Topic 9

Question 1

Describe individual?

Answer 1

A single organism

Question 2

Describe Population?

Answer 2

All the organisms of one species in a habitat

Question 3

Describe community?

Answer 3

All the organisms of different species living in a habitat

Question 4

Describe ecosystem

Answer 4

A community of organisms along with all the non-living (abiotic) conditions

Question 5

What abiotic factors affect communities?

Answer 5

1. Temperature
2. Amount of water
3. Light intensity
4. Pollutants

Question 6

What biotic factors affect communities?

Answer 6

1. Competition

2. Predation

Question 7

Describe the importance of interdependence in a community?

Answer 7

organisms depend on each other for things like food and shelter in order to survive and reproduce so a change in the population of one species could have a knock on effect for other species in the same community

Question 8

What is mutualism?

Answer 8

Mutualism is a relationship between 2 organisms in which both organisms benefit.

Question 9

What is parasitism?

Answer 9

Parasites live very closely with a host species and benefits from them by taking what it needs. The host doesnt benefit.

Question 10

What is a trophic level?

Answer 10

A trophic level is each stage of a food chain

Question 11

What happens to energy as you go up a biomass pyramid and how does this affect the shape of the pyramid?

Answer 11

Each time you go up a trophic level, the mass of the organisms decreases as energy is lost and so does not become biomass in the next level. This gives a rise to the pyramid shape

Question 12

How do you work out the efficiency of energy transfer?

Answer 12

Efficiency = (energy transferred to next level/ energy available at previous level) *100

Question 13

What is biodiversity?

Answer 13

Biodiversity is the variety of living organisms in an ecosystem

Question 14

How does fish farming reduce biodiversity?

Answer 14

1. Food is added to the nets to feed fish. This can cause waste and therefore eutrophication. This can then cause the death of wild species
2. It can act as a breeding ground for parasites. The parasites can leave the farm and infect wild animals, sometimes killing them
3. Predators may be attracted to the nets, be trapped in them and die
4. Farmed fish that escape into the wild can cause problems for indigenous species

Question 15

How can fish farming be low in biodiversity?

Answer 15

Fish can be farmed in large tanks. These farms are low in biodiversity as they only farm for one species. The tanks are kept free of plants and predators, and any parasites or microorganisms are usually killed

Question 16

How can the introduction of non-indigenous species reduce biodiversity?

Answer 16

1. The non-indigenous species may be better at finding resources to survive than the indigenous species. They may out-compete the indigenous species, who eventually die out
2. They sometimes bring new diseases to a habitat which can kill off the indigenous species

Question 17

How can fertilisers cause eutrophication?

Answer 17

1. Fertilisers enter the water, adding excess nitrates
2. The excess nitrate cause algae to grow fast and blocks out light
3. Plants cant photosynthesise due to lack of light and start to die and decompose
4. Micro-organisms that feed on decomposing plants increase and uses up the oxygen
5. Organisms that need the oxygen for aerobic respiration die

Question 18

How can reforestation increase biodiversity?

Answer 18

Growing lots of different types of trees in an area can provide food and shelter for lots of different animal species

Question 19

describe some conservation methods that can help protect at-risk species?

Answer 19

1- Protecting a species natural habitat
2- Protecting species in safe areas outside of their natural habitat and introducing captive breeding programmes to increase numbers
3- The use of seed banks to store and distribute the seeds of rare and endangered plants

Question 20

What are the benefits of maintaining biodiversity?

Answer 20

1- protecting the human food supply
2- ensuring minimal damage to food chains (protect a species)
3- providing future medicines 
4- Cultural aspects 
5- Ecotourism
6- providing new jobs

Question 21

How does an increase in the population affect food security?

Answer 21

Global food production has to increase so everyone has enough food that will have the right balance of nutrition

Question 22

How can increased animal farming and the consumption of meat and fish affect food security?

Answer 22

1- over fishing could mean there will not be enough fish in the future
2- There’s less energy and less biomass everytime you move up a trophic level so for a given area of land, you can produce a lot more food for humans by growing crops than by grazing animals
(animals and fish being reared are often fed crops that would otherwise be eaten by humans)

Question 23

How can environmental changes caused by human activity affect food security?

Answer 23

• Carbon dioxide, rising temperature, global warming, can affect crop growth, and so reduce yields.

Question 24

How can new pests and pathogens affect food security?

Answer 24

They can damage crops and livestock e.g they can infect crops with diseases that the crops are not resistant against. This reduces crop yield

Question 25

What is sustainability and how does it affect food security?

Answer 25

Sustainability means meeting the needs of todays population without affecting the needs of future populations. - e.g using biofuels instead of crops may make it too expensive for farmers in some areas to continue farming and producing food in the future

Question 26

How do different materials cycle through the abiotic and biotic components of ecosystems?

Answer 26

1- Living things are made of elements they take from the environment e.g. plants take in C/ O from air and N from the soil 2- They turn these elements into complex compounds (carbohydrates, proteins and fats) that make up living organisms. Elements are passed along food chains when animals eat the plants and each other 3- waste products and dead organisms are broken down by decomposers and the elements in them are put back in the soil or air, and the cycle starts over

Question 27

Describe the carbon cycle

Answer 27

1) one arrow downwards from CO2 in air (Photosynthesis to make complex compounds) 2) eating passed the compounds into food chain 3) Both animal and plant respiration releases CO2 back in air 4) Dead organisms are broken down by decomposers which releases CO2 back into air 5) Some useful plant and animal products are burned e.g. wood and fossil fuels, releasing CO2 into air. 6) decomposition of materials means that habitats can be maintained for the organisms that live there e.g nutrients returned to soil

Question 28

Describe the water cycle

Answer 28

1. Evaporation 2. Transpiration 3. condensation 4. precipation

Question 29

When do droughts occur?

Answer 29

Droughts occur when there isnt enough precipitation falling from the sky

Question 30

What is desalination?

Answer 30

Desalination is a method that removes salts (mineral ions) from salt water to make water pure. e.g. thermal desalination

Question 31

How can reverse osmosis be a method of desalination?

Answer 31

1- Salt water is treated to remove solids, before being fed at a high pressure into a vessel containing a partially permeable membrane 2. pressure causes water molecules to move in opposite direction - from high salt conc to a low salt conc 3. as water is forced through membrane , salts are left behind.

Question 32

What are indicator species?

Answer 32

These are species that are very sensitive to change and so therefore can be used to study the effect of human activities

Question 33

What can cause water pollution?

Answer 33

eutrophication

Question 34

What do the presence of freshwater shrimps and stonefly larvae indicate?

Answer 34

Clean water

Question 35

What do the presence of blood worms and sludgeworms indicate?

Answer 35

Dirty water

Question 36

What does bushy and crusty lichen indicate?

Answer 36

Clean air (bushy lichen will most commonly appear in clean air)

Question 37

What does blackspot fungus on roses indicate?

Answer 37

a presence of clean air

Question 38

How can temperate affect the rate of decay?

Answer 38

A warm (not too high) temperature increases the rate of enzyme-controlled reactions

Question 39

How can water content affect the rate of decay?

Answer 39

Decay is faster in moist environments as the organisms involved in decay need water to survive and carry out biological processes

Question 40

How can oxygen availability affect the rate of decay?

Answer 40

The rate of decomposition is faster as organisms need oxygen for aerobic respiration. (some dont need oxygen to respire, but these micro-organisms work slower anyway)

Question 41

How can temperature help preserve food?

Answer 41

Keeping food in the fridge slows down the rate of decomposition

Question 42

How can releasing water content help preserve food?

Answer 42

This removes the water that microorganisms need to survive and reproduce, and so therefore they will not be able to decompose

Question 43

How can storing food in airtight cans preserve food?

Answer 43

It stops micro-organisms from getting in and decomposing the food. The cans are sealed and sterilised after the food is in so that they are killed

Question 44

Describe the nitrogen cycle?

Answer 44

1. Nitrogen is turned into mineral ions, 2. Plants use these ions to make proteins 2. Animals eat the nitrogen in the form of protein 4. Decomposers break down the proteins found in dead animals and urea waste and therefore nitrogen is released back into the atmosphere

Question 45

What is nitrogen fixation?

Answer 45

This is the process of turning N2 from the air into nitrogen containing ions in the soil that plants can use

Question 46

Give two ways that nitrogen fixation can happen?

Answer 46

1) Lightning - theres so much energy in lightning that its enough to make the nitrogen react with oxygen in the air to give nitrates 2) Nitrogen-fixing bactera in roots and soils

Question 47

what are the 4 different types of bacteria that are involved in the nitrogen cycle?

Answer 47

1) decomposers - they decompose proteins and urea and turn them into ammonia. These can form ammonium ions that plants can use 2) Nitrifying bacteria - Turning ammonia in decaying matter into nitrites and then into nitrates 3) Nitrogen-fixing bacteria - Turn atmospheric N2, into ammonia, which forms ammonium ions 4) Denitrifying - Turns nitrates back into N2 gas this is of no benefit to organisms and they are often found in waterlogged soils

Question 48

Where do nitrogen-fixing bacteria live?

Answer 48

Some live in soil whilst others live in nodules on the roots of legume plants. When these plants decompose, the nitrogen stored in nodules is returned to the soil. Nitrogen ions can also leak out of the nodules during growth

Question 49

What is the mutualistic relationship between the plants and the bacteria?

Answer 49

The bacteria get food, and the plant gets nitrogen ions from the bacteria to make proteins

Question 50

What is crop rotation?

Answer 50

Crop rotation is growing different crops each year in a cycle. The cycle usually includes a nitrogen-fixing crop, which helps put nitrates back into the soil for another crop to use the following year

Question 51

What can fertilisers do for the nitrogen cycle?

Answer 51

Spreading manure and compost on fields recycle the nutrients left in plants and animal waste and returns them to the soil through decomposition. Artificial fertilisers that contain nitrates can be used, but these can be expensive

Question 52

What can cause poor crop growth and deficiency diseases?

Answer 52

This happens when the nitrogen content in the soil decreases