topic 4: reproduction and inheritance

Question 1

chromosomes

Answer 1

are long lengths of DNA coiled up

Question 2

gene

Answer 2

short section of DNA containing a chemical construction that codes for a particular protein

Question 3

genome

Answer 3

all of the organism’s DNA

Question 4

alleles

Answer 4

different versions of the same gene giving different versions of a characteristic

Question 5

DNA structure

Answer 5

two strands coiled together in the shape of a double helix

said strands are held together by chemicals called bases (adenine, thymine and cytosine, guanine)

A-T C-G

Question 6

codon

Answer 6

each amino acid is coded for by a sequence of 3 bases in the gene

Question 7

transcription

Answer 7

rna polymerase binds to a reigon of non coding DNA in front of a gene

the two dna strands unzip and the RNA polymerase moves along one of the strands of the DNA

it uses the coding DNA in the gene as a template to make the mRNA. base pairing between the DNA and RNA ensures that the mRNA is complementary to the gene

once made, the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm

Question 8

translation

Answer 8

amino acids are brought to the ribosome by another RNA molecule called transfer RNA (tRNA)

the order in which the amino acids are brought to the ribosomes matches the order of the codons in the mRNA

part of the tRNA’s structure is called an anticodon - it is complementary to the codon for the amino acid. the pairing of the coding and anticodon makes sure that the amino acids are brought to the ribosome in the correct order

the amino acids are joined together by the ribosomes. this makes a protein

Question 9

mitosis

Answer 9

when a diploid cell reproduces itself by splitting to form two cells with identical sets of chromosomes

Question 10

asexual reproduction

Answer 10

no variation

no need for a mate

identical genes to the parent

Question 11

sexual reproduction

Answer 11

genetic variation

need for two parents

Question 12

mitosis process

Answer 12

cell duplicates its DNA (46 chromosomes)

chromosomes line up at the centre of the cell and the cell fibres pull them apart

membranes form around each of the sets of chromosomes. these become the nuclei of the two new cells

cytoplasm divides

two identical daughter cells are created

Question 13

meiosis

Answer 13

produces four haploid cells whose chromosomes

Question 14

meiosis process

Answer 14

before the cell divides, it duplicates its dna

the chromosomes line up in pairs in the centre of the cell

the pairs are then pulled apart so each new cell only had one copy of each chromosome

some of the father’s + mother’s chromosomes go into each new cell. this creates genetic variation

in the second division, the chromosomes line up at the centre of the cell

chromosomes get pulled apart

this gives you four haploid gametes with only a single set of chromosomes. they are all genetically different

Question 15

stamen

Answer 15

male reproductive part

made up of the anther and filament

Question 16

carpel

Answer 16

female reproductive part

made up of the stigma, style and ovary

Question 17

pollination

Answer 17

transfer of pollen from an anther to a stigma

Question 18

cross pollination

Answer 18

pollen transferred from one plant to another

can either be insect or wind

Question 19

adaptations for wind pollination

Answer 19

small dull petals
no nectaries
long filaments that let the anther hang out
a lot of small and light pollen grains
stigma is feathery and large to catch pollen

Question 20

adaptations for insect pollination

Answer 20

brightly coloured petals
nectar for sweet scent
big sticky pollen grains that stick to insects
sticky stigma for said pollen to stick onto it

Question 21

fertilisation in plants

Answer 21

pollen lands on the stigma of a flower

pollen tube grows out of the pollen grain and down through the style to the ovary and into the ovule

a nucleus from the male gamete moves down the tube

two nuclei fuse together to make a zygote, which divides to form an embryo

each female gamete thats fertilised forms a seed. the ovary develops into a fruit around said seed

Question 21

germination

Answer 21

when the seeds start to grow

Question 22

conditions for germinating

Answer 22

water
oxygen
suitable temperature

Question 23

components in a seed

Answer 23

hard seed coat
embyro root
embryo shoot
food store

Question 24

investigate the conditions needed for seed germination (practical)

Answer 24

take four boiling tubes and put cotton wool at the bottom of each one place 10 seeds on top of the cotton wool in each boiling tube set up each boiling tube as follows: tube 1 has wet cotton wool tube 2 has dry cotton wool tube 3 has wet cotton wool and is stored in the fridge tube 4: has boiled water and oil which prevents oxygen going in

Question 25

strawberry plants

Answer 25

parent strawberry plant sends out runners the runners take root at various points and new plants start to grow the new plants are clones with no genetic variation

Question 26

components in the penis

Answer 26

urethra erectile tissue testis glands vas deferens head of penis foreskin scrotal sac

Question 27

urethra

Answer 27

tube that carries sperm through the penis during ejaculation urine also passes through the urethra to exit the body

Question 28

erectile tissue

Answer 28

swells when filled with blood to make the penis erect

Question 29

testis

Answer 29

where sperm are made

Question 30

glands

Answer 30

produce the liquid thats added to sperm to make semen

Question 31

vas deferens

Answer 31

muscular tube that carries sperm from testis towards the urethra

Question 32

foreskin

Answer 32

can be removed

Question 33

scrotal sac

Answer 33

hangs behind the penis and contains the testis

Question 34

vagina components

Answer 34

fallopian tubes muscular uterus wall uterus vulva cervix vagina ovary endometrium

Question 35

fallopian tube

Answer 35

a muscular tube that carries the ovum from the ovary to the uterus

Question 36

uterus

Answer 36

the organ where an embryo grows

Question 37

vagina

Answer 37

where the sperm is deposited

Question 38

cervix

Answer 38

the neck of the uterus

Question 39

endometrium

Answer 39

has a good blood supply for implantation of an embryo

Question 40

ovary

Answer 40

organ that produces ova and sex hormones

Question 41

fertilisation in humans

Answer 41

an ovum is produced every 28 days from one of the two ovaries it then passes into the fallopian tube where it might meet sperm if it isnt fertilised by sperm, the ovum will break up and pass out of the vagina if it is the ovum starts to divide. the new cells will travel down the fallopian tube to the uterus and attach t

Question 42

menstrual cycle

Answer 42

day 1: menstruation stars. the uterus lining breaks down for about four days the uterus lining builds up again from day 4 to day 14 into a thick, spongy layer full of blood vessels ready to receive a fertilised egg an egg develops and is released from the ovary at day 14 - ovulation!!! the wall is then maintained for about 14 days until day 28. if no fertilised egg has landed on the uterus wall by day 28, the spongy lining breaks down and the cycle starts again

Question 43

hormones that control the menstrual cycle

Answer 43

fsh oestorgen lh progesterone

Question 44

fsh

Answer 44

follicle stimulating hormone produced in pituitary gland stimulates the ovaries for oestrogen matures the egg

Question 45

lh

Answer 45

luteinising hormone produced by the pituitary gland stimulated the release of the egg by day 14

Question 46

oestrogen

Answer 46

produced in ovaries develops the lining of the uterus

Question 47

progesterone

Answer 47

produced in the ovaries by the remains of the follicle maintains the uterus lining during the second half of the ycle inhibits the release of LH and FSH

Question 48

alleles

Answer 48

different versions of the same gene

Question 49

genotype

Answer 49

alleles that you have

Question 50

codominant

Answer 50

neither allele is recessive so you show characteristics from both alleles

Question 51

homozygous

Answer 51

two alleles are the same

Question 52

heterozygous

Answer 52

two alleles are different

Question 53

phenotype

Answer 53

characteristics the alleles produce

Question 54

variation factors

Answer 54

genes environment

Question 55

environmental factors in variation

Answer 55

health intelligence sporting ability

Question 56

genetic factors in variation

Answer 56

eye colour hair colour inherited disorders blood group

Question 57

environmental factors in plant variation

Answer 57

sunlight moisture temperature mineral content of the soil

Question 58

mutation

Answer 58

a spontaneous change of the sequence of DNA bases in a gene which produces a genetic variant this leads to changes in the protein that it codes for

Question 59

factors that increase mutation

Answer 59

ionising radiation mutagens