Brainscape's Knowledge GenomeTM

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


See full index

Biology > Genetics, Populations, Evolution, And Ecosystems > Flashcards

Genetics, Populations, Evolution, And Ecosystems Flashcards

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

What is a population?

A

A group of organisms of the same species occupying a particular space at a particular time that can interbreed to produce fertile offspring.

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

What is an ecosystem?

A

All the organisms both living and non-living in a particular environment at a particular time.

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

What is a community?

A

All the living organisms in a particular area at a particular time.

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

How is the distribution and abundance of organisms in a habitat controlled?

A
  • By both biotic factors (e.g. predators, disease) and abiotic factors (e.g. light levels, temperature).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an ecological niche?

A

A species particular role in it habitat, constitutes of is biotic and abiotic interactions with its environment.

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

What are the Abiotic factors that affect population growth?

A
  • Temperature = each species has specific optimum temps that are best to for them to survive in.
  • Light = rate of photosynthesis increase as light intensity increases.
  • pH = action of enzymes = optimum pH
  • Water and Humidity = water is a necessity to all life. Humidity affects rate of transpiration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the carrying capacity?

A

An ecosystem can support a certain size of population of a species.

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

One Biotic factor affecting population size is: Competition
What is the difference between INTRA-specific competition and INTER-specific competition?

A

INTRA-specific = members of the same species compete of resources such as: food, water, mates, shelter, minerals and light.
INTER-specific = members of different species compete with on another for resources, most common when two species occupy the same niche e.g. red and grey squirrels in the Uk.

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

What is predation?
What is a predator-prey relationship?

A
  • One species is caught and eaten by another.
  • Populations of the predator and prey will both affect each other.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the predator-prey relationship occur?

A

1) prey is eaten by predator = prey population falls
2) Predator population grows as more prey is consumed
3) Reduced prey = increased competition for prey between predators
4) Predator population falls as lack of food
5) Allowing prey population to rise again
ETC

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

How can you estimate the size of slow moving/ non-motile organisms?

A
  • Randomly placed quadrants, or systematic belt quadrants.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What two ways can you measure the abundance of different species?

A
  • Percentage cover = suitable for plants or algae whose individuals numbers are difficult to count.
  • Frequency = expressed as a decimal or percentage, and is the number of times an organism appears in the sampling area.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can you measure the population size for fast-moving or hidden animals?

A
  • Capture-mark-capture-release
  • Capture a known amount of species and mark them in a way that doesn’t reduce their chance of survival.
  • Release marked individuals to the same area they are caught.
  • After a suitable length of time another known number or organisms are captured, with the number of these that are marked being recorded.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the equation for Capture-Recapture?

A

Sample one x sample two
Estimated population size = ————————————
Marked individuals

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

What assumptions must be made for capture-recapture?

A
  • Proportion of marked to unmarked Individual in the second complete is the same as the proportion of marked to unmarked individuals as a whole.
  • Marked individuals have sufficient time to reintegrate fully.
  • No immigration or emigration occurred.
  • Few to no deaths/births occurred.
  • Method of marking is not toxic/reduces the chance of survival for the population.
  • Marks have not rubbed off.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is succession?

A

The process by which ecosystems change over time due to changes in the environment, causing the plant and animal species present to change.

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

What is primary succession?

A

When an area that is devoid of life, is colonised by communities of organisms, e.g volcanic eruptions.
- No soil is present = starting with rock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is secondary succession?

A

When a previously colonised area in which an existing community has been cleared e.g. after a forest fire.
- A soil layer is already present.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What species first colonise an area?

A
  • Pioneer species
    E.g. lichens that are adapted to live in harsh conditions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does soil form in succession?

A
  • Organisms die, they are decomposed by microorganisms adding to humus.
  • This makes the environment more suitable for more complex colonisers.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the final stage of succession?

A
  • A climax community
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is a plagioclimax?

A

When deflected succession occurs usually due to human interference, and an unfinished climax is created.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the genotype?

A

All of the alleles that an organism carries on its chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the genotype?

A

All of the alleles that an organism carries on its chromosomes.

25
Q

What is the phenotype?

A

Observable characteristics of an organism which is the result of the genotype as well as environmental factors.

26
Q

What is a dominant allele?

A

Only a single allele is required for the characteristic to be expressed in the phenotype.
Organism can either be homozygous or heterozygous and the trait will still be expressed.

27
Q

What is a recessive allele?

A

The characteristic will only be expressed if there is no dominant allele present.
HAS to be homozygous for the trait to be expressed.

28
Q

What is codominance?

A

Both alleles are expressed equally and both contribute to the phenotype, either a blend of the two characteristics or both can be seen.

29
Q

What is meant by pure breeding?

A

Means that it is a homozygous pair of alleles.

30
Q

What is meant by pure breeding?

A

Means that it is a homozygous pair of alleles.

31
Q

What is an allele and locus?

A

Allele is the alternative form of a gene and the locus is the specific position of the gene on the chromosome.

32
Q

What is monohybrid inheritance?

A

When a phenotype or trait is controlled by a single gene.
If two heterozygous plant are crossed = 3:1
E.g. cystic fibrosis where individuals with doubly recessive phenotype are affected.

33
Q

What is dihybrid inheritance?

A

When a characteristic is determined by two different genes that are present on two different chromosomes at the same time.
E.g. a round, yellow seed RRGG and wrinkled, green seed rrgg both homozygous produces all yellow round offspring RrGg.
E.g. two heterozygous round, yellow seeds are crossed RrGg with RrGg = 9:3:3:1

34
Q

What is an example of co-dominance?

A
  • CRCR : red + CWCW : white = CRCW : pink 100%
  • CRCW : pink + CRCW : pink = 50% pink, 25% red, 25% white
35
Q

What is sex linkage?

A

The expression of an allele dependent on the gender of the individual as the gene is located on a sex chromosome. As most sex-linked traits are on the X chromosome with their being no equivalent locus on the Y chromosome. So females will carry two alleles of the sex linked gene, but males will only carry a single allele.

36
Q

What is sex linkage?

A

The expression of an allele dependent on the gender of the individual as the gene is located on a sex chromosome. As most sex-linked traits are on the X chromosome with their being no equivalent locus on the Y chromosome. So females will carry two alleles of the sex linked gene, but males will only carry a single allele.

37
Q

What is autosomal linkage?

A

Two or more genes are on the same autosomal chromosome.

38
Q

What is epistasis?

A

One gene loci can either mask or suppress the expression of another gene locus.

39
Q

What is recessive epistasis?

A

When the presence of a recessive allele prevents the expression of another allele prevents the expression of another allele at a second locus.
Recessive epistasis - 9:3:4

40
Q

What is dominant epistasis?

A

When a dominant allele at one locus completely mask the alleles at a second locus.
Dominant epistasis = 12:3:1

41
Q

What is the Chi-squared test?

A

Used to establish whether the difference between observed and expected results is small enough to occur purely due to chance.

42
Q

What is a population?

A

A group of organisms of the same species occupying a particular space at a particular time that can interbreed to produce fertile offspring.

43
Q

What is a gene pool?

A

The total number of alleles that are present in a population.

44
Q

What is the allelic frequency?

A

Expresses the proportion of a certain allele in a gene pool as a decimal or a percentage.

45
Q

How can you estimate the frequency of alleles in a population?

A

Hardy-Weinberg equation: sees whether a change in allele frequency is occurring in a population over time.

46
Q

What assumptions are made for the Hardy-Weinberg equation?

A
  • No mutations occur to create new alleles
  • No movement of alleles in or out of the population by migration
  • Population is large
  • No selection = every allele has equal chance of being passed to the next generation
  • Mating is random
47
Q

What are the two formulae for the Hardy-Weinburg principle?

A

p + q = 1.0 and p2 + 2pq + q2 = 1
Where:
p = frequency of dominant allele
q = frequency of recessive allele
p2 = frequency of homozygous dominant
2pq = frequency of heterozygous
q2 = frequency of homozygous recessive

48
Q

What factors result in variations int eh alleles of gens form members of the same species?

A
  • Random fertilisation - gametes that are already carrying different alleles will randomly join together
  • Meiosis - alleles will be assorted in the gametes at random
  • Mutation - mutation of an allele = could create a new allele = passed to next generation
  • Environmental influences - majority of phenotypic traits being influenced by the environment.
49
Q

Why may organisms have a unsustainably large number of offspring?

A
  • Darwin suggested so many offspring are produced so that there is a greater intraspecific competition and therefore only those that have the alleles best suited to the environment will survive to grow and reproduced passing the best alleles on to future generations.
  • High variation in genotypes and phenotypes within a population increases the chance that a species will survive in a changing habitat.
50
Q

What is the process of natural selection?

A
  • Variety of phenotypes within a population
  • An environmental change occurs and as a result the selection pressure changes
  • Some individuals possess advantageous alleles which give them a selective advantage to survive and reproduce
  • Advantageous alleles are passed onto their offspring
  • Over time, frequency of alleles in a population changes.
51
Q

What is selection?

A

The process by which individuals that are better adapted to their environment are more likely to survive and breed.

52
Q

What is directional selection?

A
  • Occurs when environmental conditions change and the phenotypes best suited to the new conditions are more likely to survive.
  • Overtime the mean population will move in the direction of these individuals.
53
Q

What is stabilising selection?

A
  • Phenotypes with successful characteristics are preserved and those of greater diversity are reduced.
  • If then environment doesn’t change the individuals closest to the mean are favoured as they have the alleles that have given them the survival advantage.
54
Q

What is disruptive selection?

A
  • Opposite of stabilising selection, where both extremes of the normal distribution are favoured over the mean.
55
Q

What is speciation?

A

New species arise after a population becomes separated and cannot interbreed.

56
Q

What is allopatric speciation?

A
  • Caused by a physical barrier, as the two groups are separated and reproductively isolated the result is that the gene flow is reduced, each group experiences different selection.
57
Q

What is allopatric speciation?

A
  • Caused by a physical barrier, as the two groups are separated and reproductively isolated the result is that the gene flow is reduced, each group experiences different selection.
58
Q

What is sympatric speciation?

A
  • New species evolve from a single ancestral species when inhabiting the same geographical region, could be as a result of chromosomal error during cell division which leads to reproductive isolation.
  • Other reasons = mutations meaning courtship behaviours isn’t recognised or anatomical changes = cannot physically mate.

Biology (5 decks)

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