Module 4:Biodiversity Flashcards
What are the 3 main factors that affect biodiversity?
deforestation
agriculture
climate change
Name examples of how deforestation occurs
1 natural cause and 2 human causes
forest fires which are a result of lightning or extreme weathers
-directly by human action(cutting down trees)
-indirectly by acid rain which is a result of pollutants being released into the atmosphere
Name the ways that deforestation affects biodiversity
3 negative and 1 positive
4 ways
-reduces number of trees in an area
-reduces species diversity as can leave just a few species of trees intact
-reduces number of animal species in an area as it destroys their habitats and food source
-this forces them to migrate to other areas which can increase the biodiversity of other areas
What methods within agriculture affect biodiversity?
4
deforestation
removal of hedgerows
use of pesticides and herbicides
monoculture
Why is deforestation used in agriculture?
it increases the area of land available for growing crops and rearing livestock
Why is hedgerow removal used in agriculture?
2 reasons
What effect does this have on biodiversity
2 ways
-it enables them to use large machinery to help them plant , fertilise and harvest crops
-it also frees up extra land for growing crops
-reduces number of plant species in the area
-destroys habitats of many species like birds etc
Why are pesticides and herbicides used in agriculture?
pesticides-used to kill pests that eat the crops or live on the animals
herbicides are used to kill weeds as weeds compete with cultivated plant for light minerals and water
What effect do pesticides and herbicides have on biodiversity
2 for each
pesticides-reduce species diversity as they kill pest species
-they also destroy food sources for other organisms
herbicides-reduces plant diversity
can also reduce animal species diversity as it destroys food sources
What is monoculture?
Why is monoculture used in agriculture?
the yielding/growing of one specific crop or species
it allows farmers to select species that will produce a high yield meaning they will make the most profit they can
What effect does monoculture have on biodiversity
Give 2 reasons
-greatly reduces species diversity as only one species is being grown/reared
-limits variety of food source meaning area will only be able to support small number of species
What is meant by climate change?
how the characteristics of the weather in certain places have changed
What does global warming refer to?
the rise in the Earth’s mean surface temperature
If global warming continues how will it affect biodiversity?
1)what will melting of polar ice caps result in
2)rising sea levels
3)higher temps and less rainfall
4)population and lifecycle of insects
5)insects affect on plants
Give 5 examples
-melting of polar ice caps could cause extinction of plant and animal species in the area
-rising sea levels could flood low lying land which will decrease available terrestrial habitats
-higher temps and less rainfall will mean some plant species will fail to survive
-insects life cycles and populations will change as they adapt to climate change
-that could affect plants causing extinction as insects are pollinators of plants
What is the primary source of genetic diversity
Why is genetic diversity important (what does low diversity cause)?
mutations
a low diversity makes a species more susceptible to environmental changes so the whole population could easily be wiped out by an event/disease
What factors increase genetic diversity and how?
3
mutations-create new alleles
interbreeding-alleles can be transferred between the 2 populations
meiosis-the processes of crossing over and independent assortment
What is an allele?
a different version of a gene
What is interbreeding?
Alleles are transferred between the populations during this process , what is the name given to this?
when an individual from one population migrates and breeds with a member of another population
gene flow
What does selective breeding mean?
Does it increase/decrease genetic diversity
selective breeding-when only a few individuals are selected for breeding due to their advantageous characteristics
rare breeds-
decreases
How does natural selection affect genetic diversity?
species evolve to primarily contain alleles that have coded for advantageous characteristics , this decreases the number of different alleles over time
What 2 other breeding factors decrease biodiversity?
Describe them
captive breeding-only a small number of individuals are available to breed so limited number of alleles available to be passed on
rare breeds-selective breeding used to produce a breed with characteristics that have become unpopular so numbers drop
if a small number are available and have all been selected because they contain desired characteristics the diversity of the population will be reduced
What is a genetic bottleneck?
What effect does this have on genetic diversity?
when few individuals survive an event/change
means only the alleles of surviving members can be passed on
What is the founder effect?
How does this affect genetic diversity?
where a small number of individuals create a new colony which is geographically isolated from the original
the gene pool of the colony will be low as there aren’t many individuals there
What is meant by genetic drift?
due to the random nature of alleles being passed on , the frequency of occurence of an allele will vary and sometimes the allele will disappear from a population
What is polymorphism?
What is monomorphism?
when a gene has more than one allele
when a gene has one allele
Are most genes polymorphic or monomorphic , why?
monomorphic as it ensures the basic structure of a species is similar
What is the calculation for the proportion of polymorphic gene loci?
= number of polymorphic gene loci divided by the total no of loci
