Biology 2004 Jamb Examination

The correct answer is B. occupy different ecological niches.

A caterpillar and an aphid living in different parts of the same plant occupy different ecological niches. Although they share the same plant (and thus a similar habitat), they exploit different resources or parts of the plant, leading to different roles in the ecosystem. This differentiation allows them to coexist without direct competition for the exact same resources.

The correct answer is A. a decrease in biomass at each successive level.

In a food chain, energy is progressively lost at each trophic level, primarily through metabolic processes and as heat. As a result, the amount of energy available to the next level decreases, leading to a corresponding decrease in biomass. This means that as you move up the food chain, the total biomass at each successive level tends to be lower than at the previous level.

The correct answer is D. clayey.

Clayey soil is composed of very fine particles that tend to stick together when wet, making it heavy and sticky. During the wet season, clayey soil becomes waterlogged and compact, making it extremely difficult to plough. The soil can also form clumps, which adds to the difficulty of working with it.

The correct answer is C. I.

Zone I has a temperature of 45°C and receives only 300 mm of rainfall annually, which are typical characteristics of a desert climate. Deserts are known for their extremely high temperatures and low precipitation levels, which makes Zone I the most likely to be a desert among the listed options.

The correct answer is A. II and III.

High relative humidity is typically associated with regions that have high temperatures combined with high levels of rainfall. Zones II and III have temperatures of 32°C and 30°C, respectively, and both receive substantial amounts of rainfall (2,000 mm and 2,200 mm). These conditions are conducive to high relative humidity, as the large amount of moisture in the air due to significant rainfall would lead to higher humidity levels.

The correct answer is C. keratinous scales.

Reptiles have keratinous scales that cover their bodies, which help to reduce water loss. These scales are made of keratin, a tough and water-resistant protein, which provides a protective barrier against dehydration in dry environments. This adaptation is crucial for reptiles, allowing them to retain moisture and survive in habitats where water is scarce.

The scarcity of food typically causes a sudden decrease in population size by:

B. raising the mortality rate

When food becomes scarce, individuals are more likely to die from starvation or malnutrition, which raises the mortality rate and leads to a decrease in population size.

The association between termites and the cellulose-digesting protozoan in their guts is an example of:

A. mutualism

In this relationship, both the termites and the protozoans benefit. The protozoans help termites digest cellulose from wood, which the termites cannot break down on their own, while the protozoans receive food and a suitable living environment within the termite's gut.

The state in Nigeria that is most susceptible to desert encroachment is:

B. Katsina

Katsina is located in the northern part of Nigeria, a region that is highly vulnerable to desertification due to its proximity to the Sahara Desert.

The farm practice that results in the loss of soil fertility is:

A. Continuous cropping

Continuous cropping involves growing the same crop repeatedly on the same piece of land without giving the soil time to recover its nutrients. This practice can lead to soil nutrient depletion and a decline in soil fertility over time.