Question 1

Which of the following best explains why negative feedback, but not positive feedback, is essential for maintaining homeostasis in physiological systems?

Accepted Answer

Negative feedback detects changes and triggers responses that counteract deviations from a set point, restoring balance, whereas positive feedback reinforces changes and drives the system further from equilibrium.

Question 2

A patient is given a drug that blocks all voltage-gated sodium channels in neurons. What would be the most immediate effect on neural signaling?

Accepted Answer

Neurons would be unable to generate action potentials, halting signal transmission.

Question 3

Which of the following statements correctly distinguishes between peptide and steroid hormones in terms of their mechanism of action?

Accepted Answer

Peptide hormones bind to cell surface receptors and activate second messenger pathways, while steroid hormones diffuse through the membrane and bind to intracellular receptors to regulate gene expression.

Question 4

A person with type 1 diabetes mellitus forgets to take their insulin. Which of the following best describes the expected changes in their blood glucose regulation?

Accepted Answer

Blood glucose will rise because insulin is absent, preventing glucose uptake by cells.

Question 5

Which adaptation allows marine bony fish to maintain osmotic balance in their environment?

Accepted Answer

They drink large amounts of seawater and excrete excess salts through specialized gill cells.

Question 6

Which of the following best describes the role of the hypothalamus in the neuroendocrine system?

Accepted Answer

It integrates neural and endocrine signals and controls the pituitary gland, which releases hormones affecting other endocrine glands.

Question 7

Which of the following is a correct sequence of events in the sliding-filament model of muscle contraction?

Accepted Answer

Calcium binds to troponin, tropomyosin shifts, myosin binds to actin, and the sarcomere shortens.

Question 8

Which of the following best explains why countercurrent exchange in fish gills is more efficient than concurrent exchange for gas uptake?

Accepted Answer

Countercurrent exchange maintains a gradient for oxygen diffusion along the entire length of the gill, maximizing oxygen uptake.

Question 9

Which of the following is a function of the large intestine in mammals?

Accepted Answer

Absorption of water and formation of feces.

Question 10

A plant growing in a dry, hot environment is found to have a low stomatal density. What is the most likely advantage of this adaptation?

Accepted Answer

It reduces water loss by limiting the number of openings for evaporation.

Question 11

Which of the following best describes the function of mycorrhizae in plant nutrition?

Accepted Answer

They increase the surface area for water and mineral absorption, especially phosphorus.

Question 12

Which hormone is released from the posterior pituitary and is responsible for stimulating uterine contractions during childbirth?

Accepted Answer

Oxytocin

Question 13

Which of the following best describes the process of pressure flow (bulk flow) in phloem transport in plants?

Accepted Answer

Water follows sugars osmotically from the source to the sink, creating a pressure gradient that drives bulk flow.

Question 14

Which of the following is a correct pairing of a sensory receptor type with the stimulus it detects?

Accepted Answer

Chemoreceptors – chemical signals

Question 15

Which of the following best explains the difference between innate and adaptive immunity?

Accepted Answer

Innate immunity provides a rapid, general defense against pathogens, while adaptive immunity develops more slowly and targets specific antigens.

Question 16

Which of the following best describes the role of the Casparian strip in plant roots?

Accepted Answer

It blocks the apoplastic route, forcing water and solutes to cross the plasma membrane of endodermal cells for selective uptake.

Question 17

Which of the following scenarios illustrates positive feedback in a physiological process?

Accepted Answer

Release of oxytocin during childbirth, intensifying uterine contractions.

Question 18

Which of the following best describes the function of the nephron in the mammalian kidney?

Accepted Answer

It filters blood, reabsorbs needed substances, secretes wastes, and produces urine.

Question 19

Which of the following is a correct description of the role of the adrenal gland during the 'fight or flight' response?

Accepted Answer

It secretes epinephrine and cortisol, increasing heart rate, blood pressure, and blood glucose.

BIO 311D Exam 3 Study Guide: Homeostasis, Nutrition, Transport, and Response in Animals and Plants

Study Guide - Practice Questions

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