3B Sexual reproduction and meiosis

Question 1

diploid (2n)

Answer 1

a cell with a nucleus containing two full sets of chromosomes

Question 2

haploid (n)

Answer 2

a cell with a nucleus containing one complete set of chromosomes

Question 3

zygote

Answer 3

the cell formed when two haploid gametes fuse at fertilisation

Question 4

fertilisation

Answer 4

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

Question 5

polyploidy

Answer 5

a cell or an organism with more than two sets of chromosomes

Question 6

gonads

Answer 6

the sex organs in animals

Question 7

anthers

Answer 7

male sex organs in plants that produce the male gametes contained in the pollen

Question 8

ovules

Answer 8

the haploid female gametes in plants

Question 9

testes

Answer 9

the male sex organs in animals that produce the male gametes - sperm

Question 10

pollen

Answer 10

the spore which contains the haploid male gametes of plants

Question 11

spermatozoa

Answer 11

the haploid male gametes in animals

Question 12

ova

Answer 12

the haploid female gametes in animals (singular =ovum)

Question 13

microspores

Answer 13

the result of meiosis in plants that develop into the spore (pollen) containing the male gametes

Question 14

megaspores

Answer 14

the result of meiosis in plants that develop into the female gametes, ovules

Question 15

homologous pairs

Answer 15

matching pairs of chromosomes in an individual which both carry the same genes, although they may have different alleles

Question 16

crossing over (recombination)

Answer 16

the process by which large multi-enzyme complexes cut and re-join parts of the maternal and parental chromatids at the end of prophase I, introducing genetic variation

Question 17

chiasmata

Answer 17

the points where the chromatids break during recombination

Question 18

mutation

Answer 18

a permanent change in the DNA of an organism

Question 19

independent assortment

Answer 19

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

Question 20

gametogenesis

Answer 20

the formation of the gametes by meiosis in the sex organs

Question 21

oocyte

Answer 21

a cell in an ovary which may form an ovum if it undergoes meiotic division

Question 22

acrosome

Answer 22

the region at the head of the sperm that contains enzymes to break down the protective layers around the ovum

Question 23

sporophyte generation

Answer 23

the diploid generation in plants that produces spores by meiosis

Question 24

zona pellucida

Answer 24

a layer of protective jelly around the unfertilised ovum

Question 25

sporophyte generation

Answer 25

the diploid generation in plants that produces spores by meiosis

Question 26

gametophyte generation

Answer 26

the haploid generation in plants that gives rise to the gametes by mitosis

Question 27

microgametes

Answer 27

the male gametes produced in plants, the pollen grains

Question 28

tube nucleus

Answer 28

the male nucleus that will control the production of the pollen tube in fertilisation

Question 29

generative nucleus

Answer 29

the male nucleus that will fuse with the female nucleus

Question 30

pollen tube

Answer 30

a tube that grows out of a pollen grain down the style, into the ovary and through the micropyle of the ovule to carry the generative nucleus (which divides to form two male nuclei) to the ovule

Question 31

placenta (plant)

Answer 31

placenta (plant) the pad of special tissue that attaches the plant ovule to the ovary wall

Question 32

placenta (plant)

Answer 32

placenta (plant) the pad of special tissue that attaches the plant ovule to the ovary wall

Question 33

megagamete

Answer 33

the female gamete, the egg cell, in plants

Question 34

pollination

Answer 34

the transfer of pollen from the anther to the stigma, often from one flower to another

Question 35

external fertilisation

Answer 35

the process of fertilisation in which the female and male gametes are released outside of the parental bodies to meet and fuse in the environment

Question 36

internal fertilisation

Answer 36

the fertilisation of the female gamete by the male gamete, which takes place inside the body of the female

Question 37

mating

Answer 37

the process by which a male animal transfers sperm from his body directly into the body of the female

Question 38

acrosome reaction

Answer 38

the reaction seen when the sperm reach the oocyte and enzymes are released from the acrosome and digest the follicle cells and the zona pellucida

Question 39

polyspermy

Answer 39

the fertilisation of an egg by more than one sperm

Question 40

cortical reaction

Answer 40

the reaction seen when cortical granules in the cytoplasm of the ovum release enzymes into the zona pellucida; these enzymes destroy the sperm-binding sites and also thicken and harden the jelly of the zona pellucida

Question 41

fertilisation membrane

Answer 41

the tough layer that forms around the fertilised ovum to prevent the entry of other sperm

Question 42

conception

Answer 42

the term used for fertilisation of the ovum in humans

Question 43

germinate

Answer 43

(of pollen) the process by which a pollen tube starts to grow out of the pollen grain to transfer the male nuclei to the ovule

Question 44

double fertilisation

Answer 44

the process that occurs in plants in which one male nucleus fuses with the two polar nuclei to form the triploid endosperm nucleus and the other fuses with the egg cell to form the diploid zygote

Question 45

sporophyte

Answer 45

the diploid main body of the plant

Question 46

ovaries

Answer 46

the female sex organs in both animals and plants; they produce the female gametes called ovules in plants and ova in animals