Quizzes for Exam 1

Question 1

If a single layer of phospholipids coats the water in a beaker (NOT A BILAYER), which parts of the molecules will face up into the air?

Answer 1

the hydrocarbon tails

Question 2

The movement of tagged proteins in hybrid cells formed form the fusion of a mice and human plasma membranes best illustrates

Answer 2

support for the fluid-mosaic model

Question 3

Glycoproteins and glycolipids are important for

Answer 3

cell-cell recognition

Question 4

Which of the following is an organelle found in a prokaryotic cell?

Answer 4

none, prokaryotes do not have organelles.

Question 5

Autotrophs use which of the following to power cellular work

Answer 5

ATP

Question 6

basic components of cell theory?

Answer 6

• All cells arise from other cells
• Cells are the most basic unit of life.
• All living organisms are composed of cells.

Question 7

Which of the following can be found in a bacterial chromosome?

Answer 7

DNA

Question 8

The fluidity of membranes in a plant in cold weather may be maintained by increasing the

Answer 8

number of phospholipids with unsaturated hydrocarbon tails.

Question 9

Facilitated diffusion of ions across a cellular membrane requires _________; and the ions move ___________.

Answer 9

channel proteins; down their electrochemical gradient

Question 10

Which of the following is TRUE about osmosis?

Answer 10

• water moves into the cell from a hypotonic solution
• it can occur rapidly though channel proteins call aquaporins
• there is no net osmosis when cells are in an isotonic solution.

Question 11

Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. As a result, these lipid rafts

Answer 11

are more rigid than the surrounding membrane.

Question 12

In a eukaryotic paramecium, cell surface integral membrane proteins are synthesized

Answer 12

by ribosomes bound to the rough endoplasmic reticulum.

Question 13

Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?

Answer 13

Water will leave the cells, causing them to shrivel and collapse.

Question 14

Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?

Answer 14

by increasing the percentage of unsaturated phospholipids in the membrane

Question 15

Which of the following membrane activities require energy from ATP hydrolysis?

Answer 15

Na+ ions moving out of a mammalian cell to reestablish the resting potential of the cell.

Question 16

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?

Answer 16

Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.

Question 17

The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane–more acidic outside the cell than inside the cell. Phosphate transport is an example of

Answer 17

cotransport.

Question 18

Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed.Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?

Answer 18

C

Question 19

Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed.Which line in the graph represents the bag with the highest initial concentration of sucrose?

Answer 19

A

Question 20

Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed.Which line or lines in the graph represent(s) bags that contain a solution that is hypertonic at 50 minutes?

Answer 20

A and B

Question 21

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?

Answer 21

Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).

Question 22

The ATP made during glycolysis is generated by

Answer 22

the action of a kinase enzyme

Question 23

Which of the following is the most correct interpretation of the figure? (ATP cycle)

Answer 23

ATP is a molecule that acts as an intermediary to store energy for cellular work.

Question 24

The primary role of oxygen in cellular respiration is to

Answer 24

act as an acceptor for electrons and hydrogen, forming water.

Question 25

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don’t often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell’s cytosol has a free calcium ion concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting?

Answer 25

ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient.

Question 26

The electrons carried by NADH and FADH2 can be

Answer 26

moved between proteins in the inner membrane of the mitochondria.

Question 27

What is the importance of fermentation to cellular metabolism?

Answer 27

It oxidizes NADH to NAD+ in the absence of O2.

Question 28

Brown fat is special type of fat cell found in human babies and hibernating animals which helps these organisms maintain a high body temperature in hostile environments. Brown fat cells contain mitochondria that express an uncoupling protein located in the inner mitochondrial membrane, thermogenin, that serves as a passive transporter for protons. Brown fat cells can generate ATP and also generate a substantial amount of body heat. What mechanism best explains the role of uncoupling proteins in generating body heat?

Answer 28

The potential energy of the proton gradient is converted to heat as the protons move down the concentration gradient into the matrix.

Question 29

Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide. After inhalation, the oxygen missing from the air will mostly be found in

Answer 29

water

Question 30

In the following redox reaction, _______ is oxidized and _______ is reduced.
Glyceraldehyde 3-phosphate (G3P) + NAD+ + H+ + Pi → 1,3-Bisphosphoglycerate (BPG) + NADH

Answer 30

G3P; NAD+