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Questions 1 - 10
1

Which of the following cells are responsible for speeding up the action potentials along the axon of a neuron?

Schwann cells

Glial cells

Astrocytes

Ependymal cells

Myocytes

Explanation

The correct answer is Schwann cells. Schwann cells are cells that produce the myelination present on the outer covering of the axon of the neuron. This lipid-rich material helps facilitate the movement of the action potential along the axon from the axon hillock to the axon terminal branches.

2

The parasympathetic nervous system is a subdivision of which branch of the nervous system?

The peripheral autonomic nervous system

The central nervous system

The peripheral somatic nervous system

The spinal cord

Explanation

There are two major criteria that can be used to define nervous system categorizations. The first is location in the body. The central nervous system consists only of the brain and spinal cord, while the peripheral nervous system extends throughout the rest of the body. The central nervous system is enclosed by the blood-brain barrier, separating it from the rest of the body. The second classifier is mechanism of control. Some nervous pathways can be controlled voluntarily (somatic), while others are involuntary (autonomic).

The sympathetic and parasympathetic divisions are both peripheral autonomic pathways.

3

Which answer choice shows the correct chemical formula for barium sulfate?

Explanation

We should first remember the difference between sulfate, sulfite, and sulfide. Sulfate is , sulfite is ` and sulfide is .

The only answer choices that could be right must have in them. We then need to see that barium usually has a charge of , as the periodic table shows us, and so we need a charge of to cancel that out. The answer is .

4

Which of the following ions are intracellularly released during the fertilized egg’s cortical reaction?

Calcium ions

Sodium ions

Chlorine ions

Potassium ions

Explanation

After fertilization and sperm cell penetration of the oocyte, the cortical reaction takes place. During the cortical reaction, a release of intracellular calcium ions triggers the exocytosis of cortical granules. Cortical granules are vesicles in the cortex of the oocyte that contain enzymes that prevent polyspermy. Exocytosis of the cortical granules releases their contents into the extracellular matrix—the zona pellucida in mammals—creating changes to prevent further sperm penetration.

5

Which of the following type(s) of cell movement are involved in the development of the neural plate into the neural tube?

Convergence and invagination

Convergence

Invagination

Neither convergence nor invagination

Explanation

During the formation of the neural tube, the neural plate—a thick layer of differentiated columnar cells—change shape and undergo certain cell movements. The formation of the neural tube is called primary neurulation. In a complex process, the cells of the neural plate change shape, invaginating the cell layer to form the neural groove. Convergence moves the cells of the neural folds towards the developing neural groove. Eventually, the two edges of the neural plate touch and join together to form the neural tube.

6

Immunoglobulins (also known as antibodies) are produced by which of the following?

B-lymphocytes, usually with input from helper T-lymphocytes

Helper T-lymphocytes, usually with input from B-lymphocytes

Natural killer cells

Dendritic cells

Explanation

B-cells produce antibodies (a subset of adaptive immunity called humoral immunity). The usual sequence involves B-cell activation via interleukins from helper T-lymphocytes, which cause the B-cell to undergo mitosis, creating numerous clones that will differentiate into plasma cells (rapid antibody producers) or memory B-cells.

7

A population of snails is in Hardy-Weinberg equilibrium. The snails come in two different colors: red, the dominant phenotype, and white, the recessive phenotype. The population consists of sixty-four red snails and thirty-six white snails.

Assuming that the population is in Hardy-Weinberg equilibrium, what is the value of ?

Explanation

We can solve this question using the Hardy-Weinberg equations:

is equal to the recessive allele frequency, while in the second Hardy-Weinberg equation corresponds to the frequency of the recessive phenotype.

The question tells us the number of dominant red snails and the number of recessive white snails. Using these values, we can find the frequency of the recessive phenotype.

From here, take the square root to find the value of .

8

Which answer choice shows the correct chemical formula for barium sulfate?

Explanation

We should first remember the difference between sulfate, sulfite, and sulfide. Sulfate is , sulfite is ` and sulfide is .

The only answer choices that could be right must have in them. We then need to see that barium usually has a charge of , as the periodic table shows us, and so we need a charge of to cancel that out. The answer is .

9

Which division of the nervous system only innervates skeletal muscle?

Somatic nervous system

Peripheral nervous system

Sympathetic nervous system

Parasympathetic nervous system

Explanation

The nervous system has two principle divisions for function and two principle divisions for structure. Structurally, there are the central and peripheral nervous system divisions. Functionally, there are the somatic and autonomic divisions.

The somatic nervous system is responsible for voluntary actions, namely the innervation of skeletal muscle. The autonomic nervous system is responsible for all involuntary actions, including smooth muscle contraction, glandular stimulation, and other functions.

The peripheral nervous system carries both somatic and autonomic signals, innervating the entire periphery (not just skeletal muscle). The sympathetic and parasympathetic divisions of the nervous system are both autonomic. Though they innervate some skeletal muscles, they also play keys roles in other bodily functions, such as heart rate and blood pressure regulation.

The somatic nervous system is the only division to only innervate skeletal muscle.

10

Which of the following best identifies the correct sequence of phases in the uterine cycle?

Menstruation, proliferative phase, and secretory phase

Secretory phase, menstruation, and proliferative phase

Proliferative phase, menstruation, and secretory phase

Proliferative phase, secretory phase, and menstruation

Explanation

The menstrual cycle is the process of preparing the human female body for potential pregnancy. The cycle can be divided into two stages—the ovarian cycle and the uterine cycle. The uterine cycle has three phases that are called menstruation, the proliferative phase, and the secretory phase.

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