SB9 Ecosystems and Material Cycles

Question 1

List abiotic factors

Answer 1

temperature, amount of water, light intensity, levels of pollutants

Question 2

List biotic factors

Answer 2

competition, predation

Question 3

Define mutualism

Answer 3

a relationship between two organisms from which both benefit

Question 4

Define interdependence

Answer 4

organisms depending on each other for food and shelter in order to survive and reproduce

Question 5

Describe the use of quadrats

Answer 5

A quadrat is a square frame enclosing a known area

Question 6

What are the energy transfers that occur between trophic levels?

Answer 6

The sun is the source of energy - plants convert light energy into glucose - a primary consumer eats the plant - a secondary consumer eats the animal

Less energy is transferred for each trophic level and the mass of organisms goes down as you go up levels

Question 7

Why are food chains only so long?

Answer 7

Each time you go up a level, the mass an therefore biomass decreases, so you would have to consume a lot to make it efficient

Question 8

Formula for efficiency between trophic levels

Answer 8

energy transferred to next level / energy available at previous level X 100

Question 9

Explain how communities are affected by abiotic factors

Answer 9

Population sizes will increase and decrease depending on the factors affecting their habitat conditions

Question 10

How do you use belt transects to study distribution along a gradient?

Answer 10

Mark a line and place quadrats on this line at regular intervals. Collect the data and find the percentage coverage in the quadrats and compare results across thegradient

Question 11

Define the biotic factor : predation

Answer 11

the more predators there are, the less prey there will be

Question 12

Define the biotic factor : competition

Answer 12

organisms compete against each other for the same resources

Question 13

Define the abiotic factor : temperature

Answer 13

eg. distribution of bird species in Germany is changing due to rise of avg. temperature

Question 14

Define the abiotic factor : amount of water

Answer 14

eg. daisies grow best in slightly damp soils. If soil becomes too dry or waterlogged, the population will decrease

Question 15

Define the abiotic factor : light intensity

Answer 15

eg. as trees grow and provide more shade, grasses may be replaced by fungi which are better to cope in low light intensity

Question 16

Define the abiotic factor : levels of pollutants

Answer 16

eg. lichen are able to survive if the concentration of sulfur dioxide is too high

Question 17

Define parasitism

Answer 17

a relationship between two species where only one benefits

Question 18

Give examples of parasites and mutualists

Answer 18

Parasites - fleas

Mutualists - bees visiting flowers and pollinating them

Question 19

Define eutrophication

Answer 19

An excess of nutrients in water due to too much nitrates and fertilisers added, which can lead to the death of many species

Question 20

Disadvantages to non-indigenous species

Answer 20

• Can compete with indigenous species over resources

- Brings new diseases that indigenous species may not be immune to

Question 21

Disadvantages of fish farming

Answer 21

• huge amounts of waste
• breeding ground for parasites
• predators (eg. sea lions) are attracted to nets and become trapped in them and die
• farmed fish can escape into the wild, and harm indigenous species

Question 22

Define conservation and give examples

Answer 22

Conservation schemes can protect biodiversity by preventing species from dying out eg. protecting a species’ natural habitats, using seed banks to store seeds, introducing captive breeding programmes

Question 23

Define reforestation

Answer 23

When land where forest previously stood is replanted to form a new forest

Question 24

Benefits to maintaining biodiversity

Answer 24

• protecting the human food supply
• ensuring minimal damage to food chains
• providing future medicines
• cultural aspects
• ecotourism
• providing new jobs

Question 25

Define food security

Answer 25

Access to enough food that is safe for us to eat with the right balance of nutrition

Question 26

How is increasing consumption of meat and fish, and increasing animal farming affecting food security?

Answer 26

As people become wealthier, people eat meats and fish that are higher up in the food chain. These have less biomass, and therefore more of it is needed to produce the same amount of food as crops. You risk over-fishing

Question 27

How is sustainability affecting food security?

Answer 27

Sustainability means meeting the needs of today’s population without affecting the ability of future generations to meet their needs

Question 28

How is environmental changed affecting food security?

Answer 28

Burning fossil fuels releases lots of CO2, causing global warming. Climate change affects the growth of crops, which could reduce yields

Question 29

How are new pests and pathogens affecting food security?

Answer 29

Pests and pathogens can cause damage to crops and livestock

Question 30

How is food preserved?

Answer 30

• Storing foods in a fridge or freezer lowers temp. of food, and slows down decomposition
• Airtight cans stops microorganisms getting in
• Drying food removes water needed for bacteria to grow and survive on the food

Question 31

How is compost made?

Answer 31

by decomposed organic matter that is then used as a fertiliser for crops and garden plants

Question 32

How does temperature affect the rate of decay?

Answer 32

A warm temp. speeds up the rate of enzyme-controlled reactions in microbes, so decay happens faster

Question 33

How does water content affect the rate of decay?

Answer 33

Decay takes place faster in moist environments as the organisms involved in decay need water to survive

Question 34

How does oxygen availability affect the rate of decay?

Answer 34

Decomposition is faster where there is plenty of O2 available as there is O2 for the microorganisms to respire with

Question 35

Name some indicator species

Answer 35

• Stonefly larvae = clean water
• Blood worms / sludge worms = polluted water
• Lichen = clean air
• Blackspot fungus = clean air

Question 36

Disadvantages to indicator species

Answer 36

Don’t give accurate figures for how much pollution is present, and there may be other factors impacting absence/presence of species

Question 37

Indicator species for water pollution

Answer 37

• Stonefly larvae / freshwater shrimps are sensitive to concentration of dissolved oxygen in the water
• Blood worms / sludge worms indicate a very high level of water pollutant as they only live in polluted conditions

Question 38

Indicator species for air pollution

Answer 38

• Lichen are sensitive to concentration of sulfur dioxide

- Blackspot fungus is found on rose leaves in clean air