2.1.1 - Cell Structure

Question 1

What is magnification?

Answer 1

how many times larger the image is than the actual size of the object being viewed

Question 2

What is resolution?

Answer 2

the ability to see individual objects as separate identities

Question 3

magnification =

Answer 3

image size
_________
object size

Question 4

What is a light microscope?

Answer 4

a microscope that uses light and has a resolution of 200nm and a magnification of x1500

Question 5

What is an electron microscope?

Answer 5

a microscope that uses electrons instead of light to form an image
they have higher resolutions than light microscopes

Question 6

What are the two types of electron microscopes?

Answer 6

transmission electron microscope (TEM)

scanning electron microscope (SEM)

Question 7

What is a laser scanning confocal microscope?

Answer 7

a type of light microscope that uses lasers to illuminate specimens that have been dyed with fluroscent chemicals

Question 8

What are the advantages and disadvantages of a light microscope?

Answer 8

✅ -small and portable
     -colours can be seen
     -samples can be living or dead
❌ -low resoltuion of 200nm
     -lower magnification (x1500) than electron microscopes

Question 9

What are the advantages and disadvantages of a TEM?

Answer 9

✅ -high resolution images of 0.2nm
-magnification of at least x 1,000,000
❌ -expensive
-is large and must be installed

Question 10

What are the advantages and disadvantages of a SEM?

Answer 10

✅ -can create 3D images
-magnification of x 500,000 and resolution of 10nm (better than light but worse than TEM)
❌ -expensive
-is large and must be installed

Question 11

What are the advantages and disadvantages of a laser scanning microscope?

Answer 11

✅ -can be done to thicker objects
-clearer image than normal light microscopes because the light is focused through a pinhole
❌ -high quality lasers are expensive

Question 12

What is the difference between a transmission electron microscope and a scanning electron microscope?

Answer 12

TEM -electrons transmitted through the specimen
-creates 2D images
-resolution of 0.5nm
SEM -electrons scanned across the specimen
-creates 3D images
-resolution of 5-10nm

Question 13

What are the two lenses in a light microscope?

Answer 13

• the objective lens (x4, x10, x40 and x100)

- the eye piece lens (x10)

Question 14

What are the methods for preparing samples for a light microscope?

Answer 14

dry mount
wet mount
squash slides
smear slides

Question 15

What is dry mount slide preparation?

Answer 15

Solid specimens are put on a slide whole (if they are thin) or thinly cut (sectioning)

Question 16

What is wet mount slide preparation?

Answer 16

Specimens are suspended in liquid (eg. oil or water)

Cover slip is placed on from an angle

Question 17

What is squash slide preparation?

Answer 17

Wet mount with a lens tissue used to gently press the cover slip
Used for soft samples

Question 18

What is a smear slide preparation?

Answer 18

Edge of the slide is used to smear the sample to create a thin, even coating (eg. blood)

Question 19

What is an artefact?

Answer 19

An unwanted structure produced on a slide in the preparation process
eg. Air bubbles, distortion, etc.

Question 20

What is the cell surface membrane?

Answer 20

the membrane found on the surface of animal cells and just inside the cell wall of animal cells

Question 21

What is the function of the cell surface membrane?

Answer 21

regulates the movement of substances in and out of the cell

has receptor molecules and responds to chemicals (like hormones)

Question 22

What is a plant cell wall?

Answer 22

rigid structure that surrounds plant cells made from cellulose

Question 23

What is the function of the cell wall?

Answer 23

supports plant cells

Question 24

What is the nucleus?

Answer 24

a large organelle surrounded by a nuclear envelope (double membrane) with many pores
contains a nucleolus and chromatins

Question 25

What is the function of the nucleus?

Answer 25

controls cell’s activities

pores allow substances to move between cytoplasm and nucleus

Question 26

What is a lyosome?

Answer 26

round organelle surrounded by a single membrane

contains digestive enzymes

Question 27

What is the function of a lyosome?

Answer 27

digests invading cells and worn out components of the cell (done by digestive enzymes)

Question 28

What is a ribosome?

Answer 28

a very small organelle that is either free in the cytoplasm or connected to the rough endoplasmic reticulum
made up of proteins and RNA
not surrounded by a membrane

Question 29

What is the function of a ribosome?

Answer 29

proteinsynthesis

Question 30

What guidelines should you follow for biological drawings?

Answer 30

• use a sharp pencil
• use ruled label lines
• include a scale bar
• use at least 50% of available space
• title/heading
• labels outside diagram
• label lines should not cross over others
• use continuous lines
• no shading
• use plain paper
• state magnification
• correct proportions