Question 1

Which of the following best explains why cell membranes are described as 'selectively permeable'?

Accepted Answer

They allow certain molecules to cross more easily than others based on size, charge, and solubility in lipids.

Question 2

Which type of molecule can most easily cross the lipid bilayer of a cell membrane without the help of a transport protein?

Accepted Answer

Small non-polar molecules such as $$\mathrm{O_2$}$$ and $$\mathrm{CO_2$}$$

Question 3

Which of the following statements correctly compares polar and non-polar covalent bonds?

Accepted Answer

Polar covalent bonds are hydrophilic and have unequal sharing of electrons, while non-polar covalent bonds are hydrophobic and have equal sharing of electrons.

Question 4

A scientist observes a molecule moving across a cell membrane from an area of high concentration to an area of low concentration without the use of cellular energy. Which type of transport is this, and which of the following could be involved?

Accepted Answer

Passive transport; simple diffusion or facilitated diffusion

Question 5

Which forms of passive transport require the use of carrier proteins?

Accepted Answer

Facilitated diffusion only

Question 6

After enzymes from the intestine and pancreas break down carbohydrates into monosaccharides, what is the next step in their absorption?

Accepted Answer

They are absorbed into the blood capillaries of the small intestine via facilitated diffusion.

Question 7

Which type of cellular transport is used to move glucose from a region of high concentration in the intestinal lumen to a region of lower concentration in the blood?

Accepted Answer

Facilitated diffusion

Question 8

Where is insulin produced, and what is its primary effect on glucose transport in the body?

Accepted Answer

Produced in the pancreas; increases glucose uptake into cells by promoting insertion of glucose transporters

Question 9

How does the mechanism of insulin deficiency differ between type 1 and type 2 diabetes?

Accepted Answer

Type 1 diabetes involves autoimmune destruction of pancreatic beta cells, leading to little or no insulin production; type 2 diabetes involves insulin resistance and relative insulin deficiency.

Question 10

Which of the following best describes the role of incretin hormones in glucose homeostasis?

Accepted Answer

They increase insulin release after eating and decrease appetite.

Question 11

A patient with type 2 diabetes is given a drug that mimics incretin hormones. What is the expected effect on their physiology?

Accepted Answer

Increased insulin secretion and reduced appetite

Question 12

Where does the majority of protein digestion occur, and what are the end products of this process?

Accepted Answer

In the stomach and small intestine; amino acids and small peptides

Question 13

After proteins are broken down into amino acids, how are these amino acids transported into the blood?

Accepted Answer

By facilitated diffusion through specific carrier proteins in the intestinal epithelium

Question 14

Which of the following best describes the process of lipid digestion and absorption?

Accepted Answer

Lipids are emulsified by bile in the small intestine, broken down by pancreatic lipase into fatty acids and monoglycerides, and absorbed into the lymphatic system.

Question 15

A patient has a genetic defect that prevents the formation of bile salts. Which of the following would most likely be impaired?

Accepted Answer

Emulsification and absorption of dietary lipids

Question 16

Which of the following scenarios best illustrates the difference between active and passive transport?

Accepted Answer

Glucose moving from the blood into a cell against its concentration gradient using ATP is active transport, while oxygen diffusing from the lungs into the blood is passive transport.

Question 17

Which equation best represents the movement of water across a selectively permeable membrane due to osmosis?

Accepted Answer

$$J = -L_p (\Delta P - \sigma \Delta \pi)$$

Question 18

A patient is unable to absorb glucose from the intestine despite normal levels of glucose in the lumen. Which of the following is the most likely cause?

Accepted Answer

Defective sodium-glucose co-transporter (SGLT) proteins in the intestinal epithelium

Question 19

Which of the following best explains why non-polar molecules are able to cross the cell membrane more easily than polar molecules?

Accepted Answer

Non-polar molecules dissolve in the hydrophobic lipid bilayer, allowing them to diffuse through.

Cell Membrane Transport, Digestion, and Hormonal Regulation: Study Guide for Anatomy & Physiology

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