Lesson 1 - Sexual reproduction and meiosis

Question 1

meaning diploid (2n)

Answer 1

signifies a cell with a nucleus containing 2 full sets of chromosomes

Question 2

meaning haploid (n)

Answer 2

signifies a cell with a nucleus containing 1 full set of chromosomes

Question 3

meaning zygote

Answer 3

the cell formed when 2 haploid gametes fuse during fertilisation

Question 4

meaning fertilisation

Answer 4

the fusing of the haploid nuclei from 2 gametes to form a diploid zygote in sexual reproduction

Question 5

meaning polypoidy

Answer 5

when a cell or organism has more than 2 sets of chromosomes

Question 6

meaning gonads

Answer 6

the sex organs in animals

Question 7

meaning anthers

Answer 7

male sex organs in plants

Question 8

meaning ovaries

Answer 8

the female sex organs in plants and animal

Question 9

meaning pollen

Answer 9

produced in the anthers, contains the haploid female gametes in plants

Question 10

meaning ovules

Answer 10

formed in the ovaries, containing haploid female gametes in plants

Question 11

meaning testes

Answer 11

male sex organs in animals

Question 12

meaning spermatozoa

Answer 12

haploid male gametes in animals

Question 13

meaning ova

Answer 13

haploid female gametes in animals

Question 14

meaning microspores

Answer 14

the result of meiosis in plants that produce the male gametes, pollen

Question 15

meaning megaspores

Answer 15

the result of meiosis in plants that produce female gametes, ovules

Question 16

meaning homologous chromosomes

Answer 16

a set of maternal chromosome and 1 paternal chromosome that pair up during meiotic cell division

Question 17

meaning crossing over (recombination)

Answer 17

the process by which large multi-enzyme complexes cut and rejoin parts of the maternal and paternal chromatids at the end of prophase 1

Question 18

meaning independent assortment (random assortment)

Answer 18

the process by which the chromosomes derived from the male and female parent are distributed into the gametes at random

Question 19

meaning chaismata

Answer 19

the points where the chromatids break during recombination

Question 20

state 3 differences between asexual and sexual reproduction

Answer 20

• asexual reproduction requires 1 parent, whilst sexual reproduction requires 2 parents
• sexual reproduction introduces genetic variance, asexual doesn’t
• asexual reproduction is completed faster than sexual reproduction

Question 21

what would happen if 2 diploid chromosomes would fuse to form a new individual

Answer 21

the offspring would have 4 sets of chromosomes, losing the characteristic number of the species. Each new generation would become more heavily loaded with genetic material until the cells break down and fail to function

Question 22

how many daughter cells does meiosis produce

Answer 22

4

Question 23

how many daughter cells does mitosis produce

Answer 23

2

Question 24

name the 8 stages of meiosis

Answer 24

• prophase 1
• metaphase 1
• anaphase 1
• telophase 1
• prophase 2
• metaphase 2
• anaphase 2
• telophase 2

Question 25

what happens during prophase 1

Answer 25

each chromosome appears in the condensed form with 2 chromatids. Homologous pairs of chromosomes associate with each other. Crossing over occurs

Question 26

what happens during metaphase 1

Answer 26

the spindle forms and the pairs of chromosomes line up on the metaphase plate

Question 27

what happens during anaphase 1

Answer 27

the centromeres do not divide. One chromosome from each homologous pair moves to each end of the cell. As a result, the chromosome number in each cell is half that of the original

Question 28

what happens during telophase 1

Answer 28

the nuclear membrane reforms and the cell begin to divide. There is no further replication of the DNA

Question 29

what happens during prophase 2

Answer 29

new spindle are formed

Question 30

what happens during metaphase 2

Answer 30

the chromosomes, still made up of pairs of chromatids, line up on the metaphase plate

Question 31

what happens during anaphase 2

Answer 31

the centromeres now divide and the chromatids move to the opposite ends of the cell

Question 32

what happens during telophase 2

Answer 32

the nuclear envelope reforms, the chromosomes return to their interphase state and cytokinesis occurs, giving 4 daughter cells, each with half the chromosome number of the original diploid cell