Lecture 7

Question 1

The Carbon Cycle

Summary

In the biosphere

Answer 1

• Photosynthesis removes carbon from the abiotic environment and incorporates it into biological molecules
• Cellular respiration, combustion of fossil fuels and wood, and weathering of limestone returns the carbon to the water and atmosphere of the abiotic environment

Question 2

CO2 concentrations have _____ exponentially over the last 200 years

Answer 2

CO2 concentrations have increased exponentially over the last 200 years

Question 3

CO2 in the atmosphere traps heat and creates the _______________

How?

Answer 3

CO2 in the atmosphere traps heat and creates the greenhouse effect

Incident radiation is absorbed by the earth’s surface and transmitted back to the atmosphere at longer wavelengths

• These longer wavelengths are absorbed by CO2, other greenhouse gases, and water vapour and then converted to heat
• This prevents the radiant energy from escaping from the atmosphere back into space

Question 4

Major greenhouse gases

Answer 4

CO2, CH4 and N2O

Question 5

__% of Bangladesh’s area and __ million of its people live in areas less than 1 m above sea level (asl)

Answer 5

7% of Bangladesh’s area and 6 million of its people live in areas less than 1 m above sea level (asl)