Question 1

Which of the following statements best explains why mitochondria and chloroplasts are considered to have originated from free-living prokaryotes?

Accepted Answer

They contain small, circular DNA devoid of protein, resembling prokaryotic chromosomes.

Question 2

A student observes a cell under a light microscope and notes the presence of a cell wall, chloroplasts, and a large central vacuole. Which type of cell is the student most likely observing?

Accepted Answer

Plant cell

Question 3

Which of the following organelles is directly involved in the synthesis of proteins for export from the cell?

Accepted Answer

Rough endoplasmic reticulum

Question 4

Why do large unicellular organisms face limitations in size, according to the surface-to-volume ratio principle?

Accepted Answer

As cells grow, their volume increases faster than their surface area, limiting nutrient uptake and internal regulation.

Question 5

A scientist is using a light microscope with a 10x objective lens. If the diameter of the field of view is 1.2 mm and a cell occupies 1/4 of this diameter, what is the approximate length of the cell in micrometers ($$\mu m$$)?

$$	ext{Cell length} = \frac{1.2\ 	ext{mm}}{4} 	imes 1000\ \mu m/	ext{mm}$$

Accepted Answer

$$300\ \mu m$$

Question 6

Which of the following structures is present in prokaryotic cells but absent in most eukaryotic animal cells?

Accepted Answer

Cell wall

Question 7

A student stains onion cells with acetocarmine and observes them under a microscope. What is the primary effect of the stain?

Accepted Answer

It enhances the visibility of the nucleus and chromosomes.

Question 8

Which of the following best describes the function of contractile vacuoles in Paramecium?

Accepted Answer

They expel excess water taken in by osmosis.

Question 9

Which of the following cell types would you expect to lack chloroplasts and a large central vacuole?

Accepted Answer

Onion root cell

Question 10

A researcher observes a unicellular organism that moves by extending pseudopodia and engulfs food particles. Which organism is most likely being observed?

Accepted Answer

Amoeba

Question 11

Which of the following statements about the resolving power of microscopes is correct?

Accepted Answer

Resolution is the smallest distance two points can be separated and still be distinguished as distinct.

Question 12

Which of the following is a key difference between prokaryotic and eukaryotic DNA organization?

Accepted Answer

Prokaryotic DNA is circular with few proteins, while eukaryotic DNA is linear and packaged with histones.

Question 13

Which of the following best explains why Euglena is considered unique among algae?

Accepted Answer

It is photosynthetic but lacks a cell wall and can also use heterotrophic metabolism.

Question 14

Which of the following cell structures is visible in both plant and animal cells under a light microscope, but not in prokaryotic cells?

Accepted Answer

Nucleus

Question 15

A student observes a cell with cilia, a macronucleus, and contractile vacuoles. Which organism is most likely being observed?

Accepted Answer

Paramecium

Question 16

Which of the following is NOT a characteristic of prokaryotic cells?

Accepted Answer

Division by mitosis

Question 17

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

Accepted Answer

It processes proteins for export or insertion into the cell membrane.

Question 18

A sample from a pond contains a single-celled organism with an eyespot, flagellum, and chloroplasts. In the dark, it switches to heterotrophic metabolism. Which organism is this?

Accepted Answer

Euglena

Question 19

Which of the following is a function of the cytoskeleton in eukaryotic cells?

Accepted Answer

Mediating movement of organelles and cell locomotion

Question 20

Which of the following best explains why most bacteria are considered saprophytic?

Accepted Answer

They live and feed on dead organic material, degrading it.

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