Topic 2 - 37

Question 1

What are gametes in males and females?

Answer 1

Sperm in males, eggs or ova in females

Question 2

What is the process of gamete formation called?

Answer 2

Gametogenesis

Question 3

Where does spermatogenesis occur?

Answer 3

In the testes

Question 4

Where does oogenesis occur?

Answer 4

In the ovaries

Question 5

Define spermatogenesis

Answer 5

The formation of spermatozoa (sperm) in the testes

Question 6

Define oogenesis

Answer 6

The formation of ova in the ovary

Question 7

What are diploid germ cells in the testes called?

Answer 7

Spermatogonia

Question 8

What do diploid spermatogonia develop into?

Answer 8

Primary spermatocytes

Question 9

What is the result of the first meiotic division in spermatogenesis?

Answer 9

Two haploid secondary spermatocytes

Question 10

What do secondary spermatocytes divide to form?

Answer 10

Four haploid spermatids

Question 11

What do spermatids differentiate into?

Answer 11

Spermatozoa (sperm)

Question 12

What is the first stage of oogenesis called?

Answer 12

Primary oocyte

Question 13

What happens to the larger cell after the first meiotic division in oogenesis?

Answer 13

It becomes the secondary oocyte

Question 14

What is the smaller cell formed during the first meiotic division in oogenesis called?

Answer 14

First polar body

Question 15

What occurs after fertilization in oogenesis?

Answer 15

The secondary oocyte divides to form the haploid ovum and another polar body

Question 16

What happens to the polar bodies during oogenesis?

Answer 16

They degenerate and die as the ovum develops

Question 17

What is the blastocyst?

Answer 17

A structure formed after 5-6 days of development that implants in the uterus

Question 18

What triggers the acrosome reaction?

Answer 18

When the front of a sperm touches the zona pellucida of the egg

Question 19

What is the role of the acrosome during fertilization?

Answer 19

It releases enzymes that digest a channel in the zona pellucida

Question 20

What happens during membrane fusion in fertilization?

Answer 20

The surface membranes of the sperm and egg fuse

Question 21

What is the cortical reaction?

Answer 21

The fusion of cortical granules with the cell membrane to prevent other sperm from entering

Question 22

What is restarted upon fertilization?

Answer 22

Meiosis in the egg

Question 23

What is the final outcome of fertilization?

Answer 23

The restoration of the diploid number of chromosomes

Question 24

What type of spores do plants form by meiosis?

Answer 24

Haploid spores

These spores undergo mitosis to develop into pollen grains and embryo sacs.

Question 25

What is produced from diploid microspore mother cells in the anther of a flower?

Answer 25

Pollen grains ## Footnote The microspore mother cell divides by meiosis to form four haploid microspores.

Question 26

What do diploid megaspore mother cells in the ovary of a flower produce?

Answer 26

Embryo sac ## Footnote The megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate.

Question 27

What is the chromosome number of haploid microspores?

Answer 27

n = 1 set of chromosomes

Question 28

What is the chromosome number of diploid microspore mother cells?

Answer 28

2n = 2 sets of chromosomes

Question 29

What is contained within a mature pollen grain?

Answer 29

Two haploid nuclei: tube nucleus and generative nucleus

Question 30

What must occur for fertilisation to happen in plants?

Answer 30

A pollen grain must be in contact with a stigma of a flower from the same plant species

Question 31

What happens to the generative nucleus during pollen grain germination?

Answer 31

It divides by mitosis to form two male gamete nuclei

Question 32

What grows down towards the ovary during fertilisation?

Answer 32

Pollen tube ## Footnote The growth is controlled by the tube nucleus.

Question 33

What do hydrolytic enzymes produced by the tip of the pollen tube do?

Answer 33

Digest the tissue of the style

Question 34

What occurs when the pollen tube enters an ovule in the ovary?

Answer 34

Double fertilisation occurs

Question 35

What does one male nucleus fuse with during double fertilisation?

Answer 35

Two polar nuclei ## Footnote This fusion forms the triploid primary endosperm nucleus.

Question 36

What is the function of the endosperm formed during fertilisation?

Answer 36

Supplies the embryo with food when it germinates

Question 37

What does the other male nucleus fuse with during double fertilisation?

Answer 37

The female gamete nucleus ## Footnote This fusion produces a diploid zygote (2n).

Question 38

What begins after the formation of the diploid zygote?

Answer 38

Development of the seed and embryo within

Question 39

What does the remaining haploid megaspore (ootid) undergo?

Answer 39

Three mitotic divisions to form an embryo sac

Question 40

What are the components of an embryo sac?

Answer 40

* 3 antipodal cells * 2 polar nuclei * Synergids * Egg cell

Question 41

True or False: The tube nucleus breaks down during the fertilisation process.

Answer 41

True

Question 42

What does one male gamete fuse with to produce a diploid zygote?

Answer 42

Female gamete nucleus

Question 43

What is produced when one male gamete fuses with two polar nuclei?

Answer 43

Triploid primary endosperm nucleus (3n)