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

two types of phenotypic variation:

A

discontinuous variation and continuous variation

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

Discontinuous variation

A

limited number of phenotypes

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

Continuous variation

A

a range of phenotypes between two extremes

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

What are mutations?

A

genetic changes

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

how are new alleles formed?

A

through mutation

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

Factors that increase the rate of mutations:

A
  • ionising radiation such as gamma rays, X-rays and high energy ultraviolet electromagnetic waves.
  • some chemicals.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

gene mutation

A

a change in the sequence of bases in DNA

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

sources of genetic variation in population:

A
  • Mutations
  • Meiosis
  • Random mating
  • Random fertilization
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

adaptive feature

A

an inherited feature that helps an organism to survive and reproduce in its environment

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

hydrophytes

A

plants that only grow on water

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

xerophytes

A

plants that need very little water

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

hydrophyte adaptations

A
  • large, thin leaves with most stomata on the upper surface rather than lower surface
  • little or no waxy cuticle on their leaves because water loss is not a problem
  • long leaf stalks with large air spaces to help them float
  • a reduced root system because they do not need to be anchored in the ground
  • aerial flowers to attract flying pollinators
  • poorly developed xylem tissue that allows the transport of water but provides little support
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

xerophyte adaptations

A
  • a thick waxy cuticle covering the upper epidermis of the leaves to reduce water loss
  • few stomata, or stomata that are sunken into pits surrounded by hair to reduce water loss by transpiration (
  • curled, rolled or folded leaves, which reduce the surface area available for transpiration
  • a thick succulent stem
  • widely spread roots that are close to the surface, so the plant can absorb as much water as possible even when there is limited rainfall, or
  • very deep roots to reach underground water sources
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

steps of natural selection (6)

A
  1. There is variation in the inherited characteristics shown by individuals in a population.
  2. Populations tend to produce many offspring, more than can be supported in the habitat where they live.
  3. There is competition between individuals for limited resources such as food, mates or space
  4. There is a struggle for survival in which some individuals are more likely to survive than others
  5. Individuals that are better adapted to their environment are more likely to survive and reproduce
  6. The offspring of the better adapted individuals are more likely to inherit alleles that make them better adapted to the environment. They are more likely to survive to reproduce successfully than other individuals in the population.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

selective breeding

A

the method used by humans to produce varieties of animals and plants with desirable characteristics

17
Q

selective breeding steps

A
  • humans select those individuals with most desirable features
  • those individuals are bred
  • offspring that display the desirable features are selected for further breeding