2024 - JAMB Biology Past Questions and Answers - page 4

The question asks for an abiotic factor affecting population growth. Abiotic factors are non-living components of an ecosystem.

• A. Predator: Predators are living organisms (biotic).
• B. Rainfall: Rainfall is a non-living (abiotic) factor and significantly influences habitat, resource availability (water), and thus, population size.
• C. Food shortage: Food (whether plants or animals) is a biotic factor.
• D. Disease: Disease is caused by living organisms (biotic).

A loamy soil texture is considered a medium texture that is also rich in organic matter.

Ecological succession is the process of change in the species structure of an ecological community over time. It begins with a newly formed or disturbed habitat.

Blood group AB is known as the universal recipient because it has both A and B antigens on the surface of its red blood cells and neither anti-A nor anti-B antibodies in its plasma. Therefore, it can receive blood from any blood group without causing an immune reaction.

The question asks which part of the diagram represents the flower of the plant. Without seeing the diagram, I can't definitively say which label corresponds to the flower. However, flowers are reproductive structures. Assuming the diagram is a typical plant structure representation, the flower would likely be indicated by label III.

Bile is a greenish-yellow fluid produced by the liver and stored in the gallbladder. Its primary function is to aid in the digestion of fats in the small intestine.

The question is incomplete because the diagram is missing. However, based on the question, it is asking about the genotypic ratio of the F₁ generation, which is the first generation of offspring. The most common example used to calculate the genotypic ratio in the F₁ generation is from a monohybrid cross (a cross between two organisms with different alleles for a single gene).

1. Monohybrid Cross: If we assume a monohybrid cross involving a dominant and recessive allele (e.g., T for tall and t for short), and the parents are heterozygous (Tt x Tt), the genotypic ratio will be 1:2:1.
2. Punnett Square: A Punnett square would be used to determine the offspring's genotypes.
   • TT (1)
   • Tt (2)
   • tt (1)
3. Ratio: Therefore, the genotypic ratio is 1 (TT):2 (Tt):1 (tt).

Lipids (fats and oils) provide the highest energy value per gram compared to other nutrients.

The feeding relationship between ruminants and the bacteria in their digestive tract is symbiotic.

• Symbiosis: Refers to a close and long-term interaction between different biological species. In this specific case, it's a mutualistic symbiosis, meaning that both organisms benefit.
• Ruminants: (like cows and goats) have specialized stomachs with multiple chambers that harbor bacteria. These bacteria help break down cellulose (from plant matter), which ruminants cannot digest on their own.
• The bacteria: Receive a stable environment and a constant supply of food from the ruminant.
• The ruminant: Benefits by being able to digest the cellulose, making nutrients available to it.

The other options are incorrect:

• Saprophytic: Refers to organisms that feed on dead or decaying organic matter.
• Parasitic: Refers to organisms that live on or in a host and benefit at the host's expense.
• Heterotrophic: Is a general term that refers to organisms that obtain nutrients by consuming other organisms or organic matter, not a specific type of feeding relationship.

The intertidal zone is the area of a marine habitat that is exposed to air at low tide and submerged at high tide. Organisms in this zone experience fluctuating conditions, including:

• Desiccation: Exposure to air can dry out organisms.
• Wave action: Waves can cause dislodgment.
• Changing salinity: Salinity changes with tides and rainfall.

Due to these conditions, organisms in the intertidal zone often require adaptations for attachment to the substrate (rocks, sand, etc.) to avoid being swept away or dislodged. Examples include:

• Barnacles: They secrete a cement-like substance to attach to rocks.
• Mussels: They use byssal threads to anchor themselves.
• Seaweeds: They have holdfasts to secure themselves to surfaces.