Q: A cell uses the Na\textsuperscript{+}/K\textsuperscript{+} pump to maintain its membrane potential. Which equation best represents the stoichiometry of ions moved per ATP hydrolyzed?

$$3\mathrm{Na}^{+}~\text{out},~2\mathrm{K}^{+}~\text{in}$$

Question 1

Which of the following best explains why electron microscopes can resolve smaller structures than light microscopes?

Accepted Answer

Electrons have a shorter wavelength than visible light, allowing for higher resolution.

Question 2

A scientist wants to study the surface details of a virus particle. Which type of microscopy should they use and why?

Accepted Answer

Scanning electron microscopy (SEM), because it creates detailed images of surfaces using reflected electrons.

Question 3

Which organelle is primarily responsible for energy production in animal cells, and what molecule does it generate?

Accepted Answer

Mitochondrion; it generates adenosine triphosphate (ATP).

Question 4

According to the endosymbiont theory, which of the following is evidence that mitochondria and chloroplasts originated from bacteria?

Accepted Answer

They have their own circular DNA and double membranes, similar to bacteria.

Question 5

Which of the following best describes the function of the Golgi apparatus in eukaryotic cells?

Accepted Answer

It processes, modifies, and sorts proteins and lipids for secretion or delivery to other organelles.

Question 6

A cell is placed in a solution with a higher concentration of solutes than its cytoplasm. What process will occur, and what is the likely outcome for the cell?

Accepted Answer

Osmosis; water will move out of the cell, causing it to shrink.

Question 7

Which of the following statements about the plasma membrane is correct?

Accepted Answer

It is a semi-permeable barrier formed by a phospholipid bilayer with embedded proteins.

Question 8

What is the primary role of membrane proteins in the plasma membrane?

Accepted Answer

They facilitate transport of molecules and ions across the membrane.

Question 9

Which of the following best describes passive transport across the cell membrane?

Accepted Answer

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

Question 10

A cell uses the Na	extsuperscript{+}/K	extsuperscript{+} pump to maintain its membrane potential. Which equation best represents the stoichiometry of ions moved per ATP hydrolyzed?

Accepted Answer

$$3\mathrm{Na}^{+}~	ext{out},~2\mathrm{K}^{+}~	ext{in}$$

Question 11

Which of the following is true about the movement of ions through voltage-gated channels?

Accepted Answer

Ions move down their electrochemical gradient when the channel is open.

Question 12

Which organelle contains hydrolytic enzymes and is responsible for breaking down macromolecules within the cell?

Accepted Answer

Lysosome

Question 13

Which of the following best describes the role of cholesterol in the animal cell membrane?

Accepted Answer

Cholesterol stiffens the membrane and helps maintain optimal fluidity.

Question 14

A mutation causes the loss of function of peroxisomes in liver cells. Which process would be most directly affected?

Accepted Answer

Detoxification of alcohol and breakdown of fatty acids

Question 15

Which of the following statements about the cytoskeleton is correct?

Accepted Answer

It consists of microfilaments, microtubules, and intermediate filaments that provide structure and movement.

Question 16

Which of the following is a correct statement about the semi-permeability of the plasma membrane?

Accepted Answer

It allows small, nonpolar molecules to diffuse rapidly, but restricts ions and large polar molecules.

Question 17

Which process is responsible for the movement of glucose into cells against its concentration gradient, and what energy source does it use?

Accepted Answer

Secondary active transport; uses the energy from Na$$^+$$ gradient established by ATP hydrolysis.

Question 18

Which of the following best describes the relationship between the concentration gradient and membrane potential in determining the direction of ion movement?

Accepted Answer

The net electrochemical gradient is determined by both the concentration gradient and membrane potential, which can work together or oppose each other.

Question 19

Which of the following is a function of the smooth endoplasmic reticulum (ER)?

Accepted Answer

Lipid synthesis and detoxification

Cell Structure, Organelles, and Microscopy: Study Notes for General Biology

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