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AQA A LEVEL Biology > Section 7 Population, Evolution, Inheritance > Flashcards

Section 7 Population, Evolution, Inheritance Flashcards

1
Q

What is a species?

A

A group of organisms that can breed together to produce a fertile offspring

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2
Q

What is a population?

A

The amount of a certain species within a particular place

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3
Q

What is a community?

A

The entire population of the different species in a particular place

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4
Q

What is a habitat?

A

The place where a organism lives

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5
Q

What is an ecosystem?

A

A mix of different communities and habitats and how they interact via abiotic and biotic factors

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6
Q

What is an ecological niche?

A

An organisms role/ position within an ecosystem in terms of its interaction with abiotic and biotic factors.

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7
Q

Why can 2 different species not occupy the same niche?

A

Due to intraspecific competition based on biotic and abiotic factors one species will out compete the other into extinction. This is known as the competitive exclusion principle.

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8
Q

How to sample plant species over a large area?

A

Obtain a map of the area

Divide the map into grids

Select a large number of coordinates using a running mean

Select a random set of coordinates using a random number chart

in each coordinate place a quadrat

Measure the abundance of plant species in whatever way (percentage or individual)

calculate the average number of the whole area.

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9
Q

How to sample plant species along a path?

A

Using a transect

Place a tape along the path count the number of plants (line transect)

OR

Place a tape along the path and at regular intervals place a quadrat and calculate the average abudance for the total amount of quadrats. (Belt transect)

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10
Q

How to sample animal species in an area?

A

Mark release recapture technique

Set a trap

Capture the animal species

Mark them (tag or florescent marker-ensuring it is not toxic and not harmful

Release them

After some time begin trap again

Count the number of marked and non marked in the second collection

Calculate the total estimated population

(Total number of sample 1 x total number of sample 2)/ marked in sample 2

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11
Q

What assumptions are made when using the mark-release-recapture method?

A

When using the mark-release-recapture method you are assuming that:

There was no immigration or emigration during the population mixing time

no births of death

marked animals distribute evenly back into the population

mark is non toxic

mark does not come off

large population

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12
Q

What are the 3 stages of population?

A

Slow/lag phase: Species becomes adapted to new environment

Rapid/log phase: species adapted abundant resources. doubling the rate of reproduction (Birth rate > Death rate)

Stationary phase: resources become limited, instraspecific competition occurs birth rate= death rate

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13
Q

How are resources and limiting factors grouped?

A

Abiotic (non-living): light, temperature, temperature, water, oxygen and carbon dioxide, pH and living space

Biotic (living): Predator, prey, mates, competition, disease

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14
Q

What is competition?

A

when organisms compete for resources abiotic and biotic.

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15
Q

What are the 2 types of competition?

A

InTRAspecific: Occurs between organisms within the SAME SPECIES only occurring when resources become limited= natural selection and adaptation.

InTERspecific: Occurs between organisms within DIFFERENT SPECIES and can occur at any time and leads to the formation of climax communities.

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16
Q

Describe the predator prey relationship?

A

Prey increases in number

More food available for predator

Predator increases in number

Predator eats more prey

Prey decreases in number

Less food availability for predator

Predator number decreases

Less prey are eaten

Prey increases in number (CYCLE REPEATS)

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17
Q

What is succession?

A

How an ecosystem changes overtime

(change in species diversity and habitat diversity) relies on environment being made less hostile by present species via death and decomposition leading to it being outcompeted and replaced by larger, better adapted species.

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18
Q

What are the 2 types of succession?

A

Primary (occurs in new land)

Secondary (occurs on previously colonised land that has become bare e.g. after a forest fire)

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19
Q

Describe primary succession (PROCESS)

A

New land appears

Pioneer species settle (adapted to surviving in hostile condition

Pioneers are: producers and have mutualistic NFB

asexually reproduce (one parent, genetically identical, faster)

Xerophytes

Can handle extreme conditions

Have wind dispersed seeds which can anchor to land

Overtime the land erodes and forms, Pioneer species die and decompose adding nutrients to the soil

Plants can now grow which outcompete the Pioneer species

Overtime, more soil forms, small plants die out adding more nutrients to the soil.

Larger plants can now grow outcompeting the smaller plants

This process continues until the climax community is reached

The climax community has the best adapted species to their environment.

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20
Q

What are the properties of succession?

A

Species diversity increases

Habitat diversity increases

Environment becomes less hostile

Food chains become more complex and biomass increases

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21
Q

Primary vs secondary succession

A

Secondary starts from small plants Pioneer species and secondary succession is faster.

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22
Q

How can conservation be used to prevent succession?

A

Used to prevent formation of woody forests

Involves deforestation, burning trees and using pesticides

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23
Q

What is evolution?

A

A change in allele frequency within a population

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24
Q

What are the 2 types of evolution?

A

Adaptation and speciation

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25
What is adaptation?
A species adapting to changes in the environment driven by natural selection where most of the individuals in the species will have the favourable allele to be adapted to their environment.
26
What is the process of adaptation?
The variation in population of species New alleles by random mutation Environment applies a selection pressure on the population Those with favourable characteristics alleles survive, the other die The ones that survive will reproduce passing on their favourable genes =reproductive success
27
What are the 3 types of selection?
Stabilising, directional and disruptive
28
What is stabilising selection?
When the environment favours those with the most common characteristics and the extremes die out. The common characteristic increases in proportion The range (standard deviation) will reduce
29
What is directional selection?
When the environment favours those individuals with characteristics on one of the extremes Overtime this will become the most common characteristic Normal distribution will shift to that extreme
30
What is disruptive selection?
When the environment changes between both extreme conditions Hence individuals on both extremes are favoured at different times and increase in number Those in the middle (average) will decrease in number
31
What is speciation?
Process by which new species arise from existing species
32
What are the 2 types of speciation?
Allopatric and sympatric
33
What is allopatic speciation?
Speciation that is driven by geographical isolation
34
Describe Allopatic speciation
Start with a population of species Variation in the population Population separated into different groups by geographical isolation Each group is exposed to different environments/ selection pressures Each group undergoes different directional selections Therefore each group changes so much in genetic diversity that they can no longer interbreed with each other to produce fertile offspring Changes include different courtship behaviour or incompatible gametes
35
What is sympatric speciation?
Speciation occurring in the same geographical area
36
What is inheritance?
Offering inheriting a combination of alleles for each gene that will help determine the characteristics
37
What is a gene?
A section of DNA that codes for a protein
38
What is an allele?
A form of a certain gene
39
What is a dominant allele?
An allele that is always expressed if present
40
What is a recessive allele?
An allele that is only expressed if 2 of these alleles are present.
41
What is a genotype?
Combination of all alleles for a particular gene
42
What is a phenotype?
Expressed or observed characteristic
43
What is homozygous?
When 2 allele are both either dominant or both recessive
44
What is heterozygous?
having 2 different alleles
45
What is monohybrid inheritance?
Inheritance dealing with one characteristic e.g. Dominant, recessive, co dominant, multiple allele, sex linkage
46
What is the expected ratio for monohybrid dominant/ recessive?
3 dominant 1 recessive.
47
Why are observed ratios different that expected?
random fertilisation of gametes Small size Mutation Selection
48
How can 2 parents with a dominant characteristic give birth to child with a recessive characteristic?
If both parents are heterozygous they have a 25% chance of giving birth to a child who is homozygous recessive
49
What is co-dominance?
When 2 different dominant alleles are inherited, both will be expressed in the phenotype
50
What are multiple alleles?
When the gene has more than 2 alleles
51
Alleles for blood group?
``` Ia, Ib, Io Ia gives A antigen on RBC Ib gives b antigen on RBC Io gives no antigen on RBC Ia, Ib are codominant Io is recessive ```
52
Genotypes/phenotypes for blood group?
``` A= IaIa, IaIo B= IbIb, IbIo AB= Ia Ib o= IoIo ```
53
Can recieve blood from whom?
``` A= from A&O B= from B&O AB= from A,B,AB,O O= only from O ```
54
What is a sex linked gene?
A gene carried on one of the sex chromosomes, normally the X chromosome
55
What is an inherited disease?
Inheriting a mutated allele that leads to production of a faulty protein, normally a recessive allele
56
What is a sex linked disease?
Inheriting a mutated allele carried on one of the sex chromosomes, normally, a recessive allele & normally carried on X chromasone.
57
Why do males have increased chance of inheriting a sex linked disease rather than females?
Males only have 1 X chromosome, females have 2 X chromosomes, females can be carriers, males cannot be carriers
58
What is dihybrid inheritance?
Inheritance dealing with 2 characteristics rather than one E.g. Dominant recessive Autosomal linkage Epistasis
59
What is the expected ratio for dihybrid dominant/recessive?
9 Dominant/Dominant 3 Dominant/Recessive 3 Dominant/Recessive 1 Recessive/Recessive
60
What is autosomal linkage?
2 genes (characteristics) carried on the same chromosome
61
What is epistasis?
The interaction between different genes
62
What are the 3 types of epistasis?
Dominant Recessive Complementary
63
What is dominant epistasis?
Dominant genotype on one gene which inhibits the expression of another gene
64
What is the expected ratios of epistasis?
``` 12 Epistasis (Inhibited) 3 Expressed (Dominant) 1 Expressed (Recessive) ```
65
What is recessive epistasis?
The recessive genotype on one gene which inhibits the expression of other genes.
66
What is the expected ratio for recessive epistasis?
``` 9 Expressed (Dominant) 3 Expressed (Recessive) 4 Epistasis (Inhibited) ```
67
What is complementary epistasis?
A dominant genotype required on both genes to achieve final product.
68
What ratio is expected for complementary epistasis?
9 Final product | 7 None
69
What does the hardy weinburg principle calculate?
Frequency of an allele in a population
70
What does the HWP assume?
That the frequency will not change over time based on: ``` An isolated population A large population Random mating No mutation No selection ```
71
What is the Hardy weinburg principle?
``` p= frequency of dominant allele q= frequency of recessive allele p+q= 1 (100 percent of the total population) P^2= frequency of homozygous dominant 2pq= frequency of heterozygous p^2+2pq= Frequency of the dominant condition ``` q^2= frequency of homozygous recessive p^2+2pq+q^2=1

AQA A LEVEL Biology (8 decks)

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