Cells

Question 1

What is the function of the Ribosomes

Answer 1

Site of protien Synthesis

Question 2

What is the function of the nucleus

Answer 2

Contains genetic material / DNA;
Controls cell activity;

Question 3

What is the function of the Mitochondria

Answer 3

Site of aerobic respiration;
ATP production by aerobic respiration

Question 4

What is the function of the Smooth Endoplasmic Reticulum

Answer 4

Site of lipid Synthesis

Question 5

What is the function of the Rough Endoplasmic reticulum

Answer 5

Encrusted in Ribosomes;
Site of protein synthesis;
Transports and stores protein within the cell

Question 6

What is the function of Golgi Apparatus

Answer 6

Modifies/packages/sorts proteins;
Produces vesicles;

Question 7

What is the function of Lysosomes

Answer 7

Contains digestive (hydrolytic) enzymes;
Digests worn out organelles/autolysis

Question 8

What is the function of Cell surface membrane

Answer 8

Made of a Phospholipid Bi-layer;
Controls what enters the cell/ is selectively permeable;
Can be folded to increase Surface Area;

Question 9

What is the function of centrioles

Answer 9

Form spindle fibers to pull apart the chromosomes/ chromatids.

Question 10

What is the function of nucleolus

Answer 10

To synthesise ribosomal RNA (rRNA) for the production of ribosomes

Question 11

Define eukaryotic cell

Answer 11

-A eukaryotic cell has membrane bound organelles
-A eukaryotic cell has a nucleus containing linear DNA/chromatin

Question 12

How does mRNA leave the nucleus to the cytoplasm?

Answer 12

Leaves through the nuclear pores in the nucleus envelope

Question 13

What is chromatin?

Answer 13

(Uncondensed) DNA within the nucleus coiled around the histones.
This super-condenses to form chromosomes during cell division

Question 14

What are microvilli?

Answer 14

Microvilli are finger like projections of cell membrane that increase the surface area to speed up absorptions.
(Found on epithelial cells in small intestine)

Question 15

What organelles have a double plasma membrane?

Answer 15

Nucleus, Mitochondrion and the Chloroplast

Question 16

What is the function of a Chloroplast?(2marks)

Answer 16

Contain Thylakoid stacked into Granum
-Absorbs/uses light
-for photosynthesis
-produces carbohydrates/sugar/lipids/protein

Question 17

Apart from the nucleus, what other organelles contain DNA?

Answer 17

Chloroplasts and the mitochondria

Question 18

What is the function of Cell Wall

Answer 18

Provides rigid shape / structure;
Stops osmotic lysis;

Question 19

What is the function of Plasmid

Answer 19

Circular DNA;
Contains antibiotic resistance genes;

Question 20

What is the function of the plasmodesmata in the cell wall?

Answer 20

Gaps in the cell walls that connect cell cytoplasm’s together to allow movement of water soluble molecules.

Question 21

What are cell walls of adjacent cells separated by?

Answer 21

A thin layer called the middle lamella.
Sticks the walls together with pectin.

Question 22

What is a capsid?

Answer 22

Its a protein coat that surrounds a virus

Question 23

Describe how you could use cell fractionation to isolate chloroplasts from leaf tissue (3)

Answer 23

1. Break open the cells in a blender/ homogeniser and filter to remove cellular debris;
2. Place in an ice cold, isotonic, buffered solution;
3. Use differential centrifugation;
4. Chloroplasts are in the second pellet;

Question 24

Scientists isolated mitochondria from liver cells. They broke the cells open in an ice-cold, buffered isotonic solution. Explain why the solution was:
a) Isotonic
b) Ice cold
c) buffered

Answer 24

1. Prevents osmosis
   so no osmotic lysis of organelles/named organelle (e.g. mitochondria);
2. Reduce/prevent enzyme activity so organelles are not digested;
3. Maintain a constant pH so proteins are not denatured;

Question 25

Name the reaction that forms ATP

Answer 25

Aerobic respiration

Question 26

Name the reaction that breaks down ATP

Answer 26

Phosphorylation

Question 27

What are Cell Surface Membranes made up of?

Answer 27

Made up of phospholipids, specific transport proteins, and carbohydrates arranged into a fluid mosaic model

Question 28

What is the folding of the inner membrane in mitochondria called and what is its function?

Answer 28

Cristae, increases surface area for the attachment of ATP synthase enzymes (enzymes that make ATP)

Question 29

Name the process by which proteins are secreted from the cell (leave the cell)

Answer 29

Exocytosis

Question 30

Explain why electron microscopes can see smaller organelles than light microscopes

Answer 30

Electron microscopes have a higher resolution
Uses electrons which have a smaller wavelength

Question 31

Describe how TEM works and what are the disadvantages

Answer 31

How it works:
- Electrons pass through / enter (very thin) specimen;
- Denser parts absorb more electrons;
- (So) denser parts appear darker;
- Electrons have short wavelength so give high resolution;

Disadvantages:
- Cannot look at living material / Must be in a vacuum;
- Specimen must be (very) thin;
- Artefacts present;
- Complex staining method / complex / long preparation time;

Question 32

Give one advantage of using a TEM rather than a SEM

Answer 32

Higher resolution / higher magnification / higher detail
OR
Allows internal details / structures within cells to be seen

Question 33

Give one advantage of using a SEM rather than a TEM

Answer 33

Thin sections do not need to be prepared / shows surface of specimen / can have 3D images

Question 34

Explain why mitochondria can appear in different shapes (2 marks)

Answer 34

• Idea of sections or cuts
• Idea of mitochondria orientated differently or in different positions (viewed from a different angle) / description of 3D structure of mitochondria, e.g sausage-shaped