phenotypic variation

Question 1

what is a phenotype?

Answer 1

an observable characteristic

Question 2

what is phenotypic variation

Answer 2

differences between observable characteristics of a group of organisms

Question 3

what is interspecific variation?

Answer 3

• differences between different species due to different genes
• code for different proteins so look and function differently
• not affected by environment

Question 4

what is intraspecific variation?

Answer 4

• differences between organisms of the same species
• same genes, different alleles
• subtle differences
• polygenic traits are affected by the environment
• monogenic less likely

Question 5

what is a gene?

Answer 5

section of DNA that codes for a particular protein

Question 6

what is meant by monogenic

Answer 6

product of a single gene

Question 7

what is meant by polygenic

Answer 7

product of multiple genes

Question 8

what is a homologous pair?

Answer 8

a pair of chromosomes carrying the same genes with different alleles

Question 9

what is an allele

Answer 9

different versions of a gene with a slightly different base sequence - slightly different proteins are produced

Question 10

what is genetic variation

Answer 10

variation caused by differences in DNA base sequences
- different hair / eye colour

Question 11

what is environmental variation

Answer 11

variation caused by the environment in which the organism lives

Question 12

what is a chromosome

Answer 12

a long section of DNA made up of many genes

Question 13

what is a genotype

Answer 13

combination of alleles an organism has

Question 14

describe environmental modification of a genetic trait

Answer 14

• phenotypes of genetic traits are often modified by the environment
• traits are usually polygenic
• eg. weight

Question 15

what is chlorosis

Answer 15

where leaves turn pale / yellow as plant is not producing chlorophyll

Question 16

what happens to photosynthesis when a plant goes into chlorosis

Answer 16

photosynthesis cannot occur

Question 17

how do variations arise

Answer 17

mutations of genetic code

Question 18

what causes chlorosis

Answer 18

changes in phenotype due to environmental factors

Question 19

what 3 environmental factors cause chlorosis

Answer 19

• lack of light
• mineral deficiencies
• virus infections

Question 20

what is etiolation

Answer 20

the process in which plants grow long, pale and unhealthy due to lack of light

Question 21

why does etiolation occur?

Answer 21

low levels of light

Question 22

which phenotypic characteristics are affected by what we eat?

Answer 22

body mass

Question 23

what genetic and environmental factors influence weight?

Question 24

how does our diet affect our genes?

Question 25

explain the difference between phenotype and genotype

Question 26

how is genetic variation created?

Answer 26

the version of genes inherited from parents

Question 27

what influences displayed characteristics?

Answer 27

the individual mixture of alleles an organism inherits

Question 28

what determines displayed characteristics?

Answer 28

• sexual reproduction in meiosis
• random fusion of gametes in fertilisation

Question 29

describe continuous variation

Answer 29

• characteristic with continuous values (within a scale)
• eg. height

Question 30

how many genes are involved in continuous variation?

Answer 30

many - polygenic

Question 31

what causes continuous variation?

Answer 31

genetics and the environment

Question 32

how would data be represented for continuous variation?

Answer 32

histogram

Question 33

describe discontinuous variation

Answer 33

characteristics with categorical (discrete) values
- eg. blood groups

Question 34

how many genes are involved in discontinuous variation?

Answer 34

one or two

Question 35

what is the cause of discontinuous variation?

Answer 35

genetics

Question 36

how would data be presented for discontinuous variation?

Answer 36

bar chart