10.5-6 Types of variation (no MATHS)

Question 1

Interspecific variation

Answer 1

variation between members of different species
e.g. mouse has 4 legs, bird has 2 legs

Question 2

intraspecific

Answer 2

differences between organisms within a species
e.g. height, build, hair colour & IQ

Question 3

Causes of variation

Answer 3

genetic material = genetic variation
environment = environmental variation

Question 4

Genetic causes of variation: OVERALL

Answer 4

Alleles (variants): genes have different alleles. In a gene for a particular characteristic, different alleles produce different effects.

Mutations: changes in DNA sequences

Meiosis

Sexual reproduction

Chance

Question 5

Genetic causes of variation: mutation

Answer 5

Mutations: changes in DNA sequences = changes in proteins that code for a gene
–> can affect physical and metabolic characteristics

Question 6

Genetic causes of variation: Meiosis

Answer 6

gametes are produced via meiosis
–> each gamete receives half the genetic content of a parent
–> genetic material inherited from two parents is mixed up via independent assortment and crossing over

Question 7

Genetic causes of variation: sexual reproduction

Answer 7

offspring produced from two individuals inherits genes and alleles from each parents

Question 8

Genetic causes of variation: Chance

Answer 8

many different gametes are produced from parental genome (during sexual reproduction it is a result of chance as to which two will combine)
–> random fertilisation

Question 9

Environmental causes of variation

Answer 9

good example is presence/ absence of any scars (caused via an accident or disease = no genetic origin)

Question 10

Discontinuous variation

Answer 10

characteristic that can only result in certain values (no inbetweens)
–> variation purely due to genetic factors e.g. sex, blood type
–> represented via barchart/ pie chart

Question 11

Continuous variation

Answer 11

characteristic that can take any value within a range
–> continuum e.g. height, mass
–> not controlled by single gene but a number of them (polygenes)
–> often influenced by environmental factors

Question 12

Normal distribution curves

Answer 12

bell shaped
- mean mode and median are equal
- distribution is symmetrical about mean
- 50% of values are less than mean and 50 % are greater
- most values lie close to mean value