Binary Fission, the Cell Cycle, and Mitosis

Question 1

What types of cells use binary fission (1 mark)

Answer 1

Prokaryotes

Question 2

Outline what is occurring during binary fission. (8 marks)

Answer 2

1 mark: Step one is DNA Replication
1 mark: During DNA replication the cell uncoils
1 mark: During DNA replication the cell replicates its chromosomes

1 mark: Step two is elongation
1 mark: During elongation the cell grows larger

1 mark: Step three is Septum formation

1 mark: Step four is cell division
1 mark: The cell splits up in the center
1 mark: Parent cell divides creating two new daughter cells

Question 3

Name three reasons why cells need to replicate. (3 marks)

Answer 3

1 mark: For the survival and growth of organisms

1 mark: Maintaining chromosomes numbers

1 mark: Damaged cells are renewed

Question 4

What is occurring during G1? (3 marks)

Answer 4

1 mark - Growth

1 mark - Cell grows physically larger

1 mark - Copies organelles

Question 5

What is occurring during S? (3 marks)

Answer 5

1 mark - Synthesis

1 mark - Duplicates centrosome

1 mark - Synthesizes complete copy of the DNA

Question 6

What is occurring during G2? (3 marks)

Answer 6

1 mark - More cell growth
1 mark - Makes proteins
1 mark - Makes organelles

Question 7

In which stage of the cell cycle does the cell spend most of its time and why? (2 marks)

Answer 7

1 mark - Interphase
1 mark - All the preparation for cell division takes place

Question 8

Describe what occurs during cytokinesis? (1 mark)

Answer 8

1 mark - Parent cell finally splits into two identical daughter cells

Question 9

Why do animal and plant cells complete cytokinesis differently? (1 mark)

Answer 9

1 mark - As plant cells have cell walls whilst animal cells do not

Question 10

What occurs during early prophase (2 marks)

Answer 10

1 mark - Chromosomes start to condense
1 mark - Nucleolus disappears

Question 11

What occurs during late prophase (3 marks)

Answer 11

1 mark - Chromosomes condense
1 mark - Nuclear envelope breaks down
1 mark - Chromosomes are release

Question 12

What occurs during metaphase (3 marks)

Answer 12

1 mark - Chromosomes continue to be condensed
1 mark -Nucleus disappears
1 mark - Chromosomes align in the center of the dividing cell

Question 13

What occurs during anaphase? (2 marks)

Answer 13

1 mark - Sister chromatids separate from each other
1 mark - Chromatids are pulled to opposite ends of the cell

Question 14

What occurs during telophase? (3 marks)

Answer 14

1 mark: Chromosomes begin to uncoil
1 mark: Nuclear membrane forms around each set of chromosomes
1 mark: Nuclear DNA is separated from the cytoplasm

Question 15

What does the G1 checkpoint check for? (1 mark)

Answer 15

1 mark: Tests if integrity of the DNA is sufficient

Question 16

What does the G2 checkpoint check for? (1 mark)

Answer 16

1 mark: Assesses chromosome duplication

Question 17

What does the M checkpoint check for? (1 mark)

Answer 17

1 mark: Assesses spindle fiber formation