Biology Questions

6.

In the absence of specific carrier proteins, which of the following can
diffuse readily across the plasma

membrane of a cell? ATP, glucose, amino acids, fatty acids, water,
gases, proteins, ions, polysaccharides,

glycerol, hemoglobin, ethanol.

7.

Using artificial liposomes researchers showed that phospholipid bilayer
membranes containing different amounts

of cholesterol have different permeability to glycerol. What was the
observed relationship between cholesterol

content and glycerol permeability? How can the effect of cholesterol be
explained? What other experimental

variable used in these experiments affected membrane permeability (and
membrane fluidity) in a consistent way?

What was the effect observed in this case and what is a reasonable
explanation for the observed effect?

8.

Cells of fish that live in the near-freezing waters off Alaska are
likely to have bilayer membranes that contain

phospholipids with what kinds of tails? How much cholesterol are their
membranes likely to contain (only a little,

a moderate amount, or a lot?)?

12.

How does “active transport� of material across membranes differ from
the movement of material across membranes

via channel proteins and transport proteins? How can dissolved materials
be moved from the outside to the inside

of a cell when the inside concentration of the material is already high?
What, if any, is the difference between

facilitated diffusion and passive transport?

22.

The components of the cytoskeleton consist of microfilaments,
intermediate filaments and microtubules. Which

component is involved in movement of organelles (transport vesicles),
chromosome movement and cell motility

involving flagella or cilia? Is vesicle transport an energy-dependent
process? How did researchers find the answer

to this question? Will transport along microtubules occur in a mixture
of purified microtubules, purified vesicles

and ATP? What protein component was ultimately isolated from the soluble
fraction of cell extracts that acts as the

“motor� for vesicle transport? How does it work?

23.

Assume a cell is respiring aerobically and is using glucose as an energy
source. What is the ultimate fate of

each of the 6 carbon atoms in a glucose molecule that begins the aerobic
pathway (i.e., what happens to each of the

carbons and where does it happen)?

28.

List all of the products of glycolysis in decreasing order of the amount
of chemical energy they contain as

single molecules. [Note: Intermediate compounds are not products.]

30.

Can proteins be used by your cells as a source of chemical energy to
make ATP? Explain.

35.

Many plant cells, such as root cells, lack chloroplasts. How do plant
cells that lack chloroplasts produce the

ATP they need? (Hint: they don't do it by photosynthesis). Do plant
cells that contain chloroplasts also contain

mitochondria? Why or why not?

37.

How would poisoning the electron transport system associated with the
light-dependent reactions of

photosynthesis affect the light-independent reactions?

40.

What is MPF? Is it different in different species of eukaryotes? MPF
protein kinase is relatively constant

across the cell cycle. How, then, can it be a trigger for initiating
M-Phase? What is the relationship of cyclin to

MPF? What “activates� MPF and when does this activation occur? What
causes the MPF concentration to decline sharply

during M-Phase?

44.

In what way are the structures of mitochondria and chloroplasts similar
and different? What molecules or

systems function in both types of organelles? Which enzymes or processes
are unique to each organelle?

45.

A photosynthesizing plant is exposed to CO2 molecules containing
radioactively labeled carbon atoms (14C02).

What stable intermediate in the light-independent pathway (the Calvin
Cycle) is the one in which the labeled carbon

will first appear?

47.

What are the overall inputs (substrates and energy sources) and outputs
(products and by products) for the

light-dependent reactions of photosynthesis and the light-independent
reactions of photosynthesis? How are the

light-dependent and light-independent parts of photosynthesis coupled?
Where do the reactions of the light-

dependent part of photosynthesis take place? the light-independent
reactions?