Variation

Question 1

What is variation?

Answer 1

Variation is the DIFFERENCES that exist between INDIVIDUALS.

Question 2

What is variation within species?

Answer 2

Variation within species is called INTRASPECIFIC variation.

For example, INDIVIDUAL European robins weigh between 16g and 22g and show some variation in many other characteristics including length, wingspan, colour and beak size.

Question 3

What is variation between species?

Answer 3

The variation between DIFFERENT SPECIES is called INTERSPECIFIC VARIATION.

For example, the LIGHTEST species of bird is the bee hummingbird, which weighs 1.6grams on average. The HEAVIEST species of bird is the ostrich, which can weigh up to 160kg (100 000 times as much).

Question 4

What is continuous variation?

Answer 4

Continuous variation is when individuals in a population vary WITHIN RANGE - there are no distinct categories.

Example: HUMANS can be ANY HEIGHT within a range (139cm, 175cm, 185.9cm) NOT JUST tall or short.

Question 5

Variation in Animals:

> Milk yield

Answer 5

E.G cows can produce any volume of milk within a range.

Question 6

Variation in Animals:

> Mass

Answer 6

Humans can be any mass within a range.

Question 7

Variation in plants:

> number of leaves

Answer 7

A tree can have any number leaves within a range.

Question 8

Variation in plants:

> Mass

Answer 8

e.g. the mass of the seeds from a flower head varies within range.

Question 9

Variation in microorganisms:

> Width

Answer 9

e.g. the width of E.Coli bacteria varies within range.

Question 10

Variation in microorganisms:

> length

Answer 10

e.g. the length of a flagellum can vary within range.

Question 11

What is discontinuous variation?

Answer 11

Discontinous variation is when there are two or more DISTINCT CATEGORIES - each indinidual falls into ONLY ONE of these categories, there are no intermediates.

Question 12

Discontinuous variation in Animals:

> BLOOD GROUP

Answer 12

e.g. Humans can be group A, B, AB, or O.

Question 13

Discontinuous variation in plants:

> COLOUR

Answer 13

e.g courgettes are either green, light green or dark green.

Question 14

Discontinuous variation in plants:

> Seed shape

Answer 14

e.g. some pea seeds have smooth seeds and some have wrinkled seeds

Question 15

Discontinuous variation in microorganisms:

> Antibiotic resistance

Answer 15

e.g. bacteria are either resistant or not

Question 16

Discontinuous variation in microorganisms:

> Pigment production

Answer 16

e.g. some types of bacteria can produce a coloured pigment, some can’t.

Question 17

Variation can be caused by…

Answer 17

Genetic factors, Environmental factors, or a combination of BOTH.

Question 18

Genetic factors:

Different species have…

Answer 18

different genes.

Question 19

Genetic factors:

> Individuals of the SAME SPECIES have the…

Answer 19

same genes, but DIFFERENT VERSIONS of them (called ALLELES).

Question 20

Genetic factors:

> The genes and alleles in an organism makes up its…

Answer 20

genotype.

Question 21

Genetic factors:

> The differences in GENOTYPE result in…

Answer 21

Variation in PHENOTYPE - the CHARACTERISTICS displayed by an organism

Question 22

Genetic factors:

> Examples of variation caused ONLY by genetic factors include…

Answer 22

BLOOD GROUP in humans (O, A, B, or AB) and ANTIBIOTIC RESISTANCE in bacteria.

Question 23

Genetic factors:

> You INHERIT your genes from your parents. This means…

Answer 23

Variation caused by genetic factors is INHERITED.

Question 24

Environmental factors:

> Variation can also be caused by….

Answer 24

DIFFERENCES BY THE ENVIRONMENT,

example: climate, food, lifestyle.

Question 25

Environmental factors: >Characteristics controlled by environmental factors can...

Answer 25

CHANGE over an organism's life

Question 26

Environmental factors: > Examples of variation caused ONLY by environmental factors include...

Answer 26

ACCENTS and whether people have PIERCED EARS.

Question 27

Both: Genetic factors determine...

Answer 27

the characteristics an organism is born with.

Question 28

Both: Environmental factors can...

Answer 28

Influence how some characteristic develop.

Question 29

Both: Height, explain why its both?

Answer 29

Height - genes determine how tall an organism CAN GROW (e.g. tall parents tend to have tall children). But DIET OR NUTRIENT AVAILABILITY affects how tall an organism ACTUALLY GROWS.

Question 30

Both: Flagellum, explain why?

Answer 30

Genes determine if a microorganism CAN GROW a flagellum, but some will only START TO GROW in CERTAIN ENVIRONMENTS, e.g. if metal ions are present.

Question 31

You can use the MEAN to look for...

Answer 31

Variation between samples.

Question 32

To investigate variation you usually...

Answer 32

take samples of a population

Question 33

The mean is an ....

Answer 33

average of the values collected in a sample. It can be used to tell if there is VARIATION BETWEEN SAMPLES.

Question 34

Most samples will include values EITHER SIDE of the MEAN...

Answer 34

so you end up with a bell-shaped graph - this is called NORMAL DISTRIBUTION. A normal distribution is SYMMETRICAL about the mean.

Question 35

The STANDARD DEVIATION tells you...

Answer 35

how much the VALUES in a SINGLE SAMPLE VARY. It's a measure of the SPRED of Values about the MEAN.

Question 36

Sometimes you'll see the mean written as as, e.g. 9 _+3. This means...

Answer 36

the mean is 9 and the STANDARD DEVIATION is 3, so most of the VALUES are spread between 6 and 12.

Question 37

A large standard deviation means the...

Answer 37

VALUES in the sample VARY ALOT. Vice versa.

Question 38

(page 124) graph The graph shows the results of an investigation into the effects of temperature on the length of time it took for ladybird larvae to emerge as adults. Two species of ladybirdwere investigated, species A and specis B. A) Describe the results of the study

Answer 38

For species A and species B, as the temperature increases the development time decreases. The development time of species B is less affected by the temperature than species A.

Question 39

(page 124) graph The graph shows the results of an investigation into the effects of temperature on the length of time it took for ladybird larvae to emerge as adults. Two species of ladybirdwere investigated, species A and specis B. B) Explain what causes variation within species?

Answer 39

Individuals within a species have different forms of the same genes (alleles), which causes genetic variation?