Chapter 6.1

Question 1

Identify 2 ways in which sexual reproduction is different from asexual reproduction.

Answer 1

• Requires 2 parents

- Produces offspring genetically different from each other, both parents and any member of their species

Question 2

Why does genetic diversity within a species more advantageous than a species with no genetic diversity?

Answer 2

Organisms will have combinations of genes from parents which may allow it to better cope with changes in its environment

Question 3

What kind of cells are in your body that contain 46 (2x23) chromosomes?

Answer 3

Diploid

Question 4

What are gametes?

Answer 4

Specialized cells necessary for reproduction

Question 5

What are female gametes called?

Answer 5

Eggs

Question 6

What are male gametes called?

Answer 6

Sperm

Question 7

How are gametes different from all other body cells?

Answer 7

Gametes carry haploid chromosomes

Question 8

What happens to the number of chromosomes during fertilization?

Answer 8

Number of chromosomes becomes 46.

Haploid male and female gametes combine, forming a diploid cell (a zygote) with 46 chromosomes

Question 9

What is the difference between a zygote and an embryo?

Answer 9

A zygote undergoes mitosis and cell division and develops into an embryo

Question 10

What is meiosis?

Answer 10

The process that produces sperm and eggs

Question 11

What happens in Prophase I?

Answer 11

Homologous chromosomes pair up and non-sister chromatids exchange genetic material (AKA Crossing Over)

Question 12

What happens in Metaphase I?

Answer 12

Homologous chromosomes pair up at the equator

Question 13

What happens in Anaphase I?

Answer 13

Homologous chromosomes seperate and are pulled to opposite poles by spindle fibres.
Independant assortment occurs.

Question 14

What happens in Telophase I?

Answer 14

One chromosome from each homologous pair is at each pole of the cell

Question 15

What happens in interkenesis?

Answer 15

The stage between cell divisions.

The cell grows and makes proteins. Similar to interphase in mitosis but there is no replication of DNA

Question 16

What happens in Prophase II?

Answer 16

There is one chromosome of the homologous pair in each cell

Question 17

What happens in Metaphase II?

Answer 17

The chromosomes form a single line across the middle

Question 18

What happens in Anaphase II?

Answer 18

Sister chromatids move to opposite poles of the cell

Question 19

What happens in Telophase II?

Answer 19

Spindle fibres begin to disappear, and a nuclear membrane forms around each set of chromosomes

Question 20

What happens in cytokenesis?

Answer 20

The 2 daughter cells are seperated.

Question 21

What is the result of meiosis I?

Answer 21

2 diploid cells, each with 46 chromosomes

Question 22

What is the result of meiosis II?

Answer 22

4 haploid cells, each with 23 chromosomes

Question 23

What are the 2 main differences between mitosis and meiosis?

Answer 23

Mitosis: Chromosomes line up along the equator and sister chromatids are pulled apart.
Meiosis: A pair of matching chromosomes line up at the equator and each chromosome is pulled apart.

Mitosis: 2 daughter cells are produced, each with 46 chromosomes.
Meiosis: 4 daughter cells are produced, each with 23 chromosomes

Question 24

What are the main differences between Meiosis I and II?

Answer 24

Meiosis I: Homologous chromosomes are pulled to opposite poles of the cell.
Meiosis II: Sister chromatids are pulled to opposite poles of the cell.

Meiosis I: 2 daughter cells are produced
Meiosis II: 4 haploid cells are produced

Meiosis I: DNA is replicated before process begins
Meiosis II: DNA is nor replicated before process begins

Question 25

What 3 events in meiosis help to increase the genetic diversity of an organism?

Answer 25

Crossing over, independent assortment and gamete formation

Question 26

What is happens in crossing over?

Answer 26

Parts of non-sister chromatids exchange segments of DNA

Question 27

What happens in independent assortment?

Answer 27

Homologous pairs of chromosomes seperate and sort themselves into daughter cells

Question 28

What happens in gamete formation?

Answer 28

Meiosis results in 4 haploid cell sperm cells for males and one haploid egg for females

Question 29

Why don’t women produce the same amount of gametes as men?

Answer 29

After meiosis II, 3 of the female gamete cells will disintegrate. The remaining one, the largest, is available for fertilization

Question 30

What types of mutations may occur in meiosis? What affect can these mutations have on an organism?

Answer 30

Parts of a chromosome can be lost, duplicated, or moved within a chromosome or moved to another chromosome.

They affect many genes in the chromosome and change the proteins made by those genes.

Question 31

What causes chromosome mutations?

Answer 31

Mutagens - such as radiation or chemicals
During Meiosis I - when homologous chromosomes fail to seperate
During Meiosis II - when sister chromatids fail to seperate

Question 32

Why are many chromosome mutations not passed from one generation to another?

Answer 32

Offspring either fails to develop or does not reach reproductive age and adulthood

Question 33

What is a karyotype?

Answer 33

A “picture” that shows all of a person’s chromosomes arranged in a particular order

Question 34

What is a karyotype used for?

Answer 34

Diagnose genetic disorders

during mitosis

Question 35

What is a syndrome? Give examples.

Answer 35

A particular disease or disorder with a specific group of symptoms that occur together.

ex: Down syndrome - 3 chromosomes are together, 21 chromosomes
ex: Edwards syndrome