human impact on the environment

Question 1

outline the potential causes for the extinction of a species

Answer 1

• natural selection
• loss of habitat
• pollution
• overhunting
• new competitors
• non-contiguous populations

Question 2

what is meant by conservation

Answer 2

maintenance of ecosystems and biodiversity by humans to preserve Earth’s resources

Question 3

how can conservation be achieved

Answer 3

• protection of habitats
• protection of endangered species
• international cooperation
• species reintroduction
• gene and sperm banks
• seed banks

Question 4

define what is meant by biodiversity

Answer 4

number of species and number of individuals in each species in a specified region

Question 5

define what is meant by extinction

Answer 5

natural process where species reproduce less successfully and population numbers decrease until there are none left

Question 6

give an explanation for natural selection causing extinction

Answer 6

existing species don’t have the ability to survive in a changing environment

Question 7

why does deforestation cause extinction

Answer 7

habitat destruction
reduced food availability
increased risk of predation

Question 8

why does habitat destruction cause extinction

Answer 8

reduces population sizes so reproduction is less successful

Question 9

why does loss of hedgerows cause extinction

Answer 9

mammals unable to move from one area to another safely

Question 10

why does pollution cause extinction

Answer 10

• neurotoxins can be ingested in food
• oil leaks contaminate drinking water
• oil floats and prevents oxidation

Question 11

why does competition from domestic animals cause extinction

Answer 11

species that is less well adapted may get fewer resources that both species need

Question 12

why does hunting and collecting cause extinction

Answer 12

overfishing
animals killed for food
use of animal body parts

Question 13

what does SSSI stand for

Answer 13

sites of special scientific interest

Question 14

how do nature reserves and SSSI’s enhance biodiversity

Answer 14

many animals and plants survive through symbiotic or predatory relationships with other species

Question 15

how do restrictions on trade enhance biodiversity

Answer 15

reduces impact of transport and pollution
no introduction of pathogens and invasive species

Question 16

how do zoo breeding programmes enhance biodiversity

Answer 16

gene diversity can be increased by deliberate choice of parents

Question 17

how do sperm banks / seed banks enhance biodiversity

Answer 17

• rather than moving animals, sperm can be sent around the world to be used in breeding programmes
• plants grown reproduce and another generation of seeds is collected

Question 18

how to reintroductions enhance biodiversity

Answer 18

increase number of species or places where species can be found

Question 19

outline why conservation of species is important

Answer 19

• ethical reasons
• agriculture and horticulture
• if environment changes, some alleles will provide an advantage to the individuals that carry them
• potential medical uses

Question 20

how do pesticides increase production

Answer 20

• insecticides kill pests that eat and damage crops
• herbicides kill weeds that cause competition for crops

Question 21

what effects do pesticides have on the environment

Answer 21

contamination of surrounding soil and water sources, causing loss of biodiversity

Question 22

how do artificial fertilisers increase production

Answer 22

replaces minerals lost from agricultural ecosystems ensuring yields remain high

Question 23

what effects do artificial fertilisers have on the environment

Answer 23

chemical fertilisers can leach out into nearby waterways causing eutrophication

Question 24

how does removal of hedges increase production

Answer 24

makes land easier and cheaper to work

Question 25

how does monoculture increase production

Answer 25

increased use of machinery and decreased labour costs mean continuous cropping of one crop bring greater economic returns per unit area of land

Question 26

what effects does monoculture have on the environment

Answer 26

reduces species and genetic diversity of all plants and also animals because there are fewer niches available

Question 27

outline the reasons for deforestation

Answer 27

- timber used for building, fuel, paper - land cleared for farming - high value trees may be targeted and damage other trees in the process - new roads built

Question 28

outline the consequences of deforestation

Answer 28

- soil erosion as roots bind soil together - causes lowland flooding - no plants left and water evaporates from the soil - less rainfall as no water to evaporate from the soil - habitat loss and reduction in biodiversity - reduces removal of CO2 from the atmosphere

Question 29

explain coppicing

Answer 29

- tree trunk cut leaving stool - new shoots emerge and form poles which can be cut in rotation - increases woodland biodiversity as more light can reach the ground

Question 30

explain selective cutting

Answer 30

- felling only some trees - valuable on steep slopes as reduces soil erosion - helps maintain nutrients in forest soil - minimises amount of soil washed into nearby waterways

Question 31

explain long rotation time as a method to manage forests

Answer 31

- many years left between harvesting adjacent areas of forest - increases sustainability - develops a variety of habitats

Question 32

what steps can be taken to improve the efficiency of forestry

Answer 32

- plant trees optimum distance apart to reduce intra-specific competition - control pests and disease so fewer trees need to be felled - cut similar number of trees each year to maintain forest ecosystem

Question 33

why is the preservation of native woodlands so important

Answer 33

- maintain and enhance biodiversity - there is a need to plant more native species to provide a wide range of habitats for the great variety of species that live there

Question 34

explain how overfishing has led to a loss of biodiversity

Answer 34

- young fish caught before they are sexually mature so fewer individuals to reproduce

Question 35

name the strategies to combat over-fishing

Answer 35

- exclusion zones - removing subsidies - quotas - reducing vessels - reducing fishing time - controlling mesh size

Question 36

outline the advantages of exclusion zones

Answer 36

- allows fish to reproduce - enhances biodiversity

Question 37

outline the disadvantages of exclusion zones

Answer 37

local fisherman lose income

Question 38

outline the advantages of removing subsidies

Answer 38

would stop encouraging fishermen to catch fish

Question 39

outline the disadvantages of removing subsidies

Answer 39

fishermen lose income and jobs

Question 40

outline the disadvantage of quotas

Answer 40

some fish thrown back when quota is met

Question 41

what is meant by a fishing quota

Answer 41

set number of fish allowed to be brought back to shore

Question 42

why are diseases common on fish farms and why do treatments lead to environmental problems

Answer 42

- fish kept packed together so diseases easily transmitted - huge doses of antibiotics needed - pesticides toxic to other organisms

Question 43

outline the negative effects of fish farming on the environment

Answer 43

- pollution - escaped fish - may outcompete wild fish - resource use - fishfeed made from other fish - environmental toxins released - environmental degredation - salinisation of soil and ground water

Question 44

name the positive benefits of fish farming

Answer 44

- food security - employment - affordable