Question 1

A person able to hear only high-frequency sounds would probably have which of the following structural problems in the ear?

Accepted Answer

High-frequency sounds are detected by hair cells located at the base of the cochlea, nearest the entrance of the ear. If the basilar membrane, which supports the hair cells, is stiffened along its entire length, high-frequency sounds would not be able to stimulate the hair cells and would therefore be undetected. Chronic ear infections and thickened ear ossicles may affect the transmission of sound waves but would not specifically affect the detection of high-frequency sounds.

Question 2

If you experimentally reduce the concentration of K⁺ in the extracellular fluid surrounding hair cells in the inner ear,the result would be like which of the following?

Accepted Answer

Hair cells in the inner ear require a high concentration of K⁺ in the extracellular fluid for proper function. If the concentration of K⁺ is reduced, the cells are unable to maintain their resting potential and cannot generate action potentials in response to sound waves. This would result in a decrease in the volume of sound reaching the hair cells.

Question 3

If a biochemist discovered an enzyme inhibitor for the enzyme photodiesterase (PDE)how would vision be affected if this enzyme inhibitor was applied to a vertebrate eye?

Accepted Answer

Photodiesterase (PDE) is responsible for breaking down cyclic guanosine monophosphate (cGMP) in the photoreceptor cells of the eye. By inhibiting PDE, cGMP levels would remain high, keeping the cGMP-gated sodium channels open in rod cells, which would continuously release glutamate at the synapses. Continuous glutamate release would inhibit bipolar and ganglion cells from generating action potentials and sending signals to the brain, causing the animal to be unable to detect light absorbed by the rod cells. This would result in impaired night vision or complete blindness in low-light conditions. The cones of the eye are responsible for color vision and are not affected by rod-specific inhibitors, so A is not correct. The lens focusing ability is not directly influenced by cGMP levels, so C is not correct. Therefore, the correct answer is B.

Question 4

When a neurobiologist is interested in determining if an animal can see in color what structures are they looking for in the eye?

Accepted Answer

Neurobiologists would be looking for opsins in the animal's eye to determine if they can see in color. Opsins are proteins found in the photoreceptor cells of the retina and are responsible for detecting different wavelengths of light, including colors. The other structures listed (electroreceptors, pupil, lens) are important for vision, but do not specifically relate to color vision.

Question 5

Researchers surgically fuse two of the three ossicles in the inner ear of a mouse,effectively leaving two functional,linked ossicles in place of three.When the mouse's hearing is tested,what outcome would be expected?

Accepted Answer

The ossicles are responsible for transmitting sound waves from the outer ear to the inner ear. By surgically fusing two of the three ossicles, the mouse's ability to transmit sound waves would likely be diminished, leading to a decreased sensitivity to sound in general.

Question 6

How would the vision of a fly be affected if several of the axons extending from the ommatidia of its compound eye were damaged?

Accepted Answer

Each ommatidium in a fly's compound eye contains multiple photoreceptor cells, and the axons of these cells join together to form the optic nerve. If some of these axons were damaged, the fly would have reduced resolution in the affected eye because fewer photoreceptor cells would be contributing to each ommatidium's output. However, the fly would still be able to detect light in the affected eye, and color vision would likely be unaffected. The remaining ommatidia cannot adjust to compensate for the damaged ones.

Question 7

Partial or complete loss of hearing (deafness)can be caused by damage to the _____.

Accepted Answer

Damage to the axons, hair cells, or tympanic membrane can all lead to partial or complete hearing loss, as they are all critical components in the process of hearing.

Question 8

Corneal surgery is now routinely performed to improve vision.This surgery _____.

Accepted Answer

Corneal surgery is performed to reshape the cornea and improve the focusing of light onto the retina. This is done to correct refractive errors such as nearsightedness, farsightedness, and astigmatism. It does not affect the circulation of nutrients to the eye, the amount of light entering the eye, or the sensitivity of the photoreceptors.

Question 9

Bat echolocation (sonar)is most closely related to which human sensory system?

Accepted Answer

Bat echolocation is a process that relies on sound waves for communication and navigation, just like hearing in humans. Both bat echolocation and hearing involve the detection of sound waves and their interpretation by the brain.

Question 10

How would an abnormally large oval window in a mouse affect that animal's hearing?

Accepted Answer

The oval window is a membrane-covered opening that leads from the middle ear to the inner ear. An abnormally large oval window could disrupt the normal transmission of sound vibrations to the inner ear, thereby reducing hearing ability compared to normal mice.

Question 11

Which type of receptor would you expect to be most abundant in the antennae of a moth?

Accepted Answer

Antennae of insects are mainly used as chemosensors to detect volatile chemicals and pheromones in the environment. Therefore, chemoreceptors would be the most abundant type of receptor in the antennae of a moth.

Question 12

Deafness caused by loud sounds often results from damage to which receptor cells?

Accepted Answer

Deafness caused by loud sounds often results from damage to the mechanoreceptor cells in the inner ear known as hair cells. These hair cells are responsible for converting sound waves into electrical signals that can be interpreted by the brain. Exposure to loud sounds can damage or destroy these hair cells, leading to hearing loss or deafness.

Question 13

Hair cells in the vertebrate ear are responsible for transducing sound pressure waves.Ion channels in the hair cell membrane open when _____.

Accepted Answer

Hair cells in the vertebrate ear are responsible for transducing sound pressure waves into electrical signals that can be transmitted to the brain. This transduction occurs through the opening of ion channels in the hair cell membrane. When the hair bundle (the structure that contains the hair cells) is deflected by the movement of the surrounding fluid, mechanically gated ion channels in the hair cell membrane open, allowing ions to flow into the cell and depolarizing the membrane. This depolarization triggers the release of neurotransmitter, which leads to the activation of auditory nerve fibers and the transmission of sound information to the brain.

Question 14

The amount of depolarization that occurs in a sound-receptor cell is proportional to the volume (loudness)of the sound.

Accepted Answer

This statement is true. The greater the volume (loudness) of a sound, the more depolarization occurs in the sound-receptor cell.

Question 15

A salmon follows a scent trail upstream to find its way back to the stream where it hatched.What type of sensory receptor cell would it use?

Accepted Answer

Chemoreceptors detect chemical stimuli, such as scent molecules, and are used by many animals to locate food, mates, and navigation. In this scenario, a salmon is following a scent trail, which would require the use of chemoreceptors.

Question 16

Damage to sensory receptor cells could result in _____.

Accepted Answer

Damage to sensory receptor cells would result in an inability to detect sensory information.

Question 17

Elephants hear sounds that are too low for humans to hear.This sensitivity is primarily due to the differences in the _____.

Accepted Answer

Elephants have a more flexible basilar membrane in the cochlea, which allows them to detect lower frequency sounds than humans can hear.

Question 18

What is the function of the cochlea?

Accepted Answer

The answer of What is the function of the cochlea?
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Question 19

How could you genetically modify an animal so that it would distinguish more shades of green?

Accepted Answer

Introducing genes for different opsins that respond in the green region of the spectrum would allow the animal to perceive more subtle variations of green. This is because each type of opsin responds to a slightly different range of wavelengths, allowing for more specificity in color vision. Increasing cone cell density (A) or production of cGMP (D) might improve overall visual acuity, but would not necessarily increase the ability to distinguish shades of green. Introducing green fluid (C) may actually interfere with the perception of green, by absorbing or scattering the wavelengths of light that the animal is trying to detect.

Question 20

How does the ear allow humans to distinguish the volume of different sounds?

Accepted Answer

To distinguish the volume of different sounds, the ear relies on the frequency of action potentials generated by the hair cells in the cochlea. Louder sounds will induce a higher frequency of action potentials than softer sounds, allowing the brain to interpret the relative volume of different sounds.

Quiz 46: Animal Sensory Systems and Movement