Biology Q 3

1.

1 point

The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is

to maintain the integrity of a fluid mosaic membrane

to mediate cell-to-cell recognition

to maintain membrane fluidity at low temperatures

to actively transport molecules against their concentration gradients

2.

1 point

Most of the energy that enters electron transport enters as

CO2

ATP

FADH2 and NADH

acetyl CoA

3.

1 point

The final electron acceptor of the electron transport chain that functions in oxidative phosphorylation is

ADP

pyruvate

NAD+

oxygen

4.

1 point

Which of the following is the greatest advantage of having multiple steps in a transduction pathway?

Having multiple steps in a pathway requires the least amount of ATP

Each step can be activated by several G proteins simultaneously

Each individual step can remove excess phosphate groups from the cytoplasm

Having multiple steps provides for greater possible amplification of a signal

5.

1 point

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

It would employ a transduction pathway directly from an external messenger.

It would be able to carry out reception and transduction but would not be able to respond to a signal

It could activate only the epinephrine system

It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane

6.

1 point

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

movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell

movement of water into a cell

movement of carbon dioxide out of a paramecium

7.

1 point

Which of the following statements is correct about diffusion?

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

It requires an expenditure of energy by the cell

It is very rapid over long distances

It requires integral proteins in the cell membrane

8.

1 point

The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell is an example of

diffusion across the lipid bilayer

cotransport

facilitated diffusion

active transport

9.

1 point

In order for a protein to be an integral membrane protein it would have to be

completely covered with phospholipids

amphipathic, with at least one hydrophobic region

exposed on only one surface of the membrane.

hydrophobic

10.

1 point

Asexual reproduction requires __________ individual(s)

1

0

4

2

11.

1 point

Testosterone (a steroid hormone) functions inside a cell by

acting as a steroid signal receptor that activates ion channel proteins

binding with a receptor protein that enters the nucleus and activates specific genes

coordinating a phosphorylation cascade that increases spermatogenesis

becoming a second messenger that inhibits nitric oxide

12.

1 point

The presence of cholesterol in the plasma membranes of some animals

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

enables the animal to add hydrogen atoms to unsaturated phospholipids

makes the animal more susceptible to circulatory disorders

enables the animal to remove hydrogen atoms from saturated phospholipids

13.

1 point

The fluid mosaic model of the membrane proposed that membranes

are a phospholipid bilayer

consist of protein molecules embedded in a fluid bilayer of phospholipids

are a phospholipid bilayer between two layers of hydrophilic proteins

consist of a mosaic of polysaccharides and proteins

14.

1 point

Which of the following would increase the electrochemical gradient across a membrane?

a chloride channel

a potassium channel

a proton pump

a sucrose-proton cotransporter

15.

1 point

What is the reducing agent in the following reaction?

Pyruvate + NADH + H+ → Lactate + NAD+

pyruvate

NAD+

NADH

oxygen

16.

1 point

The genetic material is duplicated during

G2

G1

the S phase.

the mitotic phase

17.

1 point

The light reactions of photosynthesis supply the Calvin cycle with

sugar and O2

H2O and NADPH

Co2 and ATP

ATP and NADPH

18.

1 point

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

on the ER

on the inside surface of the vesicle

on the outer surface of the nucleus

on the inside surface of the cell membrane

19.

1 point

How many ATP molecules are produced by glycolysis?

3

4

1

2

20.

1 point

Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a 0.15 M salt solution become limp and soft. From this we can deduce that

the fresh water is hypertonic and the salt solution is hypotonic to the cells of the celery stalks

the fresh water is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

the fresh water and the salt solution are both hypotonic to the cells of the celery stalks

the fresh water is isotonic and the salt solution is hypertonic to the cells of the celery stalks

21.

1 point

The function of phosphatases in signal transduction is best described as to

amplify the second messengers such as cAMP

inactivate protein kinases and turn off the signal transduction

amplify the transduction signal so it affects multiple transducers

prevent a protein kinase from being reused when there is another extracellular signal