Topic 6, Part 2 - Inheritance, Variation and Evolution

Question 1

what is gamete fusion

Answer 1

when one sperm and one egg meet and they fuse together (fertilisation) to form the full number of chromsomes

Question 2

what is asexual reproduction

Answer 2

there is only one parent so offspring is genetically identical. there is no fusion of gametes so its identical.

Question 3

how does asexual reproduction happen

Answer 3

by mitosis, an ordinary cell makes a new one by dividing in two

Question 4

how does meiosis work (5 steps)

Answer 4

1) duplicates genetic information forming two armed
chromsomes. both copies
2)first division, pairs line up in centre of cell
3)pairs pulled apart, each cell has only one copy of
chromosome
4)second division, chromosomes line up in centre and
pulled apart
5)you get 4 identical gemetes, each genetically different.

Question 5

what happens when two gemetes have fused together (how an organism is made)

Answer 5

the resulting new cell divides by mitosis to make a copy of itself. repeats many times in embryo. then cells differentiate into cells and specialised cells into an organism

Question 6

what do x and y chromosomes mean

Answer 6

22 pairs of chromosomes are matched pairs that control characteristics and the 23rd pair decides your sex

Question 7

which one is a male and female chromosome

Answer 7

XY is male

XX is female

Question 8

what chromosomes do eggs have

Answer 8

they all have x chromosomes

Question 9

what chromosomes do spern have

Answer 9

there is a 50% chance of ether getting x or y chromosome in a sperm cell

Question 10

what is cystic fibrosis

Answer 10

genetic disorder of cell membrane where body produces sticky mucus in air passage ways and in pancreas

Question 11

what is cystic fibrosis caused by

Answer 11

it is caused by recessive allele (f)

Question 12

what is a recessive allele

Answer 12

if people only have one copy of the allele wont have disorder. both parents need to be carriers for offspring to have

Question 13

what is polydactyly

Answer 13

it is a genetic disorder where you have extra fingers or toes

Question 14

what is polydactyly caused by

Answer 14

cause by dominant allele (D)

Question 15

what is a dominant allele

Answer 15

can be inherited if only one parent carries it. the parent with it will also have it.

Question 16

what does it mean to screen a embryo

Answer 16

you can screen an embryo to see if tehy have a genetic disorders then the parents can chose whether they want to keep the child or abort it.

Question 17

what is vitro fertilastion (IVF)

Answer 17

it is where embryos are fertilised in a laboratory and implanted into mother womb

Question 18

what is a mutation

Answer 18

where a gene mutates. rare and random change in an organisms dna

Question 19

what can bacteria do to overcome antibiotics

Answer 19

they can evolve and become antibiotic-resistance.

Question 20

how do bacteria become antibiotic-resistance

Answer 20

in bacteria, they have a random chance to develop mutations. this can lead to changes in the characteristics of the bacteria making antibiotics less effective

Question 21

what is meiosis

Answer 21

it produces cell with half the normal number of chromsomes. only happens in reproduction organs