UNIT 2: (2.4) Variation And Inheritance

Question 1

what are the two types of variation?

Answer 1

• discrete

- continuous

Question 2

what is discrete variation?

Answer 2

describes a characteristic for which a population can be separated into distinct categories or groups

Question 3

what are examples of discrete variation?

Answer 3

• fingerprint
• ear lobe shape
• eye color
• blood group
• tongue rolling

Question 4

what is single gene inheritance?

Answer 4

characteristics that are coded for by a single gene

Question 5

how is discrete variation shown in a graph?

Answer 5

bar graph

Question 6

what is continuous variation?

Answer 6

shown in characteristics which show a range of phenotypes between a minimum and a maximum value

Question 7

what are examples of continuous variation?

Answer 7

• height
• shell diameter
• tail length in mice
• hand size

Question 8

why does continuous variation occur?

Answer 8

several different genes control the same characteristic known as polygenic inheritance.

Question 9

how is continuous variation shown in a graph?

Answer 9

• bell-shaped curve on a line graph

- histogram

Question 10

what are genes?

Answer 10

sections of DNA that code for particular proteins

Question 11

how many sets of chromosomes are in each cell?

Answer 11

• two sets
• one inherited from mother
• one inherited from father

Question 12

how are chromosomes arranged?

Answer 12

pairs

Question 13

what are chromosomes identical in?

Answer 13

• shape
• size
• genes they carry

Question 14

what are alleles?

Answer 14

different forms of a gene

Question 15

how many alleles are in each gene?

Answer 15

two alleles ( both the same or both different)

Question 16

what is a phenotype?

Answer 16

the physical appearance of the organism

Question 17

what is meant by dominant?

Answer 17

stronger version of the gene

Question 18

what is meant by recessive?

Answer 18

weaker version of the gene

Question 19

what is meant by homozygous?

Answer 19

if an individual carries two of the same allele

Question 20

what is meant by heterozygous?

Answer 20

if an individual carries two different alleles

Question 21

what is meant by a genotype?

Answer 21

the genes (alleles) an organism has for a particular characteristic

Question 22

what are genetic crosses involving only one characteristic called?

Answer 22

monohybrid crosses

Question 23

why do ratios of offspring do not match the predicted ratios?

Answer 23

• fertilisation is a random process

- the numbers of organisms in the cross are too small

Question 24

what can be used to determine the genotype?

Answer 24

backcross or look at offspring