human influences on ecosystems (topic 20)

Question 1

what are some methods that humans use to increase food production

Answer 1

agricultural machinery, chemical fertilisers, insecticides, herbicides, selective breeding

Question 2

why is agricultural machinery used

Answer 2

reduces labor cost, time needed to farm, reduces food price, farmers can use more land to produce a greater quantity of food more efficiently,

Question 3

why is chemical fertilisers used

Answer 3

fertiliser is a substance that contains important nutrient for plant growth eg. magnesium and nitrates
they increase yield of crops
natural fertilisers improve soil structure, artificial does not

Question 4

why are insecticides used

Answer 4

Substances used to kill or control the number of unwanted insects. improved quality and yield

Question 5

why are herbicides used

Answer 5

Substances intended to kill weeds and other plant pests. reduce competition with weeds

Question 6

why is selective breeding used

Answer 6

improve production by
crop plants and livestock

Question 7

what are examples of intensive farming methods

Answer 7

monoculture, intensive livestock production

Question 8

monoculture

Answer 8

Growing a single crop across a large area.

Question 9

advantages of intensive farming are

Answer 9

more simple- only one crop considered when preparing soil choosing fertiliser specific herbicides and insecticides can be used

improves efficiency and improves yield- crop or animal grows potimally produced in efficient way, large areas can be used

reduces production cost- farmer works in focused and efficient method costs lower, increases profit for farmer

Question 10

disadvantages of intensive farming

Answer 10

land clearance- deforistation to crop plant, leads to lack of biodiversity

reduced biodiversity- pathogens and insect pasts grow more rapidly more insecticides used which may kill insects which arent pests, reducing food available for other animals

soil damage- heavy machinery used, compacts soil, reducing the amount of water and air it can hold, more difficult for plants to grow, can cause erosion, soil wahsed away by rain, wind or flooding, farmer only plants same plant nutrients used up, more fertilisers used, which can cause erosion

water pollution- water runoff from fields can carry fertilisers and herbicides, isnecticides, harm organisms in water, can cause eutrophication in rivers and lakes

air pollution- animal waste, methane, greenhouse gases,

Question 11

biodiversity

Answer 11

the number of different
species that live in an area

Question 12

what are the reasons for habitat destrcution

Answer 12

increased area for housing, crop plant
production and livestock production
extraction of natural resources (pollution is created by fuels when they are burned
the search for oil or gas damages natural habitats,drilling and mining operations need wells, roads, pipelines and other facilities.)
freshwater and marine pollution

Question 13

how can humans have a negative impact on
habitats

Answer 13

altering food webs and chains

Question 14

what can deforistation lead to

Answer 14

reduced biodiversity
flooding
loss of soil
extinction of species
an increase in carbon dioxide in the atmosphere.

Question 15

how does deforestation lead to reduced biodiversity

Answer 15

As trees in a forest are the primary producers, they are the producers of many food webs. Trees also provide valuable habitats and food for many organisms in the forest. Certain creeping plants depend on the trees for access to sunlight (Figure 1). Without the trees, many food webs would collapse.

Question 16

how does deforistation lead to flooding

Answer 16

trees removed water cycle affected, trees and other vegetation hold soil together, hold water in the ground, no vegetation rain flows directly into rivers and lakes wahses away more of the soil causing floodngs

Question 17

how does deforistation lead to loss of soil

Answer 17

trees and vegetation help keep soil in place, reduce erosion, land cleared protective layer of vegetation lost, soil may then be blown away or washed away

Question 18

how does deforistation lead to increased co2

Answer 18

during photosynthesis co2 is used as reactant, when trees or plants are cut down, this doesnt happen increasing presence of co2 in the atmosphere, also if vegetation cut down is burned this process releases co2

Question 19

pollution

Answer 19

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

Question 20

what are some sources of water pollutants and their effects

Answer 20

untreated sewage- may carry harmful pathogens that cause disease; uses up oxygen when it rots; hormones affect reproduction of some organisms

fertiliser runoffs- causes algal blooms and eutrophication

Question 21

what is the probelm with untreated sewage

Answer 21

causes diseases, skin irritation, as untreated sewage decays, decomposers respire using up oxygen in water, killing aquatic life, may alos cause eutrophication because of releasion of nitrates and phosphates

Question 22

what is the problem with fertilisers

Answer 22

contain mineral ions, help algal blooms to grow rapidly, cover surface of water, stop sunlight from entering, reduce levels of oxygen, aquatic life dies
also stop other producers from photosynthesising, dia and are decomposed by decomposers, carry out aerobic respiration, use up oxygen, killing aquatic life

Question 23

problem with plastic in aquatic life

Answer 23

takes long time to decompose, contribute to low levels of oxygen
non-biodigradbale plasticsstay in enviornment, marine life can ingest blocking digestive system animal starves, or gets tangled in plastic

Question 24

problem with plastic in terrestial life

Answer 24

break down into smaller pieces, exposed to air water and light, form toxic compounds
when plastic breaks down release greenhouse gases
toxins from plastics, can leach soil
animals can also mistakingly eat
burning plastic releases toxins

Question 25

greenhouses gases

Answer 25

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

Question 26

what can contribute to carbon dioxide releasion

Answer 26

burning fossil fuels, producing electricity and deforestation

Question 27

global warming- climate change

Answer 27

However, the additional carbon dioxide and methane is causing an enhanced greenhouse effect. More heat energy is prevented from escaping into space, leading to increases in the average global temperature

Question 28

sustainable resoucre

Answer 28

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

Question 29

non-renewable resource

Answer 29

Something that is being used up faster than it is being formed. eg. fossil fuels

Question 30

what are some areas in the forests important to conserve

Answer 30

the edges of rivers, to promote the retention of water mountain slopes, to reduce erosion areas with rare species and habitats

Question 31

what are some ways to conserve forests

Answer 31

reforestation, 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 32

how do quotas help conserve forests

Answer 32

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

Question 33

how do protected areas help conserve forests

Answer 33

an area of land that is set aside for conservation purposes only. This allows the ecosystems to thrive in that area.

Question 34

how can fish stocks be conserved

Answer 34

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

Question 35

how do closed seasons help conserve fish stocks

Answer 35

breeding season of a fish can be closed to fishing. This allows the fish to reproduce optimally.

Question 36

how do protected areas help conserve fish stocks

Answer 36

aims to provide safe havens for fish populations to recover from prior overfishing. Protected areas also protect aquatic biodiversity, which is essential to all ecosystems.

Question 37

how do quotas help conserve fish stocks

Answer 37

Banning the catching of fish below a certain size maintains the number of young fish so that they can grow and reproduce

Question 38

how do controlled mesh size help conserve fish stocks

Answer 38

Using a bigger size mesh allows immature fish and non-target fish to escape. This protects the breeding cycle of the fish and reduces unintentional catching of other species. The type of net used can also determine which species of fish are more likely to be caught

Question 39

how do monitoring help conserve fish stocks

Answer 39

includes the age at which it reproduces, where it reproduces and the size of its population. Monitoring population size and breeding patterns can also help authorities to decide which actions need to be taken for conservation.

Question 40

state reasons why a species may become endarged

Answer 40

destruction of habitat pollution climate change hunting introduced species overharvesting.

Question 41

correlation between population size and variation

Answer 41

As the size of a population decreases, genetic variation within the population is also reduced fewer different alleles expressing different phenotypes, so the population is less able to adapt to changes in the environment. more vulnerable to diseases.

Question 42

how can Endangered species be conserved

Answer 42

monitoring and protecting species and habitats education seed banks captive breeding programmes.

Question 43

explain monitoring and protecting species

Answer 43

monitor migration routes note changes in behaviour observe feeding and mating activities record changes to habitats.

Question 44

explain education

Answer 44

education helps to increase local people’s awareness and understanding of the species and the role it plays in the habitat.

Question 45

explain seedbanks

Answer 45

Seed banks store samples of seeds from many plant species 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

Question 46

explain captive breeding

Answer 46

Conservation of endangered species by planned breeding of animals that are held in zoos and wildlife parks. helps to increase the number of individuals in a population

Question 47

Describe the reasons for conservation programmes

Answer 47

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

Question 48

explain reproduction in captivity

Answer 48

Breeding animals in captivity requires a lot of management and careful monitoring If the wild population is small, then breeding programmes need to be careful not to breed closely related members. It is important to maintain genetic variation not always feasible or desirable to physically move an animal from one location to another

Question 49

explain artificial insemmination

Answer 49

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

Question 50

explain in vitro fertilisation

Answer 50

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.