Ecosystems And Material Cycles

Question 1

Interdependence definition

Answer 1

Organisms depend on each other for things like food and shelter in order to survive and reproduce £ means that a change in the population of one species can have a huge knock on effect for other species in the same community

Question 2

What is mutualism

Answer 2

A relationship between 2 organisms from which both organisms benefit e.g. bees and flowering plants

Question 3

What is parasitism

Answer 3

parasitism, relationship between two species of plants or animals in which one benefits at the expense of the other, sometimes without killing the host organism.

Question 4

What does abiotic mean

Answer 4

Non living

Question 5

What does biotic mean

Answer 5

Living

Question 6

What are 4 abiotic factors that affect communities

Answer 6

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

Question 7

What are 2 biotic factors that affect community

Answer 7

Competition, predation

Question 8

What is a quadrat

Answer 8

A square frame enclosing a known area

Question 9

Steps on how to use a quadrat to study the distribution of small organisms

Answer 9

1) place a 1m(2) quadrat on the ground at a random point within the first sample area - could use a random number generator to make up coordinates of where to place the quadrat
2) count all the organisms you’re interested in within the quadrat
3) repeat steps 1-2 lots of times
4) work out the mean number of organisms per quadrat within the first sample area
5) repeat steps 1-4 in the 2nd sample area
6) compare the 2 means

Question 10

What is a gradient

Answer 10

When abiotic factors change across a habitat

Question 11

What is a belt transect

Answer 11

Quadrat laid out along a line

Question 12

What are the steps to using a belt transect to study distribution along a gradient

Answer 12

1) mark out a line in the area u want to study
2) collect data along the line using quadrats placed next to each other - collect data by counting all the organisms of the species or by estimating percentage cover - estimating the percentage area of a quadrat covered by a particular type of organism
3) u could also record other abiotic factors in each quadrat
4) repeat steps 1 and 2 several times then find the mean number of organisms or mean percentage cover for each quadrat
5) plot graphs to see if the changing abiotic factor is correlated with a change in the distribution of the species you’re studying

Question 13

What are 3 negative human interactions with ecosystems

Answer 13

Eutrophication, fish farming, introduction of non indigenous spices

Question 14

Why is eutrophication a negative human interaction with ecosystems

Answer 14

When nitrates are put onto fields as fertilisers, if too much fertiliser is applied and it rains after, the nitrates find their way into lakes and rivers - eutrophication which can lead to the death of many species in the water reducing biodiversity of the habitat

Question 15

Steps of how fish farming is a negative human interaction with ecosystems

Answer 15

1) food is added to the nets to feed fish - producing huge amounts of waste and the waste can leak into the open water causing eutrophication and the death of wild species
2) fish farms in open water often act as a breeding ground for large numbers of parasites - which can get out and infect wild animals and kill them
3) predators (e.g. sea lions) are attracted to the nets and can become trapped in them and die
4) sometimes farmed fish can escape into the wild which can cause problems for wild populations of indigenous species

Question 16

Why does the introduction of non indigenous species negatively impact biodiversity

Answer 16

Some non indigenous species compete with indigenous species for resources like food and shelter sometimes they are better at getting these things and out-compete the indigenous species which increase in number and eventually die out
Some non indigenous species also bring new diseases to a habitat infecting and killing lots of indigenous species - reducing biodiversity in that habitat

Question 17

What are 2 ways human interaction can help conserve and maintain biodiversity

Answer 17

Reforestation, conservation schemes

Question 18

How does reforestation help

Answer 18

Deforestation reduces biodiversity as many species use trees to provide food and shelter and planting new trees help give species new places to live

Question 19

What are the conservation methods

Answer 19

Protecting a species’ natural habitat - so that they have a place to live, protecting species in safe areas outside of their natural habitat - animals protected in zoos and introducing captive breeding programmes to increase numbers, use of seed banks to store and distribute the seeds of rare and endangered plants

Question 20

What are the 6 benefits of maintaining diversity

Answer 20

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

Question 21

How are materials recycled through biotic and abiotic components of ecosystems

Answer 21

1) living things are made of elements they take from the environment e.g. plants take in carbon and oxygen from the air and nitrogen from soil
2) they turn these elements into the complex compounds (carbs, proteins, fats) that make up living organisms. Elements are passed along food chains when animals eat the plants and each other
3) the elements are recycled - waste products and dead organisms are broken down by decomposers (usually microorganisms) and the elements in them are returned to the soil or air, ready to be taken in by new plants and put back into the food chain

Question 22

Important points about the carbon cycle

Answer 22

1) only one arrow going down from co2 in the air. The whole thing is powered by photosynthesis. Green plants use the carbon from co2 to make carbs, fats, proteins
2) eating passes the carbon compounds in the plant onto animals in a food chain.
3) both plant and animal respiration while the organisms are alive releases co2 back into air
4) plants and animals eventually die and decompose or are killed and turned into useful products
5) when plants and animals decompose they’re broken down by microorganisms such as bacteria and fungi. These decomposers released co2 back into air by respiration as they break down the material
6) some useful plant and animal products e.g. wood and fossil fuels, are burned (combustion). This also released co2 back into air
7) decomposition of materials means that habitats can be maintained for the organisms that live there e.g. nutrients are returned to the soil and waste material such as dead leaves don’t just pile up

Question 23

4 steps of water cycle

Answer 23

1) energy from sun makes water evaporate from land and sea turning it into water vapour, water also evaporates from plants-transpiration
2) the warm water vapour is carried upwards when it gets higher, it cool and condenses to form clouds
3) water falls from the clouds as precipitation onto land, where it provides fresh water for animals and plants
4) it then drains into the sea and the whole process restarts

Question 24

Why is the water cycle important

Answer 24

If it wasn’t for the water cycle recycling water, we’d quickly run out of the stuff and no plants would be able to survive

Question 25

What is desalination

Answer 25

Removes salts from salt water to produce potable water

Question 26

What is thermal desalination (distillation)

Answer 26

Where 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 27

Steps to reverse osmosis as a method of desalination

Answer 27

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

Question 28

How are nitrates made available for plant uptake

Answer 28

Nitrogen in the air has to be turned into mineral ions such as nitrates before plants can use it, plants absorb these mineral ions from the soil and use the nitrogen in them to make proteins, nitrogen is then passed along food chains in the form of proteins, as animals eat plants

Question 29

What do decomposers do

Answer 29

Break down proteins in rotting plants and animals and urea in animal waste, this returns nitrogen to the soil - so the nitrogen in these organisms is recycled

Question 30

How is nitrogen turned into nitrogen contains ions for plants

Answer 30

1) Lightning - there’s so much energy in a bolt of lightning that it’s enough to make nitrogen react with o2 in the air to give nitrates
2) nitrogen-fixing bacteria in roots and soil - turn atmospheric N2 into ammonia, which forms ammonium ions

Question 31

What does nitrifying bacteria do

Answer 31

Turns ammonia in decaying matter into nitrites and then into nitrates

Question 32

What does nitrogen-fixing bacteria do

Answer 32

nitrogen-fixing bacteria in roots and soil - turn atmospheric N2 into ammonia, which forms ammonium ions

Question 33

What does denitrifying bacteria do

Answer 33

Turns nitrates back into nitrogen gas, often found in waterlogged soils.

Question 34

Where do nitrogen fixing bacteria live

Answer 34

In the soil, in nodules on the roots of legume plants (peas and beans)

Question 35

What two ways can farmers increase the amount of nitrates in the soil to help their crops grow better and how

Answer 35

1) crop rotation- instead of growing the same crop in a field year after year, different crops are grown each year in a cycle. The cycle usually includes a nitrogen-fixing crop (peas/beans) which helps put nitrates back into soil for other crops following years
2) fertilisers- spreading animal manure or compost on fields recycles the nutrients left in plant and animal waste and returns them to the soil through decomposition, artificial fertilisers containing nitrates can also be used but can be expensive