1. 1.2 Nutrient Cycles and Energy Flow
Answers to Reading Assignment
Pgs

2. 1. From where do plants obtain the carbon that is needed for their growth?
Plants obtain the carbon they need for growth from Carbon dioxide in the atmosphere.
Only 0.04% of all gases in the atmosphere is Carbon dioxide.

3. 2a) What is a biotic reservoir
A biotic reservoir is a living thing that has an accumulation of a type of matter (e.g. carbon).

4. 2b) Why are forests considered to be biotic reservoirs?
The world’s forests are biotic reservoirs of carbon because a large portion of the matter in the trees is made of carbon (about 50%).
The carbon making the structure of the tree remains in the tree until it dies. It is then burned or decomposes – both of which are processes that release carbon dioxide into the air

5. 3a) There are abiotic reservoirs of carbon found under the surface of the ground. In what form is this carbon found?
The huge carbon reservoirs underground are locked up in deposits of coal, which are pure carbon, oil and natural gas.

6. 3b) These abiotic reservoirs were formed from biotic factors
3b) These abiotic reservoirs were formed from biotic factors. Explain how this occurred.
The deposits form from dead organisms. The remains compacted over hundreds of millions of years.

7. 4. Oceans can also be carbon reservoirs. Explain how.
Carbon dioxide dissolves in water.
Marine organisms use the carbon from the dissolved carbon dioxide to build their tissues (e.g. shells).
When the organisms die, their carbon compacts over time to make fossil fuels.
Oceans contain more CO2 than the atmosphere.

8. Pg.28 5. What is chlorophyll and how is it important for plants?
Chlorophyll captures the sun’s rays and causes plant leaves to be green.
Plants use chlorophyll to capture the energy in sunlight and convert it into chemical energy (photosynthesis).

9. 6a) What is photosynthesis?
Photosynthesis is the process of producing carbohydrates (glucose – a usable chemical energy for cells) from carbon dioxide, water and sunlight.

10. 6b) Write the chemical equation for photosynthesis, pg. 28
Carbon dioxide + water + sunlight → glucose + oxygen

11. 6c) Where do the reactants of the photosynthesis reaction come from?
The light comes from the sun
Carbon dioxide comes from the atmosphere, or is dissolved in ocean/pond water
The water comes from the soil (absorbed by roots of plant) or the ocean/pond itself.

12. 6d) How does the plant use the products of photosynthesis?
The plant uses the glucose and the oxygen for the processes in its cells.
The process is CELLULAR RESPIRATION

13. 7. Give two reasons why photosynthesis is an important process for organisms other than plants.
The plant releases oxygen gas into the atmosphere. The oxygen is needed by most organisms to breathe to stay alive.
The glucose in plants provides food for organisms in the food chain.

14. 8a. What is cellular respiration?
Cellular respiration is the process that cells (plant and animal) use to obtain energy from glucose.

15. 8b) Write the chemical equation for cellular respiration given on pg
glucose + oxygen → carbon dioxide + water + energy

16. 9. How are photosynthesis and cellular respiration related?
The products of photosynthesis, glucose and oxygen gas, are the requirements for cellular respiration.
Therefore they are complementary to each other.
( Photosynthesis makes what cellular respiration needs)

17. 10. Why are the processes of photosynthesis and cellular respiration important to the carbon cycle?
Photosynthesis removes CO2 from the abiotic environment for use in biotic organisms.
Cellular respiration releases CO2 into the abiotic environment by biotic organisms.
These processes link the biotic and abiotic parts of an ecosystem.

18. 11. How do the actions of humans affect the cycling of carbon in the environment?
Cut down forests – remove large plants that take CO2 out of the air (CO2 levels go up)
2. Burn fossil fuels – releases carbon from abiotic reservoirs at high rates (CO2 levels go up)
3. Replanting trees – replaces lost plants and ensures that the number of trees gets replenished (takes CO2 levels down)

19. Carbon Cycle