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A-Level Biology > Module 7: Populations, Evolution, Inheritance > Flashcards

Module 7: Populations, Evolution, Inheritance Flashcards

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1
Q

species definition

A

group of organisms with similar characteristics that can interbreed to produce living fertile offspring

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2
Q

population definition

A

all of the individuals of a particular species in a particular place

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3
Q

community definition

A

all the population of different species in a particular place

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4
Q

habitat definition

A

the place where an organism lives

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5
Q

ecosystem definition

A

a mix of different communities and habitats and how they interact based on biotic and abiotic factors

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6
Q

ecological niche definition

A

organisms role/position in an ecosystem

in terms of its biotic and abiotic factors

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7
Q

why can two species not occupy the same niche

A

interspecific competition will take place for the limiting factors/resources (abiotic and biotic), better adapted species will outcompete the less adapted at the expense of the less adapted species.
competitive exclusion principle

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8
Q

how to sample a 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 generator
place a quadrat in each coordinate
measure abundance of the plant species in each quadrat and calculate frequency or percentage cover
calculate an average for the whole area

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9
Q

how to samples plant species along a path

A

use a transect
place tape along the path, count the number of plants touching the tape (line transect)
place tape along the path, at regular intervals along the tape place a quadrat and measure the abundance within the quadrat (belt transect)

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10
Q

how to sample animals species in an area

A 
mark release recapture 
collect a sample of animals 
mark them using non-toxic marker 
release them
after sufficient time for them to re-mix with the population recapture 
count the number in the second set and count the number of species that are marked
number in sample 1 x number in sample 2 
all divided by marked in sample 2
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11
Q

assumptions of mark release recapture

A 
no births or deaths 
no immigration ort emmigration
marked animals mix evenly with population
mark is non-toxic 
mark doesn't come off 
large population
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12
Q

3 stages of population growth

A

slow/lag phase
rapid/log phase
stationary phase

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13
Q

lag phase

A

species becomes adapted to new environment

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14
Q

rapid phase

A

species are adapted
abundant resources
doubling with reproduction
birth rate > death rate

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15
Q

stationary phase

A

resources become limited
intraspecific competition
birth rate= death rate

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16
Q

abiotic definition

A

non-living factors

light, temperature, water, O2/CO2, minerals, pH, living space

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17
Q

biotic definition

A

living factors

predator, prey, mates, competition, disease

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18
Q

competition definition

A

where organisms compete for resources, both biotic and abiotic

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19
Q

2 types of competition

A

intraspecific

interspecific

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20
Q

intraspecific definition

A

occurs between organisms of the same species, only occurs when resources become limited, leads to natural selection and adaptation

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21
Q

interspecific definition

A

occurs between organisms of different species, can happen at any time even if resources aren’t limited
leads to formation of climax communities

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22
Q

predator prey relationships

A 
prey increases 
more food for predator 
predator increases 
predators eat more of prey 
prey decreases
less food for predator 
predator decreases 
less prey eaten 
prey increases in number
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23
Q

succession definition

A

how an ecosystem changes over time, change in species diversity and habitat diversity

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24
Q

what does succession rely on

A

the environment being made less hostile by present species via death and decomposition leading it to being outcompeted and replaced by larger better adapted species

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25
2 types of succession
primary | secondary
26
primary succession definition
occurs on new land
27
secondary succession definition
occurs on previously colonised land that has become bare e.g. after a fire
28
process of primary succession
pioneer species colonies an inhospitable environment the pioneer species improves a named condition because they are (list a feature) over time the land erodes and soil will form, pioneer species are outcompeted by primary coloniser primary coloniser will continue to improve named conditions secondary coloniser will outcompete primary coloniser climax community is reached
29
properties of succession
species diversity increases (peaks just before climax) habitat diversity increases environment becomes less hostile food chains become more complex and biomass increases
30
primary succession vs secondary succession
secondary starts from small plants not pioneer species so soil and nutrients are already present secondary is faster
31
how can conservation prevent succession
used to prevent formation of woody forests | involves deforestation, burning trees, grazing and using pesticides
32
biodiversity definition
range and variety of genes, species and habitats within a particular region
33
species diversity definition
number of different species and the number of individuals of each species within a community
34
genetic diversity definition
variety of genes and allele frequency possessed by individuals that make up one species
35
ecosystem diversity
range of different habitats within a particular area
36
preservation definition
maintaining individuals, populationd and ecosystems in their current state without the exploitation of their natural resources
37
conservation definition
allowing ecosystems to evolve naturally without resources being overused
38
how to conserve an area
active human management in situ ex situ
39
in situ
whole ecosystems and landscapes within habitat monitoring succession
40
ex situ
outside natural habitat | individual endangered species in zoos
41
which stage of succession do you manage
mid succession not dominated by one species not very hostile can support multiple species/habitats/food sources as there is a higher biodiversity
42
evolution definition
change in allele frequency in a population
43
2 types of evolution
adaptation and speciation
44
adaptation definition
species adapting to changes in its environment, driven by natural selection, where most of the individuals in the species will have the favourable allele/characteristic for that environment
45
process of adaptation
variation in species population new allele arises due to random mutation environment applies a selection pressure on the population those with favourable characteristics/alleles survive at the expense of those less well adapted ones that survive will reproduce to pass on their favourable alleles if this happens for many generations then that characteristic will become most common favourable allele becomes more frequent
46
3 types of selection
stabilising directional disruptive
47
stabilising selection
when environment favours individuals with the most common characteristic at the expense of the extremes (favoured against) most common will increase in proportion range (standard deviation) will decrease e.g. birth weight
48
directional selection
``` when the environment favours one of the extremes causes curve to shift to the right mean favoured against overtime this will become most common e.g. antibiotic resistance ```
49
disruptive selection
when the environment changes between both extreme conditions individuals on both extremes are favoured at different times and increase in number the middle/average will decrease in number e.g. fur length
50
Speciation definition
Process by which new species arise from existing species
51
2 types of speciation
Allopatric | Sympatric
52
Allopatric speciation
Speciation driven by geographical isolation
53
Describe allopatric speciation
Start with a population of species variation in population Population separated into different groups by geographical isolation Each group exposed to different enironments/selection pressures Each group undergoes different directional selections Each group changes so much in genetic diversity that they can’t interbreed with each other to produce living fertile offspring= different species Changes include different courtship behaviours or incompatible gametes
54
Sympatric speciation
Speciation occuring in the same geographical area driven by random mutation
55
Inheritance definition
Offspring inheriting a combination of alleles ( paternal and maternal) for each gene which will help determine characteristics
56
gene definition
Section of DNA that codes for a protein
57
Allele definition
Version of a gene
58
Dominant allele definition
Allele that is always expressed if present
59
Recessive allele definition
Allele that is only expressed if 2 are present
60
Genotype definition
Genetic makeup of an organism, combination of alleles for a particular gene
61
Phenotype definition
Expressed/observed characteristic Continuous then determined by genotype and environment Discontinuous then only genotype
62
Homozygous definition
Having 2 of the same alleles
63
Heterozygous definition
Having 2 different alleles
64
Monohybrid inheritance
Inheritance dealing with one characteristic
65
Examples of monohybrid inheritance
Dominant/recessive Codominant Multiple allele Sex linkage
66
Expected ratio monohybrid dominant/recessive
3:1 dominant to recessive
67
Why are observed ratios different from expected ratios
Random fertilisation of gametes Small sample size Mutation Selection
68
How can 2 parents with dominant characteristic have offspring with recessive characteristic
If both are heterozygotes | 25% chance of homozygous recessive
69
What is co-dominance
When 2 different dominant alleles are inherited both will be expressed in the phenotype
70
What are multiple alleles
Gene has more than 2 alleles | Blood group
71
Alleles for blood group
``` I^A, I^B, I^O I^A gives A antigen I^B gives B antigen I^O gives no antigen I^A and I^B are codominant I^O is recessive ```
72
Genotypes/phenotypes for blood group A
I^A I^A | I^A I^O
73
4 blood groups
A B AB O
74
Genotype/phenotype for group B
I^B I^B | I^B I^O
75
Genotypes/phenotypes for group AB
I^A I^B
76
Genotype/phenotype for blood group O
I^O I^O
77
Who can receive blood from whom
A from A and O B from B and O AB from A, B, AB and O O only from O
78
What is dihybrid inheritance
Inheritance with two characteristics
79
Examples of dihybrid inheritance
Dominant/recessive Autosomal linkage Epistasis
80
Expected ratio dihybrid dominant/recessive
9 DD 3 DR 3 RD 1 RR
81
What does hardy weinberg principle calculate
Frequency of allele in a population
82
What does HWP assume
``` That frequency wont change over time based on: Isolated population Large population Random mating No mutation No selection ```
83
HWP
``` p= frequency of dominant allele q= frequency of recessive allele p+q= 1, all population p^2 homo dominant 2pq hetero q^2 homo recessive p^2 +2pq dominant p^2 + 2pq + q^2= 1 ```

A-Level Biology (14 decks)

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