Practice Questions - Week 1

Question 1

If two substances had the same molecular weight but one was more soluble in lipids than the other, which would pass through the plasma membrane of a red blood cell the quickest?

Answer 1

The one with the highest lipid solubility

Question 2

If you were a well-paid scientist working for a big drug company and were given the task of improving the delivery of a new wonder drug INTO red blood cells, which of the following strategies might you adopt?

1. Increasing the size of the molecule
2. Increasing the lipid solubility of the molecule
3. Decreasing the size of the molecule

Answer 2

2 and 3 only

Question 3

The mechanisms by which substances move across the plasma membrane without the expenditure of metabolic energy are collectively known as?

Answer 3

passive processes

Question 4

Which of the following statements about simple diffusion is TRUE?

1. the smaller the molecule the lower the rate of diffusion
2. diffusion occurs because of the continual random motion of the molecules
3. substances diffuse from a region of lower concentration to a region of higher concentration
4. large molecules travel further than small molecules following a collision
5. the smaller the surface area of a cell the more rapidly substances can diffuse across its membrane

Answer 4

diffusion occurs because of the continual random motion of the molecules

Question 5

Which of the following statements about facilitated diffusion is TRUE?

1. the smaller the surface area of a cell the more rapidly substances can diffuse across its membrane
2. substances diffuse from a region of lower concentration to a region of higher concentration
3. large molecules travel further than small molecules following a collision
4. the smaller the molecule the lower the rate of diffusion
5. diffusion occurs because of the continual random motion of the molecules

Answer 5

diffusion occurs because of the continual random motion of the molecules

Question 6

Which of the following molecules can move across the plasma membrane of cells by facilitated diffusion?

1. soluble vitamins
2. amino acids
3. enzymes

Answer 6

1 & 2 only

Question 7

Which of the following substances is/are transported across the plasma membrane of cells by receptor-mediated endocytosis?

1. cholesterol.
2. sodium.
3. insulin.

Answer 7

1 & 3 only

Question 8

The mechanism by which macrophages and some white blood cells are able to ingest cellular debris is known as?

Answer 8

phagocytosis

Question 9

The rate of diffusion of a molecule is inversely related to its molecular radius because?

Answer 9

small molecules bounce further than larger molecules following a collision with another molecule

Question 10

Which of the following statements about diffusion is FALSE?

1. The greater the distance the slower the rate of diffusion
2. The rate of diffusion is directly proportional to molecular size
3. The rate of diffusion is directly proportional to the surface area of the membrane
4. The greater the concentration gradient the faster the rate of diffusion
5. The rate of diffusion is inversely proportional to the thickness of the membrane

Answer 10

The rate of diffusion is directly proportional to molecular size

Question 11

A solution made up of 0.9 g of glucose dissolved in 100 ml of water will have an osmolarity of?

Answer 11

50 mOsm.L-1

Question 12

Which of the following routes can water use to traverse the plasma membrane of most cells?

    1. straight through both the lipid bilayer

    2. through ion channels

    3. solute pumping

Answer 12

1 & 2 only

Question 13

Which of the following statements about diffusion is TRUE?

1. The rate of diffusion is unrelated to the surface area of the membrane
2. The greater the concentration gradient the slower the rate of diffusion
3. The rate of diffusion is inversely proportional to molecular size
4. The rate of diffusion is directly proportional to the thickness of the membrane
5. The greater the distance the higher the rate of diffusion

Answer 13

The rate of diffusion is inversely proportional to molecular size

Question 14

For any substance passing through a membrane by diffusion, the rate of diffusion of this substance will do which of the following?

1. be inhibited at 39oC
2. increase as the temperature decreases
3. be unaffected by temperature
4. increase as the temperature increases
5. decrease as the temperature increases

Answer 14

increase as the temperature increases