2 Cells

Question 1

Describe two structural differences between eukaryotic and prokaryotic DNA.

Answer 1

Any from:
- DNA in eukaryotes in linear/prokaryotes is circular
- Prokaryotes have short DNA/eukaryotes is long
- Prokaryotic DNA is not associated with proteins/eukaryotic DNA is associated with histones
- Prokaryotic DNA does not have non-coding DNA/eukaryotes have introns

Question 2

Describe the role of lysosomes

Answer 2

• Fuses with vesicle
• Releases hydrolytic enzymes

(Remember lysosomes are sacs contains digestive enzymes)

Question 3

Describe how a sample of chloroplasts could be isolated from leaves (4 marks)

Answer 3

• Break open cells/blend cells/tissue and filter
• in cold isotonic , pH controlled solution
• centrifuge/spin and remove nuclei
• centrifuge/spin at higher speed, chloroplasts settled out

Question 4

Give one advantage of viewing a biological specimen using a transmission electron microscope instead of a scanning electron microscope

Answer 4

Higher resolution OR view internal structures

Question 5

Describe the role of the cell surface membrane

Answer 5

Any from:
- to control movements into and out of the cell
- display hormone receptors
- present antigens