B15 Variation (1/2)

Question 1

variation

Answer 1

differences in the characteristics of individuals in a population

Question 2

causes of variation

Answer 2

inherited genes (eye colour)

environment: culture, accidents, diet, lifestyle, climate (language)

a combination of both - genetic basis but also other factors (size)

Question 3

mutation

Answer 3

change in a DNA sequence
- arise spontaneously and occur (almost) continuously

Question 4

effect of mutations

Answer 4

very rarely lead to a new phenotype
but some may change an existing phenotype

most have no effect

Question 5

phenotype

Answer 5

the set of observable characteristics or traits of an organism

(hair colour, eye colour, height)

Question 6

selective breeding (definition + process)

Answer 6

process by which humans breed plants and animals for specific genetic characteristics

process:
1. choose parents with desiree characteristic from a mixed population
2. breed them together
3. choose offspring with the desired characteristic and breed them
4. continue over many generations until all offspring show the desired characteristic

Question 7

examples of selective breeding

Answer 7

disease resistance in food crops
animals that produce more meat/milk
domestic dogs with gentle nature
larger/unsualser flowers

Question 8

advatanges of selective breeding (in terms of agriculture)

Answer 8

• crops all have similar characteristics, so customers will
return for more (known) product
• greater mass of tomatoes produced so more profit
• more fruit produced per plant means less land
required to produce same number of tomatoes
• sweeter tomatoes more in demand so higher price can
be charged

+ faster than natural selection

Question 9

disadvantages of selective breeding

Answer 9

leads to inbreeding - some breeds are particularly prone to inherited defects/diseases
reduces variation - all of a species could be susceptible to certain diseases

Question 10

genome

Answer 10

entire genetic material of a species