Show:
Membrane Structures and Properties
Passive Transport
Facilitated Diffusion
Active Transport and Energy Dependent Processses
Bulk Transport
100

Which part of a phospholipid is nonpolar and hydrophobic?

  1. Phosphate group

  2. Glycerol backbone

  3. Fatty acid tails

  4. Polar head group

3) Fatty acid tails

100

Which best describes simple diffusion?

  1. Movement of molecules against their concentration gradient, requiring ATP

  2. Movement of molecules from high concentration to low concentration without energy

  3. Movement of water only

  4. Transport using protein channels only













2) Movement of molecules from high concentration to low concentration without energy

100

Which statement best describes facilitated diffusion?

  1. It requires ATP to move substances across a membrane.

  2. It moves molecules down their concentration gradient through a protein.

  3. It pumps molecules against their concentration gradient.

  4. It allows only gases like oxygen and carbon dioxide to cross membranes.

2) It moves molecules down their concentration gradient through a protein.

100

What best defines active transport?

  1. Movement of molecules from high to low concentration without energy.

  2. Movement of molecules against their concentration gradient using energy.

  3. Movement of gases like O₂ and CO₂ directly across the lipid bilayer.

  4. Movement of water through aquaporins down its gradient.

2) Movement of molecules against their concentration gradient using energy.

100

Which of the following processes is used by white blood cells to engulf bacteria?

  1. Exocytosis

  2. Pinocytosis

  3. Phagocytosis

  4. Facilitated diffusion

Answer: 3) Phagocytosis

200

Which statement best describes the “fluid mosaic model” of membranes?

  1. Proteins are fixed in place within the phospholipid bilayer.

  2. Lipids and proteins can move laterally within the bilayer.

  3. Cholesterol molecules form rigid patches that prevent fluidity.

  4. Only lipids move, while proteins remain immobile.

2) Lipids and proteins can move laterally within the bilayer.

200

What process describes water moving across a semipermeable membrane?

  1. Facilitated diffusion

  2. Osmosis

  3. Endocytosis

  4. Exocytosis

2) Osmosis

200

Which molecule is most likely to require facilitated diffusion to cross a cell membrane?

  1. Oxygen (O₂)

  2. Carbon dioxide (CO₂)

  3. Glucose

  4. Fatty acid

3) Glucose

200

Which of the following is an example of active transport?

  1. Oxygen entering a red blood cell.

  2. Sodium being pumped out of a neuron.

  3. Water moving into a plant root by osmosis.

  4. Glucose entering a cell through a channel protein down its gradient.

Answer: 2) Sodium being pumped out of a neuron.

200

What is the main function of exocytosis?

  1. Bringing water into the cell

  2. Releasing large molecules or waste out of the cell using vesicles

  3. Diffusion of gases across the membrane

  4. Pumping ions against their concentration gradient

2) Releasing large molecules or waste out of the cell using vesicles

300

Which factor increases membrane fluidity?

  1. Higher proportion of saturated fatty acids

  2. Lower temperature

  3. Higher proportion of unsaturated fatty acids

  4. Absence of cholesterol

3) Higher proportion of unsaturated fatty acids

300

If a red blood cell is placed in pure distilled water, what happens?

  1. Water enters the cell, and it bursts.

  2. Water leaves the cell, and it shrinks.

  3. No net water movement occurs.

  4. The cell pumps ions to prevent water entry.

1) Water enters the cell, and it bursts.

300

Facilitated diffusion differs from simple diffusion because:

  1. It can move substances against their concentration gradient.

  2. It uses specific proteins to allow certain molecules through.

  3. It always requires energy input.

  4. It can only move ions, not neutral molecules.

2) It uses specific proteins to allow certain molecules through.

300

Why does active transport require energy?

  1. Molecules move in random directions.

  2. It moves substances down their concentration gradients.

  3. It forces molecules into regions where they are already more concentrated.

  4. It only transports gases like O₂.

 3) It forces molecules into regions where they are already more concentrated.

300

Pinocytosis differs from phagocytosis in that pinocytosis:

  1. Requires ATP, while phagocytosis does not

  2. Engulfs small fluid droplets rather than large particles

  3. Releases materials instead of taking them in

  4. Uses carrier proteins rather than vesicles

2) Engulfs small fluid droplets rather than large particles

400

In a mammalian cell exposed to cold, cholesterol helps maintain membrane function by:

  1. Breaking down fatty acid tails to generate heat.

  2. Preventing fatty acid tails from packing too tightly.

  3. Making the membrane more rigid at all temperatures.

  4. Replacing unsaturated fatty acids with saturated ones.

Answer: 2) Preventing fatty acid tails from packing too tightly

400

Why does facilitated diffusion differ from simple diffusion?

  1. Facilitated diffusion requires ATP, while simple diffusion does not.

  2. Facilitated diffusion can move molecules against the concentration gradient.

  3. Facilitated diffusion uses membrane proteins but does not require ATP.

  4. Simple diffusion moves ions, while facilitated diffusion moves water.

3) Facilitated diffusion uses membrane proteins but does not require ATP.

400

Why does facilitated diffusion eventually level off (plateau) when measuring rate vs. concentration?

  1. The concentration gradient disappears.

  2. ATP is depleted.

  3. Transport proteins become saturated.

  4. The membrane becomes impermeable.

3) Transport proteins become saturated.

400

The sodium-potassium pump in animal cells moves:

  1. 3 Na⁺ out and 2 K⁺ in, using ATP.

  2. 2 Na⁺ in and 3 K⁺ out, using ATP.

  3. Only Na⁺ out, without energy.

  4. Only K⁺ in, without energy.

 1) 3 Na⁺ out and 2 K⁺ in, using ATP.

400

A nerve cell releasing neurotransmitters at a synapse is an example of:

  1. Endocytosis

  2. Exocytosis

  3. Facilitated diffusion

  4. Osmosis

Answer: 2) Exocytosis

500

A researcher engineers cells with membranes containing only saturated fatty acids and no cholesterol. Predict the main effect on these cells at low temperatures.

  1. Membranes will remain fluid and functional.

  2. Membranes will become too rigid, reducing protein mobility.

  3. Membranes will become too fluid, causing leakage of ions.

  4. No change will occur compared to normal membranes.

Answer: 2) Membranes will become too rigid, reducing protein mobility.

500

Which situation is the best example of osmosis in living cells?

  1. Oxygen moving into red blood cells

  2. Glucose entering muscle cells via transport proteins

  3. Water moving into plant root cells from soil with lower solute concentration

  4. Sodium ions being pumped out of nerve cells using ATP

3) Water moving into plant root cells from soil with lower solute concentration.

500

Insulin helps cells take up glucose from the blood. Which is the most accurate description of this process?

  1. Insulin increases the rate of glucose diffusion by opening ion channels.

  2. Insulin triggers insertion of glucose transport proteins into the membrane, allowing facilitated diffusion.

  3. Insulin directly pumps glucose into cells using ATP.

  4. Insulin lowers the blood glucose gradient, so diffusion speeds up.

2) Insulin triggers insertion of glucose transport proteins into the membrane, allowing facilitated diffusion.

500

A cell is low on ATP. Which process would be most directly affected?

  1. Diffusion of oxygen into the cell.

  2. Osmosis of water across the membrane.

  3. Uptake of glucose when extracellular concentration is lower than intracellular concentration.

  4. Movement of carbon dioxide out of the cell.

3) Uptake of glucose when extracellular concentration is lower than intracellular concentration.

500

Which statement best explains why bulk transport requires energy?

  1. Vesicles must fuse with or pinch off from the membrane, processes that require ATP.

  2. Molecules move down their concentration gradient, which always costs energy.

  3. Water passes freely through aquaporins, requiring ATP.

  4. Simple diffusion of oxygen is energy-intensive.

Answer: 1) Vesicles must fuse with or pinch off from the membrane, processes that require ATP.