5.1 - reproduction, meiosis and genetic crosses

Question 1

asexual reproduction +

Answer 1

• faster than sexual
• only one parent needed
• more time/energy efficient (don’t need to find mate)
• many identical offspring produced when conditions favourable

Question 2

sexual reproduction +

Answer 2

• produces variation in offspring
• if environment changes variation gives survival advantage by natural selection
• natural selection can be sped up in selective breeding to increase food production

Question 3

mutation

Answer 3

random change in dna

Question 4

some animals/plants can do both sexual and asexual reproduction

Answer 4

a - when conditions are favourable
s - if circumstances change - adapt to increase survival (variation)

Question 5

onion reproduction

Answer 5

a - produces bulbs that can divide and grow into new plants
s- produces seeds when flowers are pollinated

Question 6

fungi reproduction

Answer 6

a - made by mitosis and grow into genetically identical fungi
s - spores are made by meiosis

Question 7

strawberry reproduction

Answer 7

a - plant makes runners on which new plants grow
s- pollen and ovules fuse to make a seed

Question 8

malarial parasite

Answer 8

• mosquito feeds on human
• malarial parasite transferred to human
• it feeds grows + divides in the liver
• cells of the parasite invade red blood cells
• asexual cycle starts (triggered by food/ warm conditions)
• sexual forms of the malarial parasite are produced (believe this is triggered by the immune system challenging it)
• sexual forms are transferred to the mosquito
• sexual reproduction of the malarial parasite in the mosquito

Question 9

chromosome, dna , gene, genome - size order

Answer 9

• DNA - polymer of nucleotides
• gene - instructions for a characteristic
• chromosome- 46
• genome - entire genetic material of a cell/organism

Question 10

mitosis use

Answer 10

• produces 2 genetically identical offspring
• for growth and repair

Question 11

meiosis use

Answer 11

cell division - produces 4 genetically diff. cells for variation

Question 12

gametes

Answer 12

sex cells
- single set of chromosome

Question 13

zygote

Answer 13

cells formed by fusion of 2 gametes

Question 14

male chromosomes

Answer 14

XY

Question 15

female chromosomes

Answer 15

XX

Question 16

meiosis

Answer 16

• parent cell - 46 chromosomes
• chromosomes copy themselves
• chromosomes pair up (homologous chromosomes pair up - 1from mum with 1 from dad)
• sections of dna are swapped within each pair of chromosomes
• chromosome pairs sepearated and the cell divides (one member of each pair in each new cell)
• original and copied chromosomes are separated from each other + cells divide in 2
• 4 genetically different gametes are made - 23 chromosomes

Question 17

haploid

Answer 17

cells with a single chromosome from each pair

Question 18

diploid

Answer 18

cells with a pair of each chromosome - 1 from mum 1 from dad

Question 19

chromosome

Answer 19

thread like structures of DNA in the nucleus

Question 20

gene

Answer 20

a section of DNA containing instructions for a characteristic

Question 21

allele

Answer 21

an alternative form of a gene eg blue allele of eye colour

Question 22

genotype

Answer 22

the alleles present for a particular gene eg Bb for eye colour

Question 23

phenotype

Answer 23

the characteristic that is show eg brown for eye colour

Question 24

dominante allele

Answer 24

allele that’s always expressed even if another allele is present - CAPITAL

Question 25

recessive allele

Answer 25

2 copies of allele must be present to be expressed - lowercase

Question 26

homozygous

Answer 26

a person with 2 of the same allele for a characteristic

Question 27

heterozygous

Answer 27

a person with 2 diff allele for a characteristic

Question 28

cystic fibrosis

Answer 28

• thick mucus
• 7th pair of chromosomes
• recessive - have to have 2 to suffer from it but can have one and be a carrier

Question 29

generic diagram rules

Answer 29

• show parents phenotypes
• show parents genotypes
• DOMINANT recessive
• pure gametes in circles
• show all combinations of alleles
• pure an x to show the cross