Question 1

If genetically engineered bees could express a receptor for TNT in their olfactory neurons,what type of receptor would the TNT receptor be?

Accepted Answer

TNT is a chemical compound, and therefore the receptor for it would be a type of chemoreceptor, which are responsible for detecting chemicals in the environment.

Question 2

There is only a single type of pain receptor.

Accepted Answer

There are multiple types of pain receptors, including nociceptors, thermoreceptors, and mechanoreceptors.

Question 3

As CO₂ builds up in the atmosphere it also accumulates in the oceans,causing acidification.This poses a challenge to marine creatures that rely on calcium carbonate deposition such as corals,mollusks,and even fish,which use it to form otoliths.Researchers investigated whether otolith deposition was impaired at low pH,and were surprised to find that otoliths were actually larger in this condition.This means that,while coping with global climate change,at least fish will still be able to maintain which sense(s)?

Accepted Answer

The article states that fish use calcium carbonate deposition to form otoliths, which are related to hearing and balance. The researchers found that otoliths were actually larger in low pH conditions, indicating that fish will still be able to maintain their hearing and balance senses despite the acidification of the oceans. Therefore, the correct choice is E) hearing and balance.

Question 4

Nociceptors can respond to nearby tissue damage by sensing cytosolic factors released by damaged cells.Such "algogenic agents" can cause pain sensation even in the absence of tissue damage.What might be a practical use for such an agent?

Accepted Answer

The ability to activate nociceptors without causing actual tissue damage could be useful for nonlethal crowd control measures, such as dispersing crowds without causing permanent harm or injury. It would not be useful as an anesthetic drug or treatment for damaged tissue, and would not be a practical application as a tasty food additive.

Question 5

You decide to perform an experiment to test this why plants possess TRP channel agonists.You first set up batches of plants in the field WITH or WITHOUT applied capsaicin or menthol.What parameter do you then measure?

Accepted Answer

The presence of TRP channel agonists like capsaicin or menthol in plants is often related to their defense mechanisms against herbivores. By applying these substances and measuring the amount of leaf or fruit damage, you can assess whether these compounds reduce herbivory, thus supporting the hypothesis that TRP channel agonists serve as a protective measure.

Question 6

Beta-N-Methylamino-L-Alanine,or BMAA,is a glutamate receptor agonist produced by cyanobacteria.Since Glu is an excitatory neurotransmitter,it is not surprising that BMAA is associated with neurological damage.Buildup of BMAA in fruit bats was hypothesized to cause neurodegenerative disease in islanders that fed on the bats.A recent study found high levels of BMAA in sharks,suggesting that consumption of shark fin soup is also dangerous.The researchers suggested that a secondary effect of BMAA may actually make these hazardous foods surprisingly desirable.What might this be?

Accepted Answer

The question suggests that BMAA can make hazardous foods surprisingly desirable, which indicates an increase in food appeal. The researchers suggest that a secondary effect of BMAA is that it imparts a strong umami flavor that makes food more delicious. Therefore, the most appropriate choice is C.

Question 7

Mutations in the DFNA20/26 locus,which codes for the actin gamma 1 protein,are associated with congenital deafness.An irate senator complains that government money is being wasted on studies of this mutant gene -- in yeast! "I am no biologist," says the senator,"but I am pretty sure yeast don't have ears." How do you respond?

Accepted Answer

Studying the mutant gene in yeast allows researchers to express and study the mutant protein in a controlled environment, which is difficult to do with tiny hair cells or human patients. Yeast cells provide a reliable and ethical way to study the structure and function of the protein.

Question 8

If genetically engineered bees could express a receptor for TNT in their olfactory neurons,how could the transgenic bees be useful for detecting explosives?

Accepted Answer

Training the bees to respond in a predictable way when the TNT neuron is activated would be the most practical and efficient method for detecting explosives. This is because the bees could be trained to associate the presence of TNT with a food reward, and then used to detect the presence of TNT in a particular area. The other options, such as monitoring brain activity or grinding up the bees for an assay, are either impractical or inefficient for practical use. Watching for the death of the bee could also be an option, but it would not be an ethical or sustainable method.

Question 9

One patient at your audiology clinic has an actin defect,and another patient has a microtubule defect.What sense other than hearing may be affected in these patients?

Accepted Answer

Actin and microtubules are involved in the structure and function of cells throughout the body, including those in the inner ear that contribute to balance and spatial orientation. Defects in these proteins can therefore affect balance and potentially lead to dizziness or vertigo. The other senses listed are not as directly linked to these cytoskeletal proteins.

Question 10

Pain receptors are activated by tissue damage,but pain perception requires intact,functional neurons.How does this work?

Accepted Answer

Pain receptors (nociceptors) are activated by tissue damage, but the perception of pain requires intact, functional neurons. When tissue damage occurs, damaged cells release chemicals such as prostaglandins, histamines, and cytokines. These chemical signals then bind to the nociceptors located in nearby nerve endings and activate them, sending signals up the spinal cord to the brain. The neuron itself does not need to be damaged for pain perception to occur; it responds to signals released by nearby damaged cells.

Question 11

You make a knockout of a gene involved in neurological development,and find that the mice have malformed semicircular canals.Instead of being orthogonal (at right angles)to each other,they are parallel.What aberrant behavior might you see in these mice?

Accepted Answer

The semicircular canals are sensory organs in the inner ear that help with balance and coordination. Malformations in these canals can lead to difficulty in maintaining balance and coordination, making it difficult to walk or even stand without falling over. Therefore, the aberrant behavior seen in these mice would be falling over.

Question 12

What is the molecular basis of touch sensation?

Accepted Answer

When pressure is applied to the skin, it causes deformation of the cell membrane of touch receptors, which in turn open ion channels and create a receptor potential. This potential generates an electrical signal that is transmitted through sensory neurons to the brain, where it is interpreted as a sensation of touch.

Question 13

What is the most likely hypothesis for the presence of TRP channel agonists in plants?

Accepted Answer

TRP channel agonists in plants are often found in tissues that are vulnerable to herbivores, such as leaves and stems. It is believed that the presence of these chemicals serves as a defense mechanism, discouraging feeding by herbivorous insects or mammals.

Question 14

What are the categories of taste sensation?

Accepted Answer

The categories of taste sensation are sweetness, sourness, saltiness, bitterness, and umami. Creamy, chocolate, and coffee are not categories of taste sensation. Savory is sometimes considered a separate taste sensation, but it can also be interpreted as a combination of saltiness and umami. Therefore, the correct answer is B, which includes sweetness, sourness, saltiness, bitterness, and umami.

Question 15

In "The Disembodied Lady," neurologist Oliver Sacks tells the story of a patient who suffered a catastrophic loss of sensory function.She said,"I feel my body is blind and deaf to itself....It has no sense of itself." The patient's nerve damage was strikingly specific.What single type of neuron most likely suffered damage?

Accepted Answer

Proprioceptors are the sensory receptors that provide information about body position and movement. Damage to proprioceptors would impair the patient's ability to sense the position and movement of her body, which is consistent with her description of feeling "blind and deaf" to her own body.

Question 16

In 1908,chemist Kikunae Ikeda identified a new taste modality he called "umami",or "delicious" in Japanese.It gives a savory flavor to meat,seaweed,and tomatoes.What molecule is responsible for umami?

Accepted Answer

Glutamate is the molecule responsible for the umami taste sensation. It is an amino acid commonly found in many foods, including meat, seaweed, and tomatoes. The other answer choices consist of ions that are not directly related to taste.

Question 17

If genetically engineered bees could express a receptor for TNT in their olfactory neurons,how would the bees respond to the presence of TNT?

Accepted Answer

The response of genetically engineered bees to TNT would depend on which specific olfactory neuron expresses the transgene. Different olfactory neurons can trigger different behaviors, such as attraction or repulsion, depending on the neural circuits they are part of and how they are integrated into the bee's overall sensory and behavioral response system.

Question 18

Unlike sweet,salty,sour,or umami,the "bitter" category of tastants includes wide structural variety of detected molecules.Multiple receptors are required to sense the different bitter tastants.What do they have in common? Bitter taste is thought to have evolved as a warning system for toxic compounds.
-The bitter receptor hTAS2R38 is activated by glucosinolates found in plants such as turnips and broccoli.The gene variant a person has determines how sensitive their neurons are to these compounds.What would you predict for people who have the high-sensitivity variant of hTAS2R38?

Accepted Answer

The high-sensitivity variant of hTAS2R38 would make a person more sensitive to the bitter glucosinolates found in turnips and broccoli. This increased sensitivity could lead to a dislike of turnips and broccoli due to the bitter taste.

Question 19

A single type of receptor is responsible for detecting all tactile pressure in humans.

Accepted Answer

There are multiple types of receptors responsible for detecting tactile pressure, including meissner's corpuscles, pacinian corpuscles, Merkel cells, and Ruffini endings.

Question 20

The discovery that ATP is a pain-signaling factor immediately suggested what possible therapeutic approach to alleviate chronic pain?

Accepted Answer

If ATP is a pain-signaling factor, blocking its receptor could alleviate chronic pain. Therefore, treating with an ATP receptor antagonist (option B) is the best choice.

Quiz 43: Sensory Systems