Question 1

Which of the following statements best summarizes the third principle of the cell theory as proposed by Rudolf Virchow in 1855?

Accepted Answer

All cells arise only from preexisting cells.

Question 2

A scientist is using a light microscope to observe a stained tissue section. The smallest distance between two points that can still be distinguished as separate is 250 nm. What is the term for this property, and what is its typical value for light microscopes?

Accepted Answer

Resolution; typically 200–350 nm for light microscopes.

Question 3

Which historical figure was the first to observe and describe 'animalcules' such as bacteria and protozoa using a single-lens microscope?

Accepted Answer

Antonie van Leeuwenhoek

Question 4

A researcher wants to visualize the spatial distribution of a specific protein in living cells over time. Which technique would be most appropriate?

Accepted Answer

Fluorescence microscopy using green fluorescent protein (GFP)

Question 5

Which of the following best explains why electron microscopes have a much higher resolving power than light microscopes?

Accepted Answer

They use electrons, which have a much shorter wavelength than visible light.

Question 6

A pathologist is examining a tissue sample using hematoxylin and eosin (H&E) staining. What is the main advantage of using this dual staining technique?

Accepted Answer

It differentially stains acidic and basic molecules, increasing contrast between cell structures.

Question 7

Which of the following units would be most appropriate for measuring the diameter of a ribosome?

Accepted Answer

Nanometer ($$1 \ nm)$$

Question 8

A scientist is interested in observing the three-dimensional surface structure of a pollen grain. Which microscopy technique should they use?

Accepted Answer

Scanning electron microscopy (SEM)

Question 9

Which of the following best describes the main contribution of cytology to modern cell biology?

Accepted Answer

It emphasizes the study of cellular structure using optical techniques.

Question 10

A researcher uses immunostaining to detect collagen II in cartilage tissue. What is the principle behind this technique?

Accepted Answer

It uses antibodies labeled with fluorescent molecules to bind specifically to collagen II.

Question 11

Which of the following is a correct conversion between units commonly used in cell biology?

Accepted Answer

$$1 \ nm = 10$$^{-9}$$ \ m$$

Question 12

Which of the following statements about the development of cell theory is correct?

Accepted Answer

It was made possible by advances in microscopy and the integration of cytology, genetics, and biochemistry.

Question 13

A scientist is using a confocal microscope to study the microvilli of the intestine. What is a key advantage of confocal microscopy in this context?

Accepted Answer

It combines 2D images from multiple layers to create a 3D reconstruction.

Question 14

Which of the following best explains why the microtome was a significant advancement for cytology?

Accepted Answer

It allowed for the preparation of very thin tissue sections, minimizing interference and enabling the study of subcellular structures.

Question 15

A student is comparing the sizes of a plant cell, an animal cell, and a bacterium. Which of the following correctly ranks them from largest to smallest?

Accepted Answer

Plant cell \u003e Animal cell \u003e Bacterium

Question 16

Which of the following best describes the main limitation of brightfield microscopy when observing living cells?

Accepted Answer

It requires cells to be dead, fixed, and stained, which can introduce artifacts.

Question 17

A researcher is interested in measuring the diameter of a DNA double helix. Which unit and approximate value should they use?

Accepted Answer

Nanometer; about $$2 \ nm$$

Question 18

Which of the following is NOT a strand of biological inquiry that contributed to the emergence of modern cell biology?

Accepted Answer

Physiology

Question 19

A scientist is using phase-contrast microscopy to observe a sample. What is the main advantage of this technique over brightfield microscopy?

Accepted Answer

It allows visualization of living, unstained cells by exploiting differences in refractive index.

A Preview of Cell Biology: Foundations, Microscopy, and the Cell Theory

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