Key Definitions - Reproduction and Inheritance

Question 1

define follicle stimulating hormone (FSH).

Answer 1

a hormone produced by the pituitary gland that stimulates the growth of follicles in the ovary and stimulates the release of oestrogen

Question 2

define luteinising hormone (LH).

Answer 2

a hormone secreted by the pituitary gland that stimulates ovulation (the release of an egg from the ovary) and the release of progesterone.

Question 3

define progesterone.

Answer 3

a hormone produced in the ovaries, specifically by the corpus luteum and the placenta that maintains the uterus lining and inhibits the release of FSH and LH.

Question 4

define amniotic fluid.

Answer 4

the fluid that surrounds and protects the embryo from bumps and sudden changes from the mother in the uterus

Question 5

define asexual reproduction.

Answer 5

a form of reproduction involving a single parent CELL. It created genetically identical offspring which have survival value in a stable environment. Usually producing large numbers of offspring and quickly

Question 6

define cuttings.

Answer 6

method of cloning plants. A section of the stem is cut, with at least one leaf, from a parent plant that you want to clone and is replanted in damp compost with hormones that stimulate root growth (auxins)

Question 7

define embryo.

Answer 7

an unborn organism in an early stage of development formed by mitosis

Question 8

define fertilisation.

Answer 8

the fusion of the nucleus of a male and female gametes to form a diploid zygote

Question 9

define gametes.

Answer 9

sex cells, sperm in males and egg cells in females, each being haploid (half the number of chromosomes). Pollen is the male gamete of a plant

Question 10

define germination.

Answer 10

seeds need oxygen (for respiration), warmth (for enzymes), water (activate enzymes) to germinate. This occurs until photosynthesis can take place in the leaves, then germination has finished.

Question 11

define menstrual cycle.

Answer 11

a monthly cycle in women that involves the growth of the uterus lining, release of an egg, maintenance of the uterus lining and then its shedding

Question 12

define meiosis.

Answer 12

a form of cellular division that produces gametes, genetically different, haploid cells. 4 daughter cells produced over two divisions involving two parent CELLS only occurs in the reproductive organs and used to produced gametes

Question 13

define mitosis.

Answer 13

a form of cellular division that produces two genetically identical, diploid cells from a single parent CELL. 2 daughter cells produced over one division, occurs everywhere in the body and used for the growth and repair of cells/tissues

Question 14

define monohybrid cross.

Answer 14

a cross between two organisms that is used to investigate the inheritance of a single gene

Question 15

define oestrogen.

Answer 15

female reproductive hormone that causes the uterus lining to develop. It inhibits FSH. Also responsible for the development of the secondary sexual characteristics

Question 16

define placenta.

Answer 16

attached to the uterus lining during pregnancy. Acts as an exchange surface between the mother and foetal blood where glucose (for respiration), amino acids (for protein synthesis) and oxygen (for respiration) diffuse into the foetal blood and waste products like carbon dioxide and urea diffuse into the mother’s blood. Also produces progesterone

Question 17

define pollination.

Answer 17

transfer of pollen grains (either by wind or insects) from the anther to the stigma, where fertilisation occurs. Can be self-pollination (same flower) or cross pollination (flowers on different plants). Also wind or insect pollination

Question 18

define wind pollinating flowers.

Answer 18

exposed stigma and stamen, dull/colourless flowers, no nectar, small and smooth pollen grains, feathery stigma

Question 19

define insect pollinating flowers.

Answer 19

enclosed stigma and stamen, large, colourful petals with nectar present, stigma is sticky and large, sticky pollen grains

Question 20

define secondary sexual characteristics.

Answer 20

features that appear during puberty and differ between genders. Examples; voice changing, growth of hair, development of breasts, hips widening, growth of male reproductive organs, start of menstrual cycle

Question 21

define sexual reproduction.

Answer 21

a form of reproduction that involves the fusion of male and female gametes, creating genetic variation in the offspring and has survival value in a changing environment. Involves two parent CELLS

Question 22

define testosterone.

Answer 22

the main male reproductive hormone, produced by the testes, stimulates sperm production (along with FSH) and responsible for the development of male secondary sexual characteristics

Question 23

define zygote.

Answer 23

a fertilised egg cell (diploid)

Question 24

define allele.

Answer 24

an alternative version of a gene that cause difference in inherited characteristics such as hair colour

Question 25

define chromosome.

Answer 25

a long, coiled molecule of DNA that carries genetic information in the form of genes

Question 26

define codominance.

Answer 26

two different alleles both being expressed in the phenotype

Question 27

define deoxyribonucleic acid (DNA)

Answer 27

double stranded polymer arranged in a double helix, made up of DNA nucleotides that carry the genetic code. There are 4 DNA nucleotides, each made up of a phosphate molecule and a deoxyribose sugar but differ due to their nitrogenous base, adenine, thymine, cytosine and guanine

Question 28

define dominant.

Answer 28

the allele that is always expressed in the phenotype when in the genotype, denoted by a capital letter

Question 29

define evolution.

Answer 29

the change in inherited traits within a population over time. Modelled by natural selection

Question 30

define gene.

Answer 30

a section of DNA that codes for a specific sequence of amino acids that forms a protein and is responsible for a particular trait (phenotype)

Question 31

define genome.

Answer 31

the complete genetic material of an organism

Question 32

define genotype.

Answer 32

all of the alleles present in an organism

Question 33

define haploid.

Answer 33

a cell that contains half the amount of genetic information. Human gametes have 23 chromosomes (it only contains 1 chromosome of each homologous pair)

Question 34

define heterozygous.

Answer 34

when an organism has two different alleles of a gene, e.g. Gg

Question 35

define homozygous.

Answer 35

when an organism has two of the same alleles, e.g. GG/g

Question 36

define mutagens.

Answer 36

chemicals that increase the frequency of mutations in DNA

Question 37

define mutation.

Answer 37

a random change in DNA which may result in genetic variations that can produce a slightly different protein and therefore a different phenotype if the mutation occurs in a gene. Examples being addition, substitution and deletion

Question 38

define natural selection.

Answer 38

a change in the environment (selection pressure) causes an organism with a mutated allele to be at an advantage, they are more likely to survive, reproduce and pass on their advantageous, mutated allele to their offspring. This happens over many generations and results in the mutated allele becoming more frequent in the population at the expense of the previously dominant allele

Question 39

define nucleus.

Answer 39

an organelle found in most eukaryotic cells that contain the genetic material of the cell and controls the activities of the cell

Question 40

define phenotype.

Answer 40

an organisms visual characteristics due to the organism’s genotype and interactions with the environment. E.g. hair colour

Question 41

define recessive.

Answer 41

an allele that is only expressed in the phenotype when present with another recessive allele in the genotype (homozygous). Denoted by a lower case letter, e.g. q

Question 42

define sex chromosomes.

Answer 42

a pair of chromosomes that determine the sex of an individual. In humans this is the 23rd pair and is XX in females and XY in males

Question 43

define variation.

Answer 43

the differences between individuals due to genes, the environment or a combination of both