3.7 Genetics, Population, Evolution And Ecosystems Flashcards

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1
Q

What is a population?

A

Group of all organisms of the same species living in the same habitat

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2
Q

What is a habitat?

A

Part of an ecosystem in which particular organisms live in

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3
Q

What is a community?

A

All the populations of the different species in the same area at the same time

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4
Q

What is an ecosystem?

A

A community and the non-living components of an environment (biotic and abiotic factors)

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5
Q

What is a niche?

A

An organisms role within an ecosystem, including position in the food web and habitat. Each species occupies its own niche

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6
Q

What is carrying capacity?

A

Maximum population size an ecosystem can support

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7
Q

What are abiotic factors and examples?

A

•Non-living conditions
e.g temperature, oxygen, CO2 and light intensity

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8
Q

What are biotic factors and examples?

A

Living conditions (impact of interactions between organisms)
e.g competition, predation, disease

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9
Q

What are the different types of competition?

A

Interspecific: members of different species compete for the same limited resources and better adapted individuals survive

Intraspecific: members of the same species compete for resources and mates. Fitter individuals attract a mate

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10
Q

What does a predator-prey relationship show?

A

•both population sizes will fluctuate
•at most times, more prey than predators so prey no. peaks more
•size of population changes in prey and then predators due to lag time

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11
Q

How can you accurately represent a population?

A

•large no. of samples (representative 30+)
•random samples (avoids bias)

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12
Q

Outline a random sampling method

A

1.lie 2 tape measures at a right angle to create a gridded area
2.use a random number generator to generate 2 coordinates e.g calculator
3.place a quadrat and collect data e.g total no.
4. Repeat at least 30 times (or until running mean as more reliable and allows for a statistical test to be done)
5.multiply to give estimate for total field area

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13
Q

What are the 2 types of transects?

A

Belt: quadrat placed at every position along tape measure
Interrupted: quadrat placed at uniform intervals along the tape measure

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14
Q

Outline a method for a line transect

A

1.place tape measure at right angles to e.g the shore line
2.place quadrat every 1 metre along the tape measure
3. Collect data
4. Repeat by placing another 30 transects along each e.g the beach at right angles to the shore line

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15
Q

What is local frequency and ad/dis of using it to estimate abundance?

A

•% of squares in quadrat with species
Ad: •quick for large areas
•useful if too many to count or hard to identify individual
Dis: •poor accuracy as it doesn’t consider overlapping plants or size of plants

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16
Q

What is density and ad/dis of using it to estimate abundance?

A

•no. of one species in a given area
Ad: •more accurate
•used to estimate species richness
Dis: •more time consuming

17
Q

What is % cover and ad/dis of using it to estimate abundance?

A

•proportion of ground occupied by the species
Ad: •quicker method than density
•useful if too many to count or difficult to identify
Dis: •subjective so limiting accuracy
•doesn’t consider overlapping plants or the size of the plant

18
Q

How is mark-release-recapture done to estimate population?

A

1.collect sample in each area and mark unobtrusively
2.allow time to re-integrate with rest of the population
3.collect second sample and count no. marked
4.estimate using equation =
S1X S2
———-
no. marked in S2

19
Q

What assumptions are made in mark-release-recapture?

A

•no immigration/migration
•no reproduction
•marking doesn’t increase predation
•population is large enough

20
Q

What is meant by uniformly distributed?

A

Same no. of organisms in each region/equally spread

21
Q

What is ecological succession?

A

Process by which communities change over time as a result of interactions between abiotic and biotic factors.
Proceeds with a series of stages with one community of organisms being replaced by another

22
Q

What is primary and secondary succession?

A

1)occurs in environment where there is no pre-existing vegetation or soil
2)occurs on substrate that previously supported vegetation before and ecological disturbance

23
Q

What is the process of succession?

A

1.pioneer species colonise first as they can tolerate hostile abiotic conditions
2.pioneer species reproduce, grow and die, this changes abiotic conditions to make it less hostile e.g increase the mineral nutrients in soil
3.this allows other new species to colonise and eventually outcompete the pioneer community and outcompete each other
4.over time new communities continue replacing previous communities and biodiversity increases (biomass and productivity increase)
5.eventually a stable climax community is reached

24
Q

What is deflected succession and what does it produce?

A

•occurs when the climax community is prevented from being reached e.g due to coppicing and grazing by animals
•it intervenes and prevents succession completing as large trees are prevented from growing
•this produces a sub-climax community called plagioclimax

25
Q

What are features of climax communities?

A

•same species present over a long time
•stable population
•abiotic conditions remain stable

26
Q

Why does a population decrease when temperatures change?

A

•use more energy to maintain right internal temperature
•less energy for growth and reproduction

27
Q

What is the genotype?

A

2 alleles an individual possess for a particular gene

28
Q

What is the phenotype?

A

The expression of the genes and its interactions with the environment

29
Q

What is homozygous?

A

Pair of homologous chromosomes carrying the same alleles for a single gene

30
Q

What is heterozygous?

A

Pair of homologous chromosomes carrying 2 different alleles for a single gene

31
Q

What is a recessive allele?

A

An allele only expressed if no dominant allele is present

32
Q

What is a dominant allele?

A

An allele that will always be expressed in the phenotype

33
Q

What is a codominant allele?

A

Neither allele completely dominates another. Alleles of the same gene are expressed separately to yield different traits in an individual

(Equally dominant and equally expressed)

34
Q

What causes multiple alleles?

A

Mutations in a gene that occur at different positions in the gene

35
Q

What are the alleles for blood group?

A

IAIO IAIA = A
IBIO IBIB = B
IAIB = AB (codominant)
IOIO = O

36
Q

What is a dihybrid cross?

A

Inheritance of 2 different genes

37
Q

Why are males more likely to have recessive conditions?

A

•some genes are on the X or Y = sex linked
•Y is shorter than X where X has an inequivalent portion (non-homologous portion)
•only need one copy of a recessive mutant allele on X to give disease