Human influences on ecosystems Flashcards
How humans have increased food production:
agricultural machinery to use larger areas of land and improve efficiency
chemical fertilisers to improve yields
insecticides to improve quality and yield
herbicides to reduce competition with weeds
selective breeding to improve production by crop plants and livestock
Disadvantages of monoculture:
loss of biodiversity
outbreaks
extinction of species
disruption of food chain
Advantages of monoculture:
higher revenue.
easier to manage.
yields maximization.
specialised production.
increased productivity and
efficiency.
Disadvantages of intensive livestock production:
loss of biodiversity ;
deforestation / habitat loss ;
effect of waste (faeces and urine) on, waterways/crops;
disease spreading to, wild populations / humans ;
use of antibiotics and (spread of) antibiotic resistance ;
Advantages of intensive livestock production:
help to provide more food for people
sometime provide food more cheaply than extensive systems
fewer people go hungry
take up less land
more land could be left in its natural state, providing habitats for other species
Biodiversity
number of different species that live in an area.
Reasons for habitat destruction:
increased area for housing, crop plant production and livestock production
extraction of natural resources
freshwater and marine pollution
Through altering food webs and food chains, humans can have a negative impact on
habitats.
Effects of deforestation:
habitat destruction
reducing biodiversity
extinction
loss of soil
flooding
increase of carbon dioxide in the atmosphere
Effect of pollution and excess fertilisers in aquatic ecosystems:
lake/ river pH decrease
aluminium ions become mobile
nutrients leached
shell damage
fish/ frog fail to reproduce
aquatic plants die
disruption of food chain
loss of biodiversity
Biology notes By Vasumitra Gajbhiye 51
low pH toxic to aquatic animals
fish produce mucus which blocks gills.
Effect of plastic on aquatic ecosystem:
plastic remains /persists / lasts a long time/ not decomposed ;
swallowed/ ingested/eaten/ cannot be digested/ blocks gut ;
caught, around/ strangle/trapped/ entangled/ smother/ suffocate / injure/ cut /
trap/ stuck in, organism AW ;
plastic blocks light for, photosynthesis ;
may, contain/release, (oil-soluble) toxins / poisons / harmful chemicals;
blocks the flow of water in streams or rivers ;
so less aeration of water/reduces concentration of (dissolved) oxygen ;
destruction of, habitat/ ecosystem/ food chain ;
idea of bioaccumulation/ biomagnification ;
trapped / stationary water acts as a breeding site for mosquitoes ;
AVP ; e.g. visual pollution /releases hormone-like chemicals / less oxygen from
photosynthesis
Effect of plastic on terrestrial ecosystem:
CHOKES/ strangles / traps / blocks digestive systems / AW (of animals)
ingested ;
reference to, chemical exposure / fumes / toxins ;
(plastic) accumulates in an organism / is passed down a food chain ;
(described) habitat destruction ;
e.g. plastic covers the habitats (plastic) blocks (light / water for) photosynthesis
(for land plants) ;
visual pollution ;
(plastic) block roots / prevents root growth ;
remain in the ecosystem (for a very long time) ;
green house gases
Methane and carbon dioxide
how do greenhouse gasses affect climate
They trap infrared radiation
emitted from the sun towards the earth. This keeps the planet warm enough to
support life. If level of these green house gases rise, more infrared radiation is
trapped, this increase the average temperature of earth. Resulting in enhanced
green house effect, leading to climate change.
Eutrophication of water:
increased availability of nitrate and other ions
increased growth of producers
increased decomposition after death of producers
increased aerobic respiration by decomposers
reduction in dissolved oxygen
death of organisms requiring dissolved oxygen in water
Sustainable resource
one which is produced as rapidly as it is removed from the
environment so that it does not run out
Some resources can be
conserved and managed sustainably, e.g. forests and fish stocks.
Why an organism becomes
endangered:
climate change
habitat
destruction
hunting
overharvesting
pollution
introduced species
Reasons why a plant species can become endangered species:
plant hunting
disease
lack of pollinators
competition from introduced
species
deforestation
climate change
desertification
pollution
increase in gazing
habitat destruction
removing too many of a plant
species
Reasons why a fish
species can become
endangered species.
habitat destruction ;
climate change ;
(described) overfishing
/ hunting ;
food chain disrupted
(described);
overconsumption (by
humans) ;
(named) pollution ;
introduced diseases /
species ;
Reasons why a animal species can become
endangered species.
1 habitat loss/deforestation;
2 large mammals need large amounts of space ;
3 (named example of) climate change; e.g.
desertification
Use of land for
4 land developed for agriculture ;
5 land developed for, housing / transport /
factories
6 land used for extraction of (named) material(s)
7 competing with humans for space ;
8 idea that populations are isolated ;
9 hunt / trophies / high value / poaching ;
10 laws are not enforced to protect from hunting
11 lack of education ;
12 poisoning / pollution ;
13 need a large quantity of food / lack of food
sources / starvation ;
14 slow reproduction rate / hard to breed in
captivity ;
How endangered species can be conserved:
monitoring and protecting species and habitats
education
Biology notes By Vasumitra Gajbhiye 54
captive breeding programmes
seed banks
How endangered species can be conserved:
monitoring / AW, population(s) /
individual(s) ;
habitat, protection / restoration ;
reducing / prevention, of pollution
;
removal / AW, of alien species ;
preventing colonisation by alien
species ;
hunting ban / prevent poaching ;
government / legislation, to
protect species ;
create, exclusion zones /
reserves (so not disturbed by
people) ;
specific, times when / areas
where, hunting / AW, not allowed
international agreements to limit
trade ;
removal to, zoos / botanical
gardens / wildlife parks ;
captive breeding / breeding
programme (in situ or ex situ) ;
seed banks / frozen zoos /
cryopreservation / AW ;
artificial insemination / IVF / use
of surrogates / AW ;
reintroduction programmes ;
education / awareness ;
How can we prevent overfishing:
1 education / awareness ; Accept
commercials / advertising / tax
consumer
2 reduced demand (to eat from
unsustainable fish stocks) / public
pressure / campaigning ;
3 steps taken by fisherman voluntarily
/ AW ;
4 (legal) quotas / treaties / licenses /
laws / restricted catch weight ;
5 ensuring sustainable population
size / recovery of, endangered /
specific, species
6 nursery zones (using this is
much safer)/ no-catch zones / /
protected areas / MPAs ;
7 overflow of target species / increase
in population outside zone / breeding
recovery ;
8 limited fishing season ;
9 stock recovery / optimises breeding
seasons ;
10 fines;
11 discourage / punish, poor practice
12 restocking / captive breeding and
release ;
13 increases gene pool / number of
young / reproductively-viable, fish ;
14 fish farming ;
15 alternative source of fish
Reasons for conserve animals
maintains natural habitat/
prevent, human
interference/ development
prevention of extinction
less, hunting/ poaching/
killing
tourism/ economic reason
maintain (bio)diversity/
genetic diversity
maintain, gene,
pool/diversity
maintain, food chain/
balanced ecosystems
available for scientific study
retain for future generations
maintain nutrient recycling
maintain, resource
provision/ food/ drugs
prevent soil erosion/
flooding
education
Reasons to maintain ecosystems like
wetlands
- to prevent extinction;
- maintain biodiversity;
- provide feeding grounds for animals /
ref. to disruption of food, chains / web; - provide, breeding grounds / places for
breeding; - provide, habitats / shelter;
- vulnerable to the effects of,
development / drainage / AW; - ref to flooding / natural disasters;
- ref to nitrogen cycle;
- ref to maintenance of water cycle;
- ref to carbon cycle; e.g. greenhouse
gas / carbon storage / carbon sink - waste disposal;
- provide, resources / food / fuel / drugs /
raw materials; - idea of areas for, recreation /
(eco)tourism / education; - ethical reasons / aesthetic reasons /
AW; - AVP; e.g. soil erosion
Artificial insemination:
- collect semen / sperm (implied by
context) ; - freeze semen / sperm, / use
sperm bank / use sperm
collected, far away/ long ago ; - selecting / washing / screening, of
sperm / AW ; - use fertility drugs containing
hormones for (super)ovulation ; - determine when female is about
to ovulate ; - insert, semen / sperm, into
female (vagina / uterus) ;
The risks to a plant species of
having very small numbers:
high risk of extinction
less reproduction
high risk of genetic disease
less variation
small population so more
vulnerable to diseases.
reduced number of alleles
less likely to adapt to change in
environment
In vitro fertilisation (IVF):
collect / extract, eggs ;
collect / extract, sperm ;
use of donor, eggs / sperm ;
fertilisation / described / IVF,
outside the body / in a dish / in a
laboratory ;
embryo development in dish / AW
screening of embryos ;
inserting embryos into uterus ;
give mother progesterone after
inserting embryos (to maintain
lining) ;
