NES Profile: Biology (305)

The process of conjugation is significant in the bacterial life cycle because it allows:

1. a bacterium to switch from being heterotrophic to autotrophic.
2. deleterious mutations in a bacterium's genome to be corrected.
3. a bacterium to make an exact duplicate of itself.
4. genetic material to be transferred from one bacterium to another.

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D. This question requires the examinee to demonstrate knowledge of the characteristics of viruses, prokaryotes, protists, and fungi, including their reproduction and life cycles. Conjugation in prokaryotes is the direct one-way transfer of DNA from one cell to another.

Which of the following best describes how mushrooms and similar fungi obtain nutrients?

1. The hyphae secrete enzymes that break down large molecules in the immediate environment and then absorb the smaller molecules.
2. Cells in the hyphae engulf large food particles, forming food vacuoles that fuse with lysosomes so that digestive enzymes can break down the particles.
3. Tubes formed by the hyphae transport food particles to specialized storage structures where the food is digested and the nutrients are absorbed.
4. Hyphae periodically organize into structures that grow toward sunlight and produce nutrients by photosynthesis.

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A. This question requires the examinee to analyze how prokaryotes, protists, and fungi obtain, store, and use energy, nutrients, and water to maintain homeostasis. Unlike animals, fungi do not ingest their food before digesting it. Instead they secrete enzymes that break down complex organic molecules in the surrounding environment and then absorb the nutrients.

In many vertebrates, including humans, blood flows in two circuits in an arrangement called double circulation. Which of the following is an advantage of double circulation over the single circulation organization found in fish?

1. There is greater surface area over which gas exchange between the blood and environment occurs, resulting in higher oxygen levels.
2. Oxygenated blood can be mixed with deoxygenated blood before passing through the tissues of the body.
3. The blood flows to the body tissues under higher pressure and faster, allowing for more efficient delivery of oxygen.
4. Blood flow to different parts of the body can be regulated more precisely to meet localized oxygen needs.

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C. This question requires the examinee to analyze the general structure, organization, function, and homeostatic relationships of the respiratory, circulatory, digestive, and excretory systems. Having a pulmonary circulation and pump that are separate from the systemic circulation and pump allows the systemic pump to repressurize the blood flow as it leaves the heart for the body's tissues. This increases the rate at which oxygen can be delivered to the tissues.