20 Human Influences on Environment

Biodiversity

the number of different species that live in an area.

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

Advantages of monoculture

higher revenue.
easier to manage.
yields maximization.
specialised production.
increased productivity and efficiency.

Disadvantages of monoculture

loss of biodiversity
outbreaks/ spreading of diseases/ pests/ plagues
endangered/ extinction of species

loss of habitats/ habitat destruction

deforestation

competition for resources
disruption of food chain
disrupted soil fertility/ infertility of soil
desertification
soil erosion (by water/ wind)
increased pollution
flooding
disrupted nutrient cycling

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

Disadvantages of intensive livestock production

loss of biodiversity:

disease spreading to, wild populations / humans;

release of, (named) greenhouse gases / carbon emissions ;

named consequence; e.g. climate change / global warming

use of pesticides;
deforestation / habitat loss ;
effect of waste (faeces and urine) on, waterways / crops ;
use of antibiotics and (spread of antibiotic resistance;
providing food for livestock requires monocultures;
inefficient use of, crop plants / energy

Humans negative impact on habitats

Through altering food webs and food chains, humans can have a negative impact on habitats.

Reasons for habitat destruction

increased area for housing, crop plant production and livestock production
extraction of natural resources
freshwater and marine pollution

Effects of deforestation

habitat destruction
reducing biodiversity
loss of soil
extinction
flooding
increase of carbon dioxide in the atmosphere

Effects of untreated sewage and excess fertilisers in aquatic ecosystems

surface runoff with agricultural fertilisers sewage outflows supply algae with excess nutrients. algae grows rapidly, blocks light for photosynthesis in plants and decreases oxygen levels which kill fish, ecosystem collapses

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

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

remain in the ecosystem (for a very long time;

chokes / strangles / traps / blocks digestive systems / AW (of animals)
ingested;

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) ;
reference to, chemical exposure / fumes / toxins ;
(
visual pollution;
(plastic) block roots / prevents root growth ;

Methane and carbon dioxide

green house gases. Released by natural processes and human activity, they accumulate and 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.

Sustainable resource

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

habitat destruction

climate change

plant hunting

increase in grazing

deforestation

pollution
competition from introduced species
disease
lack of pollinators
desertification
removing too many of a plant species

Reasons why a fish species can become endangered species

habitat destruction ;
climate change;
(described) overfishing
/ hunting ;
named) pollution;
introduced diseases / species;

food chain disrupted (described);
overconsumption (by humans;
(

Reasons why an animal species can become endangered species.

3 (named example of climate change; e.g. desertification

1 habitat loss / deforestation ;

9 hunt / trophies / high value / poaching ;

10 laws are not enforced to protect from hunting

7 competing with humans for space;

12 poisoning / pollution;
2 large mammals need large amounts of space ;
Use of land for
4 land developed for agriculture;
5 land developed for, housing / transport / factories
6 land used for extraction of (named) materials)
8 idea that populations are isolated ;
11 lack of education;
13 need a large quantity of food/lack of food sources / starvation;
14 slow reproduction rate / hard to breed in captivity :

How can we prevent overfishing

education, closed seasons, protected areas, controlled net types and mesh size, quotas and monitoring

6 nursery zones (using this is much safer)/ no-catch zones / / protected areas / MPAS ;
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
1AW;
4 (legal) quotas / treaties / licenses / laws / restricted catch weight;
5 ensuring sustainable population size / recovery of, endangered / specific, species
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;
artificial insemination / IVF / use of surrogates /AW:
reintroduction programmes;
education/ awareness

How endangered species can be conserved

(a) monitoring and protecting species andhabitats
(b) education
(c) captive breeding programmes
(d) seed banks
monitoring populations and protecting species and habitats
education
captive breeding programmes
seed banks
monitoring / AW, populations) / individuals) :
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;

how forests can be conserved using

education, protected areas, quotas and replanting

Describe the reasons for conservation programmes

(a) maintaining or increasing biodiversity
(b) reducing extinction
(c) protecting vulnerable ecosystems
(d) maintaining ecosystem functions, limited to nutrient cycling and resource provision, including food, drugs, fuel and genes

Reasons for conserve animals

maintain (bio)diversity/ genetic diversity

prevention of extinction

maintains natural habitat/ prevent, human interference/ development
maintain, food chain/ balanced ecosystems
maintain nutrient recycling

maintain, resource provision/ food/ drugs

less, hunting/poaching/
Killing
tourism/ economic reason
maintain, gene, pool/diversity
available for scientific study
retain for future generations
prevent soil erosion/ flooding
education

Reasons to maintain ecosystems like wetlands

1. maintain biodiversity;

2. to prevent extinction;

3. provide, habitats / shelter;

4. ref to nitrogen cycle;

5. provide, resources / food / fuel / drugs / raw materials;

6. provide, breeding grounds / places for breeding;

7. vulnerable to the effects of, development / drainage /AW;

8. ref to flooding / natural disasters;

9. provide feeding grounds for animals / ref. to disruption of food, chains / web;

10. ref to maintenance of water cycle;

11. ref to carbon cycle; e.g. greenhouse gas / carbon storage / carbon sink

waste disposal;

idea of areas for, recreation / (eco) tourism / education

ethical reasons / aesthetic reasons /
AW;

The risks to a plant species of having very small numbers

small population so more vulnerable to diseases.

high risk of genetic disease

high risk of extinction
less reproduction
less variation

less likely to adapt to change in environment
reduced number of alleles

The disadvantage of captive breeding programme involving very small number of animals

increased risk of genetic disease

not enough animals to breed

can not reproduce

less genetic variation
less likely to adapt to change in environment

reduced number of alleles
inbreeding
cost

Artificial insemination

1. Collect semen/sperm implied by context);
2. freeze semen / sperm, / use sperm bank / use sperm collected, far away/ long ago;
3. selecting / washing / screening, of sperm / AW;
4. use fertility drugs containing hormones for (super)ovulation;
5. determine when female is about to ovulate;
6. insert, semen/ sperm, into female (vagina/ uterus)

In vitro fertilisation (IVF)

collect / extract, eggs ;
collect / extract, sperm;
use of donor, eggs/ sperm;
fertilisation / described / IVE,
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) ;