1) Genetics

Question 1

what kind of cells does meiosis produce?

Answer 1

• diploid cells

- 23 chromosomes

Question 2

what happens in meiosis?

Answer 2

• chromosome replicates
• chromosomes stay attached
• they pair up
• then separate into two new cells
• produces 4 haploid daughter cells

Question 3

why are the cells different?

Answer 3

-different versions of the same genes

Question 4

what is a zygote?

Answer 4

single fertilised egg cell

Question 5

what is the structure of DNA?

Answer 5

• two strands in helix shape
• joined together by bases
• to make a double helix

Question 6

what are the 4 bases and what are their pairs?

what kind of bone do they have?

Answer 6

• adenine, thymine, cytosine, guanine
• T and C
• A and G
• weak hydrogen bond

Question 7

what is a genome?

Answer 7

• all the DNA in an organism

- each cell contains a copy of the genome

Question 8

what is a gene and its role?

Answer 8

• section of DNA in a chromosome

- coded instructions which allow scientists to see your DNA

Question 9

how can DNA be extracted from fruit?

Answer 9

• dissolve 3g of salt in 100cm3 of water. add 10cm3 of washing up liquid. stir.
• mash 50g of peas and add to the solution. stir.
• water bath(60degrees) for 15 min
• filter the mixture
• 10cm3 of filtrate into a testube
• two drops of protest enzyme solution
• add ice Cold ethanol
• white layer of DNA should form

Question 10

why is there differences in inherited characteristics?

Answer 10

• contain slightly different instructions
• create variations
• different forms of the same gene are alleles

Question 11

what is a chromosome?

Answer 11

• found in nuclei

- contain DNA

Question 12

what is a gene?

Answer 12

-section of DNA in a chromosome

Question 13

what is allele?

Answer 13

-different forms of the same gene

Question 14

what is dominant?

Answer 14

• allele always affects phenotype

- opposite to recessive alleles

Question 15

what is recessive?

Answer 15

-allele that will only affect phenotype if other alleles are recessive

Question 16

what is heterozygous?

Answer 16

-if the alleles are different in the gene

Question 17

what is homozygous?

Answer 17

-if both alleles of the same gene are the same

Question 18

what is a gamete?

Answer 18

• only one copy of each chromosome

- one copy of each gene

Question 19

what is zygote?

Answer 19

-fertilised egg

Question 20

what is monohybrid inheritance? How can it be shown/explained?

Answer 20

• inheritance of one gene

- shown using Punnett squares and Family Predigrees

Question 21

what are sex chromosomes and which do male and females have?

Answer 21

• two chromosomes decide what sex you are
• females- X
• male- X and Y

Question 22

which sex chromosome is more dominant and decides what sex you will be?

Answer 22

-male Y

Question 23

how can pungent squares be used to determine your sex?

Answer 23

• boxes show possible genotypes
• two contain XX
• two contain XY
• ratio= 2:2
• equal chance of a boy or girl

Question 24

what does a family pedigree chart show?

Answer 24

-shows hoe genotypes + phenotypes are inherited

Question 25

how are most phenotypes inherited?

Answer 25

-result of multiple genes rather than single gene inheritance.

Question 26

what are the causes of variation?

Answer 26

• mutations
• genetic variation
• environmental variation

Question 27

what is a mutation? when do they occur?

Answer 27

• change in gene that creates a new allele

- occur in cell devision

Question 28

what causes mutation?

Answer 28

• mistake in copying DNA

- likely to happen if DNA is damaged due to radiation

Question 29

what causes genetic variation?

Answer 29

-alleles inherited in sex

Question 30

what causes environmental variation? give example.

Answer 30

• effect by surroundings

- i.e. plant grows depending on how much water and sunlight it gets.

Question 31

what did the ‘Human Genome Project’ do/ what did they find out?

Answer 31

• map of 3.3 billion complimentary base pairs in on set of human chromosomes.
• 99% are the same in every person

Question 32

why is the HUMAN GENOME PROJECT good for medicine?

Answer 32

• indicate risk of diseases

- identify what medicines are needed

Question 33

why is there expensive genetic variation in a population?

Answer 33

-they all arise through mutations