B17 - Variation and Selection

Question 1

What is variation? [2]

Answer 1

differences between individuals of the same species

Question 2

What is the biological name for humans? [1]

Answer 2

homo sapiens

Question 3

What two ways do humans get differences from? [2]

Answer 3

• environment
• genes

Question 4

What are examples of environmental differences? [5]

Answer 4

• dyed hair
• piercings
• accent
• scars
• fashion sense

Question 5

What are examples of genetic differences? [5]

Answer 5

• eye colour
• natural hair colour
• nose shape
• blood group
• tongue rolling

Question 6

What is continuous variation? [3]

Answer 6

• results in a range of phenotypes between a minimum and maximum
• quantitative
• histogram

Question 7

What is discontinuous variation? [4]

Answer 7

• results in a limited number of phenotypes with no intermediates
• characteristic falls into a distinct group
• qualitative
• bar chart

Question 8

What are examples of continuous variation? [4]

Answer 8

• height
• arm span
• head circumference
• leaf surface area

Question 9

What are examples of discontinuous variation? [4]

Answer 9

• eye colour
• tongue rolling
• skin colour
• left or right handed

Question 10

What is the cause and genetic control of continuous variation? [2]

Answer 10

• genetic & environmental
• multiple genes

Question 11

What is the cause and genetic control of discontinuous variation? [2]

Answer 11

• genetic
• one (or few) genes

Question 12

What is a mutation? [1]

Answer 12

a change in the base sequence of DNA

Question 13

How are new alleles formed? [3]

Answer 13

• mutations
• they cause a change in the sequence of DNA bases
• this results in different proteins being coded for

Question 14

How are mutations formed? [1]

Answer 14

mistakes happen when DNA is being copied

Question 15

How are mutations increased? [2]

Answer 15

• ethanol
• xrays

Question 16

What is a genetic variant? [2]

Answer 16

• different version of a gene (allele) caused by mutations

Question 17

What is genetic variation? [1]

Answer 17

differences in genotype

Question 18

What is phenotypic variation? [1]

Answer 18

differences in phenotype

Question 19

What is the formula for pecentage change? [2]

Answer 19

(new - old / old) x 100

Question 20

What is selective breeding? [4]

Answer 20

• when humans artificially select
• the plants or animal that are going to breed
• so that the frequency of alleles for desired characteristics
• increases in a population.

Question 21

What are desired characteristics in animals? [4]

Answer 21

• docile (peaceful)
• more muscle (meat)
• produce more milk
• more wool

Question 22

What are desired characteristics in plants? [2]

Answer 22

• increased yield
• disease resistant

Question 23

What are the 5 stages in selective breeding? [5]

Answer 23

1. decide most important characteristic and select parents with the highest levels of this characteristic
2. breed these individuals
3. select the best offspring
4. breed again
5. repeat process over many generations and eventually all will have that characteristic

Question 24

What does selective breeding mean? [1]

Answer 24

you’re choosing which alleles are passed on

Question 25

What are the problems with selective breeding? [2]

Answer 25

• increased risk of genetic disease
• reduction in variation

Question 26

What is natural selection? [1]

Answer 26

how organisms adapt from one generation to another

Question 27

What is the cause of genetic variation? [1]

Answer 27

mutations

Question 28

What are the steps for natural selection? [5]

Answer 28

1. any population has genetic mutations
2. all organisms overproduce when good conditions (to ensure survival of species)
3. competition for resources - leads to struggle for survival
4. those who do survive will reproduce
5. their alleles for characteristics will be passed onto their offspring and more common in the population

Question 29

How do bacteria become resistant to antibiotics? [1]

Answer 29

natural selection