Cell division

Question 1

What does the cell membrane do? (1 mark)

Answer 1

It controls the movement of substances in and out of cells

Question 2

What is the function of the cytoplasm? (1 mark)

Answer 2

It is a gel-like substance where chemical reactions inside the cell take place (e.g. anaerobic respiration)

Question 3

What is the function of the nucleus (or DNA)? (1 mark)

Answer 3

It contains genetic material and controls cell activities

Question 4

What is the function of ribosomes? (1 mark)

Answer 4

They are the site of protein synthesis

Question 5

What are some differences between prokaryotic and eukaryotic cells? (4 marks)

Answer 5

The genetic material (DNA) in eukaryotic cells is enclosed within a nucleus. Whereas, the genetic material in prokaryotic cells is not enclosed within a nucleus, but is rather found as a single loop of DNA within the cytoplasm.
Eukaryotic cells vary in size, usually between 10 and 100 µm. Whereas, prokaryotic cells are smaller in comparison, measuring around ~ 1 µm in size

Question 6

What are the cell membranes of all prokaryotic cells surrounded by? (1 mark)

Answer 6

A cell wall (usually made from a substance called peptidoglycan)

Question 7

What are some examples of eukaryotic cells? (4 marks)

Answer 7

animals and plant cells, fungi and protists

Question 8

What are some examples of prokaryotic cells? (1 mark)

Answer 8

Bacterial cells

Question 9

Where is the genetic material (DNA) in prokaryotic cells found? (2 marks)

Answer 9

The genetic material is found as a single loop of DNA within the cytoplasm
Additional smaller, circular pieces of DNA is found as plasmids

Question 10

What do scientists measure the size of cells in? (1 mark)

Answer 10

Micrometres (µm)

Question 11

What is the order of measurement? (1 mark)

Answer 11

metre (m)
millimetre (mm)
micrometre (µm)
nanometre (nm)

Question 12

How do you change between the measurements? (1 mark)

Answer 12

/ 1000 or x 1000

Question 13

What is the size of a palisade mesophyll cell? (1 mark)

Answer 13

70 µm

Question 14

What is the size of a cheek cell? (1 mark)

Answer 14

65 µm

Question 15

What is the size of mitochondria and chloroplast? (1 mark)

Answer 15

1.5 µm

Question 16

What is the size of cholera bacterium? (1 mark)

Answer 16

1.5 µm

Question 17

What is the size of the HIV virus? (1 mark)

Answer 17

100 nm

Question 18

How do you work out the order of magnitude? (2 marks)

Answer 18

order of magnitude is 10 to the power of n

e.g. 100x greater = 10^2 = 2 orders of magnitude

Question 19

What is the purpose of mitochondria? (1 mark)

Answer 19

It is the site of aerobic respiration and energy release

Question 20

What is an organelle? (2 mark)

Answer 20

It is a subcellular structure that is specialised to carry out a particular function or process within a cell

Question 21

Why are some organelles not membrane bound? (2 marks)

Answer 21

Some organelles are more solid structures that are not fluid-filled (e.g. ribosomes and the cell wall)

Question 22

What are some examples of organelles in animal cells? (5 marks)

Answer 22

The nucleus
Cell membrane
Mitochondria
Ribosomes
Cytoplasm

Question 23

What are some examples of organelles in plant cells? (2 marks)

Answer 23

Cell wall made of cellulose

A permanent vacuole filled with cell sap

Question 24

What is the function of a cell wall? (1 mark)

Answer 24

It is made of cellulose to strengthen the cell

Question 25

What is the purpose of chloroplast? (1 mark)

Answer 25

It contains chlorophyll (green pigment to absorb light energy) and is the site for photosynthesis

Question 26

What is the purpose of a permanent vacuole? (2 marks)

Answer 26

It is filled with cell sap (a solution of sugars and salts dissolved in water) to keep cells rigid. It also stores certain materials (e.g. salts and minerals)

Question 27

What do light microscopes use? (1 mark)

Answer 27

They use light and lenses to form a magnified image of a specimen

Question 28

What are light microscopes used for seeing? (1 mark)

Answer 28

to see images of cells and large subcellular structures (like nuclei and vacuoles)

Question 29

When were the first light microscopes invented? (1 mark)

Answer 29

In the 17th Century

Question 30

Which scientists used microscopes to develop our first understanding of cells? (2 marks)

Answer 30

Anton van Leeuwenhoek and Robert Hooke

Question 31

When were the first electron microscopes developed? (1 mark)

Answer 31

in the first half of the 20th Century

Question 32

What do electron microscopes use?

Answer 32

They use beams of electrons, rather than light, to visualise specimens

Question 33

Why do electron microscopes use an electron beam? (2 marks)

Answer 33

The wavelength of an electron beam is much smaller than that of visible light, which gives electron microscopes a much higher resolution and magnification

Question 34

What are electron microscopes used for? (2 marks)

Answer 34

To study cells in much finer detail (e.g. subcellular structures such as the mitochondrion) They also help to develop an understanding of the structure of the nucleus and cell membrane

Question 35

What is the equation for magnification? (1 mark)

Answer 35

actual size = image size / magnification