Question 1

Which scientist first observed cells by examining cork under a microscope in 1665, leading to the concept of the cell as the fundamental unit of life?

Accepted Answer

Robert Hooke

Question 2

According to the cell theory developed by Schleiden and Schwann in 1838, which statement is correct?

Accepted Answer

All living things are composed of cells, and new cells are formed from division of existing cells.

Question 3

Why are most cells small, typically between 1–100 $$\mum in $$diameter?

Accepted Answer

Smaller cells have a higher surface area to volume ratio, allowing efficient exchange of essential molecules and waste.

Question 4

Which of the following structures is found in all cells and acts as a selective barrier regulating the passage of substances?

Accepted Answer

Plasma membrane

Question 5

A scientist is studying a cell that contains a nucleus, mitochondria, and chloroplasts. Which type of cell is she most likely examining?

Accepted Answer

Plant cell

Question 6

Which organelle is responsible for cellular respiration and contains its own DNA and ribosomes?

Accepted Answer

Mitochondrion

Question 7

Which cytoskeletal element is primarily responsible for maintaining cell shape and anchoring organelles, and is made of keratin?

Accepted Answer

Intermediate filaments

Question 8

Microtubules are constructed from which protein, and what is their typical diameter?

Accepted Answer

Tubulin, 25 nm

Question 9

During muscle contraction, which cytoskeletal element interacts with myosin to produce movement?

Accepted Answer

Microfilaments (actin)

Question 10

Which cell junction in animal cells forms a water-tight barrier, such as that found in the skin and intestinal lining?

Accepted Answer

Tight junctions

Question 11

A researcher observes that adjacent animal cells are fastened together into sheets and reinforced by intermediate filaments. Which type of junction is she observing?

Accepted Answer

Desmosomes

Question 12

Which junction allows direct passage of small molecules between adjacent animal cells, functioning similarly to plasmodesmata in plants?

Accepted Answer

Gap junctions

Question 13

Which organelle contains enzymes that transfer oxygen from other compounds to generate and degrade $$\mathrm{H_2O_2}$$, and is bound by a single membrane?

Accepted Answer

Peroxisome

Question 14

Which cytoskeletal element is responsible for cytoplasmic streaming in plant cells, allowing transport of nutrients and organelles?

Accepted Answer

Microfilaments (actin)

Question 15

A mutation disrupts the dynein arms in the 9+2 structure of cilia and flagella. Which cellular process would be most directly affected?

Accepted Answer

Cell movement

Question 16

Which of the following best explains why eukaryotic cells have membrane-bound organelles?

Accepted Answer

To provide compartments for incompatible metabolic functions to occur simultaneously.

Question 17

Which component of the extracellular matrix (ECM) in animal cells connects the ECM to the cytoskeleton via cell membrane proteins?

Accepted Answer

Integrins

Question 18

A plant cell is observed to have a thickened secondary cell wall. Which molecule is most likely abundant in this structure?

Accepted Answer

Cellulose

Question 19

Which of the following is a function of microtubules during cell division?

Accepted Answer

Chromosome movement via centrioles

Question 20

If a cell loses its ability to assemble and disassemble actin filaments, which process would be most directly impaired?

Accepted Answer

Extension of pseudopodia for movement

Cell Structure and Function: Study Notes

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