Question 1

Which of the following best describes homeostasis in biological systems?

Accepted Answer

The maintenance of a stable internal environment despite external fluctuations.

Question 2

In the signal transduction pathway shown, what is the role of cAMP?

Accepted Answer

It is a second messenger that activates protein kinase A.

Question 3

Why can't adenylyl cyclase directly activate protein kinase A in the signal transduction pathway?

Accepted Answer

Adenylyl cyclase produces cAMP, which acts as a secondary messenger to activate protein kinase A.

Question 4

Which of the following is an example of a cellular response in a signal transduction pathway?

Accepted Answer

Phosphorylation of target proteins by protein kinase A.

Question 5

Based on the graph comparing river otters and largemouth bass, which statement is correct?

Accepted Answer

River otters maintain a constant body temperature regardless of environmental temperature.

Question 6

Which equation best represents the relationship between body temperature ($$T_b) $$and ambient temperature ($$T_a) $$for an ectotherm?

Accepted Answer

$$T_b = T_a$$

Question 7

What is the main difference between endotherms and ectotherms?

Accepted Answer

Endotherms use internal mechanisms to regulate body temperature, while ectotherms' body temperature depends on the environment.

Question 8

Which of the following is an example of negative feedback in homeostasis?

Accepted Answer

When blood glucose rises, insulin is released to lower it back to normal.

Question 9

A person skips a meal and their blood glucose level falls. Which hormone is released and what is its effect?

Accepted Answer

Glucagon is released, causing the liver to break down glycogen and release glucose.

Question 10

Which of the following best illustrates positive feedback?

Accepted Answer

Release of oxytocin during childbirth, increasing uterine contractions.

Question 11

In a home heating system, what component acts as the sensor in the feedback loop?

Accepted Answer

The thermostat

Question 12

Which of the following is NOT a variable regulated by homeostasis in humans?

Accepted Answer

Hair color

Question 13

A patient with diabetes drinks a sugary beverage. What is the expected physiological response in a healthy individual?

Accepted Answer

Insulin is released, causing body cells to take up more glucose and the liver to store glucose as glycogen.

Question 14

Which of the following best describes the sequence of events in a negative feedback loop?

Accepted Answer

Stimulus → Sensor → Response → Return to set point

Question 15

Which formula represents the normal range for blood glucose concentration in humans?

Accepted Answer

$$70 \leq 	ext{Blood glucose (mg/100 mL)} \leq 110$$

Question 16

Which scenario would most likely trigger a negative feedback response in the human body?

Accepted Answer

A sudden drop in blood pH below the normal range.

Question 17

Which of the following is a plausible reason for using a secondary messenger like cAMP in cell signaling?

Accepted Answer

Secondary messengers allow for amplification and diversification of the signal within the cell.

Question 18

A snake's body temperature increases as the ambient temperature rises. What does this indicate about the snake's thermoregulation?

Accepted Answer

The snake is an ectotherm and a temperature conformer.

Question 19

During childbirth, which hormone is released in response to the baby's head pushing against the cervix, and what is its effect?

Accepted Answer

Oxytocin; stimulates uterine contractions.

Question 20

Which of the following best explains why negative feedback is essential for homeostasis?

Accepted Answer

It counteracts deviations from the set point, maintaining internal stability.

Homeostasis and Feedback Mechanisms in Animals

Study Guide - Practice Questions