Nutrient Cycles

Question 1

Global warming

Answer 1

The increase in average global temperature over the last century.

Question 2

Has global warming been caused by human activity?

Answer 2

Human activity has caused global warming by enhancing the greenhouse effect with carbon dioxide and methane.

Question 3

Greenhouse effect

Answer 3

The effect of greenhouse gases absorbing outgoing energy so that less is lost to space.

Question 4

What is saprobiontic nutrition?

Answer 4

Feeding on dead matter.

Question 5

Describe how carbon is cycled through living organisms and the non living environment. 6 marks.

Answer 5

Carbon from CO2 in the air and water becomes carbon compounds in plants when they photosynthesise.
Carbon is then passed onto primary consumers when they eat the plants and secondary or tertiary consumers when they eat the other organisms.
When organisms die the carbon in the dead organisms is digested by microorganisms called decomposes.
Carbon is returned to the atmosphere as CO2 because all living organisms carry out respiration.
When dead organic matter ends up in a place where there aren’t any decomposers the carbon can be turned into fossil fuels over millions of years.
Carbon in fossil fuels is released back into the atmosphere when fossil fuels are burnt.

Question 6

Explain why atmospheric CO2 and methane concentrations have increased since the mid-19th century. 6 marks

Answer 6

CO2 concentration has increased rapidly since the mid-19th century due to the increased burning of fossil fuels e.g. For cars or industry.
And the increased destruction of natural carbon dioxide sinks.
E.g. By deforestation.

Methane concentration has also been increasing rapidly since the mid-19th century due to things like the increased extraction of fossil fuels.
More decaying waste in landfill sites.
More cattle giving off methane as a waste gas.
Methane can also be released when natural stores, such as frozen ground, thaw.

Question 7

What is global warming? How are rising atmospheric CO2 and methane concentrations causing it? 4 marks

Answer 7

Global warming is the term for the increase in average global temperature over the last century.
Global warming is caused by the enhancement of the greenhouse effect. The greenhouse effect is when atmospheric greenhouse gases absorb outgoing energy so less is lost to space.
The greenhouse effect helps to keep the planet warm, but too much greenhouse gas causes the planet to warm up.
Increasing atmospheric concentrations of the greenhouse gases CO2 and methane are enhancing the greenhouse effect, and so causing global warming.