bio chap 5

Which of the following statements regarding thermodynamics is false?

An automobile engine is a closed system because it does not exchange energy and matter with its surroundings.

Which of the following statements regarding diffusion is false?

Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

Frequently, transplanted organs are rejected by the recipient's body. How is this reaction related to plasma membranes?

Each person has a unique set of carbohydrate chains attached to his or her plasma membranes.

Which of the following statements regarding enzyme function is false?

Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction.

Which statement regarding enzyme function is true?

Excessive salt ions can cause an enzyme to denature.

What is the basic difference between exergonic and endergonic reactions?

Exergonic reactions release energy; endergonic reactions absorb it.

Which of these statements describes what occurs in facilitated diffusion?

Facilitated diffusion of solutes occurs through protein pores in the membrane.

You are working in the medical tent at an Ironman triathlon. A finisher comes into the tent and appears to be suffering from hyponatremia. Which of the following would be best for you to do?

Give her sodium.

You are a high school soccer coach. One of your players appears to be overheated. Which of the following would be best for you to do?

Have him sit in the shade.

In a theoretical world where all things are possible, how could you increase the amount of energy that could be stored in a molecule of ATP?

Increase the negative charge of each phosphate group.

Which of the following statements about ATP is true?

It releases energy when one phosphate group leaves ATP.

The eukaryotic cell has multiple membrane-enclosed compartments. This evolutionary innovation provides what advantage to the cell?

The different membrane-enclosed spaces allow different parts of the cell to perform specific functions.

According to the second law of thermodynamics, which of the following is true?

The ordering of one system depends on the disordering of another.

A person suffering from hyponatremia has which of the following?

Too little sodium in the bloodstream.

Which of the following processes can move a solute against its concentration gradient?

active transport

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of

active transport.

Membrane phospholipids

are able to drift about in the plasma membrane.

Americans spend up to $100 billion annually for bottled water (41 billion gallons). The only beverages with higher sales are carbonated soft drinks. Recent news stories have highlighted the fact that most bottled water comes from municipal water supplies (the same source as your tap water), although it may undergo an extra purification step called reverse osmosis. Imagine two tanks that are separated by a membrane that is permeable to water, but not to the dissolved minerals present in the water. Tank A contains tap water and tank B contains the purified water. In the reverse osmosis process, pressure is applied to the tap water tank to force the water molecules across the membrane into the pure water tank. After the reverse osmosis system has been operating for 30 minutes, the solution in tank A would

be hypertonic to tank B

Which figure depicts an animal cell placed in a solution hypotonic to the cell?

cell A

Heating inactivates enzymes by

changing the enzyme's three-dimensional shape.

The fluid mosaic model describes the plasma membrane as consisting of

diverse proteins embedded in a phospholipid bilayer.

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of

endocytosis.

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

facilitated diffusion.

You decide to take up running. In the middle of a three mile run, your legs cramp. Which of the following is the most likely cause of this?

fatigue

Which of the following direct energy transfers is impossible in living systems?

heat to light energy

3. There is a net diffusion of water out of an animal cell when it is placed in a(n) _____ solution.

hypertonic

5. A plant cell placed in a(n)_____ solution will lose water and plasmolyze.

hypertonic

2. An animal cell placed in a(n) _____ solution will gain water, swell, and possibly burst.

hypotonic

4. The ideal osmotic environment for a plant cell is a(n) _____ environment.

hypotonic

Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment

is hypotonic to the protozoan.

1. The ideal osmotic environment for an animal cell is a(n) _____ environment.

isotonic

6. A plant cell surrounded by a(n) _____ solution will be flaccid (limp).

isotonic

The mechanism of enzyme action is to _____.

lower the energy of the activation of a reaction

In active transport,

molecules move across the plasma membrane against their concentration gradient.

Hyponatremia is the result of what process?

osmosis

The process of a white blood cell engulfing a bacterium is

phagocytosis.

The transfer of a phosphate group to a molecule or compound is called

phosphorylation.

An energy barrier

prevents the spontaneous breakdown of molecules in the cell.

Most of a cell's enzymes are

proteins

For an enzyme to catalyze a reaction there must be a specific fit between the __________ and the enzyme's __________.

substrate ... active site

Osmosis can be defined as

the diffusion of water.

Plasma membranes are selectively permeable. This means that

the plasma membrane allows some substances to enter or leave a cell more easily than others.

In the reaction A → B + C + heat,

the potential energy of the products is less than that of the reactant.

Which of the following statements is true of an exergonic reaction, but NOT true of an endergonic reaction?

the potential energy of the products is less than the potential energy of the reactants

The active site of an enzyme is

the region of an enzyme that attaches to a substrate.

Which of the following processes is endergonic?

the synthesis of glucose from carbon dioxide and water

Water crosses the plasma membrane

through facilitated diffusion or diffusion.