B1 Cells

Question 1

What are eukaryotic cells?

Answer 1

Have a nucleus which contains the genetic material (DNA)

Animal and plant cell

Question 2

What are prokaryotic cells?

Answer 2

Don’t have a nucleus

Bacterial cells

Smaller and simpler in comparison to eukaryotic cells

Question 3

What are the features of all eukaryotic & prokaryotic cells?

Answer 3

1. Genetic material (DNA)
2. Cell membrane
3. Cytoplasm

Question 4

Describe the genetic material (DNA) in a prokaryotic cell

Answer 4

A single loop of DNA
May also have plasmids - small rings of DNA

Question 5

Name the 5 sub-cellular structures in animal cells

Answer 5

Question 6

What is the function of the cytoplasm?

Answer 6

Gel-like substance where chemical reactions take place

Question 7

What is the function of the nucleus?

Answer 7

Contains the genetic material (DNA)

Controls activities of cell

Question 8

What is the function of the cell membrane?

Answer 8

Controls movement of substances in and out of cell.

Question 9

What is the function of the ribosomes?

Answer 9

Where proteins are made

Question 10

What is the function of the mitochondria?

Answer 10

Where aerobic respiration takes place → releases energy from glucose

Question 11

Name the additional 3 sub-cellular structures in plant cells

Answer 11

Question 12

What is the function of the cell wall?

Answer 12

Strengthens the cell

Made of cellulose

Question 13

What is the function of the chloroplasts?

Answer 13

Contain chlorophyll to absorb light for photosynthesis to make glucose

Question 14

What is the function of the permanent vacuole?

Answer 14

Contains cell sap

Keeps cell rigid

Question 15

What is the function of a nerve cell?

Answer 15

Carry electrical impulses

Question 16

What features of a nerve cell help it carry out its function?

Answer 16

Long → carry electrical impulses over long distances

Many branches → connect to many other cells forming a network

Insulation → speeds up transmission of impulses

Question 17

What is the function of a sperm cell?

Answer 17

Fertilize an egg

Question 18

What features of a sperm cell help it carry out its function?

Answer 18

Long tail → allows sperm to swim / move towards egg

Many mitochondria → high rate of respiration to release energy for swimming

Question 19

What is the function of a red blood cell?

Answer 19

Carry oxygen around the body

Question 20

What features of a red blood cell help it carry out its function?

Answer 20

Contains haemoglobin → Binds to oxygen

No nucleus → More space for haemoglobin

Biconcave shape → Gives a large surface area for a fast rate of diffusion of oxygen

Question 21

What is the function of a muscle cell?

Answer 21

Contract to cause movement

Question 22

What features of a muscle cell help it carry out its function?

Answer 22

Many mitochondria → high rate of respiration to release energy for contraction

Question 23

What is the function of a root hair cell?

Answer 23

Absorb (take up) water and mineral ions from soil

Question 24

What features of a root hair cell help it carry out its function?

Answer 24

Long projection → large surface area for absorption of water by osmosis

Many mitochondria → high rate of respiration to release energy for active transport of mineral ions

No chloroplasts → underground → no light / do not carry out photosynthesis

Question 25

What is the function of the xylem?

Answer 25

Transport water and mineral ions from roots to leaves

Question 26

What features of a xylem cell help it carry out its function?

Answer 26

Lignin in cell wall → waterproof & strong to withstand pressure of water moving Hollow cells (no nucleus & sub-cellular structures) → more space for movement of water No end walls between cells → cells form a long tube so water can flow easily

Question 27

What is the function of the phloem?

Answer 27

Transports sugars up & down plant

Question 28

What features of a phloem cell help it carry out its function?

Answer 28

Cells have few sub-cellular structures → more space for movement of dissolved sugars Pores in end walls → dissolved sugars can move from cell to cell

Question 29

Name the parts of a light microscope

Answer 29

Question 30

Describe how to use a microscope to view a prepared slide

Answer 30

1. Clip slide on stage and turn on light 2. Select lowest power objective lens (usually x 4) 3. Use coarse focusing wheel to move stage close to lens 4. Turn coarse focusing wheel to move stage away from lens until image comes into focus 5. Adjust fine focusing wheel to get a clear image 6. Swap to a higher power objective lens, then refocus

Question 31

When preparing a slide of onion cells why do each of the following steps: Use a thin layer of onion tissue Add stain Lower coverslip at an angle

Answer 31

Thin layer of onion tissue → light can pass through & help see individual cells Add stain → help see sub-cellular structures Lower coverslip at an angle → prevent air bubbles

Question 32

How is the total magnification of a microscope calculated?

Answer 32

Magnification of eyepiece lens x magnification of objective lens e.g. 10 x 4 = x 40

Question 33

What are the rules of scientific drawing

Answer 33

No colouring / shading – only use clear, continuous lines Include the magnification Label important features e.g. nucleus

Question 34

What is the difference between magnification and resolution?

Answer 34

Magnification = Number of times bigger image is compared to real object Resolution = Ability to distinguish (tell apart) two points that are close together (level of detail)

Question 35

What are the differences between light and electron microscopes?

Answer 35

Higher magnification in electron microscopes Higher resolution in electron microscopes So can study cells in much finer detail → see more sub-cellular structures e.g. ribosomes

Question 36

List the steps in calculations involving magnification, real size and image size

Answer 36

1. Note formula / rearrange if necessary 2. Convert units if necessary – image and actual size must be in the same unit 3. Calculate answer and check units required

Question 37

How do you convert millimetres (mm) into micrometres (µm)

Answer 37

x1000

Question 38

How do you convert micrometres (mm) into millimetres (µm)

Answer 38

÷1000

Question 39

An image of an cheek cell measures 40 mm wide. The real width of the cell was 0.01 mm. Calculate the magnification.

Answer 39

1. Formula: magnification = image size ÷ real size 2. Calculation: magnification = 40 ÷ 0.01 = 400x

Question 40

An image of an onion cell measures 48 mm long when viewed at a magnification of x400. Calculate the real length of the onion cell. Give your answer in micrometers.

Answer 40

1. Formula: real size = image size ÷ magnification 2. Calculation: real size = 48 ÷ 400 = 0.12mm 3. Convert to required unit: to convert mm to µm x 1000 → 0.12mm x 1000 = 120µm