Cell Division

Question 1

What is binary fission? Describe the basic steps in binary fission

Answer 1

Process by which bacteria/prokaryotes reproduce through cell division
- DNA replicates prior to division (single circular chromosome and attached to inside of cell membrane)
- Chromosomes gradually separate, cell wall and membrane grow inwards and divide cell in two.
- Two genetically identical daughter cells are produced.

Question 2

What is mitosis?

Answer 2

The process by which eukaryotic cells divide to produce two genetically identical daughter cells.

Question 3

State the name of the non-dividing phase of the cell cycle in eukaryotic cells.

Answer 3

Interphase

Question 4

4. Name the four stages of mitosis and dot point the major processes that occur in each of the four stages of mitosis.

Answer 4

Prophase: Chromosomes condense, nuclear membrane dissolves, mitotic spindle forms.
Metaphase: Chromosomes line up (single file) along metaphase plate, spindle fibers attach to chromosomes at centromeres.
Anaphase: Sister chromatids separate and are drawn to opposite poles of the cell.
Telophase: Nuclear membranes reform around two new nuclei. Cell membrane cleaves (cytokinesis)
Two genetically identical daughter cells are produced.

Question 5

State two differences between mitosis and binary fission.

Answer 5

• Eukaryotic cells have multiple linear chromosomes in mitosis, whereas prokaryotic cells have a single, circular chromosome.
• Eukaryotic cells have the mitotic spindle in mitosis, whereas prokaryotic cells do not in binary fission.
• Chromosome remains attached to cell membrane in binary fission, whereas chromosomes attach to spindle fibres in mitosis.
• Binary fission is faster than mitosis

Question 6

State the type of cell division that gives rise to body cells in organisms.

Answer 6

Mitosis

Question 7

Explain why DNA doubles prior to cell division.

Answer 7

So that each daughter cell receives an identical copy of the DNA to the parent cell

Question 8

Explain how crossing over contributes to variation in offspring.

Answer 8

Crossing over is the reciprocal exchange of segments of DNA between non-sister chromatids on homologous chromosomes leading to new combinations of maternal and paternal genes, leading to variation in offspring.

Question 9

Explain how independent assortment contributes to variation in offspring.

Answer 9

Independent assortment is the alignment of homologous chromosome pairs (maternal + paternal) independent of other pairs. This leads to new combinations of chromosomes and hence new combinations of genes in the gametes.

Question 10

Describe two differences between mitosis and meiosis.

Answer 10

Mitosis- Produces TWO genetically identical daughter cells (somatic cells), one division

Meiosis- Produces FOUR genetically different daughter cells (gametes), two divisions