6.2 Patterns Of Inheritance & Variation Flashcards Preview

A Level Biology > 6.2 Patterns Of Inheritance & Variation > Flashcards

Flashcards in 6.2 Patterns Of Inheritance & Variation Deck (32):
1

Why does variation arise?

Due to random mutations

2

Random mutations are essential for what to take place?

Natural selection
Evolution

3

Variation within a species can arise from which factors?

Genetic
Environmental

4

Give examples of variation arising from both genetic and environmental factors?

Chlorosis
Body mass

5

Some plants suffer from chlorosis what does this affect?

A plants ability to photosynthesise
Don't produce enough chlorophyll
Plants look pale and yellow

6

Most plants have genes coding for chlorophyll so what causes chlorosis?

Environmental factors

7

What 3 environmental factors can cause chlorosis?

Lack of light
Mineral deficiency
Virus infections

8

How does chlorosis occur due to lack of light?

Plants turn off chlorophyll production to reserve resources

9

How does chlorosis occur due to mineral deficiency?

Lack of iron which is needed as a cofactor to the enzymes making chlorophyll
Lack of magnesium to make chlorophyll

10

How does chlorosis occur due to virus infections?

Interfere with metabolism of infected cells so they can no longer make chlorophyll

11

what is body mass mostly determined by?

environmental factors - diet

12

in some cases body mass is genetic, what happened to the obese mouse?

mutation in chromosome 8 caused it to deposit more fat

13

genetic variation is caused by what?

the alleles you inherit resulting in different characteristics being displayed

14

combination of alleles inherited are determined by what?

meiosis and random fusion of gametes at fertilisation

15

what are alleles?

different versions of genes

16

what is an organisms genotype?

the combination of alleles an organism inherits for a characteristic

17

what is an organisms phenotype?

an organisms physical observable characteristics

18

what is a dominant allele?

version of gene always expressed if present

19

what is a recessive allele?

version of a gene only expressed if two copies are present in an organism

20

what is homozygous?

two identical alleles for a characteristic

21

what is heterozygous?

two different alleles for a characteristic

22

what is continuous variation?

a characteristic that can take any value within a range

23

what is discontinuous variation?

a characteristic which can only appear is specific discreet categories

24

what factors cause continuous variation?

genetic and environmental

25

what factors cause discontinuous variation?

mostly genetic

26

what is continuous variation controlled by?

polygenes - a number of genes

27

what is discontinuous variation controlled by?

one or two genes

28

give examples of continuous variation:

leaf surface area
animal mass
skin colour
height
mass
length of parts of the body

29

give examples of discontinuous variation:

blood group
albinism
round and wrinkled pea shape
tongue rolling
attached earlobes
eye colour

30

is discontinuous variation qualitative or quantitative?

qualitative

31

is continuous variation qualitative or quantitative?

quantitative

32

what 4 things are genetic variation due to?

1. independent assortment of homologous chromosomes
2. crossing over in meiosis
3. random fertilisation of gametes
4. mutation

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