Mitosis & Meiosis

Question 1

List 2 functions/ purpose for Mitosis

Answer 1

1) Growth
2) Replacement of worn out cells (repair tissue)
3) Asexual reproduction

Mitosis doesn’t repair oldcells, it REPLACES them with new cells

Organisms who engage in asexual reproduction via mitosis include: Hydra, sea anemone & starfish

Question 2

What form is the genetic material in, when a cell is not dividing?

Answer 2

Chromatin

It is a complex of proteins and DNA in a compact, dense shape

Question 3

This is the basic structural unit of Chromatin.

Consists of a length of DNA wrapped around histones

Answer 3

Nucleosome

Question 4

During Cell division, chromatin fibres undergo further condensation and coiling to form ____

Answer 4

Chromosomes

Question 5

How many chromosomes are in a normal somatic cell?

Answer 5

46

Question 6

How many chromatids are present in a somatic cell ready to undergo mitosis?

Answer 6

92

There are still 46 chromosomes present

2 chromatids are attached to 1 centromere. 46 chromosomes are still present

Question 7

In the G1 phase the cell grows in size & organelle numbers. After this phase is the ____ phase. What happens in this next phase?

Answer 7

S Phase. DNA is replicated to form duplicate chromosomes.

After this is the G2 phase
(which acts as a checkpoint phase)

Question 8

Identify 2 events that happen in prophase

Answer 8

1. Chromosomes become visible.
2. Centriole divides and moves to opposite poles of the cell (In animal cells) and microtubules form.
3. Nucleolus disappears.
4. Nuclear membrane begins to breakdown

Question 9

What’s a difference between animal and plant cells during prophase?

Answer 9

There are no centrioles in plant cells.

Question 10

Identify which stage of mitosis is being described

Duplicated chromosomes which are attahced to spindle fibres at the centromere are lined up at the equator of the cell.

Answer 10

Metaphase

Question 11

Identify which stage of mitosis is being described

The spindle fibres shorten and pull chromatids to opposite poles of the cell.

Answer 11

Anaphase

The spindle fibres are attached to the centromere of the chromosome in metaphase. The centromere divides during this phase to allow for chromatids to be pulled to opposite poles.

Question 12

Identify 2 events that occur during telophase

Answer 12

1. Chromosomes arrive at the poles of the parent cell.
2. Spindle apparatus disintegrates.
3. A nuclear envelope reforms around each set of chromosomes.

Question 13

Which statement(s) is/are false regarding mitosis?

I) Aims to replace old tissue
II) Aims to create genetically unique daughter cells
III) Maintains the number of chromosomes as the parent cell
IV) Generates 2 daughter cells

Answer 13

II) Aims to create genetically unique daughter cells

Mitosis aims to produce genetically identical daughter cells

Question 14

Which statement(s) is/are false regarding meiosis?

I) Same no. of chromosomes is maintained in daughter cells
II) There are 2 cycles of cell divison
III) Results in genetically unique daughter cells
IV) Occurs in somatic cells
V) Contributes to variation and natural selection

Answer 14

I) Same no. of chromosomes is maintained in daughter cells

IV) Occurs in somatic cells

Meiosis results in 4 daughter cells with the haploid no. of chromosomes (half of original parent amt).
Meiosis does not occur in somatic (normal body) cells, it occurs in germ cells (cells producing gametes).

Question 15

What event takes place in prophase I which leads to variation?

Answer 15

Crossing-over

This process mixes up alleles from homologues (M & P chromosomes)

Question 16

What event takes place in metaphase I to create different combinations of maternal and paternal homologues?

Answer 16

Random Assortment

Question 17

The following question pertains to variation

This term describes the phenomenon where 1 of the many gametes produced by 1 parent meets with 1 of the many gametes produced by the other parent

Answer 17

Random Fusion