B9- Ecosystems and Material Cycles

Question 1

What is interdependency?

Answer 1

When organisms in a community depend on each other to survive and reproduce. This means that a change in the population of one species can have huge knock on impacts for other species in the same community

Question 2

What is an abiotic factor?

Answer 2

Non-living factors

Question 3

What is a biotic factor?

Answer 3

Living factors

Question 4

What are some examples of abiotic factors?

Answer 4

Light intensity
Temperature

Question 5

What are some examples of biotic factors?

Answer 5

Competition
Predation

Question 6

What is eutrophication?

Answer 6

Fertilisers enter the water, adding excess nitrates

These excess nitrates cause algae to grow fast and block out the light

Plants can’t photosynthesise due to the lack of light and start to die and decompose

With more food available, microorganisms that feed on decomposing plants increase in number and use up oxygen in the water

Organisms that need oxygen for aerobic respiration die

Question 7

How can we conserve biodivesity?

Answer 7

Reforestation

Conservation schemes

Question 8

What are some conservation schemes?

Answer 8

Protecting a species’ natural habitat

Protecting species in safe areas
outside of their natural habitats and introduce captive breeding programmes to increase their numbers

Question 9

What are the advantages of maintaining biodiversity?

Answer 9

Protecting the human food supply

Ensuring minimal damage to food chains

Providing future medicines

Culture

Ecotourism

Providing new jobs

Question 10

What is food security?

Answer 10

When there is enough food that is safe for us to eat and has the right balance of nutrition

Question 11

What is the role of nitrogen fixing bacteria?

Answer 11

They are in the root nodules of leguminous plants and turn atmospheric nitrogen into ammonia

Question 12

What is the role of nitrifying bacteria?

Answer 12

They turn ammonia into nitrates

Question 13

What is the role of denitrifying bacteria?

Answer 13

They convert nitrates into atmospheric nitrogen

Question 14

How can farmers increase the amount of nitrates in the soil?

Answer 14

Crop rotation with at least one nitrogen-fixing crop

Spreading animal manure or compost on fields recycles the nutrients left in plant and animal water and returns them to the soil through decomposition. Artificial fertilisers containing nitrates can also be used, but these are expensive

Question 15

How can you see the levels of water pollution?

Answer 15

Presence of stonefly larvae and freshwater shrimps are good indicators of water pollution because they are very sensitive to the concentration of dissolved oxygen and indicate clean water.

Presence of blood worms and sludge worms indicate high levels of water pollution as they are adapted to live in these polluted conditions

Question 16

How can you see the levels of air pollution?

Answer 16

Presence of lots of lichen, especially bushy lichen indicate clean air as they are sensitive to the sulphur dioxide concentration. Crusty lichen show less clean air.

Blackspot fungus is also found on rose leaves and its presence indicates clean air as they are sensitive to the sulphur dioxide concentration in the air

Question 17

What factors affect the rate of decay?

Answer 17

Temperature

Water content

Oxygen availability

Question 18

What are some methods of preserving food?

Answer 18

Storing in a fridge in cold temperatures

Storing food in airtight containers

Drying food by removing water

Question 19

What is an individual?

Answer 19

A single organism

Question 20

What is a population?

Answer 20

All the organisms of one species in a habitat

Question 21

What is a community?

Answer 21

All the organisms of different species living in a habitat

Question 22

What is an ecosystem?

Answer 22

A community of organisms along with all the non living conditions

Question 23

What is mutualism?

Answer 23

A relationship between two organisms, from which both organisms benefit

Question 24

What is a parasitic relationship?

Answer 24

The parasite takes what it needs to survive, but the host doesn’t benefit

Question 25

How can you use a quadrat to study the distribution of small organisms?

Answer 25

Place a 1m2 quadrat on the ground at a random point within the first sample area. You should do this by dividing the sample area into a grid and using a random number generator to pick coordinates to place your quadrats at Count all the organisms you're interested in within the quadrat Repeat steps 1 and 2 a lot of times Work out the mean number of organisms per quadrat within the first sample area Repeat steps 1 to 4 in the second sample area Compare the 2 means

Question 26

How can you use a belt transect to study the distribution of small organisms?

Answer 26

Mark out a line in the area you want to study (e.g from the hedge to the middle of the fiels) Then collect data along the line using quadrats placed next to each other. Collect data by counting all the organisms of the species you're interested in repeat steps 1-3 several times then find a mean number of organisms in each quadrat

Question 27

What does a pyramid of biomass show?

Answer 27

How much the creatures at each level of a food chain would weigh if you put them together

Question 28

How does fish farming decrease biodiversity?

Answer 28

Food is added to the nets to feed the fish which produce huge amounts of waste. Both the food and the waste can leak into the open water, causing eutrophication and the death of wild species Fish farms in open water often act as a breeding ground for a large number of parasite Animals can get trapped in the nets Sometimes farmed fish can escape into the wild, which can cause problems for wild populations of indigenous species

Question 29

Why are fish farms in large tanks low in biodiversity?

Answer 29

Often only one species is farmed

Question 30

How can the introduction of non-indigenous species reduce bio-diversity?

Answer 30

Competition Bringing disease

Question 31

What are the 5 stages of the nitrogen cycle?

Answer 31

Nitrogen fixation Nitrification Assimilation Decomposition Denitrification

Question 32

What happens in nitrogen fixation?

Answer 32

Atmospheric nitrogen is converted to nitrates, ammonia in the soil This can happen in two ways: Lightning: directly converts nitrogen into nitrates Nitrogen fixing bacteria: Converts atmospheric nitrogen into ammonia

Question 33

What happens in nitrification?

Answer 33

Ammonia in the soil is converted to nitrites These nitrites are converted to nitrates

Question 34

What happens in assimilation

Answer 34

This is how nitrogen enters the food chain Plants absorb ammonium ions and nitrates and use them to create biological molecules such as proteins

Question 35

What happens in decomposition?

Answer 35

Decomposers feed on the waste excretions of animals. They convert urea and proteins into ammonia

Question 36

Why is decomposition important?

Answer 36

Because ammonia in the soil forms ammonium ions which is one of the few nitrogen containing compounds that plants can absorb

Question 37

What happens in denitrification?

Answer 37

Denitrifying bacteria converts nitrates back into atmospheric nitrogen Means there are fewer nitrates in the soil

Question 38

How can reforestation schemes be optimized in terms of biodiversity?

Answer 38

Replanting a forest with a variety of tree species will result in a higher biodiversity that replanting using only a single type of tree

Question 39

What are 4 examples of biological factors that affect the level of food security

Answer 39

Increasing consumption of meat and fish, and increasing animal farming Environmental changes caused by human activity Sustainability New pests and pathogens

Question 40

Describe the stages of the water cycle

Answer 40

Energy from the sun makes water evaporate from the land and sea, turning it into water vapour Water also evaporates from plants- this is known as transpiration The warm water vapour is carried upwards (as warm air rises) Where it cools and condenses to form clouds Water falls from the clouds as precipitation It then drains into the sea and the process starts again

Question 41

What is a method used to produce potable water during a drought?

Answer 41

Desalination

Question 42

What is desalination?

Answer 42

-Removes salts from salt water

Question 43

What is thermal desalination?

Answer 43

Salt water is boiled in a large enclosed vessel, so that the water evaporates. The steam rises to the top of the vessel, but the salts stay at the bottom. The steam then travels down a pipe from the top of the vessel and condenses back into pure water

Question 44

What is reverse osmosis?

Answer 44

Salt water is first treated to remove solids, before being fed at a very high pressure into a vessel containing a partially permeable membrane The pressure causes the water molecules to move in the opposite direction to osmosis- from a higher salt concentration to a lower salt concentration As the water is forced through the membrane, the salts are left behind, removing them from the water

Question 45

Where does nitrogen fixing bacteria live?

Answer 45

- In the soil - In root nodules on the root of legume plants. When these plants decompose, the nitrogen stored in them and in their nodules is returned to the soil

Question 46

What happens when legume plants containing nitrogen fixing bacteria decompose?

Answer 46

When these plants decompose, the nitrogen stored in them and in their nodules is returned to the soil. Nitrogen containing ions can also leak out of their nodules during pant growth. The plants have a mutualistic relationship with the bacteria. The bacteria get food from the plant and the plant gets nitrogen containing ions from the bacteria to make proteins

Question 47

Describe the relationship between legume plants and nitrogen-fixing bacteria

Answer 47

The plants have a mutualistic relationship with the bacteria. The bacteria get food from the plant and the plant gets nitrogen containing ions from the bacteria to make proteins

Question 48

How can you use indicator species to measure pollution?

Answer 48

- Doing a simple survey to see if a species is present or absent from an area- not good for telling how polluted an area is - Counting the number of times an indicator species occurs in an area will give you a numerical value, allowing you to see roughly how polluted one area is in comparison with another

Question 49

What are some drawbacks to testing pollution with indicator species?

Answer 49

There may also be factors other than pollution playing a role in the presence or absence of a species in an environment

Question 50

What are some examples of non-living indicators to measure pollution?

Answer 50

Dissolved oxygen meters and chemical tests shows the level of water pollution Electronic meters and various laboratory tests are also used to accurately measure the concentration of sulfur dioxide in the air

Question 51

Why do compost bins create the ideal conditions for decomposers?

Answer 51

They have mesh sides to increase oxygen availability The decomposing material is kept moist and heat is generated by the decomposers themselves Some compost bins are insulated to increase temperature