Types and causes of variation

Question 1

what is variation

Answer 1

difference between individuals due to genetic and environmental factors

Question 2

what is genotype
what is phenotype

Answer 2

• the genes that an organism has/ alleles present
  -physical appearance/ characteristics visible due to expressed genes (controlled by genes and environment)

Question 3

what is genetic variation
what is environmental variation

Answer 3

-variation caused by possessing a different combination of alleles
-variation caused by response to environmental factors such as light intensity

Question 4

what are genetic causes of variation

Answer 4

-mutations: chromosome mutations and gene mutations (insertion, deletion, substitution)

-sexual reproduction

Question 5

what is a mutation and what can it affect

Answer 5

a change in the DNA base sequence, can be spontaneous or caused by a mutagen

-can affect protein coding genes (exons) = alter proteins
-can affect non protein coding DNA (introns) with a regulatory role

Question 6

give examples of mutagenic agents

Answer 6

physical= UV light
chemical= tar in tobacco
biological = viruses

Question 7

what are the different chromosome mutations

Answer 7

-deletion
-translocation
-duplication
-non-disjunction

Question 8

explain deletion chromosome mutation

Answer 8

-loss of genetic material e.g section of chromosome/ missing chromosome

Question 9

explain inversion chromosome mutation

Answer 9

relocation of genetic material in a chromosome

Question 10

explain translocation chromosome mutation

Answer 10

relocation of genetic material but piece of chromosome comes from another chromosome

Question 11

explain duplication chromosome mutation

Answer 11

gain of genetic material, duplicated section added in chromosome

Question 12

explain non-disjunction chromosome mutation

Answer 12

failure of chromosomes or chromatids to separate during meiosis (anaphase) leading to extra chromosome(s) in a cell or missing chromosome(s)

Question 13

what is aneuploidy and polyploidy

Answer 13

aneuploidy- + or - one chromosome, often fatal and a result of non-disjunction

polyploidy- more than 2 complete sets of chromosomes as all chromosomes fail to separate

Question 14

how does sexual reproduction create genetic variation

Answer 14

random assortment(meiosis)
crossing over(meiosis)
random fertilisation= random sperm fertilises egg

Question 15

what are examples of environmental factors creating variation

Answer 15

-diet in animals
-etiolation in plants

Question 16

what is etiolation

Answer 16

tall spindy growth in plants due to lack of light

Question 17

explain discontinuous variation

Answer 17

-individuals can be placed i distinct categories
-monogenic
-largely unaffected by the environment
-qualitative characteristics
-e.g eye colour

Question 18

explain continuous variation

Answer 18

-measured range
-quantitative
-polygenic
-affected by environment
-e.g height, heart rate, rate of photosynthesis, growth rate