Exam 1 (Compiled quiz questions)

Question 1

Compare two blood cells, a macrophage and a lymphocyte. Both are spherical, but the diameter of the macrophage is 18 um and the diameter of the lymphocyte is 9 um. By how many times is the volume of the macrophage larger than the volume of the lymphocyte?

Answer 1

2^3 = 8x

Question 2

Compare the concentrations of pH 3 and pH 5… how much higher is the pH of 5 than 3?

Answer 2

pH 5 is 100x higher than pH3

Question 3

Compare concentrations of hydrogen ions at pH3 and pH5.5

Answer 3

pH 5.5 is 300x higher than pH 3

Question 4

MW = 10 kD, concentration = 10 mg/ml. What is the molar concentration?

Answer 4

10,000 mg/ml = 1 M , 10 mg/ml = 1 Mm

Question 5

What is the mass of 1 ml of water?

Answer 5

1 g

Question 6

Suppose you have the same mass per volume concentrations of small molecules X and of large molecules Y. What can you say about their molar concentrations?

Answer 6

Molar concentration of X would be larger than Y

Question 7

How much energy does a typical adult person consume at rest(in Watts)?

Answer 7

100 W

Question 8

True/False

When a volume of nitrogen is mixed with a volume of oxygen, their total energy is reduced.

Answer 8

True

Question 9

Which is true regarding heat?

a) Any form of energy can be turned into heat
b) Heat = temperature
c) Heat cannot be fully converted into other forms of energy

Answer 9

A and C

Question 10

What are the three forms of dry heat?

Answer 10

Conduction, radiation and convection

Question 11

“A common misconception is that soap (increases or decreases) the water’s surface tension. Actually, soap does the exact opposite, therefore it (increases or decreases)

Answer 11

A common misconception is that soap INCREASES the water’s surface tension. Actually soap does the exact opposite therefore it DECREASES surface tension appx 1/3

Question 12

Why does water have a relatively high boiling point?

Answer 12

Molecules are kept together by hydrogen bonds

Question 13

The smallest size that is clearly visible under an optical microscope is close to ____

Answer 13

250 nm

Question 14

Which of these molecules should be able to pass through gap junctions:

a) Hexokinase
b) Glucose
c) Potassium ion
d) Influenza virus

Answer 14

B and C

Question 15

Which of these would form micelles in water?

a) Cholesterol
b) Bile acid
c) Soap
d) Ethanol

Answer 15

B and C

Question 16

Which of the following is true at a time when a reversible reaction L + R ↔LR reaches equilibrium?

a) Kon = Koff
b) Kon[L][R] = Koff[LR]
c) [L]+[R]=[LR]

Answer 16

B) Kon[L][R] = Koff[LR]

Question 17

Calcium binds troponin and initiates muscle contraction. Why does removal of free calcium from the cytosol terminate muscle contraction?

Answer 17

Equilibrium between free and troponin-bound calcium shifts towards dissociation

Question 18

Explain the meaning of turnover number in one sentence

Answer 18

The maximum number of reactions that can be catalyzed by a single enzyme molecule in one second

Question 19

True/False

Most proteins carry a negative charge because their isoelectric point is lower than physiological pH

Answer 19

True, a protein would be neutral at pH equal to its isoelectric point.

Question 20

The height of the energy barrier affects…

Answer 20

Reaction rate

Question 21

Estimate the concentration of H+at pH 2.5

a) 1 mM
b) 3 mM
c) 10 mM

Answer 21

B) 3 mM

Question 22

Using the formula E = 1.4log(C2/C1) calculate the energy stored in the gradient when the concentration is 105times higher on one side than on the other.

Answer 22

1.4log(10^5) = 1.45 = 7 kcal/mol

Question 23

If protons were distributed passively, would you expect a higher, lower or equal pH in the cytosol compared to that of the extracellular fluid? Assume that the membrane potential is negative.

Answer 23

Lower pH in the cytosol
(Positive protons would accumulate in the negatively charged cytosol, a higher concentration of protons means a lower pH)

Question 24

True/False

Both permeant and impermeant solutes contribute to osmolarity

Answer 24

True

Question 25

Some pain receptors are membrane proteins that pass cations, such as Na+or Ca2+, in response to mechanical pressure. Such proteins can be characterized (using the standard nomenclature) as….

Answer 25

Mechanically gated channels

Question 26

In what sense is the term “semipermeable membrane” used in physiology?

Answer 26

Permeable for water, impermeable for some chemicals.

Question 27

How are most large molecules (such as proteins) transported into the cell?

Answer 27

Endocytosis

Question 28

Many molecules are too large to be handled by membrane transporters. In these cases, whole patches of the plasma membrane become involved in transport. The process is called what?

Answer 28

Endocytosis

Question 29

Why do we usually disregard hydrogen ions when calculating osmolarity?

Answer 29

They have low free concentration

Question 30

Osmotic pressure of a 1 M solution of glucose is 25 atm. What does it mean?

Answer 30

If this solution was separated by a semipermeable membrane from pure water, a pressure of 25 atm would have to be applied to the glucose side to prevent water accumulation there.

Question 31

How do we know that the Na/K pump is electrogenic?

Answer 31

More Na+ is exported than K+ imported.

Question 32

Calculate the equilibrium potential for a positive monovalent ion, Cin= 0.1uM, Cout= 10 uM

Answer 32

60log(10/0.1) = 60log(100) = 60*2 = 120 mV

Question 33

If the membrane potential is -30 mV and the equilibrium potential for a positive ion is +30mV, which way would the ion move passively?

Answer 33

Into the cell

Question 34

How would the membrane potential be affected if permeability for Ca2+ increased?

Answer 34

Depolarization, Positive Ca2+ will move inside and make the cell less negative. This depolarization mechanism operates in the heart muscle