B6

Question 1

What sex chromosomes do males have

Answer 1

XY

Question 2

What sex chromosomes do females have

Answer 2

XX

Question 3

How many chromosomes do humans have in body cells

Answer 3

23 pairs
46 chromosomes

Question 4

Where is DNA found

Answer 4

Chromosomes

Question 5

What are genes

Answer 5

Section of DNA on a chromosome

Question 6

What are alleles

Answer 6

Versions of genes

Question 7

What does the genotype tell us

Answer 7

The genotype of a person Tells us the alleles present

Question 8

What is it called when a person has two copies of the same allele

Answer 8

Homozygous

Question 9

When does phenotype tell us

Answer 9

The phenotype tells us the characteristics caused by the persons alleles

Question 10

What is it called when a person has two copies of different alleles

Answer 10

Heterozygous

Question 11

What is a dominant allele

Answer 11

A dominant allele will show in the phenotype even if there is only one copy present

Question 12

When is a recessive allele

Answer 12

A recessive allele will only show in the phenotype if two copes are present

Question 13

What is cystic fibrosis

Answer 13

A disorder of cell membrane

Question 14

What is the structure of DNA

Answer 14

-two strands,each on a polymer
-double helix

Question 15

What do genesis make amino acids do

Answer 15

Each gene encodes a specific sequence of amino acids to make a specific protein

Question 16

What is a genome

Answer 16

-the genome is the entire genetic material of an organism

Question 17

Why is it important we understand the human genome

Answer 17

-search for genes linked to disease
-understand and treat inherited disorders
-trace human migration patterns

Question 18

Where do we find chromosomes

Answer 18

In the nucleus of cells

Question 19

What are the stages of mitosis

Answer 19

1.DNA replicates forming two copies of each chromosome
2.mitosis takes place and one set of chromosomes are pulled to each end of the cell,nucleus also divided
3.cell membrane and cytoplasm divide forming two identical cells

Question 20

Functions of mitosis

Answer 20

1.growth and development of multicellular organisms
2.repair
3.asexual reproduction

Question 21

What do gametes such as sperm and egg cells contain

Answer 21

-single chromosome
-chromosomes are not paired
-23 single chromosomes

Question 22

What are the stages of meiosis

Answer 22

1-all the chromosomes are copied
2-cell divided into two
3-both of the new cells divide once more forming the gametes

Question 23

What does meiosis form

Answer 23

-four Gametes
-each gamete is genetically different

Question 24

What happens to gamate’s in sexual reproduction

Answer 24

-gametes join together(fertilisation)
-the cell now has a normal number of chromosomes

Question 25

What happened to the number of chromosomes in meiosis

Answer 25

The number of chromosomes is halved

Question 26

What is an embryo

Answer 26

A clump of identical cells

Question 27

What is polydactyl

Answer 27

-a disorder where people have extra fingers or toes

Question 28

Polydactyl is caused by a dominant allele , what does this mean

Answer 28

-you cannot be a carrier -a person with one copy of polydactyl will have it

Question 29

What is embryo screening

Answer 29

-Embryos are tested to see if they have the alleles for inherited disorders -embryos which don’t have the defective allele are implanted into the women

Question 30

What are solutions for inherited disorders

Answer 30

Embryo screening

Question 31

What are the issues with embryo screening

Answer 31

-Expensive-money could be spent elsewhere -embryos are destroyed,seen as unethical -may be able to screen embryos to have desired features, unethical

Question 32

What is variation

Answer 32

The differences in characteristics of individuals in a population

Question 33

What are the causes of variation

Answer 33

-inherited alleles -genetics and environmental

Question 34

What are some examples of environmental variation

Answer 34

-flower colour, PH of soul -Langauge

Question 35

What are mutations

Answer 35

Random changes to DNA

Question 36

What can mutation lead to

Answer 36

-Very rarely mutation can lead to new phenotype -can be beneficial if environment changes

Question 37

what is the three domain system

Answer 37

-based on DNA their are three domains -archaea,prokaryota,eukaryota

Question 38

what is archaea

Answer 38

primitive/simple bacteria

Question 39

what is prokaryota

Answer 39

true/modern bacteria

Question 40

what is eukaryota

Answer 40

- includes organisms with cells having a nucleus

Question 41

what domains are extremophiles

Answer 41

arachea

Question 42

what are the steps involved with selective breeding

Answer 42

-breed plants -choose plants with desired characteristics -breed repeatedly until all plants have the desired traits

Question 43

advantages of GM crops

Answer 43

-resistance to disease /pests / pathogens so higher yield -larger / more grains per plant or higher yield so more food for people or more income for farmers -better nutritional content (vitamins / protein / low GIndex) so will improve health

Question 44

disadvantages of gm crops

Answer 44

-may affect health of people who eat the rice because not enough research done yet -traditional varieties no longer grown -so reduction in biodiversity

Question 45

what are vectors used for in genetic engineering

Answer 45

-vectors are used to insert genes into cells -vectors are usually plasmids or viruses

Question 46

The herbicide resistant variety of wheat will give a higher yield than the non-herbicide resistant variety.

Answer 46

-wheats are not damaged by herbivores -therefore they are exposed to more light -meaning an increased rate of photosynthesis, increasing proteins made within the plant increasing yield