Chemical Environment

Question 1

Water cycle (4)

Answer 1

1) Energy from the sun evaporates water from the land and sea, forming water vapour. Water vapour is also lost from plants via transpiration
2) Warm water vapour rises in the atmosphere where it cools and condenses to for clouds
3) Water falls from clouds as precipitation, supplying fresh water for animals and plants
4) Water drains back into the sea through soil and rocks via percolation

Question 2

Water cycle reservoirs

Answer 2

Oceans - 97%
Glaciers and Polar Ice caps - 2%
Lakes, Rivers and Ground water - 1%

Question 3

Carbon cycle (5)

Answer 3

1) Whole cycle is powered by photosynthesis. Plants use CO2 from the atmosphere to produce carbohydrates, lipids and proteins
2) Consumption passes carbon compounds from plants to animals in a food chain
3) Plants and animals respire, which releases CO2 back into the atmosphere - largely equal to photosynthesis
4) When plants and animals die, their carbon compounds enter the soil
5) Dead plants and animals decompose (broken down by microorganisms), the decomposers release CO2 into the atmosphere via respiration

Question 4

Carbon cycle reservoirs

Answer 4

Plant/Animal biomass
Soils
Dissolved in oceans, atmosphere, fossil fuels

Question 5

Phosphorus cycle (5)

Answer 5

1) Weathering of rocks releases phosphorus containing compounds from the soil
2) Some can leach into groundwater and may reach the sea
3) Plants uptake phosphorus from the soil and animals consume those plants and each other, passing phosphorus through the food chain
4) Phosphorus returns to the soil/sediment via excretion or decomposition
5) Sediment from lakes and oceans form new rocks - the new rocks can be moved by geological uplift, if they are moved above sea level, phosphorus can be released via weathering

Question 6

Phosphorus cycle reservoirs

Answer 6

Sedimentary rocks
Soil
Oceans
Animal/plant biomass

Question 7

Nitrogen cycle key processes

Answer 7

Nitrogen fixation
Consumption
Agricultural runoff
Denitrification