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Biology IGCSE > Unit 20 - Human influences on ecosystems > Flashcards

Unit 20 - Human influences on ecosystems Flashcards

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1
Q

Impacts of agricultural machinery

A
  • Reduces labor costs
  • Reduces food prices
  • More land mass can be used
  • Greater quantities of food can be made more efficiently
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2
Q

Function of chemical fertilizers

A

Give nutrients for plants to grow

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3
Q

Impact of chemical fertilizers

A
  • Increase crop yields
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4
Q

Impact of insecticides

A
  • Kill insects
  • Protect crops from damage - improve yield and quality
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5
Q

Impact of herbicides

A
  • Reduces competition for resources between weeds and plants
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6
Q

Selective breeding

A

Humans selecting individual animals or plants with desirable features, crossing them to produce the next generation

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7
Q

Monoculture

A

Growing only one variety of crop in an area at a given time

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8
Q

Advantages of intensive farming

A
  • Simplicity - tailored to one crop
  • Higher yields - more efficient because crops grow optimally
  • Reduced costs - Costs of production are lowered and then cost of produce as well
  • Larger land and machinery - large areas of land can be used and hence machinery to increase efficiency
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9
Q

Disadvantages of intensive farming

A
  • Land clearance - deforestation & destroying habitats of native species
  • Reduced biodiversity - pathogens and pests spread more quickly, more substances like insecticides need to be used - not enough food for animals and damages the food web
  • Soil damage - machinery can compact soil making it harder for plants to grow - land is vulnerable to erosion after nutrients are depleted
  • Water pollution - water runoff can be contaminated and hurt organisms
  • Air pollution - animal waste pollutes
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10
Q

Biodiversity

A

The diversity or variety of living organisms in a certain habitat or ecosystem

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11
Q

Habitat

A

A place where an organism lives

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12
Q

Human activities that lead to habitat destruction

A
  • Increased use of land - Natural habitats are destroyed for crops ad farming due to more need for food with a higher population
  • Extraction of natural resources - pollution from fuels burning, damaging habitats while searching for resources, facilities needed
  • Water pollution - oil spills, untreated sewage, careless trash disposal, mining waste, nitrates from fertilizers, herbicides & pesticides, metal runoff
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13
Q

Deforestation

A

The cutting down of trees in forests

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14
Q

Impacts of deforestation

A
  • Reduced biodiversity - many food webs collapse without trees
  • Flooding - rain flows directly into rivers and lakes because no vegetation restricts water flow + soil washes away
  • Loss of soil - protective vegetation is lost and soil can be eroded
  • Species extinction - species migrating due to habitat destruction can go extinct and slow-growing plants can
  • Increased carbon dioxide - less photosynthesis so the concentration of carbon dioxide in the atmosphere increases
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15
Q

Pollution

A

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

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16
Q

Untreated sewage - source and effects

A
  • Source - human and animal waste released without passing through sewage treatment plants
  • Effects - Can contain harmful pathogens that cause disease, oxygen used by decomposers when rotting, hormones can affect organisms, eutrophication
17
Q

Fertilizers - source & effects

A
  • Source - runoff from farmland
  • Effects - Algal bloom and eutrophication
18
Q

Eutrophication

A

A process in which additional nitrate and other ions in water lead to the death of aquatic organisms

19
Q

Occurrences in eutrophication

A
  • Increased nitrate concentration in water
  • algae grows to algal bloom that blocks sunlight from the surface of the water
  • Aquatic plants can’t carry out photosynthesis
  • Plants die and are decomposed by decomposers that carry out aerobic respiration
  • Fish and other organisms die because oxygen is used up by decomposers
20
Q

Non-biodegradable plastics

A

Plastics that cannot be digested by bacteria

21
Q

Impacts of non-biodegradable plastics

A
  • Long-term exposure to air, water & light can make toxic compounds
  • When broken down, greenhouse gases release
  • Toxins can leach in soil and pollute water sources
  • Animals eating plastic
  • Burning leads to emissions
  • Animals can be entangled
22
Q

The Greenhouse effect

A

A natural process that maintains the temperature range on earth

23
Q

Two main greenhouse gases

A

Carbon dioxide & methane

24
Q

Sustainable resource

A

Something that is produced as rapidly as it is removed from the environment

25
Q

Non-renewable resources

A

Resources that are being used up faster than they are being formed

26
Q

Methods of conserving forests

A
  • Setting quotas for logging which can lead to banning
  • Using education programs
  • Creating protected areas
27
Q

Solutions to overfishing

A
  • Education
  • Closed seasons
  • Protected areas
  • Quotas
  • Controlled net types and mesh size
  • Monitoring
28
Q

Threats to wildlife

A
  • Climate change - sudden changes which species might not be able to adapt to
  • Hunting - killing specific animals
  • Introduced species - can disrupt the balance of the ecosystem
  • Over-harvesting - can lead to extinction
29
Q

Types of conservation programs

A
  • Monitoring and protecting - routes, behavior, feeding, mating and habitat changed can be recorded
  • Education - educating people and raising awareness and understanding
  • Seed banks - storing samples of seeds from many plant species
  • Captive breeding - can increase number of individuals in a population - often done in zoos or sanctuaries
30
Q

Artificial insemination / AI

A
  • Obtaining sperm from a desired male
  • Semen is harvested and transported to a breeding female
  • Semen is artificially inserted into the female’s reproductive tract
31
Q

In vitro fertilization / IVF

A
  • Sperm from the male and eggs from the female are both extracted
  • Fertilization is carried out under controlled conditions in a Petri dish
  • Once the egg has divided into an embryo, it is inserted into the reproductive tract of a female
32
Q

Reasons for conservation

A
  • Reducing extinction of species
  • Increasing biodiversity
  • Protecting vulnerable ecosystems
  • Maintaining important ecosystem functions

Biology IGCSE (21 decks)

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