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Y13 A2 Biology > Nutrient cycles > Flashcards

Nutrient cycles Flashcards

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1
Q

What are saprobionts?

A

A type of microorganism

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2
Q

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

A

Decomposers

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

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3
Q

What can saprobionts also do?

A

Extracellular digestion

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4
Q

What is extracellular digestion?

A

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

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5
Q

What is saprobiotic nutrition?

A

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

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6
Q

What is a mycorrhizae relationship?

A

A symbiotic relationship between fungi and the roots of plants

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7
Q

What are hyphae?

A

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

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8
Q

What is the purpose of hyphae?

A

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

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9
Q

What are the 4 parts of the nitrogen cycle?

A

Nitrogen fixation
Ammonification
Nitrification
Denitrification

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10
Q

What percentage of the atmosphere is made up of nitrogen?

A

78%

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11
Q

What is nitrogen fixation?

A

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

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12
Q

What carries out biological nitrogen fixation?

A

nitrogen-fixing bacteria such as Rhizobium

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13
Q

What does Rhizobium do?

A

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

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14
Q

Where are Rhizobium found?

A

On root nodules of leguminous plants

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15
Q

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

A

A mutualistic relationship

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

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16
Q

What is a mutualistic relationship?

A

Type of symbiotic relationship where both species benefit

17
Q

What is ammonification?

A

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

18
Q

What, other than dead organisms, contain nitrogen compounds?

A

Animal urine and faeces

19
Q

What is nitrification?

A

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

20
Q

What is the first stage of nitrification?

A

Nitrifying bacteria called nitrosomnas change ammonium ions into nitrites

21
Q

What is the second stage of nitrification?

A

Other nitrifying bacteria called nitrobacter change the nitrites into nitrates

22
Q

What is denitrification?

A

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

23
Q

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

A

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

24
Q

What are other ways that nitrogen can enter an ecosystem?

A

Lightning

Artificial fertilisers

25
Q

Why is phosphorus important in organisms?

A

To make biological molecules;

  • Phospholipids
  • DNA
  • ATP
26
Q

Where is phosphorus found?

A

in rocks

27
Q

Where does phosphorus go after the rocks?

A

Dissolves into the oceans in the form of phosphorus ions

28
Q

How are phosphate ions from rocks released?

A

Weathering

29
Q

How does weathering occur?

A

by mechanical, chemical and biological processes

30
Q

How do plants take up phosphate ions?

A

By assimilation through the roots

31
Q

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

A

Mycorrhizae

32
Q

How is phosphorus transferred through the food chain?

A

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

33
Q

How are phosphate ions lost from the animals?

A

Waste products eg. excretion

34
Q

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

A

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

35
Q

How can aquatic producers take up phosphate ions?

A

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

36
Q

How do birds get phosphate ions?

A

They eat the aquatic producers who have taken up the phosphate

37
Q

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

A

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

38
Q

How does phosphorus get back into the rocks and mountains?

A

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

39
Q

What is a use of guano?

A

Natural fertiliser

Y13 A2 Biology (45 decks)

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