variation and inheritance

Question 1

why is variation in a species important?

Answer 1

• for species evolution​
• ensures species can adapt to changing environments.

Question 2

what is discrete variation?

Answer 2

variation that is clear cut and observable

Question 3

what are examples of discrete variation?

Answer 3

• tongue rolling​
• eye colour​
• ear lobe attached or not

Question 4

what is continuous variation?

Answer 4

characteristics that show a range of values between a maximum and a minimum

Question 5

what are examples of continuous variation?

Answer 5

• height
• weight
• hand span

Question 6

what is variation caused by?

Answer 6

the genes we inherit during reproduction

Question 7

what is polygenic inheritance?

Answer 7

a characteristic controlled by more than one gene

Question 8

what is single gene inheritance?

Answer 8

a single gene controlling a single characteristic

Question 9

what type of variation is single gene inheritance?

Answer 9

discrete

Question 10

what type of graph can single gene inheritance be shown by?

Answer 10

bar graph

Question 11

what type of variation is polygenic inheritance?

Answer 11

continuous

Question 12

what type of graph can polygenic inheritance be shown by?

Answer 12

line graph

Question 13

gene

Answer 13

made up of DNA and code for a protein to give us characteristics such as eye and hair colour

Question 14

allele

Answer 14

different forms of a gene for example brown or blonde hair

Question 15

genotype

Answer 15

the 2 alleles shown in your genome (letters)

Question 16

phenotype

Answer 16

physical characteristic shown (appearance) ​
for example curly or straight hair

Question 17

heterozygous

Answer 17

2 different alleles ​
Bb

Question 18

homozygous

Answer 18

2 of the same alleles ​
BB or bb

Question 19

dominant

Answer 19

stronger allele will show characteristic with only one present
BB or Bb

Question 20

recessive

Answer 20

weaker allele is only shown when there are 2 copies of it
bb

Question 21

true breeding

Answer 21

contain 2 of the same allele
BB or bb

Question 22

what are the two types of alleles?

Answer 22

• dominant allele
• recessive allele

Question 23

dominant allele

Answer 23

• symbol is a capital letter (e.g. B)​
• if this is present in an individual, this characteristic is shown

Question 24

recessive allele

Answer 24

• symbol is a small letter (e.g. b)​
• this characteristic is only visible if an individual has 2 of these alleles

Question 25

steps to determining family tree genetics

Answer 25

Step 1​
Find out the recessive characteristics from the information provided and fill in all these individuals as double small allele (e.g bb)​

Step 2​
Secondly fill in ONLY 1 capital letter on the others​

Step 3​
Use any other information provided to work out if the dominant individual is BB or Bb​

Tip – if your mum and dad are dominant but they have a child that is recessive they are heterozygous