Inherited variation

Question 1

Evolution is possible via

Answer 1

inherited variation

Question 2

2 types of inherited variation?

Answer 2

gene variation and chromosomal variation

Question 3

2 types of gene variation?

Answer 3

variation due to single genes and poly genes

Question 4

types of inheritance for single genes?

Answer 4

recessive/dominant, codominant (spots), incomplete dominance (combined)

Question 5

what populations can single gene variation result in?

Answer 5

monomorphic and polymorphic populations

Question 6

define: monomorphic population

Answer 6

members show no variation of a particular trait (due to single gene with one allele)

Question 7

define: polymorphic poluation

Answer 7

members show several variants of a particular trait (due to single gene with multiple alleles)

Question 8

is variation for single genes discontinuous or continuous?

Answer 8

discontinous

Question 9

define: continous

Answer 9

variation in a population forming a continuum of phenotypes. Includes heigh, eye colour.

Question 10

define: discontinous

Answer 10

variation in a population consisting of discrete, non-overlapping phenotypes. Include blood type, yellow/green pea seeds

Question 11

is variation for polygenes continous or discontinous?

Answer 11

continuos

Question 12

can polygene expression be affected by environment

Answer 12

yes but still occurs under controlled conditiosn

Question 13

2 types of chromosomal variation

Answer 13

polyploidy and aneuploidy

Question 14

define: polyploidy

Answer 14

when an organism has more than 2 matching sets of chromosomes

Question 15

how are polyploids formed?

Answer 15

ASK LABROOY

Question 16

define: autopolyploidy

Answer 16

additional sets of chromosomes come from the same species.

Question 17

define: allopolyploidy

Answer 17

additional sets of chromosomes come from another species.

Question 18

many alloploids show

Answer 18

hybrid vigour - superior qualities to that of both parents

Question 19

define: aneuploidy

Answer 19

when the chromosome differs by a small number (usually 1-2) from the standard number of chromosomes for the species

Question 20

why does aneuploidy occur?

Answer 20

usually due to non disjunction (also translocation…)

Question 21

describe non disjunction

Answer 21

when a chromosome pair fails to separate during meiosis and both copies of it go to the same gamete. This results in the gametes having 2/0 copies of a particular chromosome.

Question 22

define: monosomy

Answer 22

 Normal gamete + gamete with 0 copies of a chromosome

Question 23

why is monosomy usually lethal

Answer 23

due to loss of key genes; though polyploids can tolerate loss of 1-2 members of a chromosome set, due to presence of other chromosomes.

Question 24

example of monosomy

Answer 24

Turners’ syndrome 45, X0: affects females, causes sterility due to lack of uterus, abnormal breast development

Question 25

define: trisomy

Answer 25

 Normal gamete + gamete with 2 copies of a chromosome

Question 26

why is trisomy usually lethal

Answer 26

causing miscarriage or severe physical/mental abnormalities leading to early death. Trisomy-21 is the only exception.

Question 27

example of trisomy

Answer 27

47, XY+21 (Down’s syndrome) – characteristic facial features, mild-moderate intellectual disability.