Recycling Through Ecosystems

Question 1

What is decomposition?

Answer 1

Chemical process by which a compound is broken down into smaller molecules, or it’s constituent elements. Often an essential element, like nitrogen or carbon, cannot be used directly by an organism in the organic form that it is in, in dead or waste matter. It must be processed into its inorganic elements and compounds which are more usable, and returned to the environment

Question 2

What is a decimposer

Answer 2

An organisms that feeds on and breaks down dead plant or animal matter, thus turning the organic compounds into inorganic ones, which are available to photosynthetic produces in the ecosystem to use. Decomposers are mainly microscopic fungi and bacteria, but can include larger fungi such as toadstools and bracket fungi

Question 3

Decomposers are saprotrophs, why is this important?

Answer 3

They obtain their energy from dead or waste organic material. They digest their food externally by secreting enzymes into dead organisms or organic waste matter. These enzymes break down the complex molecules into simpler ones. The decomposers absorb these simpler molecules. Through this process, decomposers release stored inorganic elements and compounds back into the environment

Question 4

What are detritivores

Answer 4

Another class of organisms involved in decomposition. They help speed up decay process by feeding on dead and decaying material. They break it down into smaller pieces of organic material, increasing the surface area for decomposers to work on. Detritivores internally digest. Some include woodlice, which break down wood

Question 5

The role of nitrogen in the ecosystem

Answer 5

Nitrogen is an essential element in the production of amino acids, and therefore proteins, and nucleic acids in both plants and animals. Animals obtain the nitrogen they need from he food they eat, but plants have to take it in from the environment.

Question 6

What is the problem with plants and nitrogen gas

Answer 6

Plants need to take in the nitrogen from the environment. 78% of the air is nitrogen gas. However plants can’t use it in this form. In order to be used, the nitrogen needs to be combined with other elements such as oxygen or hydrogen. This is nitrogen fixing and bacteria have a very important role in converting this nitrogen gas into a useable form. Without bacteria, nitrogen would quickly become a limiting factor in an ecosystem

Question 7

What are some nitrogen fixing bacteria and what do they do?

Answer 7

Azotobacter and Rhizobium both have the enzyme nitrogenase, which combines atmospheric nitrogen with hydrogen to produce ammonia - a form of nitrogen that can be absorbed and used by plants. This is nitrogen fixation.

Question 8

Where do azotobacter and Rhizobium live and what kind of relationship do they have with the plant?

Answer 8

Azotobacter is a free living soil bacterium. However, other nitrogen fixing bacteria such as Rhizobium live inside root nodules. These are growths on the roots of leguminous plants such as peas and beans and clover. And the relationship that NF bacteria have with the plants is symbiotic and mutualistic!

1) plants gain amino acids from Rhizobium, which are produced by fixing nitrogen gas from the air into ammonia by the bacteria
2) the bacteria gains carbohydrates produced by the plant during photosynthesis which they use as an energy source

Question 9

What will decomposers turn dead nitrates into?

Answer 9

Ammonium/ammonia ions

This is ammonification - this can be absorbed by the plants by diffusion or active transport.

Or it can be converted to nitrites

Question 10

What bacteria converts amoonium ions into nitrites

Answer 10

Nitrosomonas

Question 11

What bacteria converts nitrites to nitrates?

Answer 11

Nitrobacter. These nitrates can be reabsorbee or converted to nitrogen gas

Question 12

What does denitrifying bacteria do?

Answer 12

Converts nitrates back into nitrogen gas through pseudomonas. This occurs during anaerobic conditions (waterlogged)

Question 13

What converts nitrogen gas into ammonia/ammonium?

Answer 13

Bacteria such as Azotobacter and rhizobium which has the enzyme nitrogenase. This is nitrogen fixing

Question 14

Reaction for nitrification

Answer 14

NH4+ —> NO2- —> NO3-

Nitrosomonas —> Nitrobacter

Question 15

Process of ammonification

Answer 15

NO2/3- —> NH4+/NH3

Decomposers turn nitrates into ammonium/ammonia

Question 16

Process of denitrification

Answer 16

NO3- —> N2 only occurs in anaerobic

Pseudomonas

Question 17

Process of nitrogen fixation

Answer 17

N2 + 3H2 —> 2NH3

Azotobacter and rhizobium both have nitrogenase

Question 18

What happens the co2 in the atmosphere

Answer 18

Producers will take it in during photosynthesis but release a small amount due to respiration. Consumers will also release co2 into the atmosphere.

Question 19

How do animals cycle carbon?

Answer 19

They eat producers which transmits carbon. They then die and decomposers digest the organic matter. These decomposers and detritivores also release co2 when breaking down the mattwem

Question 20

What happens to undigested dead matter from decomposers

Answer 20

It fossilises which is a store of carbon as well. Some become fossil fuels, which can be dug out by humans to do combustion for energy and electricity. This combustion releases co2

Question 21

How does deforestation contribute?

Answer 21

Trees removed = less co2 being withdraw from a rmosphere. Burning trees also releases