b5.1

Question 1

define gamete

Answer 1

an organisms reproductive cell (egg in female, sperm in male) that contains half the chromosomes: 23

Question 2

define chromosome

Answer 2

a structure found in the nucleus whixh is made of a long strand of DNA

Question 3

define gene

Answer 3

a section of DNA which codes for a specific protein and therefore contributes to a characteristic

Question 4

define allele

Answer 4

the different forms of a gene

Question 5

define dominant and recessive allele

Answer 5

dominant: only one is needed to be expressed
recessive: two are needed to be expressed

Question 6

define homozygous

Answer 6

when both inherited genes are the same

Question 7

define heterozygous

Answer 7

when one of the inherited genes is dominant and the other is recessive

Question 8

define genotype

Answer 8

the combination of alleles an individual has

Question 9

define phenotype

Answer 9

the physical characteristics observed in the individual eg eye colour

Question 10

what is the genome described as?

Answer 10

all the genetic information of an organism

Question 11

what are all alleles caused by?

Answer 11

mutation

Question 12

how does mutation influence the phenotype in coding DNA?

Answer 12

it can alter the activity of the protein
can occur by changing the protein structure, such as shape of an enzymes active site

Question 13

how does mutation influence the phenotype in non coding DNA

Answer 13

it can alter how genes are expressed
it can stop transcription of mRNA

Question 14

what are the advantages of sexual reproduction?

Answer 14

• allows us to use selective breeding
• produces variation in offspring which aids in survival
• organisms with desirable characteristics can be bred
• speeds up natural selection

Question 15

what are the advantages of asexual reproduction?

Answer 15

• only one parent needed
• uses less energy
• lots of identical offspring can be produced

Question 16

what is meiosis?

Answer 16

the formation of four non identical cells from one cell

Question 17

describe the process of meiosis

Answer 17

• the cells make copies of its own chromosomes so it has double the amount of genetic information (diploid)
• the cell divides into two cells, each have 46 chromosomes
• each cell divides again to have 23 chromosomes (haploid)
• these cells are called gametes

Question 18

what is the chromosome pair for a female?

Answer 18

XX

Question 19

what is the chromosome pair for a male?

Answer 19

XY

Question 20

what did Mendel do?

Answer 20

• he carried out breeding experiments on pea plants using different types of peas to see which characteristics they would inherit

Question 21

what did Mendel conclude?

Answer 21

• offspring inherit one “hereditary” unit from each parent
• units can be dominant or recessive