earth, including portions of the atmosphere, lithosphere, and hydrosphere where living organisms exist. While 'environment' is a general term for surroundings, the biosphere specifically defines the biological zone supporting life.
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Question 112
An example of application of variation is
Genetic variation, specifically unique DNA sequences and blood group differences, is practically applied in paternity determination. By comparing the variations in genetic markers between a child and a potential father, scientists can confirm biological relationships. Survival of the fittest is a mechanism of evolution, not a human application of variation.
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Question 113
The level of organization in onion bulb is
An onion bulb is classified at the organ level of organization. It is a specialized underground storage structure consisting of a highly compressed stem and fleshy, modified leaves. Since it is a collection of different tissues working together to perform the functions of food storage and vegetative reproduction, it is an organ.
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Question 114
The type of germination in which the cotyledons remain below the soil surface is
In hypogeal germination, the epicotyl elongates while the hypocotyl remains short. This results in the cotyledons remaining below the soil surface (e.g., in maize and broad beans). This is the opposite of epigeal germination, where the cotyledons are pushed above the ground.
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Question 115
The stamen of a flower consists of
The stamen is the male reproductive organ of a flower. It is composed of two main parts: the anther, which produces pollen grains, and the filament, the slender stalk that supports the anther. The ovary and stigma are parts of the female organ (pistil/carpel).
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Question 116
Chemical breakdown of large food molecules into smaller and soluble substances is the function of
Digestion is the process of breaking down large, insoluble food molecules into small, water-soluble molecules that can be absorbed into the blood plasma. While the mouth and stomach begin this process, the duodenum (the first part of the small intestine) is the primary site where most chemical breakdown occurs. Here, chyme from the stomach is mixed with bile from the liver and pancreatic juice, which contains enzymes like amylase, trypsin, and lipase that complete the digestion of carbohydrates, proteins, and fats. The ileum is mainly for absorption, while the large intestine and rectum handle water reabsorption and waste storage.
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Question 117
The type of holozoic nutrition where organisms feed on both plant and animal substances is
Holozoic nutrition involves the ingestion of solid or liquid organic food, which is then digested and absorbed. Within this category, an omnivorous organism is one that has a generalized diet and is capable of feeding on both plant and animal substances. Humans, pigs, and chimpanzees are well-known examples. Herbivores feed strictly on plants, carnivores feed on other animals, and saprophytes are not holozoic but rather decomposers that absorb nutrients from dead organic matter.