inheritance 2.4

Question 1

what allows for variation

Answer 1

sexual reproduction

Question 2

what is a species

Answer 2

a group of organisms which reproduce to produce fertile offspring

Question 3

the types of variation

Answer 3

discrete and continuous

Question 4

discrete variation

Answer 4

when a characteristic can be used to divide up the members of a species into two or more distinct groups

Question 5

examples of discrete variation

Answer 5

ear lobes, dog coat colour, hair colour and finger prints

Question 6

continuous variation

Answer 6

when a characteristic varies in a smooth continuous way and doesn’t fall into distinct groups

Question 7

examples of continuous variation

Answer 7

petal length, body mass, height and hand span

Question 8

what type of variation does single gene show

Answer 8

discrete variation

Question 9

when are characteristics single gene

Answer 9

when they are controlled by only one single gene

Question 10

what type of variation does polygenetic show

Answer 10

continuous variation

Question 11

when do characteristics involve polygenetic inheritance

Answer 11

when a characteristic is controlled by more than one gene

most characteristic are controlled by more that one gene

Question 12

homozygous

Answer 12

an organism that has two identical alleles

example:BB or bb

Question 13

hetrozygous

Answer 13

an organism that has two different alleles, one being dominant and one being recessive

example:Bb

Question 14

are homozygous organisms true-breeding

Answer 14

yes

Question 15

are heterozygous organisms true-breeding

Answer 15

no

Question 16

phenotype

Answer 16

a person’s physical characteristics as a result of their gene

Question 17

genotype

Answer 17

complete set of genes

Question 18

allele

Answer 18

different form of the same gene

Question 19

what is true-breeding

Answer 19

when an organism is crossed with another organism who has the same genotype and all of the offspring produced have the same phenotype as parents

Question 20

dominant alleles

Answer 20

• written as capital letters (B)

- only one copy of dominant allele needed to display dominant phenotype

Question 21

recessive alleles

Answer 21

• written as small letter (b)

- two copies of recessive allele is needed to display recessive phenotype

Question 22

monohybrid crosses

Answer 22

allows us to determine the genotype and phenotype of offspring

Question 23

why are family trees used

Answer 23

to trace through several generations of families to see passing genes

Question 24

why is the genotypical ratio not always achieved

Answer 24

because fertilisation is a random process that involves an element of chance