7. People and the Biosphere: Role of the Biosphere

Question 1

What does the biosphere do

Answer 1

Biosphere helps to control the proportion of different gases in the atmosphere

Plants : take in carbon dioxide and give out oxygen - photosynthesis
Animals : take in oxygen and give out carbon dioxide

Question 2

Why is maintaining the balance of gases in the atmosphere important

Answer 2

Living organisms need oxygen to survive
Increased levels of CO2 lead to global warming
Increased levels of CO2 - also make oceans acidic - affects the organisms that live there
Some CO2 - needed to keep earth warm enough to support life

Question 3

The biosphere keeping the soil healthy

Answer 3

Plant roots and animals spread nutrients through the soil - helps maintain soil structure and fertility - allows plants to grow
Roots of vegetation also hold the soil together - without this, soil van be eroded by wind and rain
Vegetation intercepts rainfall - helps prevent leaching - where nutrients in soil washed downwards out of reach of plants

Question 4

The biosphere regulating the water cycle

Answer 4

The water cycle is the movement of water between land, bodies of water and the atmosphere

Water is taken up by plants - less of it reaches rivers - helps prevent flooding and soil erosion
Plants also regulate the global water cycle - storing and releasing water into the atmosphere slowly