Meiosis

Question 1

What is meiosis?

Answer 1

It’s a type of cell division that happens in the reproductive organs to produce gametes.

Question 2

True or False: Meiosis involves a reduction division. The cells that are formed from meiosis have half the number of what they started with.

Answer 2

True

Question 3

True or False: The whole of meiosis does not begin with interphase.

Answer 3

False

Question 4

Fill in the blank about prophase I in meiosis I (1st stage):

The chromosomes ________. The chromosomes then arrange themselves into __________ pairs and crossing-over occurs. The __________ move to opposite ends of the cell, forming the spindle fibres. The nuclear envelope breaks down.

Answer 4

The chromosomes (condense). The chromosomes then arrange themselves into (homologous) pairs and crossing-over occurs. The (centrioles) move to the opposite ends of the cell, forming the spindle fibres. The nuclear envelope breaks down.

Question 5

Fill in the blank about metaphase I in meiosis I (2nd stage):

The homologous pairs attach to the _______ ______ by their centromeres and ____ __ across the centre of the cell.

Answer 5

The homologous pairs attach to the (spindle) (fibres) by their centromeres and (line) (up) across the centre of the cell.

Question 6

Fill in the blank about anaphase I in meiosis I (3rd stage):

The spindles ________, separating the homologous pairs - one chromosome goes to each end of the ____.

Answer 6

The spindles (contract), separating the homologous pairs - one chromosome goes to each end of the (cell).

Question 7

Fill in the blank about telophase I in meiosis I (4th stage):

A _______ ________ forms around each group of chromosomes.

Answer 7

A (nuclear) (envelope) forms around each group of chromosomes.

Question 8

Fill in the blank about cytokinesis in meiosis I (after telophase I):

Cytokinesis occurs and two _______ ________ cells are produced.

Answer 8

Cytokinesis occurs and two (haploid) (daughter) cells are produced.

Question 9

Explain how the crossing over of chromatids in meiosis I can lead to genetic variation.

Answer 9

Each of the four daughter cells formed from meiosis contains chromatids with different alleles.

Question 10

Explain how the independent assortment of chromosomes can lead to genetic variation.

Answer 10

When the homologous pairs line up in metaphase I and are separated in anaphase I, it’s completely random which chromosome from each pair ends up in which daughter cell.

So the four daughter cells produced by meiosis have completely different combinations of those maternal and paternal chromosomes.

Question 11

Fill in the blank about anaphase II in meiosis II:

The pairs of sister chromatids are _________ - each new daughter cell inherits one _________ from each chromosome.

Answer 11

The pairs of sister chromatids are (separated) - each new daughter cell inherits one (chromatid) from each chromosome.