Unit 20 - Human influences on ecosystems

Question 1

Impacts of agricultural machinery

Answer 1

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

Question 2

Function of chemical fertilizers

Answer 2

Give nutrients for plants to grow

Question 3

Impact of chemical fertilizers

Answer 3

• Increase crop yields

Question 4

Impact of insecticides

Answer 4

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

Question 5

Impact of herbicides

Answer 5

• Reduces competition for resources between weeds and plants

Question 6

Selective breeding

Answer 6

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

Question 7

Monoculture

Answer 7

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

Question 8

Advantages of intensive farming

Answer 8

• 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

Question 9

Disadvantages of intensive farming

Answer 9

• 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

Question 10

Biodiversity

Answer 10

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

Question 11

Habitat

Answer 11

A place where an organism lives

Question 12

Human activities that lead to habitat destruction

Answer 12

• 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

Question 13

Deforestation

Answer 13

The cutting down of trees in forests

Question 14

Impacts of deforestation

Answer 14

• 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

Question 15

Pollution

Answer 15

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

Question 16

Untreated sewage - source and effects

Answer 16

• 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

Question 17

Fertilizers - source & effects

Answer 17

• Source - runoff from farmland
• Effects - Algal bloom and eutrophication

Question 18

Eutrophication

Answer 18

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

Question 19

Occurrences in eutrophication

Answer 19

• 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

Question 20

Non-biodegradable plastics

Answer 20

Plastics that cannot be digested by bacteria

Question 21

Impacts of non-biodegradable plastics

Answer 21

• 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

Question 22

The Greenhouse effect

Answer 22

A natural process that maintains the temperature range on earth

Question 23

Two main greenhouse gases

Answer 23

Carbon dioxide & methane

Question 24

Sustainable resource

Answer 24

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

Question 25

Non-renewable resources

Answer 25

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

Question 26

Methods of conserving forests

Answer 26

- Setting quotas for logging which can lead to banning - Using education programs - Creating protected areas

Question 27

Solutions to overfishing

Answer 27

- Education - Closed seasons - Protected areas - Quotas - Controlled net types and mesh size - Monitoring

Question 28

Threats to wildlife

Answer 28

- 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

Question 29

Types of conservation programs

Answer 29

- 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

Question 30

Artificial insemination / AI

Answer 30

- 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

Question 31

In vitro fertilization / IVF

Answer 31

- 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

Question 32

Reasons for conservation

Answer 32

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