Question 1

Soon after a certain molecule enters a cell, the cell begins producing a new type of protein. The molecule was probably a

Accepted Answer

A) receptor molecule. 
B) hydrophilic molecule. 
C) carrier protein. 
D) hydrophobic hormone.

Question 2

After a steroid hormone enters a target cell it

Accepted Answer

A) binds to the nucleus. 
B) becomes a signaling protein. 
C) binds to an internal receptor protein. 
D) becomes a gene.

Question 3

During ____________________ endocytosis, specific substances interact with proteins located on the plasma membrane of the cell.

Accepted Answer

The answer of During ____________________ endocytosis, specific substances interact with...

Question 4

The figure below illustrates a plasma membrane. 
Which solute in the figure is crossing the membrane using simple diffusion?

Accepted Answer

A) Ca2+ 
B) Na+ 
C) K+ 
D) H2O

Question 5

Which of the following signaling molecules would not be found in animals?

Accepted Answer

A) auxin 
B) insulin 
C) adrenalin 
D) acetylcholine

Question 6

Objects suspended in the extracellular fluid can cross the plasma membrane and enter a cell by

Accepted Answer

A) pinocytosis. 
B) receptor-mediated endocytosis. 
C) phagocytosis. 
D) all of the above

Question 7

When the solute concentration outside of a cell is equal to the solute concentration inside of the cell, the cell is in a(n)____________________ solution.

Accepted Answer

The answer of When the solute concentration outside of a...

Question 8

Elevated HDL (high-density lipoprotein)levels seem to provide positive cardiovascular health effects even for individuals with abnormally high blood cholesterol. What best describes the beneficial action of HDL?

Accepted Answer

A) HDL lines the blood vessel walls, preventing the attachment of cholesterol and the consequential inflammation that follows. 
B) HDL is an anti-inflammatory agent; it suppresses the inflammatory response in blood vessel walls following the entry of cholesterol. 
C) HDL has cardio-stimulatory effects; it elevates heart rate and blood pressure in a fashion similar to exercise. 
D) HDL collects surplus cholesterol from peripheral tissues and transports it to the liver, reproductive, and adrenal glands where it is converted to bile or hormones.

Question 9

What best explains the double-headed arrows associated with water, carbon dioxide, and molecular oxygen shown in the illustration below?

Accepted Answer

A) Each molecule is unable to cross the membrane, but can be found in relatively large numbers on both sides. 
B) The membrane is permeable to these small molecules and they enter or leave rapidly as their concentration gradients change. 
C) An isotonic condition exists for each molecule, so no net movement takes place. 
D) Homeostasis requires that surplus molecules entering the cell be rejected and returned to the outside.

Question 10

Even though the concentration of water in a cell remains constant in an isotonic solution, the random movement of water molecules during ____________________ requires that water be constantly moving in both directions across the plasma membrane.

Accepted Answer

The answer of Even though the concentration of water in...

Question 11

Which of the following statements about hormones is false?

Accepted Answer

A) They are not used in the part of the body where they are produced. 
B) They are long-range signaling molecules. 
C) They are not used by multicellular organisms. 
D) They are transported in an organism by fluids.

Question 12

Why do some hormones, like thyroxin, affect most or all body cells while others only affect a single organ or type of cell?

Accepted Answer

A) Because of variations in hormone concentration-when present in high concentration a hormone can stimulate a greater number of body locations. 
B) Because of variations in receptor distribution-all cells or organs with receptors for the hormone will be affected. 
C) Because of variations in membrane permeability-hydrophobic hormones enter and affect all cells, whereas hydrophilic hormones have more limited affects. 
D) Because of variations in signal transduction-only cells with the appropriate enzymes needed to activate the hormone will respond to its signal.

Question 13

Hydrophilic signaling molecules

Accepted Answer

A) move into cells by active transport through carrier protein channels. 
B) bind to cell surface receptors and do not enter cells. 
C) can passively cross the plasma membrane and bind to intracellular receptor proteins. 
D) move directly into the nucleus through carrier proteins that span the distance from the plasma membrane to the nuclear envelope.

Question 14

A white blood cell at the site of a puncture wound engulfs a large cluster of bacteria forming a large internal vesicle. This is an example of

Accepted Answer

A) exocytosis. 
B) pinocytosis. 
C) receptor-mediated endocytosis. 
D) phagocytosis.

Question 15

The figure below shows the movement of solutes across a plasma membrane in the direction indicated by the arrows. 
This movement across the membrane

Accepted Answer

A) requires a direct input of cellular energy. 
B) occurs independently of carrier proteins. 
C) occurs by diffusion. 
D) is an example of osmosis.

Question 16

Hikers can detect a dead skunk along a trail long before they actually see it. What process allows the scent of the skunk to be so widely dispersed?

Accepted Answer

A) osmosis 
B) active transport 
C) diffusion 
D) transduction

Question 17

To coordinate the contraction of the numerous muscle cells that form the heart, signals must travel rapidly between muscle cells. In order to allow this rapid communication, muscle cells in the heart are connected by

Accepted Answer

A) tight junctions. 
B) gap junctions. 
C) anchoring junctions. 
D) carrier proteins.

Question 18

After eating a meal high in carbohydrates, the pancreas begins releasing insulin by the process of ____________________.

Accepted Answer

The answer of After eating a meal high in carbohydrates,...

Question 19

Cell-to-cell communication in humans involves the brain.

Accepted Answer

A) True 
 B)False

Question 20

Passive carrier molecules often require active carrier proteins to provide amino acids for transport.

Accepted Answer