Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

bio > variation and selection > Flashcards

variation and selection Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

what is variation (definition)

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

what is phenotypic variation

A

differences in physical characteristics between individuals of the same species

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

what are the 2 types of phenotypic variation

A

continuous and discontinuous

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

what is continuous variation

A

when there are very many small degrees of difference for a particular characteristic between individuals and they are arranged in order and can usually be measured on a scale.
Results in a range of phenotypes between two extremes

Examples include height, mass, finger length etc. where there can be many ‘in-between’ groups

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

what is a discontinuous variation

A

is when there are distinct differences in a characteristic.
results in a limited number of phenotypes with no intermediates

For example, people are either blood group A, B, AB or O; are either male or female; can either roll their tongue or not - there are no ‘inbetweens’

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

what would a continuous variation graph look like

A

smooth bell curve

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

what would a discontinuous variation graph look like

A

step-shaped bar graph with distinct values

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

what are the 2 causes of continuous variation

A

genetic and environmental

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

what is the only cause of discontinuous variation

A

genetic

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

examples of genetic variation

A

-blood group
-eye colour
-gender
-ability to roll the tongue
-whether ear lobes are free or fixed

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

examples of environmental variation

A

-An accident may lead to scarring on the body
-Eating too much and not leading an active lifestyle will cause weight gain
-Being raised in a certain country will cause you to speak a certain language with a certain accent
-A plant in the shade of a big tree will grow taller to reach more light

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

examples of genetic variation

A

-blood group
-eye colour
-gender
-Ability to roll the tongue
-whether ear lobes are free or fixed

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

how do continuous features vary through a combination of genetic and environmental variation

A

although genes decide what characteristics we inherit, the surrounding environment will affect how these inherited characteristics develop

eg:
-tall parents will pass genes to their children for height
-their children have the genetic potential to also be tall
-however if their diet is poor then they will not grow very well
-therefore their environment also has an impact on their height

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

what is a mutation (definition)

A

random genetic change in the base sequence of dna

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

what can mutation create

A

new alleles

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

what can increase the rate of mutation

A

ionizing radiation and some chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are the sources of genetic variation in populations

A

mutation, meiosis, random mating
and random fertilisation

18
Q

which gene is mutated in the body to cause sickle cell anaemia and how is it mutated

A

the gene that codes for haemoglobin
causes the red blood cells to become stiff and sometimes sickle-shaped when they release oxygen to the body tissues

19
Q

what are the 2 possible genotypes that can cause sickle cell anaemia

A

HNHn - some abnormal haemoglobin can be carriers of the disease
HnHn - sickle cell anaemia, life threatining

20
Q

symptoms of sickle cell anaemia

A

strokes, blindness, or damage to the lungs, kidneys, or heart

21
Q

what are the alleles for sickle cell anaemia

A

codominant

22
Q

what do heterozygous individuals for sickle cell anaemia experience

A

suffer some symptoms of sickle cell anaemia under conditions of low blood oxygen
and they are said to be carriers of sickle cell anaemia
resistance to malaria

23
Q

what is an adaptive feature

A

an inherited feature that helps an organism to survive and reproduce

24
Q

what is fitness

A

probability of an organism surviving and reproducing in the environment in which it is found

25
Q

what are hydrophytes

A

plants that are adapted to live in extremely wet conditions

26
Q

what are the adaptations of hydrophytes

A

large air spaces in their leaves
-to keep them close to the surface of the water where there is more light for photosynthesis

small roots
-as they can also extract nutrients from the surrounding water through their tissues

stomata placed on the upper epidermis rather than the lower and is open all the time
-they can exchange gasses much easier

27
Q

what are xerophytes

A

plants adapted to live in extremely dry conditions

28
Q

what are the adaptations of xerophytes?

A

Thick waxy cuticle
-the cuticle cuts down water loss in two ways: it acts as a barrier to evaporation and also the shiny surface reflects heat and so lowers the temperature (essentially helps to reduce water loss from the surface of the leaf)

Sunken stomata
-stomata may be sunk in pits in the epidermis; moist air trapped here lengthens the diffusion pathway and reduces the evaporation rate

Small leaves
-many xerophytic plants have small, needle-shaped leaves which reduce the surface area and therefore the evaporating surface

29
Q

what is natural selection

A

the individuals that have the best adaptive features are the ones most likely to survive and reproduce

30
Q

how does the survival of the fittest occur

A

individuals with adaptive features reproduce, this will cause there too be too many individuals and there will be a competition for resources (food etc.)
due to this only the strongest individuals or individuals best suited for the environment will get the resources and survive

31
Q

evolution definition

A

change in adaptive features of a population over time as a result of natural selection

32
Q

selection pressure definition

A

something in the environment that affects the chance that individuals with different features will survive and reproduce

33
Q

adaptation definition

A

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

34
Q

drug definition

A

any substance taken into the body that modifies or affects chemical reactions in the body

35
Q

antibiotic definition

A

a substance that is taken into the body and which kills bacteria but does not affect human cells or viruses

36
Q

how do bacteria become antibiotic resistant?

A

bacteria reproduce every 20 minutes
this increases the chance of chance mutation as they reproduce so often
a mutation can cause them to be resistant to antibiotics
the resistant bacteria do not die
they can continue to reproduce with less competition
hence the genes for antibiotic resistance are passed on with much higher frequency

37
Q

example of bacteria that are antibiotic resistant

A

MRSA (methicilin-resistant staphylococcus aureus)

38
Q

selective breeding def

A

select individuals with desirable characteristics and breed them together

39
Q

natural selection vs selective breeding

A

natural selection:
occurs naturally
results in the development of populations with features that are better adapted to their environment and survival
usually takes a long time to occur

selective breeding:
only occurs when humans intervene
results in the development of populations with features that are better adapted to humans and not necessarily to the survival of the species
takes less time to occur as only individuals with the desired features are allowed to reproduce

40
Q

why are plants selectively bred for development by humans

A

disease resistance in food crops
increased crop yield
hardiness to weather conditions (e.g. drought tolerance)
better tasting fruits
large or unusual flowers

41
Q

why are animals selectively bred for development by humans

A

cows, goats and sheep that produce lots of milk or meat
chickens that lay large eggs
domestic dogs that have a gentle nature
sheep with good quality wool
horses with fine features and a very fast pace

42
Q

Explain why sickle cell anaemia is common in people who live in areas where malaria occurs.

A

malaria is a severe disease that can be fatal
patients with sickle cell anaemia are resistant to malaria
homozygous dominant susceptible to malaria (hAhA)
heterzygous are resistant (hAhS)
they are more likely to survive and reproduce hence passing on the allele for resistance to malaria

bio (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions