AP Biology Practice Test 7: Feedback Mechanisms

The correct answer is (B). Negative feedback is the most common type of regulation in which the accumulation of the end product slows the process of producing more.

The correct answer is (C). One way in which an animal adjusts to changes in their external environment within the normal range of homeostasis is known as acclimatization. Acclimatization is a temporary change.

The correct answer is (D). Conduction takes place when heat moves between two objects that are touching each other, such as a snake basking on a rock.

The correct answer is (D). Countercurrent exchange reduces heat loss when arteries carrying warm blood down the legs of waterfowl are in close contact with veins returning cold blood from cold lakes or ponds. This allows the heat from the blood in the arteries to warm the cold blood returning in the veins. When the blood from the veins reaches the body core, it is almost as warm as the body.

The correct answer is (A). The osmolarity of the body fluids of sea stars (starfish) conforms to that of marine waters in which they are found.

The correct answer is (C). When there is physical or emotional stress, nervous and hormonal responses trigger smooth muscles in arteriole walls to contract. This causes the arterioles to narrow, increasing blood pressure in the upstream arteries.

The correct answer is (C). Gravity provides the environmental cue signaling for the roots display positive gravitropism (growing downward) and the shoots to display negative gravitropism (growing upward). Photomorphogenesis describes the effects of sunlight on plant growth. Photoperiodism is the physiological response to a photoperiod (relative lengths of day and night), such as long-day and short-day plants. Thigmotropism is directional growth in response to touch, such as a vine wrapping its tendrils around another plant’s stem.