20. Human influences on the environment

Question 1

Agricultural machinery

Answer 1

• Machinery has developed to large and complex powered (used for planting, harvesting, fertilising etc.)
• Increased use of machinery in agriculture reduces labour costs for farmers + time needed for farming tasks –> reduces food price for customers.
• Also machines are large and more efficiently work the land –> more efficient production of large quantities of food.

Question 2

Fertiliser

Answer 2

A substance that contains important mineral ions needed for plant growth. It is added to soil by farmers and gardeners.

Question 3

Chemical fertiliser

Answer 3

• Fertilisers can be artificial or natural
• Use of chemical fertilisers increases the yield of crops
• Natural fertilisers (eg. manure/compost) add organic matter, nitrogen + other nutrients. Also imporve soil structure byt the concentrations of the nutrients can’t be tailored to specific crop.
• Artificial fertilisers utilise purified chemicals, carefully selected + mixed together –> Can be adapted to supply exactly right nutrients for specific crop. However, they don’t improve soil structure.

Question 4

Insecticides

Answer 4

• Substances used to kill or control the number of unwanted insects (pests)
• Insects can reduce yiled + increase costs for farmers + consumers. Insecticides protect crops from this damage.

Question 5

Herbicides

Answer 5

• Substances intended to kill weeds and other plant pests.
• Plants compete for resrouces (eg. light, soil nutrients + water)
• Weeds use up resources needed for crop plants.
• Herbicides kill weeds by disrupting growth in some wat.
• Best herbicies can kill weed species without harming the crop plants.

Question 6

Selective breeding

Answer 6

The process by which animals or plants are bred to produce offspring with particular, desirable, characteristics.

• Crops/ animals are bred. Offspring with specific characteristic (eg. size) is selected + further bred.
• Process is carried out over several generations to improve crops/ animals.

Examples of selective breeding include…

• Fish that grow more quickly and become larger
• Cows that produce more milk
• Chickens that lay more eggs.

Question 7

Monoculture

Answer 7

Growing a single crop across a large area.

Question 8

Intensive farming - Disadvantages

Answer 8

Land clearance

• Intensive farming uses large amoutn of land –> need to clear alnd of other plant species
• Leads to deforestation + destroys habitat/ decreases biodiversity of area. (Similar for livestock)

Reduced biodiversity

• Monoculture = pathogens + insect pests spread faster –> means farmers use more insecticies –> also kill insects that aren’t pests.
• Damages food web + reduces number of species in area.

Soil damage

• Intensive farming uses heavy machinery –> compacts soil (reduces amount of water + air it can hold) –> Makes it more difficult for plants to grow –> large areas of land exposed bc no vegetation –>Soil erosion caused by this.
• If farmer uses the same crops year after year –> organic matter + nutrients in soil will be used up –> will have to use more fertiliser –> damages soil structure –> makes land vulnerable to erosion.
• Organic matter also helps hold water in soil –> loss of organic matter = more water needed to irrigate crops.

Water pollution

• Water run-off can carry fertiliser/ insecticides/ herbicides into local water courses.
• May harm organisms in water (directly/indirectly)
• Fertiliser/ waste run-off can also cause eutrophication.

Air pollution

• Animal waste = air pollution
• Decomposing animal waste releases ammonia –> can cause skin irritation + respiratory problems in humans.
• Also livestock (usually cattle) produce large amounts of methan –> greenhouse gas concentration increases.

Question 8

Intensive farming - Advantages

Answer 8

Simplicity (monoculture)

• Simplifies farming
• Only one type of crop needs have to be satisfied (eg. soil, fertiliser, irrigation, herbicides + pesiticide type.)
• Similarly, livestock needs eg. meds + food can be simplified.

Higher yields

• More efficient + effective at growing crops + animals.
• Bc crop/ animals grows optimally + can be produced in efficient wat –> increases amount produced from land.

Reduced costs

• Costs of production decreases bc farmer works in focused + efficient manner.
• Increases profit for farmer + decreases cost of product for consumer.

Larger land + machinery

• Monoculture –> allows farmer to use very large areas of land (bc similar crop) –> can use large agricultural machinery –> increases efficiency.
• In livesotck –> farmer can allocate large pieces of land/buildings to meet needs of one animal –> more efficient.

Question 9

Biodiversity

Answer 9

A measure of how many different species of organisms live in an ecosystem.

• Vital for maintenance of healthy ecosystem
• Removal of a species causes collapse of food chains –> biodiversity thus important.

Question 10

Human activities causing habitat destruction

Answer 10

Using more land for food crops, livestock production and housing

The extraction of natural resources

Freshwater and marine pollution

Question 11

Habitat destruction - Increased use of land

Answer 11

• Human pop = increasing –> more land needed for housing + food prod.
• Intensive farming uses huge areas of land –> natural habitats destroyed to make way for crops.
• More people also afford to eat meat –> increase land needed for meat production (livestock prod. = less land efficient in its usage)

Question 12

Habitat destruction - Extraction of natural resources

Answer 12

• Raw materials (eg. minerals + oil), needed for industrial purposes.
• Extraction of curde oil + natural gas (fuels) destroys habitats bc…
• Pollution created by combustion of fuels.
• Search for fuels damages natural habitats
• Drilling + mining operations need wells, roads pipelines etc. —> widespread building.
• Stone extracted from quarries + sand taken from rivers
• Quarries (deep hole in ground from where stone is removed) destroy large areas of habitats + change landscape –> also create pollution from machinery + chemicals
• Extraction of sand affect aquatic species downstream + at extraction zone.
• Eg. may change volume + speed of water flow. Could also change course of river. Also alters composition of riverbed –> changing chemistry of water.

Question 13

Habitat destruction - Water pollution

Answer 13

• Pollution of marine (seas, oceans, seashores) /freshwater (rivers, lakes, dams) –> habitat destruction
• Occurs when particles, chemicals, unnatural sounds enter ecosystem.

Question 14

Examples of water pollution - Habitat destruction

Answer 14

• Oil spills
• Untreated sewage
• Careless disposal of rubbish
• Mining waste
• Nitrates entering rivers from fertiliser use
• Herbicides and pesticides
• Heavy metal runoff (this can carry toxic metals such as mercury that pose a danger to water life and human health).

Question 15

Deforestation

Answer 15

The clearing of large areas of trees to create land for human purposes (eg. energy, timber, food production etc.)

Environmental effects include…

• Reduced biodiversity
• Flooding
• Loss of soil
• Extinction of species
• An increase in carbon dioxide in the atmosphere.

Question 16

Deforestation - Reduced biodiversity

Answer 16

• Forests, especially rainforests = very high biodiversity.
• Trees provide habitats + food for many organisms (producers in many food webs)
• Certain creeping plants need trees to be able to access sunlight.
• Without trees –> food webs collapse.

Question 17

Deforestation - Flooding

Answer 17

• Trees + other vegetation hold soil together + hold water in ground.
• No trees = no vegetation to restrict flow of water –> rain flows quickly into lakes/rivers –> washes away more soil + can lead to flooding

Question 18

Deforestation - Loss of soil

Answer 18

• Trees + vegetation keep soil in place + reduce wind/ rain erosion.
• If large areas cleared –> protective layer of vegetation lost –> soil blown away by wind / washed away by rain.
• Some areas also suffer from huge dust storms as the wind picks up earth from the exposed land

Question 19

Deforestation - Extinction of species

Answer 19

• Habitat destrction means animals have to migrate + search for similar habitats.
• Not all species are able to do this –> struggle to find food / mates / shelter in small or fragmented habitats.
• Slowgrowing plants/ plants that only disperse seeds over small distance = also wiped out if habitat destroyed.
• These reasosn cause extinction.

Question 20

Deforestation - Increased carbon dioxide

Answer 20

• Trees use carbon dioxide to make carbohydrates during photosynthesis.
• Deforestation = less trees = less photosynthesis = larger carbon dioxide concentration
• Vegetation cut down may also be burnt –> releases even more carbon dioxide into atmosphere.

Question 21

Pollution (+ source/effect)

Answer 21

Release of any substance that has an undesired, unexpected, harmful or toxic effect on the environment.

• A source of pollution is where and how a pollutant enters the environment.
• An effect of pollution is the harm that the pollutant does when it is in the environment.

Question 22

Pollutant

Answer 22

Substance that causes pollution.

Question 23

Water pollution - Untreated sewage

Answer 23

• Greywater (water from baths/washing machines), food scraps + human waste needs to be traeted before released into environment.
• Helps curb spread of disease + recycles water + protects aquatoic ecosystems.
• Sewage contains harmful bacterias –> causing skin irritation + diarrhoea in humnas.
• If released in ocean –> can infect corals –> leading to bleaching + death.
• Untreated sewage also contains hormones + drugs –> harm reproduction abilistes of fish / amphibians.
• Untreated sewage can also cause eutrophication.
• If sewage incudes runoff form roads into sewers –> rubbish (plastic) can also end up in water.
• Untreated sewage also sometimes contains industrial waste water from factories (contains toxic heavy metals, eg. mercury.)
• Toxins become concentrated in bodies of species further up in food chain –> animals eventually die / become infertile.

Question 24

Water pollution - Eutrophication

Answer 24

• Eutrophication = process in which additional nitrate + other ions in water –> lead to deaths of aquatic organisms.
• Fertilisers (nitrate and phosphate mineral ions) + untreated sewage enter water systems by rainwater runoff –> increase in nitrate concentration in water –> nitrates increase gorwht of algea in water –> leads to algal blooms.
• Algal blooms on surface of water block sunlight –> other aquatic plants can’t carry out phtosyntehsis.
• Plant die –> decomposed by decomposers carrying out aerobic respiration (uses up oxygen in water) (also aquatic plants = no longer creating dissolved oxygen –> Ask Miss Chip) –> other organisms needing dissoleved oxygen in water die.

Question 25

Eutrophication

Answer 25

Rapid, uncontrolled growth of plants (usually algae) in a water body. It is caused by excessive nutrients in the water.

Question 26

Plastic pollution

Answer 26

• Large amoutns of rubbis dumped into rivers + oceans (either accidental or poor wast management)
• Rubbish takes long time to decompose.
• Decomposition of rubbish –> causes low oxygen levels in water (bc decomposer reproduce rapidly + use up oxygen.
• Plastic = non-biodegradable –> (bacteria cannot digest them) –> stay in oceans for hundreds of years.
• Birds, fish, turtles etc. mistake plastic for food –> blocks digestive system of the animal –> animal straves
• Animals may also get entangled in plastic eg. fishing lines.
• Platic is made commercially from small pellets called nurdles.
• Due to accidental pollution –> nurdles = often found in ocean
• Nurdles (microplastics) = so small animals mistake them for food.
• Larger animals consume smaller animals –> concentration of microplastic increases further up the food chain you go.
• Long term exposure to air, water, light –> cause toxic compounds to form –> affect aquatic + land ecosystems.
• When plastic breaks down toxins + greenhouse gases released. Toxins –> leach into soil –> pollutes land/underground water sources
• Burning of plastic in landfills can also lead to toxic chemicals being released into the air.

Question 27

Greenhouse gases

Answer 27

Any atmospheric gas, such as carbon dioxide or methane, that can absorb thermal energy and so contribute to the greenhouse effect.

Question 28

Greenhouse effect

Answer 28

The absorption of reflected radiation by greenhouse gases in the atmosphere that reduces the transfer of energy into space, so increasing the average temperature of the Earth.

Question 29

Climate change

Answer 29

Changes in long-term weather patterns associated with global warming and the greenhouse effect.

Question 30

Greenhouse effect - Explained

Answer 30

• Greenhouse effect = natural process which maintains temp. range on Earth.
• Carbon dioxide, methane + other greenhouse gases trap heat energy that would otherwise escape from the Earth into space –> keeps planet warm enough for life to exist.
• Carbon dioxide is released naturally by volcanoes and during respiration in living organisms.
• Himan activity (fossil fuels (bc natural carbon sinks), electricity, deforestation) –> increases concentration.
• Methane released by livestock bc of bacteria in digestive system which helps cattle digest plant matter.
• Additional carbon dioxide + methane (greenhouse gases) –> causes enhances greenhouse effect.
• More heat energy is being trapped –> leads to increased global temp –> climate change
• Climate change –> droughts + flooding mroe common (problem for farmers), + species migration/ extinction + changes in sea level.

Question 31

Sustainable resource

Answer 31

Something which is produced as rapidly as it is removed from the environment, so that it does not run out.

Eg. Hydro-electric power/ solar power. + water cycle + fuel from trees (if felled trees are replaced with new trees)

Question 32

Non-renewable resources

Answer 32

Something that is being used up faster than it is being formed.

Eg. Fossil fuels –> took millions of years to form

Question 33

Maintaining resources - Forests (why it has to be done and areas that should be prioritised)

Answer 33

• Forests necessary for biodiversity –> need to be conserved –> to do this effectively we must target the areas where action is needed most (also needs of local peopls have to be met)

Important areas to conserve include…

• The edges of rivers, to promote the retention of water
• Mountain slopes, to reduce erosion
• Areas with rare species and habitats .

Question 34

Maintaining resources - Forests (methods of conserving forests)

Answer 34

• Planting new trees to replace felled trees. (Reforestation) –> although important, better to conserve forest in first place.

How to conserve forests.

• Setting quotas for logging, which may mean banning logging entirely in some areas.
• Using education programmes to help local people to understand why the forest is important
• Creating protected areas.

Question 35

Maintaining resources - Quotas

Answer 35

A quota is a limited amount of a resource that may be removed from a given area or within a set time period.

Quotas are determined by the government of a country and are protected by law.

Eg. Only logs over certain diameter can be removed from this forest.

Question 36

Maintaining resources - Education programmes

Answer 36

Many people do not understand food webs and how important it is to protect biodiversity.

Education programmes can help local people understand why they should conserve or sustainably maintain their forests.

Such education can be delivered through, for example, the school curriculum, social media drives or messages from the government.

Question 37

Maintaining resources - Creating protected areas

Answer 37

A ​​protected area is an area of land that is set aside for conservation purposes only.

• Farming, hunting/ removal of plant or animal = illegal in protect areas
• People also not allowed to live in protected areas / heavily restricted.

—> Allows ecosystems to thrive in that area.

Question 38

Maintaining resources - Fish stocks

Answer 38

• Overfishing has led to a massive reduction of fish stocks bc new tech / fishing methods –> fish being removed from sea faster than they can breed.
• Fishing needs to managed to allow stocks to recover to levels that can be maintained.

Ways to conserve fishing stocks….

• Fishers educated on why fishing stocks have to maintained. Increase possibility of them agreeing on quotas etc.
• Closed season during breeding seasons –> allows fish to reproduce optimally. Stops inteference eg. catching females which haven’t laid eggs yet. (closed seasons also limit amount of fish annually caught)
• Protected ocean/water areas –> safe havens in which fish can recover from overfishing –> promotes aquatic biodiversity.
• Fishing quotas (during breeding seasons/breeding grounds) –> banning catching of fish under certain size –> allows young fish to grow + reproduce.
• Controlled mesh in fishing nets –> allows immature fish + non-target fish to escape –> protects breeding cycle. Type of net also regulated. Dragging nets destroy abitats –> leads to reduces biodiversity –> thus banned.
• Monitoring population size + breeding patterns allows authorities to decide which actions need to be taken for conservation.

Question 39

Overfishing

Answer 39

Catching too many fish, causing the population size to decrease.

Question 40

Reasons why animals become endangered / extinct

Answer 40

• Destruction of habitat
• Pollution
• Climate change
• Hunting
• Introduced species
• Overharvesting.

Question 41

Endangerment of species - Climate change

Answer 41

• Condition are fast-changing bc of climate change (eg. floods + drougts/ damage to habitats). If animals cannot adapt to this –> extinction/ endangerment.

Question 42

Endangerment of species - Hunting

Answer 42

• Some tribes kill animals for food (usually hunt sustainable then)
• However people who hunt recreationally/ poachers (kill animals illegally for horns/tusks/ furs) = unsustainable –> enangered species

Question 43

Endangerment of species - Introducing species

Answer 43

• Habitats have delicate balance (food webs) –> hcanges in poplation of one species affect rest of species in ecosystem.
• Introduced species (invasive species) disrupt balance of ecosystem.
• Eg. predator feeding on existing animal/ now competing for resources –> decreases pop. of original species.

Question 44

Overharvesting

Answer 44

Harvesting too high a proportion of a population of animals or plants, causing the population size to decrease.

Question 45

Endangerment of species - Overharvesting

Answer 45

• Overharvesting means taking more of a resource than can be produced again.
• Leads to extinction bc not enough individuals left in area for viable breeding population (eg. Dodo bird)

Question 46

Effect of shrinking populations - Population size and variability

Answer 46

• As population size decrease –> so does genetic variation wihing population.
• Now less alleles expressing different phenotypes –> population less able to adapt to changes in the environment.

Eg. Cheetahs

• Cheetah females usually reproduce with several males per litter so her cubs have several different fathers –> large genetic diversity –> higher chance of good genes –> increases survival rate.
• Shrinking population –> Reduced genetic diverstiy –> population vulnerable to disease now bc if a pathogen affects on individual, it is likely to affec thte whole population due to lack of variability.

Question 47

Conservation programmes - Types

Answer 47

• Monitoring and protecting species and habitats
• Education
• Seed banks
• Captive breeding programmes.

Question 48

Conservation programmes - Monitoring + protecting

Answer 48

• To develop effective conservation programmes, scientists must understand the threats to species and their habitats.

This is done by…

• Monitoring migration routes
• Noting changes in behaviour
• Observing feeding and mating activities
• Recording changes to habitats.
• Once set up, conservation programs require monitoring —> eg. To stop poachers armed rangers used to protect animals in reserve.

Question 49

Conservation programmes - Education

Answer 49

• Education increases people’s awareness and understanding of the species and the role it plays in the habitat.
• Spreading awareness –> more people aware of issue –> Creates global pressure on governments and industries, encouraging them to act in support of nature

Question 50

Conservation programmes - Seed banks

Answer 50

• Selective breeding used in modern agricultural practises to produce plants with specific characteristics –> causes low genetic diversity.
• This means a new disease or pest could wipe out a whole variety or species.
• Seed banks store samples of seeds from many plant species.
• In the case of a species being wiped up –> seeds in seed banks can be used to reintroduce it.
• The biodiversity stored in seed banks also provides resources and breeds that can be used to develop new varieties of plants.
• Seeds are kept at a low temperature and humidity to help preserve them. These facilities are also flood, bomb and radiation proof.

Question 51

Conservation programmes - Captive breeding

Answer 51

• Captive breeding helps to increase the number of individuals in a population.
• Zoos and wildlife sanctuaries play a vital role in captive breeding programmes.
• Programmes require a lot of space and time because it can be difficult to get species to reproduce away from their natural habitat.
• Also seeing rare or exotic animals up close can excite people and encourage them to value these animals –> increases donations to charities etc.
• Captive breeding requires careful monitoring + management bc genetic variation has to be conserved.
• If the population is small, then breeding programmes need to be careful not to breed closely related members.
• It’s not always possible to always move animal from one location to another.
• Captive pair may also not have bonded / male is infertile.

Solution to this include artificial insemination (AI) or in vitro fertilisation (IVF)

Question 52

Captive breeding - Artificial insemination

Answer 52

• First step = obtain a sperm sample from the desired male.
• Semen is then harvested from the sample and transported to the breeding female.
• Semen is artificially inserted into the female’s reproductive tract by a veterinarian.

It is hoped that the sperm then fertilises her eggs, leading to a successful pregnancy.

Question 53

Captive breeding - In vitro fertilisation (IVF)

Answer 53

• In IVF, the sperm from the male and eggs from the female are both extracted.
• Fertilisation is carried out under controlled conditions in a Petri dish in the laboratory.
• Once the egg is fertilised and has started to divide into an embryo, it is inserted into the reproductive tract of a female.
• IVF = useful in cases where female produces healthy eggs but cannot become pregnant by natural methods.
• Likelihood of reproductive success increases bc several embyros can be created in lab.
• Besy of these embryoes –> chosen. (sometimes even embryos are inserted into other females –> resulting in multiple possible pregnancies)

Question 54

Reasons for conservation

Answer 54

Reduces extinction of species

• Once a species is extinct, it cannot come back again.
• Moral responsibility towards these species.
• Also it is likely species may help us in future with medicinal innovations –> important to conserve species.

Increases biodiversity

• Biodiversity is essential for the healthy functioning of all ecosystems on Earth.

Protects ecosystems

• Some environments are particularly vulnerable.
• If they are not protected, this may cause problems for the ecosystem and for ourselves.
• Eg. Sand dunes prevent coastal erosion. If dunes were damaged, buildings and roads close to the sea would be at risk of falling into the sea as a result of coastal erosion.

Maintains important ecosystem functions.

• Conservation preserves ecosystems and the functions they carry out.
• These functions include effective nutrient cycling and providing resources.
• Many of our activities, such as farming, rely on effective nutrient.
• Healthy ecosystems also provide food, fuel and substances which could be developed into useful drugs. eg. marine ecosystems provide seafood.
• Protecting ecosystems protects all organisms within that ecosystem.
• The species they contain may have genes that could provide useful substances, such as novel antibiotics . Many future medicines could be lost if we do not preserve our ecosystems.