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unit 7 Flashcards

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1
Q

species

A

organisms that can interbreed to produce fertile offspring

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2
Q

speciation

A

when 2 or more species arise from an existing species

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3
Q

gene pool

A

all the different alleles in a population

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4
Q

allele frequency

A

the number of times an allele appears in a population

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5
Q

genetic drift

A

change in allele frequency in a population due to chance
happens more rapidly and has a greater effect on smaller populations

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6
Q

why does genetic drift have a greater impact and a more rapid effect on smaller population?

A

-larger population has more variety of alleles and a bigger gene pool, but smaller populations have less variety and a smaller gene pool and the population is more easily lost as if the allele is lost the population is wiped

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7
Q

state the two types of speciation

A

allopatric speciation
sympatric speciation

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8
Q

allopatric speciation

A

a form of speciation where a population becomes georaphically isolated

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9
Q

what happens in allopatric speciation

A

the populations becomes physically seperated which leads to reproductive isolation

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10
Q

what is meant by reproductive isolation

A

where two populations of the same species can no longer interbreed to produce fertile offspring which leads to the formation of new species

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11
Q

give an example of something which may cause allopatric speciation

A

river, volcano,forest,sea

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12
Q

model answer for allopatric speciation

A

geographic barrier seperates 2 population
leads to reproductive isolation as they cannot breed due to the barrier
genetic variation due to mutation
different environmental condtions and selection pressures
natural selection occurs in different directions
different alleles are selected for due to different environmental conditions which lead to different advantageous alleles
allele frequency changes
populations can no longer interbreed to produce fertile offspring
so speciation occurs

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13
Q

sympatric speciation

A

the form of speciation where the populations live in the same srea but still become reproductively isolated

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14
Q

3 examples of how sympatric speciation might occur

A

behavioural- mutations lead to different courtship behaviours
temporal- mutations lead to different mating times/seasons
ecological-mutations lead to individuals living in a different area of the same habitat

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15
Q

suggest how two species of …. could have arose from sympatric speciation

A

-occurs in the same habitat
-mutations cause different flowering times
-reproductive seperation
-different alleles selected for
-natural selection occurs
-species can no longer interbreed to produce fertile offspring

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16
Q

Explain how the
Caribbean species could have evolved. (5)

A

-geographical isolation
-reproductive isolation
-variation due to mutation
-different selection pressures
-different alleles selectd for

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17
Q

population

A

all the memebrs of the same speicies in an area at the same time that can interbreed to produce fertile off spring

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18
Q

community

A

all members of different species in an area at the same time

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19
Q

Carrying capacity

A

maximum population size an ecosystem can support

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20
Q

what is carrying capapciry determines by

A

biotic and abiotic factors

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21
Q

differnece between abiotic and biotic factors

A

abiotic is non living environmental factors which affect organisms such as light water and temperature
biotic are living factors which affect organisms like competetion, disease and predication

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22
Q

state the 2 types of competition

A

intraspecififc competition is between members of the same speices e.g two tigers
interspeficic compeition is between members of different species

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23
Q

difference between predator and prey

A

predator is something which hunts and kills the prey whereas the prey is something which gets killed and eaten by the predator

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24
Q

ecosystem

A

all living organisims and how they interact with the abiotic factors in their environment

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25
population
members of the same species present in the same area at the same time that can interbreed to produce fertile offspring
26
community
memebrs of all species present in a particular area at a particular time
27
habitat
place where an organism leaves
28
niche
role of a species in an ecosystem, how it interacts with the biotic/abiotic factors
29
adaptations
characteristics/behaviours that allow an organism to survive in its habitat
30
what is the competitive exclusion principle
the idea that 2 species cannot occupy the same niche, there will always be differneces, if they do occupy the same species, they will compete with each other until only one species is left
31
2 advantages of species occupying different niches
-reduces competition for resources such as food/shelter -ensures both species survive
32
sampling
a method of studying a portion of a population to estimate the characteristics of the whole population
33
why is sampling done
to study a population we must count the number of all species, it is alsmot impossible to do that, so the habitat is sampled so an estimate can be made of the population size
34
how do we make a sample more representative
select samples at random to avoid bias large sample as possible so can use more quadrats atleast 10
35
what is a quadrant
aquare frame with a known area
36
when and why do we use a quadrat
we use it when there is 100% grass coverage, and we use to calcuate % cover or when we cannot see individual plants
37
things to consider when using quadrats
size of quadrat- depends of the size of the plant and size of area positioning of quadrat- should be random, to avoid, bias, use number generator to generate coordinates -quantity of quadrats- 10 or more should be used
38
describe how to do random sampling
-use random number generator to generate coordinates -place quadrats at coordinates -use atleast 10 -count number of plant species pin each quadrat -c
39
what is abundance
number of individual species in a given area
40
2 ways how abundance can be measured for species that do not move
percentage cover, useful when species cannot be counted individually such as grass and moss calculating mean number of species per quadrat and multiplying it by the area of whole site
41
what is variation
differences between species
42
what causes variation
genotype-different species have different genes, same species have same genes but different alleles -our environment, phenotypic variation is caused by differences within the environment
43
examples of things caused by variation in genes/environment
genes= eye colour, blood type environment=accent, piercings
44
difference between interspecific/intraspecific variation
inter is variation between different species, intra variation between members of the same species
45
what causes variation
crossing over in prophase 1 and indepedent assortment in metaphase 1 which creates new combo of alleles mutations in dna, which changes base sequence of dna creating new alleles environmental differences- environment interacts with genotype to give phenotype random fertilisation, mixing of dna from 2 parents
46
continous variation
variation measured in a number such as height, weight, iq controlled by 2 or more genes so is polygenic and influenced by the environment
47
discontinous variation
variation which is in categories, describes as absent or present with no intermediates little influence by the environment controlled by 1 gene
48
what results in natural selection
predatation disease competition
49
natural selection model answer
-genetic variation due to mutation -there are selection pressures -individuals best adapted are more likely to survive (say why) -more likely to reproduce -pass on their genes -including alleles that gave them the advantage -frequency of allele increases over time -repeated over many generation
50
define evoloution
change in allele frequencies over time
51
stabilising selection
.
52
directional selection
.
53
disruptive selection
.
54
state mark release recapture method
-count as much individuals as you can, mark them and count them -release them into their own habitat -allow enough time to pass so they can mix with rest of population -catch another sample using same method -count number of marked and unmarked individuals -estimate population size
55
how to calculate population size
number caught in first sample x number caught in second sample// number of marked indivudals in second sample
56
state assumptions on which the mark release recapture relies on
-marking has not affected survival chances/non toxic marker e.g not make them visible to markers -allow enough time after collecting first sample to mix with rest of population before collecting second sample -marking is till visible/not washed of due to rain -no change in population size due to births/reproduction/deaths -sample musrt be large enough so representatgive sample -no change in population size due to migration/immigration
57
what is succession
the process by which an ecosystem will change, the biotic/abiotic factors will change
58
state the two types of succession
primary- occurs on newly exposed land which has never been colonised before, only rick, no soil no orgnaic matter secondary-occurs on previously colonised land that has been damaged, no plants but soil still remains
59
what is pioneer species
species which are first to colonise the land/area and usually adapted to the harsh hostile conditions
60
state the stages of primary succession
-bare rock with no soil to retain water, harsh hostile conditions -pioneer species change the abiotic environment, they die and decompose by micro organisms which forms basic soil -conditions become less hostile, there is some soil to retain water and minerals -other species start to grow such as moss -larger plants which need more water and minerals start to grown when soil deepens, when these plants die and decompose more minerals enter soil -trees, shrubs begin to grow as soil holds more water and minerals which outcompete the smaller species to become dominant species and diversity increases -finally enough soil and minerals to support large trees which outcompete the smaller ones to become dominant species this is called the climax community -
61
state the terms climax community dominant species
-community which has higher biomass and biodiversity and is a stable community -most abundant species
62
state the stages of secondary succession
happens in the same way as primary succession, but because theres already a layer of soil, it starts at a later stage, poineer species are usually larger such as shrubs
63
describe and explain how succession occurs 4
-pioneer species colonise -pioneer species change conditions of environment -less hostile for other species -increase in diversity
64
what is conservation
protection and careful managment of an ecosystem and its natural resources
65
state some methods of conservation
-making laws to make it illegal to hunt for some species -using coppicing, mowing,grazing to manage land -controlling predators and poachers -fencing of areas to limit human impact -protecting habitats and restricting building
66
why is conservation important
-to protect species and prevent disruption to food chains -econmic reasons, so many products are produced from plants and animals which are traded on a global scale such as crops -aethetic reasons, to make sure we have pleasant landscaped for tourists, eco tourism also has financial value
67
state the two male/female chromosomes
males = xy females = xx
68
homologous pairs
pair of chromosomes that have same genes but different alleles
69
state the difference between x/Y chromosomes
x= larger and contains around 2000 genes y= shorter contain less genes fewer than 100
70
during meiosis when x/y chromosomes pair up, they do not form a bivalent explain why
x/y chromosomes are different sizes -chromatids unable to line up and form bivalent
71
how does sex linkage occur
occurs when the gene for a certain characteristic are carried on the x chromosome y never carries alleles
72
explain colour blindness in terms of sex linkage
-colour blindness is caused by a recessive allele -alleles are only carried on x chromosomes, therefore if females inherit one reccessive allele theyre unaffected, but if males inherit one they are affected showing how colour blindness is prevalent in males
73
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unit 6 (6 decks)

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