CLEP Science and Mathematics Exam Questions and Answers

QUESTION: 51 Exam Topic: 1, Biology

The toad Bufo marinus generally lies in wait for prey such as cockroaches to wander past. As the cockroach enters the toad's field of view, the toad strikes with its sticky tongue. Yet, the cockroach begins its escape from the toad even before the tongue has left the toad's mouth, even though it may still be caught. Attacks generally occur at night and the tongue makes no detectable sound at all. Cockroaches have also seen climbing on the backs of sedentary toads.

These observations suggest that

cockroaches are repelled by the odor of a toad
cockroaches begin to flee at the sight of a toad
cockroaches can detect slight changes in wind direction
toads produce a high frequency sound detectable by the cockroach at the time of attack
the cockroach is responding to a previously misdirected attack

Answer(s): C

Explanation:

It the toads make no sound upon attack, attacks occur at night, and roaches climb on the backs of sitting toads, these observations suggests that roaches are not warned by any auditory, olfactory, or visual cues. However, as the frog opens its mouth and tenses its muscles, the wind nearby would change direction suddenly. This is picked up by the sensitive hairs on the underside and tail end of roaches, which quickly move to escape.

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QUESTION: 52 Exam Topic: 1, Biology

The data below show the response of a neuron on the skin surface to repeated stimulation with varying degrees of pressure.

Which of the following conclusions concerning the pressure-sensitive neurons of the skin can be drawn from this data?

The neurons fatigue quickly after repeated stimulation.
There is a prolonged period of depolarization that leaves the neurons refractory for as long as one second after each firing.
Increasing pressure results in an increase in amplitude of the action potential.
The neurons signal increased pressure by increasing the frequency of signals sent per unit time.
The neurons fire only after a certain pressure threshold is reached.

Answer(s): D

Explanation:

Neurons respond to stimulation in an all-or-none manner, and they do not show an increased response when presented with a greater stimulus. Rather, they signal the intensity of a stimulus by increasing or decreasing the frequency of action potentials that are generated, not by changing the amplitude (degree) of each action potential.

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QUESTION: 53 Exam Topic: 1, Biology

In contrast to spermatogenesis, oogenesis

produces one functional haploid cell for every diploid cell that begins the process
is started by the hormones FSH and LH
takes place in the fallopian tubes
produces gametes
features equal divisions of cytoplasm and organelles into daughter cells

Answer(s): A

Explanation:

Oogenesis, the formation of egg cells (ova) in the female, takes place in the ovaries each month. Because there is an evolutionary advantage to having a large ovum, complete with a supply of organelles, at the end of the process, there is unequal division of the cells leading up to the egg. The result: three polar bodies, which are nonfunctional and will be destroyed, and one large, functional egg cell. Spermatogenesis, in contrast, produces four sperm cells for every diploid spermatocyte that starts the process.

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QUESTION: 54 Exam Topic: 1, Biology

The white blood cells responsible for attacking specific pathogens with antibodies are a type of

erythrocyte
lymphocyte
neutrophil
macrophage
platelet

Answer(s): B

Explanation:

The lymphocytes are B and T cells, the specific arms of the immune system, producing antibodies and enzymes that destroy pathogens. Erythrocytes are red blood cells, while neutrophils and macrophages engulf and destroy pathogens directly.
Platelets are involved in clotting.

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QUESTION: 55 Exam Topic: 1, Biology

Guard cells are kidney-shaped cells surrounding the stomata on the underside of leaves. These cells change their shape according to the amount of water that exists within them. The more water within, the more swollen the guard cells are and the stomata open. When water is sparse the guard cells shrivel and close the stomata. Recent evidence suggests that there are blue-light receptors on the plasma membrane surface of guard cells that are coupled to potassium (K+) ion channels. K+ ions are normally found in high concentration outside guard cell membranes when the channels are closed.

What mechanism may account for the fact that guard cells are usually open during the day and closed at night?

Photosynthesis uses K+ ions; therefore, lower concentrations of potassium within the leaf drive the movement of K+ into the leaf through the guard cells.
The presence of sunlight drives K+ into guard cells, while driving water out of the guard cells and opening the stomata.
There is more water in the air during daylight hours than during nighttime hours.
K+ ions enter the cell through active transport only when enough water is present.
The presence of sunlight opens the K+ ion channels, driving potassium inside, and causing water to follow by osmosis, swelling the guard cells.

Answer(s): E

Explanation:

The information about guard cells states that they must be swollen with water in order for them to open the stomata. It is advantageous to have the stomata open during the day, since that is when the sun is shining for photosynthesis to take place. Light falling on the blue-light receptors causes an influx of potassium ions, which draw water into the guard cells via osmosis. This causes the stomata to open.

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Test Prep CLEP Science and Mathematics Exam (page: 11) Test Prep CLEP Science and Mathematics: Biology, Calculus, Chemistry, College Algebra & Mathematics, Precalculus, Natural Sciences Updated on: 09-Feb-2026

QUESTION: 51 Exam Topic: 1, Biology

Explanation:

QUESTION: 52 Exam Topic: 1, Biology

Explanation:

QUESTION: 53 Exam Topic: 1, Biology

Explanation:

QUESTION: 54 Exam Topic: 1, Biology

Explanation:

QUESTION: 55 Exam Topic: 1, Biology

Explanation:

Test Prep CLEP Science and Mathematics Exam (page: 11)
Test Prep CLEP Science and Mathematics: Biology, Calculus, Chemistry, College Algebra & Mathematics, Precalculus, Natural Sciences
Updated on: 09-Feb-2026