Topic 9: ecosystems, relationships,food security and more

Question 1

What factors affect food security?

Answer 1

• New pests and pathogens affecting farming
• Increasing human population
• Changing diets in developed countries –scarce food resources transported around world
• Environmental changes affect food production
• new pathogens/pests

Question 2

What is a detritivor?

Answer 2

an animal which feeds on dead organic material, especially plant detritus

Question 3

What is a decomposer?

Answer 3

Decomposers are organisms that break down dead or decaying organisms

Question 4

What 3 factors affect the rate of decay?

Answer 4

• Heat
• Oxygen
• Water

Question 5

How do people prevent Food from decaying or rotting?

Answer 5

Preservation by:

• canning(heated and sealed killin’ bacteria)
• cooling or chilling
• drying (removes water so bacteria cant survive)
• salt/sugar(removes water)
• Adding vinegar(changes PH so reactions cant occur)

Question 6

How does adding salt or sugar preserve food?

Answer 6

removes water via osmosis

Question 7

Why does adding vinegar preserve food?

Answer 7

Changes PH so reactions cant occur

Question 8

Why is compost useful for gardeners?

Answer 8

It has been decayed into a form easier for plants to absorb the nutrients

Question 9

What is the equation for rate of decomposition?

Answer 9

mass lost/number of days

can use triangle

Question 10

What is potable water?

Answer 10

Water that is safe to drink and free from dirt, pathogens and harmful bacteria

Question 11

What Is the carbon cycle?

Answer 11

All animals and living things contain carbon and the carbon is passed about in a cycle. Animals that respire also give carbon to the atmosphere by respiration and to the ground when they die. Plants that photosynthesise take in carbon from the air. This Is basically the carbon cycle.

Question 12

What is the nitrogen cycle?

Answer 12

1) Nitrogen gas is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules.
2) Plants absorb nitrates from the soil and use these to build up proteins. The plant may be eaten by an animal.
3) Dead plant broken down by decomposers. This results in nitrogen being returned to the soil as ammonia.
4) denitrifying bacteria in the soil break down nitrates and return nitrogen to the air.

Question 13

What is a carbon sink?

Answer 13

Carbon sinks absorb carbon dioxide from the atmosphere.

Question 14

What is a carbon source?

Answer 14

Carbon sources release carbon dioxide into the atmosphere.

Question 15

How do people protect biodiversity?

Answer 15

There are conservation methods:

• legal protection stopping hunting
• artificial ecosystems
• educating
• zoos and seedbanks

Question 16

Equation for efficiency

Answer 16

Efficiency = energy used for growth(output) /energy supplied (input) x100

Question 17

What is eutrophication and effect?

Answer 17

excessive richness of nutrients in a lake, due to run-off fertiliser, which causes a dense growth of plant life which blocks of sunlight and increases amount of bacteria which starves the lake of oxygen so fish die.

Question 18

How do we measure the level of pollution in an area?

Answer 18

we use an indicator species such as lichen.

Polluted water can be determined by the type of larvae.

Question 19

What is the equation for working out population size?

Answer 19

no. in sample (inside quadrat) x totals size of area/total size in sample(inside quadrat)

Question 20

What is an example of a mutualistic relationship?

Answer 20

The hermit crab and an anemone which protects the crab and the hermit crab move to areas rich in nutrients

Question 21

What is an example of a parasitic relationship?

Answer 21

cordyceps fungi spreads its spores onto insects and causes them to move up to a high area so the spores can grow out of the ant and have lots of light

Question 22

How do you calculate the percentage of wasted energy?(efficiency)

Answer 22

energy lost/energy gained x 100

Question 23

How to calculate species abundance

Answer 23

population of species/total population

Question 24

What do nitrifying bacteria do?

Answer 24

turn ammonium in the soil into nitrates

Question 25

What do denitrifying bacteria do?

Answer 25

Turns ammonium in the soil into nitrogen gas

Question 26

What do nitrogen fixing bacteria do?

Answer 26

absorb nitrogen gas and turn it into nitrates in the soil