TOPIC 3: Voice of the genome

Question 1

Describe how DNA is organised in a bacterial cell. (3)

Answer 1

• circular DNA
• several plasmids
• located in cytoplasm

Question 2

Describe roles of g.a and vesicles in the formation and transport of extracellular enzymes. (4)

Answer 2

• vesicles fuse w/ G.A
• proteins modified in G.A
• proteins packaged into vesicles
• vesicles fuse w/ cell membranes

Question 3

What happens to lysosomes once their contents have been digested. (2)

Answer 3

• fuse w/ cell membrane
• contents released from cell by exocytosis

Question 4

Describe features that can help identify prokaryotic cells in the blood sample. (4)

Answer 4

• presence of cell wall
• circular DNA
• small ribosomes
• flagellum

Question 5

Explain why the nucleus cannot be observed at the end of prophase in a eukaryotic cell. (2)

Answer 5

• bcs nuclear membrane is broken down
• DNA is condensed into individual chromosomes

Question 6

Describe how this polypeptide is then processed to make AFGP. (4)

Answer 6

• polypeptide chain moves through endoplasmic reticulum then the G.A
• in the rER, polypeptide is folded
• in the G.A, carbohydrate is added
• polypeptide is transported around cell in a vesicle

Question 7

State two features that cells of all living organisms share (2)

Answer 7

• DNA
• Ribosome

Question 8

Explain why certain cells, e.g. muscle cells, contain more mitochondria then cells used for storage. (2)

Answer 8

• muscle cells require more energy
• mitochondria releases energy

Question 9

Compare and contrast a transmission electron microscope (TEM) with a scanning electron microscope (SEM). (5)

Answer 9

similarities:
- both use a beam of electrons
- both require dead specimens
- high detailed image

differences:
- TEM = higher resolution

Question 10

Explain the importance of specialised cells in a multicellular organism. (2)

Answer 10

• cells differentiate to perform a specific function
• form the basis if tissues, organs and organ systems

Question 11

Explain why, during this practical, the root tip must be firmly squashed. (1)

Answer 11

• to let light through

Question 12

Give two reasons why mitosis is so important. (2)

Answer 12

• for growth
• to replace cells

Question 13

Describe the appearance and behaviour of chromosomes during mitosis. (6)

Answer 13

prophase:
- appear as chromatids joined
- at the centromere

metaphase:
- line up at centre of cell
- attached to spindle fibres

anaphase:
- centromere splits
- chromosomes pulled to opposite ends of cells

telophase:
- chromosomes uncoil

Question 14

Describe the changes that occur b/w prophase and metaphase. (5)

Answer 14

• chromosomes become shorter & thicker
• nucleolus disappears
• spindle is formed
• nuclear envelope disintegrates
• chromosomes line up at equator of cell