Nutrient cycles

Question 1

What are saprobionts?

Answer 1

A type of microorganism

Question 2

What are saprobionts a type of and why is this the case?

Answer 2

Decomposers

They feed on the remains of dead plants and animals and on their waste products, breaking them down

Question 3

What can saprobionts also do?

Answer 3

Extracellular digestion

Question 4

What is extracellular digestion?

Answer 4

Saprobionts secrete enzymes and digest their food externally and then absorb the nutrients they need

Question 5

What is saprobiotic nutrition?

Answer 5

Obtaining nutrients from dead organic matter and animal waste using extracellular digestion

Question 6

What is a mycorrhizae relationship?

Answer 6

A symbiotic relationship between fungi and the roots of plants

Question 7

What are hyphae?

Answer 7

Long, thin strands made up of fungi connected to the plant’s roots

Question 8

What is the purpose of hyphae?

Answer 8

To significantly increase surface area of the plant’s root system, helping the plant to absorb ions from the soil that are usually scarce

Question 9

What are the 4 parts of the nitrogen cycle?

Answer 9

Nitrogen fixation
Ammonification
Nitrification
Denitrification

Question 10

What percentage of the atmosphere is made up of nitrogen?

Answer 10

78%

Question 11

What is nitrogen fixation?

Answer 11

When nitrogen gas from the atmosphere is turned into useful nitrogen-containing compounds

Question 12

What carries out biological nitrogen fixation?

Answer 12

nitrogen-fixing bacteria such as Rhizobium

Question 13

What does Rhizobium do?

Answer 13

Turn nitrogen into ammonia which goes on to form ammonia ions in solution that can be used by plants

Question 14

Where are Rhizobium found?

Answer 14

On root nodules of leguminous plants

Question 15

What do Rhizobium form with the plant? What does this entail?

Answer 15

A mutualistic relationship

They provide the plant with nitrogen-containing compounds and the plant provides them with carbohydrates

Question 16

What is a mutualistic relationship?

Answer 16

Type of symbiotic relationship where both species benefit

Question 17

What is ammonification?

Answer 17

When nitrogen compounds from dead organisms are turned into ammonia by saprobionts, which goes on to form ammonium ions.

Question 18

What, other than dead organisms, contain nitrogen compounds?

Answer 18

Animal urine and faeces

Question 19

What is nitrification?

Answer 19

When ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants

Question 20

What is the first stage of nitrification?

Answer 20

Nitrifying bacteria called nitrosomnas change ammonium ions into nitrites

Question 21

What is the second stage of nitrification?

Answer 21

Other nitrifying bacteria called nitrobacter change the nitrites into nitrates

Question 22

What is denitrification?

Answer 22

When nitrates in the soil are converted into nitrogen gas by denitrifying bacteria.

Question 23

How do denitrifying bacteria carry out their job? What conditions are required?

Answer 23

Use nitrates in the soil to carry out respiration and produce nitrogen gas
Anaerobic conditions eg. waterlogged field

Question 24

What are other ways that nitrogen can enter an ecosystem?

Answer 24

Lightning

Artificial fertilisers

Question 25

Why is phosphorus important in organisms?

Answer 25

To make biological molecules; - Phospholipids - DNA - ATP

Question 26

Where is phosphorus found?

Answer 26

in rocks

Question 27

Where does phosphorus go after the rocks?

Answer 27

Dissolves into the oceans in the form of phosphorus ions

Question 28

How are phosphate ions from rocks released?

Answer 28

Weathering

Question 29

How does weathering occur?

Answer 29

by mechanical, chemical and biological processes

Question 30

How do plants take up phosphate ions?

Answer 30

By assimilation through the roots

Question 31

What is there on the roots of plants which greatly increase the intake of the phosphorus in plants?

Answer 31

Mycorrhizae

Question 32

How is phosphorus transferred through the food chain?

Answer 32

When animals eat the plants and then in turn are eaten by other animals

Question 33

How are phosphate ions lost from the animals?

Answer 33

Waste products eg. excretion

Question 34

What happens to the phosphorus ions when the animals and plants die?

Answer 34

Saprobionts break the organic compounds and release the phosphate ions into the soil so the plants can assimilate it

Question 35

How can aquatic producers take up phosphate ions?

Answer 35

When the rocks weather, some ions will enter rivers, lakes and oceans

Question 36

How do birds get phosphate ions?

Answer 36

They eat the aquatic producers who have taken up the phosphate

Question 37

What is guano and how is it involved in the phosphorus cycle?

Answer 37

The waste product of birds which contains phosphate ions that get returned back to the rocks and soil

Question 38

How does phosphorus get back into the rocks and mountains?

Answer 38

When fish die, their remains lie on the bottom of the ocean floor and eventually become part of the ground and this will eventually rise up to form the rocks and mountains

Question 39

What is a use of guano?

Answer 39

Natural fertiliser