Q: A microbiologist discovers two new types of algae. Organism 1 is cubic (1.5 μm per side), and Organism 2 is rectangular (2 μm × 5 μm × 2 μm). What is the surface area to volume ratio (SA/V) for Organism 1?

$$\text{SA/V} = \frac{13.5\ \mu m^2$}{3.375\ \mu m^3$} = 4.0\ \mu m$$^{-1}$$

Question 1

A microbiologist discovers two new types of algae. Organism 1 is cubic (1.5 μm per side), and Organism 2 is rectangular (2 μm × 5 μm × 2 μm). What is the surface area to volume ratio (SA/V) for Organism 1?

Accepted Answer

$$	ext{SA/V} = \frac{13.5\ \mu m^2$}{3.375\ \mu m^3$} = 4.0\ \mu m$$^{-1}$$

Question 2

Which of the following best explains why Organism 2 (rectangular) will find it more difficult to interact with its environment compared to Organism 1 (cubic)?

Accepted Answer

Organism 2 has a lower surface area to volume ratio, reducing the efficiency of nutrient uptake and waste removal.

Question 3

How might a cell with a low surface area to volume ratio compensate for its reduced capacity to exchange materials with its environment?

Accepted Answer

It may develop specialized transport proteins or increase membrane folding to enhance surface area.

Question 4

Which of the following molecules can cross the plasma membrane by simple diffusion most efficiently?

Accepted Answer

Oxygen ($$O_2)$$

Question 5

Which statement best describes facilitated diffusion?

Accepted Answer

It is the movement of molecules across a membrane with the help of transport proteins, down their concentration gradient.

Question 6

Which of the following is an example of indirect active transport?

Accepted Answer

The sodium/glucose symporter, which uses the $$Na^+$$ gradient to transport glucose against its gradient.

Question 7

A red blood cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

It will swell and may lyse due to water influx.

Question 8

Which of the following best describes the difference between simple diffusion and facilitated diffusion as shown in the rate of diffusion graph?

Accepted Answer

Facilitated diffusion shows a hyperbolic curve due to saturation of transport proteins, while simple diffusion is linear.

Question 9

Which of the following is NOT a characteristic of active transport?

Accepted Answer

It moves molecules down their concentration gradient.

Question 10

Which of the following best describes the function of the Na+/K+ ATPase?

Accepted Answer

It pumps 3 $$Na^+$$ ions out of the cell and 2 $$K^+$$ ions into the cell, using ATP.

Question 11

Which of the following is a correct statement about osmosis?

Accepted Answer

Osmosis is the diffusion of water across a selectively permeable membrane.

Question 12

Which type of membrane transport protein moves two different molecules in opposite directions?

Accepted Answer

Antiporter

Question 13

Which of the following is a real-life example of indirect active transport in human physiology?

Accepted Answer

The sodium/glucose symporter in the intestinal epithelium.

Question 14

Which of the following is true about ligand-gated ion channels?

Accepted Answer

They open in response to the binding of a specific molecule (ligand).

Question 15

A plant cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will undergo plasmolysis as water leaves the cell.

Question 16

Which of the following best describes the role of aquaporins in cells?

Accepted Answer

They facilitate the rapid movement of water across the plasma membrane.

Question 17

Which of the following is a feature of ABC transporters?

Accepted Answer

They use ATP hydrolysis to transport various molecules across membranes.

Question 18

Which of the following is a consequence of a defective CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein in human airway epithelia?

Accepted Answer

Impaired chloride ion transport, leading to thick mucus accumulation.

Question 19

Which of the following best describes the patch clamp technique?

Accepted Answer

It allows the measurement of ionic currents through individual ion channels.

Membrane Transport Mechanisms in Cell Biology

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