Biology Exam 2

A patient was involved a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water — equal to the volume of blood lost — is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.

A sodium-potassium pump _____.

move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle

Cell membranes are asymmetrical. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

The two sides of a cell membrane face different environments and carry out different functions.

Diffusion _____.

is a passive process in which molecules move from a region of higher concentration to a region of lower concentration

For a protein to be an integral membrane protein, it would have to be _____.

amphipathic, with at least one hydrophobic region

In what way do the membranes of a eukaryotic cell vary?

Certain proteins are unique to each membrane.

Membrane proteins are not very soluble in water, because they possess long stretches of non-polar amino acids that are _____.

hydrophobic.

The membranes of winter wheat are able to remain fluid when it is extremely cold by _____.

increasing the percentage of unsaturated phospholipids in the membrane

The presence of cholesterol in the plasma membranes of some animals _____.

enables the membrane to stay fluid more easily when cell temperature drops.

The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. After the system reaches equilibrium, what changes are observed?

The water level is higher in side A than in side B.

The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Initially, in terms of tonicity, the solution in side A with respect to the solution in side B is _____.

isotonic

What kinds of molecules pass through a cell membrane most easily?

small and hydrophobic

When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?

The cell will become turgid.

Which of the following allows water to move much faster across cell membranes?

aquaporins

Which of the following is true of osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

Which of the following processes includes all others?

passive transport

Which of the following types of molecules are the major structural components of the cell membrane?

phospholipids and proteins

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO₂

Which of these are NOT embedded in the hydrophobic portion of the lipid bilayer at all?

peripheral proteins

A drug binds to the active site of an enzyme. If it is bound to the active site of the enzyme, it prevents substrate binding. This drug would be considered a(n)

competitive inhibitor.

A particular chemical reaction is exergonic. What can you say about the relationship between the reactants and the products in this exergonic reaction?

The reactants have more free energy than the products.

Energy is defined as

the capacity to do work.

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

by changing the shape of the enzyme's active site.

If the ΔG of a reaction was -31.45 kJoules, you would know that:

the reaction is spontaneous.

Metabolic reactions fall under two general categories: anabolic and catabolic. What type of chemical reactions are these two classes of metabolic reactions?

Anabolic reactions are endergonic reactions, whereas catabolic reactions are exergonic.

The Law of Thermodynamics that states that energy cannot be created or destroyed is:

The First Law of Thermodynamics.

The Law of Thermodynamics that states that increases in entropy are favored is:

The Second Law of Thermodynamics.

The active site of an enzyme is the region that

is involved in the catalytic reaction of the enzyme.

The chemistry of living systems representing all chemical reactions is called

metabolism.

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following is correct?

ΔG is the change in free energy.

The synthesis of sugar molecules through the process of photosynthesis requires energy absorbed from sunlight. Bearing this in mind, what kind of reaction is photosynthesis?

endergonic.

Whenever energy is transformed, there is always an increase in the

entropy of the universe.

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy.

Which of the following is true for anabolic pathways?

They consume energy to build up polymers from monomers.

Which of the following statements regarding enzymes is true?

Enzymes increase the rate of a reaction by lowering the activation energy barrier.

Which of the following types of reactions would decrease the entropy within a cell?

anabolic reactions.

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

catabolism.

Why do we have storage macromolecules, such as fats, in our bodies?

We can break down these macromolecules to provide energy for the endergonic reactions in our bodies.

Why is ATP an important molecule in metabolism?

It provides energy coupling between exergonic and endergonic reactions.

Every ecosystem must have _____.

autotrophs.

In a plant cell, where are the ATP synthase complexes located?

thylakoid membrane and inner mitochondrial membrane.

In a plant, the reactions that produce molecular oxygen (O2) take place in _____.

the light reactions alone.

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____.

photosynthesis and respiration.

Plants photosynthesize _____.

only in the light but respire in light and dark.

What wavelength of light in the figure is most effective in driving photosynthesis?

420 mm.

What is the primary function of the Calvin cycle?

synthesize simple sugars from carbon dioxide.

Where do the carbon atoms in glucose come from?

Carbon dioxide.

Where does the Calvin cycle take place?

stroma of the chloroplast.

Which of the following does NOT occur during the Calvin cycle?

release of oxygen.