Topic 5B: Nutrient Cycle

Question 1

What are saprobiants?

Answer 1

Microorganisms that secrete enzymes and absorb desired nutrients from digested dead organisms (extracellular digestion)

Question 2

What is ploughing?

Answer 2

• This is provides oxygen to the soil
• saprobiants use the oxygen to respire
• so more nitrates/mineral ions given to soil

Question 3

What is called when organic molecules turn into inorganic molecules?

Answer 3

Saprobiotic nutrition

Question 4

How does saprobiants respire?

Answer 4

aerobically

Question 5

How much of nitrogen in the air?

Answer 5

78%

Question 6

What is nitrogen needed for in plants?

Answer 6

Biological molecules

• DNA
• RNA
• Proteins/AA

Question 7

What are the stages for nitrogen cycle?

Answer 7

1) Nitrogen Fixation
2) Ammonification
3) Nitrification
5) Denitrification

Question 8

What is Nitrogen Fixation?

Answer 8

• Nitrogen gas are converted to ammonia then to ammonium ion

- by nitrogen fixing bacteria (Rhizobidium)

Question 9

What is Rhizobidium?

Answer 9

Root Noodle which has mutuallistic relationship

Question 10

What is Ammonification?

Answer 10

• dead organisms are decomposed by saprobiants

- converts to ammonium ion to soil

Question 11

What is Nitrification?

Answer 11

• ammonium ion converts to nitrite by nitrosomas
• Nitrite ions converts to nitrate ions by nitrobacteria
• by nitrifying bacteria

Question 12

What is Denitrification?

Answer 12

• Nitrate ions in the soil are returned back into the atmosphere as nitrogen gas
• by denitrifying bacteria anaerobically
• respiring out N2 gas

Question 13

What is mycorrhaze?

Answer 13

-fungi having symbiotic relationship with plant roots

Question 14

Fungi have long thin strands called?

Answer 14

Hyphae that attaches to roots

Question 15

Features of hyphae?

Answer 15

• increases SA

- so that more water and scarce ions like phosphate can be absorbed into the plant

Question 16

How is phosphorus used in organisms?

Answer 16

For biological molecules:

• ATP
• DNA
• phospholipid bilayer

Question 17

Outline the stages in the Phosphorus Cycle?

Answer 17

• Phosphorus found in rocks
• due to weathering it gets dissolved in soil/ocean
• plant can use there roots which are mycorrhaze so assimilate
• animals eat plants
• animals/plants die and decompose
• by saprobiotic bacteria back into the soil

Question 18

What is sea bird waste callled?

Answer 18

Guano

Question 19

What does guano contain?

Answer 19

• high proportion of phosphate ions

- many use it as a natural fertiliser

Question 20

Why are fertilisers used by farmers?

Answer 20

• Crops get harvested
• animals move around
• so don’t go back to soil
• Farmers need to replace them through fertilising

Question 21

What is a natural fertiliser?

Answer 21

organic matter like manure/sewage/guano

Question 22

What is artificial fertiliser?

Answer 22

inorganic matter like ammonium nitrates (pure chemicals)

Question 23

What does too much fertiliser result in?

Answer 23

• damage to crops and die

- leaching

Question 24

What is Leaching?

Answer 24

it is caused by when fertilisers used an excess amount.

Question 25

What is leaching cause?

Answer 25

Eutraphication

Question 26

What is eutraphication?

Answer 26

• mineral ions/water soluble wash away to lakes/rivers due to heavy rainfall
• mineral ions stimulate rapid growth of algae
• algae blocks light
• so plants under algae receive less light
• less photosynthesis
• plants under algae die and decompose by saprobiants
• saprobiants respire aerobically and uses up oxygen in the water
• less conc of oxygen for fish to respire so they die

Question 27

What is leaching not common in?

Answer 27

Natural Fertilisers because they already contain organic compounds