Cell Structure

Question 1

What types of microscopes can be used to observe cell structure?

Answer 1

Light microscope,
transmission electron microscope (TEM),
scanning electron microscope (SEM)

Question 2

What is the function of a light microscope?

Answer 2

Produces coloured 2D images of whole cells or tissues. Lower resolution and magnification than electron microscopes.

Question 3

What is the function of a transmission electron microscope (TEM)?

Answer 3

Produces 2D black-and-white images showing internal ultrastructure at high resolution.

Question 4

What is the function of a scanning electron microscope (SEM)?

Answer 4

Produces 3D black-and-white images of surfaces at high resolution.

Question 5

What is an eyepiece graticule and how is it used?

Answer 5

Eyepiece graticule is a scale in the microscope eyepiece used to measure cells when calibrated.

Question 6

What is a stage micrometer and how is it used?

Answer 6

Stage micrometer is a slide with a known scale used to calibrate the eyepiece graticule.

Question 7

Why are stains used in light microscopy?

Answer 7

To increase contrast and allow identification of specific cell components.

Question 8

What is differential staining?

Answer 8

Uses different stains to distinguish between different structures or cell types.

Question 9

What are the key rules when drawing cells seen under a microscope?

Answer 9

Use sharp pencil. No shading. Label lines must not cross. Include magnification.
Accurate proportions

Question 10

What is the formula for magnification?

Answer 10

magnification = size of image / size of real object

Question 11

What is the difference between magnification and resolution?

Answer 11

Magnification is how much larger the image appears. Resolution is the ability to distinguish two separate points

Question 12

What structures are visible under an electron microscope that aren’t visible with light microscopy?

Answer 12

Internal structures like ER, Golgi, ribosomes, and ultrastructure details.

Question 13

What is the function of the nucleus?

Answer 13

Contains DNA. Controls cell activities.

Question 14

What is the function of the nucleolus

Answer 14

Makes ribosomes and RNA

Question 15

What is the function of the nuclear envelope?

Answer 15

Double membrane with pores for exchange between nucleus and cytoplasm

Question 16

What is the function of the rough endoplasmic reticulum (rER)?

Answer 16

Synthesises and transports proteins. Has ribosomes.

Question 17

What is the function of the smooth endoplasmic reticulum (sER)?

Answer 17

Synthesises and transports lipids and steroids. No ribosomes.

Question 18

What is the function of the Golgi apparatus?

Answer 18

Modifies and packages proteins into vesicles.

Question 19

What is the function of ribosomes?

Answer 19

Synthesises proteins. Found free or on rER

Question 20

What is the function of mitochondria?

Answer 20

Site of aerobic respiration and ATP production.

Question 21

What is the function of lysosomes?

Answer 21

Contains digestive enzymes for breaking down waste.

Question 22

What is the function of chloroplasts?

Answer 22

Site of photosynthesis. Contains chlorophyll.

Question 23

What is the function of the plasma membrane?

Answer 23

Controls entry and exit of substances. Cell signalling

Question 24

What is the function of centrioles?

Answer 24

Involved in spindle formation during cell division.

Question 25

What is the function of the cell wall in plants?

Answer 25

Provides strength and structure. Made of cellulose.

Question 26

What is the function of flagella?

Answer 26

Enables cell movement or locomotion.

Question 27

What is the function of cilia?

Answer 27

Move substances across cell surfaces or sense environment.

Question 28

What is the cytoskeleton and what are its three main functions?

Answer 28

(A) Provides mechanical strength. (B) Aids transport of materials. (C) Enables cell movement.

Question 29

Which organelles are involved in protein production and secretion?

Answer 29

Nucleus, nucleolus, rER, Golgi apparatus, ribosomes, vesicles, plasma membrane.

Question 30

What is the relationship between these organelles in protein secretion?

Answer 30

DNA in nucleus → mRNA → ribosomes on rER → protein synthesis → Golgi modifies/packages → vesicles → plasma membrane.

Question 31

What are the key structural differences between eukaryotic and prokaryotic cells?

Answer 31

Prokaryotes: no nucleus, circular DNA, no membrane-bound organelles, smaller ribosomes. Eukaryotes: nucleus, linear DNA, membrane-bound organelles, larger ribosomes.

Question 32

What are the similarities between eukaryotic and prokaryotic cells

Answer 32

Both have plasma membrane, cytoplasm, DNA, ribosomes.

Question 33

How do photomicrographs differ when viewed under TEM vs SEM?

Answer 33

TEM shows internal detail in thin sections. SEM shows surface structure in 3D.