Variation and Selection Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Variation

A

differences between individuals of the same species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Continuous variation

A

results in a range of phenotypes between two extremes; examples include body length and body mass.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Discontinuous variation

A

results in a limited number of phenotypes with no
intermediates; examples include ABO blood groups, seed shape in peas and seed
colour in peas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Discontinuous variation is usually caused by

A

genes only and continuous variation is
caused by both genes and the environment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Mutation

A

genetic change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The mutation is the way in

A

which new alleles are formed?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ionising radiation and some chemicals increase the

A

rate of mutation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Gene mutation

A

random change in the base sequence of DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

sources of genetic
variation in populations

A

Mutation, meiosis, random mating and random fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

An adaptive feature

A

the inherited feature that helps an organism to survive and
reproduce in its environment, i.e. increase fitness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Adaptive features of hydrophytes:

A

1 submerged leaves are divided ;
2 providing large area for, photosynthesis
/ absorption ;
3 leaves have large surface area ;
4 to float ;
5 (floating leaves so) little xylem/ little
lignin ;
6 water provides support ;
7 little/ no roots /root hairs ;
8 roots for anchorage only / no need for
roots to absorb water or mineral ions ;
9 little/ no, cuticle ;
10 no need to conserve water ;
11 stomata only on upper surface ;
12 only upper surface exposed to air/ to
allow diffusion of gases ;
13 lots of air spaces (between cells) ;
14 for flotation/ buoyancy ;
15 floating leaves ;
16 to allow, diffusion/AW of (named)
gas(es) ;
17 aerial roots ;
18 to allow roots to receive oxygen ;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Adaptive features of xerophytes:

A

few stomata / low stomatal density ;
sunken stomata ;
stomata close during the day and
open at night ;
rolled leaves ;
thick epidermis / thick cuticle ;
few / no / small, leaves ;
hairs on leaves ;
low rates of transpiration ;
deep roots / AW ;
to absorb water from the water table /
AW
long and spread out below the
surface ;
to absorb water when it rains ;
root cells have low water potential ;
to absorb water by osmosis ;
from (very) salty soils / AW ;
roots branch many times ;
have many roots hairs ;
to give a large surface area (for
absorption of water) ;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Natural selection:

A

genetic variation within populations
production of many offspring
struggle for survival, there is competition for resources
a greater chance of reproduction by individuals that are better adapted to the
environment than others
these individuals pass on their alleles to the next generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Selective breeding:

A

selection by humans of individuals with desirable features
crossing these individuals to produce the next generation
selection of offspring showing the desirable features.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Selective breeding by artificial selection is carried out over

A

many generations to
improve crop plants and domesticated animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Adaptation

A

process, resulting from natural selection, by which populations
become more suited to their environment over many generations.

17
Q

example of natural
selection

A

The development of strains of antibiotic-resistant bacteria

18
Q

Difference between natural and artificial
selection:

A

features are adaptive
caused by environment
slower changes
increase in fitness
explained: ability to survive AND
reproduce (in natural environment)
maintain (genetic) variation/ less
(genetic) variation in selective breeding
random mating

19
Q

Difference between artificial and
natural selection:

A

human choice (rather than
environmental pressures) /
AW ;
less, diversity / variation ;
faster change ;
AVP ; e.g. mating is not
random