Question 1

A concentration ________ is said to exist when a molecule is more abundant in one area than it is in another.

Accepted Answer

The answer of A concentration ________ is said to exist...

Question 2

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

HDL collects excess cholesterol from peripheral tissues and transports it to the liver, adrenal glands, and reproductive organs where it is converted into bile or hormones. This prevents cholesterol buildup in the blood vessels, reducing the risk of blockages and heart disease.

Question 3

Which of the following statements about hormones is FALSE?

Accepted Answer

Hormones are used by multicellular organisms as signaling molecules to coordinate and regulate various physiological processes. Therefore, statement C is false.

Question 4

The human hormone insulin is produced only by a single organ,the pancreas,yet insulin is used to move glucose from the bloodstream into cells all over the body.What aspect of hormones makes it possible for insulin to work throughout the body?

Accepted Answer

Hormones are long-range signaling molecules, enabling insulin to work throughout the body despite being produced in only one organ (the pancreas).

Question 5

The passive movement of water across a selectively permeable membrane is called ________.

Accepted Answer

The answer of The passive movement of water across a...

Question 6

Hydrophilic signaling molecules

Accepted Answer

Hydrophilic signaling molecules are not able to pass through the hydrophobic lipid bilayer of the plasma membrane, so they bind to cell-surface receptors instead. This binding initiates a cascade of intracellular signaling events that ultimately lead to a cellular response. Some hydrophilic signaling molecules may also bind to receptor proteins inside the cell, but they do not cross the plasma membrane on their own.

Question 7

Muscle cells require high concentrations of calcium to function properly.As a result,these cells use ________ transport to move calcium from areas of low concentration outside the cell into the cytoplasm.

Accepted Answer

The answer of Muscle cells require high concentrations of calcium...

Question 8

Water moves across a membrane from a hypotonic solution to a ________ solution.

Accepted Answer

The answer of Water moves across a membrane from a...

Question 9

After a sex hormone enters a target cell,it

Accepted Answer

Sex hormones typically bind to internal receptor proteins located in the cytoplasm or nucleus of the target cell. Once the hormone binds to the receptor, the hormone-receptor complex undergoes a conformational change and moves into the nucleus, where it can bind to specific DNA sequences and regulate gene expression. Therefore, the correct choice is C, which states that the hormone binds to an internal receptor protein.

Question 10

Lipids often move within the body in complexes known as lipoproteins;what advantage does this strategy provide?

Accepted Answer

Lipoproteins provide an advantage because their protein component serves as an identifier for cells needing lipids. This allows cells to use membrane receptors to acquire only as much lipid as they need at any given moment. This helps prevent an excess buildup of lipids in cells and tissues, which can lead to negative health consequences such as atherosclerosis. Additionally, lipoproteins can be further transported to the liver and kidneys for disposal or modification, rather than diffusing into adjacent cell membranes as free lipids would do.

Question 11

For a cell to be a target for a particular hormone,it must usually

Accepted Answer

A cell must have a specific receptor for a particular hormone in order for the hormone to bind to and affect the cell. Having an ATP source or being larger than normal is not necessary for hormone targeting. A cell does not need a receptor for any hormone, only for the specific hormone it is targeted by.

Question 12

Cell signaling

Accepted Answer

Cell signaling can be fast or slow depending on the type of signal and the pathway involved. Some signaling pathways involve immediate responses (such as opening ion channels), while others may result in long-term changes in gene expression. Cell signaling occurs in plants as well as in other organisms.

Question 13

The concentration of solutes is higher within the mitochondria than it is in the cytosol.Therefore,the cytosol is ________ to the inside of the mitochondrion.

Accepted Answer

The answer of The concentration of solutes is higher within...

Question 14

Many hormones are large and hydrophilic.Where would you expect the receptor proteins for these hormones to be located?

Accepted Answer

Receptor proteins for large and hydrophilic hormones are typically located in the cell membrane with the hormone-binding site exposed to the cell exterior. This allows the hormone to bind to the receptor on the outside of the cell and initiate a signal that is transmitted inside the cell.

Question 15

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

Accepted Answer

The fact that the molecule is able to enter the cell suggests that it is a hydrophobic molecule, as only hydrophobic molecules can cross the hydrophobic plasma membrane of the cell without the help of transport proteins. Furthermore, the production of a new type of protein suggests that the molecule is a hormone, which typically act as signals that trigger cellular responses. Therefore, the best choice is option D, hydrophobic hormone.

Question 16

Short-lived signaling molecules are most effective for

Accepted Answer

Short-lived signaling molecules are most effective for local cell-to-cell communication because they are quickly degraded and do not have the ability to travel long distances. Long-distance cell-to-cell communication requires signaling molecules that are more stable and can travel through the bloodstream or extracellular fluid to reach their target cells. Short-lived signaling molecules also do not have the ability to activate genes in the nucleus or break down receptor proteins.

Question 17

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

Accepted Answer

Auxin is a plant hormone involved in plant growth and development. It would not be found in animals. The other options (insulin, adrenaline, and testosterone) are all signaling molecules found in animals.

Question 18

Some hormones,like thyroxine,affect most or all body cells,while others only affect a single organ or type of cell.This is because of variations in

Accepted Answer

The varying effects of hormones are due to receptor distribution. Only cells or organs with receptors for a particular hormone will be affected by its signal, resulting in selective targeting of certain cells or tissues. Hormones like thyroxine that affect most or all cells have receptors that are widely distributed throughout the body.

Question 19

Elevated cholesterol and LDL (the particles that transport cholesterol)have been strongly associated with vascular disease;what process(es)lead to the elevated levels?

Accepted Answer

Elevated cholesterol levels can be caused by excessive absorption of cholesterol from the GI tract. This can occur due to a diet high in cholesterol and saturated fats, as well as genetic factors that affect how efficiently the body absorbs and processes cholesterol. When excess cholesterol accumulates in the bloodstream, it can eventually lead to the formation of fatty deposits on the walls of arteries, which can increase the risk of cardiovascular disease.

Question 20

Signaling molecules can be "tagged" by attaching glow-in-the-dark molecules to them.After adding tagged signaling molecules to the fluid around several cells,you observe the cells with a microscope designed to see the glow-in-the-dark molecules.After a few minutes,you notice that the plasma membrane of some of the cells begins to glow.This observation indicates that some cells

Accepted Answer

The fact that some cells' plasma membranes begin to glow after adding tagged signaling molecules suggests that these cells have receptors that bind to the signaling molecules, causing the glow. This is indicative of a cellular response to the signaling molecule.

Quiz 4: Cell Membranes, Transport, and Communication