Cell structure extra

Question 1

Nuclear membrane

3 points

Answer 1

1) Controls the exchange of materials in the intercellular and external environment
2) semi permeable
3) Formed from a Phospholipid bilayer which is constantly in motion and 10 nm

Question 2

Cell wall

3 point

Answer 2

1) Offers structural support
2) This is provided by the polysaccharide cellulose in plants and peptidoglycan in bacterial cells and chitin in fungi
3) Permeable

Question 3

What is the cytoplasm that connects the cytoplasm of neighbouring plant cells?

Answer 3

Plasmodesmata

Question 4

What separates the nucleus from the rest of the cell?

Answer 4

The nuclear envelope which contains many pores

Question 5

What do the nuclear pores allow to happen?

Answer 5

It allows mRNA and ribosomes to travel out of the nucleus as well as allowing enzymes and signalling molecules in

Question 6

What is chromatin?

Answer 6

The genetic material of the cell

Question 7

Mitochondria

3 points

Answer 7

1) Site for aerobic respiration
2) Surrounded by a double membrane with the inner membrane highly folded into cristae
3) Small circular pieces of DNA and ribosomes are also found in the matrix for replication

Question 8

Why are cristae needed in the mitochondria?

Answer 8

It contains enzymes needed for aerobic respiration

Question 9

Chloroplasts

4 points

Answer 9

1) Larger then mitochondria and surrounded by a double membrane
2) membrane bound compartments called thylakoids which contain chlorophyll and stack to form structures called grana held together by llamale
3) Site for photosynthesis
4) Contains small pieces of DNA and ribosomes to synthesise proteins for chloroplast replication and photosynthesis

Question 10

What joins the thylakoids together?

Answer 10

Lamllele

Question 11

Where does the light independent stage of photosynthesis take place?

Answer 11

Thylakoids

Question 12

Where does the light independent stage of photosynthesis take place?

Answer 12

Stroma

Question 13

Ribosome

6 points

Answer 13

1) Found in the cytoplasm/ RER
2) Each ribosome is a complex of rRNA and proteins
3) Site of translation
4) Formed in the nucleolus
5) In eukaryotes they are 80s in prokaryotes they are 70s
6) Do not have a membrane

Question 14

RER

3 points

Answer 14

1) Surface covered in ribosomes
2) Formed from continuous folds of membrane continuous with the nuclear envelope
3) Processes proteins made by ribosomes

Question 15

SER

2 points

Answer 15

1) No ribosomes
2) Involved in the production, processing and storage of lipids, carbohydrates and steroids

synthesizes lipids

Question 16

Golgi Apparatus

2 points

Answer 16

1) Flattened stacks of membrane

2) Modifies proteins and packages them into vesicles and lysosomes

Question 17

Vacuole

3 points

Answer 17

1) Sac in plant cells surrounded by tonoplast
2) Semi permeable membrane
3) Vacuoles in animal cells are non permanent and small
4) Controls pressure
5) absorbs and hydrolyses potentially harmful substances within the cytoplasm

Question 18

Lysosomes

3 points

Answer 18

1) Specialist forms of vesicles which contain hydrolytic enzymes
2) Break down waste material such as worn out organelles
3) Used extensively by cells of the immune system and in apoptosis ( cell death)

Question 19

What are hydrolytic enzymes?

Answer 19

Enzymes that break down biological molecules

Question 20

Vesicle

Answer 20

Membrane bound sac used for transportation and storage

Question 21

Centriole

3 points

Answer 21

1) Hollow fibres made from microtubules
2) Two centrioles at right angles to each other form a centrosome, which organises the cell during cell division
3) Not found in flowering plants/ fungi

Question 22

Microtubules

2 points

Answer 22

1) Make up the cytoskeleton of a cell

2) Made of tubulin combined to form dimers, the dimers then combine to form protofilaments

Question 23

How big are microtubules?

Answer 23

about 25 nm in diameter

Question 24

How many protofilaments make up a microtubule?

Answer 24

13 in a cylinder

Question 25

Microvilli

Answer 25

Cell membrane projections that increase the SA of absorption

Question 26

Cilia

2 points

Answer 26

1) Hair like projections formed from microtubules

2) Allows movement of substances over the cell surface

Question 27

Flagella

Answer 27

1) Similar to cilia structure but made from longer microtubules
2) Contract to provide cell movement

Question 28

What is in the nuclear membrane and what are there roles?

Answer 28

Cholesterol - steroid molecule= connects phospholipids and maintains fluidity
Glycoproteins - cell signalling/ recognition(antigens) and binding cells together
Glycolipids- cell signalling/ recognition