AP Biology : Types of Cells and Tissues

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #7 : Understanding Neural Cells

Which part of the neuron receives information?

Possible Answers:

Dendrites

Axon hillock

Cell body

Synaptic cleft

Axon

Correct answer:

Dendrites

Explanation:

Neurotransmitters bind to receptors on the dendrites, which causes an electrical signal to be sent to the cell body. The cell body then transfers this signal to the axon hillock before an action potential is sent down the axon. The axon terminates at the synaptic cleft, where it releases neurotransmitters to the dendrites of the next neuron.

Example Question #8 : Understanding Neural Cells

What does it mean to say that a neural cell is bipolar?

Possible Answers:

It has two cell bodies, but only one with a nucleus

It sends signals to two other neurons

It has two projections coming off of the cell body

It can send signals in two opposing directions

Correct answer:

It has two projections coming off of the cell body

Explanation:

Neurons can be unipolar, bipolar, or multipolar, depending on how many projections are coming off of the cell body. Bipolar neurons are found in the retina and inner ear, and have a single dendritic extension as well as a single axonal extension. Most neurons are multipolar; they have numerous dendrites and a single axon.

Example Question #1 : Understanding Neural Cells

Which event causes repolarization of neuronal cells during an action potential?

Possible Answers:

The opening of voltage-gated calcium channels

The closing of voltage-gated potassium channels

The opening of voltage-gated potassium channels

The opening of voltage-gated sodium channels

Correct answer:

The opening of voltage-gated calcium channels

Explanation:

During the initial phase of an action potential, voltage-gated sodium channels open and allow sodium ions to enter the cell. This causes the membrane potential to rise to a positive value, resulting in depolarization.

Next, voltage-gated potassium channels open and potassium ions rush out of the cell. This reduces the membrane potential, resulting in repolarization as the potential becomes negative.

As more and more potassium exits the cell, the membrane potential declines below the resting potential, resulting in the hyperpolarized state. The sodium-potassium pump then functions to import potassium ions and export sodium ions to reestablish the resting membrane potential.

Example Question #10 : Understanding Neural Cells

Which of the following is true about the relative refractory period?

Possible Answers:

It takes place during hyperpolarization

It is easier to generate an action potential during this time

It takes place during depolarization

It is possible only when the cell has a positive cell potential

Correct answer:

It takes place during hyperpolarization

Explanation:

The relative refractory period is a time frame near the end of an action potential where another action potential can be generated only if a larger than normal stimulus is encountered by the neural cell. The relative refractory period takes place during the hyperpolarization of the cell. Since the membrane potential during hyperpolarization is more negative than the resting potential, it requires a much larger stimulus in order to reach threshold.

Example Question #81 : Types Of Cells And Tissues

Which of the following is a differentiating feature of the two photoreceptors—rods and cones—in the human retina?

Possible Answers:

Rods transduce signals through depolarization; cones do not

Cones use sodium ion channels to transmit light signals; rods use glutamate as a neurotransmitter to bipolar cells

Only cones use rhodopsin to absorb light

Cones provide color vision; rods do not

Correct answer:

Cones provide color vision; rods do not

Explanation:

Rods and cones are contained in the human retina, but they differ in shape and function.  

The functional difference between the two is that rods are more sensitive to light, but do not distinguish colors. Comparatively, cones are able to sense color and are less sensitive to distinctions fo light and dark. There are three different types of cone photoreceptors that have different sensitivity across the visible spectrum, with optimal responses to red, blue and green light, respectively. 

Both types of receptors use rhodopsin as the visual pigment that is activated when exposed to light. This initiates a signaling cascade that causes cellular depolarization through sodium ion channels and the release of the neurotransmitter glutamate by bipolar neuron cells to further transmit the visual signal.

Example Question #82 : Types Of Cells And Tissues

Which of the following is the correct sequence of events of for the initial signaling in response to light detection by photoreceptors in the eye?

Possible Answers:

Light activates rhodopsin; sodium channels close and the photoreceptor become hyperpolarized, initiating the release of glutamate

Light activates rhodopsin; sodium channels open and the photoreceptor become depolarized, halting the release of glutamate

Light activates rhodopsin; sodium channels close and the photoreceptor become hyperpolarized, halting the release of glutamate

Light activates rhodopsin; sodium channels open and the photoreceptor become depolarized, initiating the release of glutamate

Correct answer:

Light activates rhodopsin; sodium channels close and the photoreceptor become hyperpolarized, halting the release of glutamate

Explanation:

The signaling cascade in response to light  in the human eye is caused by two types of photoreceptors present in the retina—rods and cones. Rods provide dark and light vision (black and white) and cones are capable of discerning color along the visible spectrum.

Rhodopsin is the visual pigment in photoreceptors and is made up of a light-absorbing vitamin-like molecule (retinal) that is bound to a cell membrane protein called opsin. The absorbtion of light by rhodopsin results in chemical bond shifting and a change in the molecule's shape. This causes rhodopsin to activate. The active rhodopsin initiates a G-protein cascade that causes sodium channels on the receptor's cell membrane to close. This prevents sodium ions from entering the cell, resulting in a build-up of ions in the extracellular space in comparison to the cell interior. The membrane potential is directly related to this difference in concentration; a higher concentration of positive ions outside the cell will result in hyperpolarization.

In response to being in a hyperpolarized state, the photoreceptor cell will stop its release of the neurotransmitter glutamate across the cell synapse with retinal neurons. Glutamate is an inhibitory neurotransmitter; halting the release of glutamate will leave the neurons capable of stimulation by visual signals.

Example Question #81 : Types Of Cells And Tissues

Which of the following best describes the role of nervous tissue in the human body?

Possible Answers:

Skeletal movement

Protection

Transmission of electrical impulses

Support for tissues and organs

Correct answer:

Transmission of electrical impulses

Explanation:

Nervous tissue is responsible for the transmission of electrical impulses throughout the human body. This transmission occurs in nerve cells called neurons. It regulates sensory input, muscle control, homeostasis, and mental activity.

Example Question #82 : Types Of Cells And Tissues

Which of the following best describes the peripheral nervous system (PNS)?

Possible Answers:

It is exposed to toxins

It is composed of nerves outside of the central nervous system

All of these

It includes the somatic and autonomic nervous system

Correct answer:

All of these

Explanation:

The PNS is the part of the nervous system that is comprised of all the nerves located outside of the central nervous system. The PNS nerves are not protected by bone; therefore, they are susceptible to toxins and injury. The PNS can be further divided into the somatic and autonomic nervous systems.

Example Question #83 : Types Of Cells And Tissues

Which of the following is not a function of glial cells?

Possible Answers:

Insulate neurons

Hold neurons in place

Transmit electrical signals to the brain

Supply nutrients and oxygen to neurons

Correct answer:

Transmit electrical signals to the brain

Explanation:

Glial cells are important in maintaining nervous system homeostasis. The major functions of glial cells include insulating neurons, holding them in place, and supplying them with nutrients and oxygen. Glial cells also degrade pathogens and dead neurons.

Example Question #84 : Types Of Cells And Tissues

Which of the following best represent features of neuron cells?

Possible Answers:

Sarcoplasmic reticulum

Axons

Axons and dendrites

Axons and sarcoplasmic reticulum

Correct answer:

Axons and dendrites

Explanation:

Neuron cells are functional units of nervous tissue that transmit electrical signals. Neurons typically are composed of a soma, dendrites, and an axon. The soma is the body of the cell, the dendrites are branched projections that receive signals, and the axon conducts signals away from the cell body.

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