AQA AS Biology B3 Cell Structure Kerboodle Answers

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C3.1 Methods of studying cells AQA AS Biology B3 Cell Structure Kerboodle Answers: Page No. 60

1 Magnification is how many times bigger the image is compared to the real object.

• Resolution is the minimum distance apart that two objects can be in order for them to appear as separate items.

2 200 times

3 10mm

4 500nm (0.5 μm)

5 Keep the plant cells in a cold, buffered solution with the same water potential as the cells. Break up the cells using a mortar and pestle I homogeniser. Filter the homogenate to remove cell debris. Centrifuge the homogenate at 1000 times gravity and remove the supernatant liquid (leaving nuclei behind in the sediment). Then centrifuge the supernatant liquid at 2000-3000 times gravity. The sediment produced will be rich in chloroplasts.

6

a The organelle in box e

l.5μm;

b The organelle in box g

19nm

3.2 The electron microscope AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 63

1 The EM uses a beam of electrons that has a much smaller wavelength than light.

2. Electrons arc absorbed by the molecules in air and, if present. this would prevent the electrons reaching the specimen.

3

Plant cell and bacteria.

b a transmission electron microscope

All of them.

c a scanning electron microscope.

Plant cell, bacterium and virus

4 The preparation or the specimens may not be good enough. A higher energy electron beam is required and this may destroy the specimen

5 The organelle measures 25 mm(= 25000μm) long and represents 5 μm. Magnification is therefore 25000μm + 5μm = 5000 times.

3.3 Microscope measurements and calculations AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 66

To measure the size of an object underlight aa microscope you can use an eyepiece b graticule and a stage c micrometer. Before you can use the graticule to measure the size of objects it must first be calibrated d. To do this you line up the scale on the eyepiece with that on the micrometer using an objective lens that magnifies 400 times. Suppose this shows that 50 graticule units are equivalent to 10 micrometer units. If each micrometer unit is 10 pm, then each graticule unit equals 2 e pm. If an objective lens magnifying 100 times is used, each graticule unit would be equivalent to 8 f pm. A photograph of a cell under an electron microscope is magnified 5000 times. On the photograph the nucleus measures 100 mm in diameter. The actual size of the nucleus is therefore 20 g pm. A chloroplast that is 5 pm in diameter measures 15 mm in a drawing made of a plant cell as seen under a microscope. The magnification of this drawing is therefore 3000 h times.

3.4 Eukaryotic cell structure AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 72

1 Protein synthesis

2 Glucose, fructose, galactose

3 a It possesses structures called cristae.

Mitochondrion.

b It contains chromatin,

Nucleus.

c It synthesises glycoproteins.

Golgi apparatus.

d It digests worn out organelles.

Lysosome

4 a) Mitochondria, nucleus.

b Golgi apparatus, lysosomes.

c Rough endoplasmic reticulum / ribosomes, mitochondria I smooth endoplasmic reticulum.

3.5 Cell specialisation and organization AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 74

1 A collection of similar cells aggregated together to perform a specific function.

2 An artery is made up or more than one tissue (epithelial muscle connective), whereas a blood capillary is made up of only one tissue (epithelial).

3

Organ

b xylem

Tissue

c lungs

Organ

d epithelium.

Tissue

3.6 Prokaryotic cells and viruses AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 76

 

1 A= absent.

B = present.

C = present.

D =sometimes.

E =sometimes.

F =sometimes.

G = present.

H =present.

l =sometimes.

J =absent.

K =present.

L = present.

M =absent.

N =present.

2

3.7 Mitosis AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 79

1 The period when a cell is not dividing is called interphase a. The stage of mitosis when the chromosomes are first visible as distinct structures is called prophase b. During this stage thin threads develop that span the cell from end to end and together form a structure called the spindle c. Towards the end of this Stage, the nuclear envelope d breaks down and the nucleolus e disappears. The stage when the chromosomes arrange themselves across the centre of the cell is called metaphase f. During the stage called anaphase g the chromatids move to opposite ends of the cell.

3.8 The cell cycle AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No. 81

1 Interphase, nuclear division and cell division

2 12 hours and 24 hours.

b 6-9hoursand 18-21 hours.

Banner 2 Practice questions: Chapter 3 AQA AS Biology B3 Cell Structure Kerboodle Answers : Page No.82-83

1.(a)  (i) Golgi (apparatus/body).

(ii) 1. Nucleus.

2. Mitochondrion.
3. Endoplasmic reticulum/ER.
4. Lysosome.

(b) What is the function of organelle Z?

(Aerobic) respiration/ATP

Production/provide energy.

(c)  1. High/ better resolution.

2. Shorter wavelength.
3. To see internal structures/organelles/named organelles.

2 The photograph shows part of the cytoplasm of a cell.

2 (a) (i) (Aerobic) respiration.

(ii) Golgi (apparatus/body).

(b) (‘It’ = Optical microscope)

1. Has low resolution/not high enough resolution.
2. (Because) wavelength of light not short enough/too long.

3

 (a) 1. Granum/grana/thylakoid.

2. Stroma.

(b) 1. Absorbs/traps/uses light.

2. For photosynthesis.
3. Produces carbohydrates/sugars/lipids/protein.

(c) 2.53 –2.66.

4 (a)

(b)

 (i)

1. Mitochondria respire.
2. Release energy/ produce ATP.
3. Transport against gradient.

OR

4. Infolding of membrane.

(ii)

2. Enzymes are proteins.

OR

3. Mitochondria respire.
4. Release energy/produce ATP.
5. (Energy/ATP) for protein /enzyme synthesis.

(iii) Microvilli increase area / have large area.

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