Sexual reproduction and Meiosis

Question 1

What are the two processes of sexual reproduction

Answer 1

-Formation of gametes
-Fertilization of gametes to form zygote

Question 2

What are gametes

Answer 2

Sex cells, sperm and eggs

Question 3

What are zygotes

Answer 3

Cells made by fussion of sex cells

Question 4

What are the reproductive organs in animals and what do they make

Answer 4

-Testes (Make sperm)
-Ovaries (Make ova)

Question 5

What happens to the number of chromosomes when sperm and egg fuse

Answer 5

They become diploid, 46 chromosomes

Question 6

What is meiosis

Answer 6

A 2 stage cell division where the resulting daughter cells have half the number of chromosomes

Question 7

Why does meiosis result in half the number of chromosomes?

Answer 7

Because meiosis results in the making of gametes

Question 8

How many chromosomes does mitosis end in and how many chromosomes does meiosis end with

Answer 8

Mitosis ends with 46 body cells
Meiosis ends with 23 sex cells

Question 9

why are gametes called the haploid number?

Answer 9

Because they are half the number of chromosomes in the body cells

Question 10

What are homologous chromosomes

Answer 10

-We recieve one from each parent
-carry information for the same genes
-Same size and shape unless X and Y chromosomes (determine the sex)

Question 11

In mitosis there is one cell division, how many cell divisions does meiosis go through

Answer 11

2

Question 12

How many daughter cells are produced at the end of meiosis

Answer 12

4 haploid cells

Question 13

What are the two meiosis stages called

Answer 13

Meiosi 1 and meiosis 2

Question 14

What are the phases in meiosis 1

Answer 14

Interphase, prophase 1, metaphase 1, anaphase 1 and telophase 1

Question 15

What are the phases in meiosis 2

Answer 15

Prophase 2, metaphase 2, anaphase 2, telophase 2 and cytokenisis

Question 16

What happens during interphase in meiosis

Answer 16

DNA is replicated to make a tetrad

Question 17

What is a tetrad

Answer 17

A pair of homologous chromosomes (One from each parent)

Question 18

What happens during Prophase 1

Answer 18

-Chromosomes shorten and thicken
-Genetic information “crosses over” from both homologous chromosomes
-Nuclear membrane dissolves
-Spindle fibres form and centrioles go to opposite sides

Question 19

What happens in metaphase 1

Answer 19

-Spindle fibres attach to the centromeres of the chromosomes
-Line up in the middle of the cell

Question 20

What happens in anaphase 1

Answer 20

-Spindle fibres pull tetrads apart
-Homologous pairs move to opposite sides

Question 21

What happens in telophase 1

Answer 21

-The cell divides into two
-Spindle fibres disappear
-Nuclear membrane forms
-Each daughter nucleus gets 1 member of the og chromosome pair

Question 22

What happens in prophase 2

Answer 22

-No DNA duplication
-Each cell has 46 chromosomes
-Spindle fibres form
-Nuclear membrane dissolves

Question 23

What happens in metaphase 2

Answer 23

-Sister chromatids line up in the middle of the cell

Question 24

What happens in Anaphase 2

Answer 24

Sister chromatids seperate to opposite sides

Question 25

What happens in telophase 2

Answer 25

-Cell begins to pinch in -Spindle fibres disappear -Nuclear membrane reforms

Question 26

What happens in cytokenisis

Answer 26

Makes 4 cells, each have haploid number of chromosomes

Question 27

Why are humans so unique from one another

Answer 27

Because there are so many different possible combinations of chromosomes during meiosis

Question 28

What is gametogenesis

Answer 28

Production of gametes in animals

Question 29

What produces sperm in animals

Answer 29

Spermatogenesis

Question 30

What produces ova in animals

Answer 30

Oogenesis

Question 31

In spermatogenesis how many sperm cells do we get

Answer 31

4

Question 32

Are the sperm cells different or equal in size

Answer 32

Same size

Question 33

In Oogenesis, does cytoplasm divide equally

Answer 33

No, some cells get more cytoplasm than others

Question 34

What are cells that dont recieve enough cytoplasm during oognesis called and why

Answer 34

Polar bodies because they die

Question 35

How many ova is produced in oogenesis

Answer 35

1 ovum

Question 36

What are sex chromosomes

Answer 36

Chromosomes that are different in men and women of the same species

Question 37

What are the human sex chromosomes of women

Answer 37

XX

Question 38

What are the human sex chromosomes of men

Answer 38

XY

Question 39

If sex chromosomes are chromosomes, why are they not considered honologous pair?

Answer 39

Because Y is smaller than X

Question 40

Can something go wrong in meisis for the chromosomes to not seperate properly

Answer 40

Yes

Question 41

What is non disjunction

Answer 41

When homologous chromosomes fail go seperate during meiosis

Question 42

What happens when non disjunction happens

Answer 42

One cell has an extra chromosome or one cell is missing a chromosome (22 or 24 chromosomes)

Question 43

What happens if a gamete with 24 chromosomes combines with a gamete with normal 23 chromosomes

Answer 43

It will have 47 chromosomes, will lead to a genetic problem

Question 44

What is trisomy

Answer 44

When there are 3 homologous chromosomes instead of a pair

Question 45

What is monosomy

Answer 45

When there is 1 chromosome instead of a pair

Question 46

How do we diagnose non-disjunction

Answer 46

using a Karyotype

Question 47

What is a karyotype

Answer 47

A picture of all chromosomes organized by size, number and shape

Question 48

In karyotypes, humans have ___ pairs of autosomes and ___ pair of sex chromosomes

Answer 48

22 pairs of autosomes (body chromosomes) ane 1 pair of sex chromosomes

Question 49

What disorder is it when there is only 1 X chromosome

Answer 49

Turner syndrome (affect women)

Question 50

What disorder is it when there are 2 X chromosomes and 1 Y chromosome

Answer 50

Klinefelter syndrome (Affect men)

Question 51

What disorder is it when there are 3 chromosomes in chromosome 13

Answer 51

Patau syndrome, trisomy of chromosome 13

Question 52

What disorder is it when there are 3 chromosomes in chromosome 18

Answer 52

Edwards syndrome, trisomy of chromosome 18

Question 53

What disorder is it when there are 3 chromosomes in chromosome 21

Answer 53

Down syndrome, trisomy of chromosome 21

Question 54

How does a daughter cell compare to the parent cell after meiosis

Answer 54

It is different than the parent

Question 55

What process in prophase 1 makes every gamete different

Answer 55

Crossing over

Question 56

Why does a chromosome have two sister chromatids

Answer 56

Because each chromosome was duplicated during S phase