Question 1

Growth and development in all insects include both molting and metamorphosis.

Accepted Answer

Not all insects undergo metamorphosis. While all insects molt to grow, some, like silverfish, do not undergo metamorphosis; they grow through a series of molts without significant changes in form.

Question 2

Blood glucose levels are regulated by _____, in which an increase or decrease in glucose signals the pancreas to stop producing glucagon or insulin, respectively.

Accepted Answer

negative feedback

Question 3

Which of the following statements about nervous and endocrine signaling is NOT true?

Accepted Answer

This statement is not true as there is direct communication between the nervous system and endocrine system through the hypothalamus and pituitary gland.

Question 4

Calcium levels in the blood are primarily maintained through the interactions of two different hormones: calcitonin and parathyroid hormone. Based on your understanding of homeostasis through feedback mechanisms, we could also describe the action of these hormones as:

Accepted Answer

Calcitonin works to lower blood calcium levels by promoting its deposition in bones, while parathyroid hormone works to increase blood calcium levels by promoting its release from bones, absorption from the intestines, and reabsorption from the kidneys. These two hormones have opposite actions on blood calcium levels, demonstrating the concept of feedback mechanisms in homeostasis.

Question 5

Consider the positive feedback that regulates mammalian childbirth. In this process, the pituitary gland is _____, oxytocin is _____, and a uterine contraction is _____.

Accepted Answer

The pituitary gland releases oxytocin, which stimulates uterine contractions. The uterine contractions are the response to the stimulus of oxytocin.

Question 6

Which of the following is NOT a function of the endocrine system?

Accepted Answer

All of these choices are functions of the endocrine system. The endocrine system plays a role in responding to the environment, coordinating body processes, regulating growth, and regulating development.

Question 7

Type 1 and type 2 diabetes mellitus have different underlying causes. Type 1 diabetes is characterized by a loss of the insulin-producing cells of the pancreas, leading to insulin deficiency. Type 2 diabetes, at least in its early stages, is characterized by a loss of sensitivity to the hormone insulin by cells that normally respond to the hormone. Which step labeled in the diagram is inhibited in BOTH type 1 and type 2 diabetes (either directly or indirectly)?

Accepted Answer

The answer of Type 1 and type 2 diabetes mellitus...

Question 8

In the late 1960s, Carroll Williams and Karel Salma discovered that the insect Pyrrhocoris apterus, when grown in jars with paper towels made from balsam fir, underwent several extra larval molts and finally died without completing metamorphosis. Further investigation led to the conclusion that the fir trees synthesize a hormonal analog that acts as an insecticide. Which hormone is this natural insecticide mimicking?

Accepted Answer

The insecticide mimics juvenile hormone, which is responsible for maintaining the larval stage of insects and preventing metamorphosis into the adult stage. Just like the natural insecticide synthesized by the balsam fir, synthetic juvenile hormone analogs are also used as insecticides.

Question 9

It has been discovered that many plants synthesize molecules that destroy the corpora allata, which are the structures responsible for synthesis of juvenile hormone, and that insects exposed to these molecules do not molt. Which of the following statements reflects how levels of juvenile hormone disrupt the insect life cycle?

Accepted Answer

The answer of It has been discovered that many plants...

Question 10

In response to low sugar levels in the blood, the hormone glucagon is released by the pancreas. In a negative feedback system, the pancreas would represent the _____ of the system.

Accepted Answer

In a negative feedback system, the effector is the component that responds to the stimulus and works to reverse or counteract the original change. In this case, the pancreas releases glucagon in response to low blood sugar levels, which is the effector of the system. The sensor would be the component that detects the change in the system (such as a glucose-sensing receptor on a pancreatic cell), the stimulus would be the low blood sugar levels, and the response would be the increase in blood glucose levels due to the actions of glucagon.

Question 11

If you were to remove the prothoracic glands from the insect larva, what would you expect the results to be? The larva would:

Accepted Answer

The prothoracic glands stimulate the molting process in insects, so removal of these glands would prevent the insect larva from molting again. Therefore, the larva would remain in its current developmental stage and never molt again. It would not pupate or emerge as an adult since these processes require molting.

Question 12

Hormones are typically involved in maintaining _____, which is a given steady state for a particular factor (such as sugar or calcium levels in the blood).

Accepted Answer

Hormones are an important part of the endocrine system and play a major role in maintaining homeostasis, which is the steady state of factors within the body such as temperature, pH, and glucose levels. Hormones can help regulate these factors to keep them within a normal range and prevent fluctuations that could be harmful to the body.

Question 13

Hormones that help maintain homeostasis typically operate through a negative feedback system.

Accepted Answer

Hormones that help maintain homeostasis typically operate through a negative feedback system, where a stimulus causes the release of a hormone that works to counteract the stimulus and return the body to a balanced state. This helps to maintain stability in the body's internal environment.

Question 14

Positive and negative feedback systems have all the same components (that is, stimulus, sensor, effector, and response). The primary difference between the two is that the response in a positive feedback system stimulates the sensor.

Accepted Answer

Both positive and negative feedback systems share the same basic components, but in positive feedback, the response amplifies the initial stimulus, enhancing the sensor's activity, whereas in negative feedback, the response reduces the stimulus.

Question 15

What is an example of positive feedback involving hormones?

Accepted Answer

During childbirth, increased levels of oxytocin hormone cause the uterine contractions to intensify, which further stimulates the release of more oxytocin, creating a positive feedback loop. This ultimately leads to the delivery of the baby.

Question 16

What is the difference between negative feedback and positive feedback mechanisms?

Accepted Answer

Negative feedback mechanisms work to return a system to a set point by counteracting any changes that move the system away from that set point. Positive feedback mechanisms, on the other hand, amplify a response and move the system further away from the set point. Therefore, A is the correct answer as it accurately describes the difference between negative and positive feedback mechanisms.

Question 17

When a doctor suspects that a patient may have diabetes, she will often have the patient take a glucose challenge test. After the patient drinks a large amount of sugary solution, his blood is drawn and the circulating levels of glucose in the blood are determined. Which of the following curves do you expect from a patient with diabetes?

Accepted Answer

The answer of When a doctor suspects that a patient...

Question 18

In the late 1960s, Carroll Williams and Karel Salma discovered that the insect Pyrrhocoris apterus, when grown in jars with paper towels made from balsam fir, underwent several extra larval molts and finally died without completing metamorphosis. Further investigation led to the conclusion that the fir trees synthesize a hormonal analog that acts as an insecticide. The molecule is actually an analog of juvenile hormone. Furthermore, the juvenile hormone analog discovered by Salma and Williams has no effect on most other metamorphosing insects, suggesting that:

Accepted Answer

The fact that the juvenile hormone analog discovered by Salma and Williams has no effect on most other metamorphosing insects suggests that there has been some evolutionary divergence in the structure of juvenile hormone and in the juvenile hormone receptors of different insects. This would explain why the balsam fir molecule only affects Pyrrhocoris apterus and not other insect species.

Question 19

Hormones are involved in which of the following processes?

Accepted Answer

Hormones are involved in many different processes in the body, including molting (shedding of exoskeletons) in insects, regeneration of body parts in starfish, regulating sleep and wake cycles in animals such as lions, and maintaining blood sugar levels in humans. Therefore, all of the choices listed are correct.

Question 20

You call an exterminator to your house because you have noticed many nymphs of a specific insect everywhere in your cupboards. The exterminator proudly tells you that they are using biological concepts to get rid of these pests, and he generously sprays a solution of juvenile hormone all over your house. Assuming there are no breeding adults and only nonreproductive nymphs, which of the following would you expect in the days after the visit from the exterminator?

Accepted Answer

The juvenile hormone sprayed by the exterminator will prevent the nymphs from maturing into adults, but it will not immediately kill them. Therefore, the number of nymphs will remain the same in the days after the spraying. However, without any breeding adults, there will be no new nymphs to replace the ones that do eventually die off.

Quiz 38: Animal Endocrine Systems