cell cycle Exam Qs

Question 1

describe binary fission in bacteria

Answer 1

• replication of circular DNA
• replication of plasmids
• division of cytoplasm to produce daughter cells

Question 2

suggest two environmental variables that could be changed to increase growth rate of bacterial cells

Answer 2

• increased conc of glucose or oxygen SO increased respiration
• increased temperature SO increased enzyme activity
• increased phosphate concentration SO increased ATP, DNA and RNA
• increased conc of nucleotides SO increased DNA synthesis

Question 3

name the fixed position occupied by DNA molecule

Answer 3

locus

Question 4

describe role of spindle fibres and behavior of chromosomes during:
- prophase
- metaphase
- anaphase

Answer 4

prophase- chromosomes condense

metaphase- centromeres attach to spindle fibres, pairs of chromatids at equator/ centre of cell

anaphase- centromeres divide, chromatids pulled to opposite poles of cell.

Question 5

suggest why stopping spindle fibre activity stops the cell cycle

Answer 5

centromeres can’t attach to spindle, so no metaphase
OR
chromatids can’t separate on spindle, so no anaphase