CELLS AND MICROSCOPY PMT

Question 1

State the two types of cells

Answer 1

-Eukaryotic (animal and plants)
-Prokaryotic

Question 2

what is the difference between a eukaryotic and prokaryotic cell?

Answer 2

A eukaryotic cell contains a nucleus and membrane bound organelles. A prokaryotic cell does not.

Question 3

how is genetic information stored in a eukaryotic cell?

Answer 3

Within the nucleus, arranged in chromosomes

Question 4

Other than storing genetic information, what is the function of the nucleus?

Answer 4

controls cellular activities

Question 5

describe the structure of cytoplasm

Answer 5

• Fluid component of the cell
• Contains organelles, enzymes and dissolved ions and nutrient

Question 6

What is the function of the cytoplasm?

Answer 6

sight of reactions e.g. first stage of respiration

Question 7

what is the function of the cell membrane?

Answer 7

Controls the entry and exit of materials in and out the cell

Question 8

what is the function of mitochondria?

Answer 8

Site of respiration

Question 9

what is the function of ribosome?

Answer 9

Join amino acid in a specific order

Question 10

which organelles are found only in plant cells?

Answer 10

• Permanent vacuole
• Cell wall
• Chloroplast

Question 11

what is the cell wall made of?

Answer 11

Cellulose

Question 12

What is the function of the cell wall?

Answer 12

• provide strength
• Prevents the cell bursting when water enters by osmosis

Question 13

what does the permanent vacuole contain?

Answer 13

A solution of salt, sugars and organic acids

Question 14

What is the function of the permanent vacuole?

Answer 14

supports the cell

Question 15

What is the function of chloroplasts?

Answer 15

site of photosynthesis

Question 16

When looking at a cell using a microscope, why do chloroplast appear green?

Answer 16

They contain chlorophyll, which is a green pigment

Question 17

List the organelles found in prokaryotic cells

Answer 17

• Chromosomal DNA
• Plasmid DNA
• Cell wall
• Cell membrane
• Ribosomes
• Flagella

Question 18

how is genetic information stored in a prokaryotic cell?

Answer 18

Found free in the cytoplasm as:
- Chromosomal DNA
- Plasmid DNA

Question 19

what is the prokaryotic cell wall composed of?

Answer 19

Peptidoglycan

Question 20

what is a flagellum

Answer 20

• Long, rotating, whiplike protrusion

Question 21

what is a haploid cell?

Answer 21

A cell that contains a single copy of each chromosome e.g. 23 chromosomes in humans

Question 22

what is a diploid cell?

Answer 22

A cell that contains two copies of each chromosome e.g. 46 chromosomes in humans

Question 23

what are gametes?

Answer 23

• reproductive cells (e.g. egg and sperm cells)
• they are haploid cells

Question 24

Describe how egg cells are adapted to their function

Answer 24

-Haploid nucleus contains genetic material
-Mitochondria in cytoplasm produce energy for the developing embryo
-Cell membrane hardens after fertilisation, preventing the entry of other sperm and ensuring the zygote is diploid

Question 25

Describe how sperm cells are adapted to their function

Answer 25

-Haploid nucleus contains genetic information -Tail enables movement -Mitochondria provide energy for tail movement -Acrosome contains enzymes that digest the egg cell membrane

Question 26

where are ciliated epithelial cells found?

Answer 26

found lining the surface of structures such as the respiratory tract and uterus

Question 27

Describe the function of ciliated epithelial cells lining the airways

Answer 27

Move in synchronised waves to beat mucus up to the back of the throat where it can be swallowed

Question 28

what is magnification

Answer 28

the number of times bigger an image appears compared to the size of the specimen

Question 29

how can the magnification of an image be calculated

Answer 29

magnification = size of image ——————- size of specimen

Question 30

what is resolution

Answer 30

the ability to distinguish between two different points

Question 31

what are the advantages of light microscopes

Answer 31

- cheap - easy to use - portable - coloured images

Question 32

what is the advantage of electron microscope

Answer 32

greater magnification and resolution

Question 33

what are the disadvantages of electron microscopes

Answer 33

-expensive -large so less portable -require training to use -only dead specimens can be used

Question 34

how do you convert m to mm

Answer 34

x 1000

Question 35

how do you convert m to um

Answer 35

x 1,000,000

Question 36

how do you convert m to nm

Answer 36

x 1,000,000,000 (x10^9)

Question 37

how do you convert nm to m

Answer 37

divide by 1,000,000,000 (x10^-9)

Question 38

What are plasmids?

Answer 38

- Small, circular loops of DNA found free in the cytoplasm and separate from the main DNA - Carries genes that provide genetic advantages

Question 39

How does a light microscope work?

Answer 39

Passes a beam of light through specimen which travels through the eye piece lens, allowing the specimen to be observed

Question 40

How does an electron microscope work?

Answer 40

It is a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.

Question 41

Why do electron microscopes have a greater magnification and resolution?

Answer 41

They use a beam of electrons which has a shorter wavelength than photons of light