Q: A student measures a specimen under a microscope. The specimen is 2.5 mm long in the image, the field of view (FOV) in the image is 7.5 mm, and the actual FOV is 450 \mu m. What is the actual length of the specimen in \mu m?

$$\frac{2.5}{7.5} \times 450 = 150\ \mu m$$

Question 1

A student measures a specimen under a microscope. The specimen is 2.5 mm long in the image, the field of view (FOV) in the image is 7.5 mm, and the actual FOV is 450 \mu m. What is the actual length of the specimen in \mu m?

Accepted Answer

$$\frac{2.5}{7.5} 	imes 450 = 150\ \mu m$$

Question 2

Why are cells generally small in size rather than large?

Accepted Answer

Small cells have a larger surface area-to-volume ratio, allowing efficient exchange of materials with their environment.

Question 3

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A double layer of phospholipids with proteins and other molecules embedded throughout, allowing selective permeability.

Question 4

Which type of molecule can most easily diffuse through the phospholipid bilayer of the plasma membrane?

Accepted Answer

Small, nonpolar molecules such as $$O_2$$ and $$CO_2$$

Question 5

A red blood cell is placed in a 10% NaCl solution. What will happen to the cell, and why?

Accepted Answer

The cell will shrink because water will move out of the cell into the hypertonic solution.

Question 6

Which process requires energy input from the cell and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 7

A plant cell is placed in a hypotonic solution. What is the expected outcome?

Accepted Answer

The cell will become turgid as water enters the cell.

Question 8

Which of the following best explains why facilitated diffusion is necessary for some molecules?

Accepted Answer

Facilitated diffusion allows polar or charged molecules to cross the membrane via specific transport proteins.

Question 9

Which of the following is an example of endocytosis?

Accepted Answer

A white blood cell engulfing a bacterium by phagocytosis.

Question 10

Which statement about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy of a reaction, increasing the reaction rate.

Question 11

A competitive inhibitor affects an enzyme by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 12

Which of the following best describes the second law of thermodynamics as it applies to cells?

Accepted Answer

Energy transformations increase the entropy (disorder) of the universe.

Question 13

Which of the following is an example of a coupled reaction in cellular metabolism?

Accepted Answer

The hydrolysis of ATP ($$ATP \rightarrow ADP + P_i) $$provides energy for active transport.

Question 14

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

There will be no net movement of water, and the cell will remain the same size.

Question 15

Which of the following best explains why the sodium-potassium pump is essential for nerve function?

Accepted Answer

It maintains the resting membrane potential by actively transporting $$Na^+$$ out and $$K^+$$ into the neuron.

Question 16

Which of the following is a property of an exergonic reaction?

Accepted Answer

The products have less free energy than the reactants, and energy is released.

Question 17

Which adaptation increases surface area without significantly increasing cell volume?

Accepted Answer

Microvilli on intestinal epithelial cells.

Question 18

Which of the following best describes feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway inhibits an enzyme involved earlier in the pathway.

Question 19

Which of the following statements about osmosis is correct?

Accepted Answer

Water moves from an area of low solute concentration to an area of high solute concentration across a semipermeable membrane.

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