EKQu's | Energy and Nutrient Cycles

State the equation that links gross primary productivity and net primary productivity.

NPP= GPP-R

What is meant by the term biomass?

The mass of carbon or dry mass of tissue per given area

Give three reasons for the low efficiency of photosynthesis

. Reflection, evaporation as heat and transmission

What is meant by the term respiratory loss?

The energy lost to the environment as heat when organisms respire

State why it is rare that food chains seldom contain more than five organisms

Too much energy would be lost, leaving the tertiary consumers with very little

Aproximately how much energy is passed from producers to primary consumers?

10%.

By what method could the energy content of a peanut be estimated?

By using a calorimeter.

How could you ensure a sample of biomass was dry before measuring the energy content?

Dry sample in an oven, weigh, return to oven, reweigh until sample does not ch

How do mycorrhizae benefit plants?

Increase the surface area of the roots for better absorption of mineral ions.

What is nitrification?

Bacteria involved in the conversion of ammonia or ammonium ions to nitrites and nitrates.

What term is used to describe bacteria that feed on dead organic material?

Saprobionts

Fertilisers usually contain which three elements?

Nitrogen, phosphorus and potassium.

What is meant by leaching?

When water soluble compounds in the soil are washed into waterways

Give one example of an environmental issue arising from using fertilisers.

Eutrophication

Nitrate from fertiliser applied to crops may enter ponds and lakes. Explain how nitrate may cause the death of fish in fresh water

1. Growth of algae / surfaceplants / algal bloom blocks light;

2. Reduced / no photosynthesis so (submerged) plants die;

3. Saprobiotic (microorganisms / bacteria);

3. Accept: Saprobiont /

4. Aerobically respire / use oxygen in respiration;

5. Less oxygen for fish to respire / aerobic organisms die;

Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants. (5)

1. Protein / amino acids / DNA into ammonium compounds / ammonia;

2. By saprobionts;

3. Ammonium / ammonia into nitrite;

4. Nitrite into nitrate;

5. By nitrifying bacteria / microorganisms;

6. Nitrogen to ammonia / ammonium;

7. By nitrogen-fixing bacteria / microorganisms in soil;

Describe the role of saprobionts in the nitrogen cycle.

1. (They use enzymes to) decompose proteins/DNA/RNA/urea;

2. Producing/releasing ammonia/ammonium compounds/ammonium ions;

Give a biological molecule that contains: 1. nitrogen 2. phosphorus

1. Amino acid / protein / enzyme / urea / nucleic acid / chlorophyll / DNA / RNA / / ATP / ADP / AMP / NAD / NADP;

2. DNA / RNA / nucleic acid / ATP / ADP / AMP / NADP / TP / GP / RuBP / phospholipids;

Describe the role of microorganisms in producing nitrates from the remains of dead organisms.

1. Saprobiotic (microorganisms / bacteria) break down remains / dead material / protein / DNA into ammonia / ammonium;

2. Ammonia / ammonium ions into nitrite and then into nitrate;

3. (By) Nitrifying bacteria / nitrification;

On soils with a low concentration of nitrate ions, leguminous crops often grow better than other types of crop. Explain why.

1. Leguminous crop plants have nitrogen-fixing bacteria in nodules on their roots.

2. (Nitrogen) to ammonia / NH3 / ammonium;

3. Produce protein / amino acids / named protein / DNA / RNA;

Describe how phosphorus moves from one form to another:

1. Ions in plants to animals

2. Ions in animals to dissolved in rivers, lakes and soil

3. Ions in animals to ions in waste and skeletal remains

4. Ions in remains to phosphates in rocks

5. Phosphates in remains and rocks to phosphates in water (rivers, lakes etc)

6. Phosphates in water to phosphates in rocks

7. Phosphates in water to phosphates in plants

1. Feeding and digestion

2. Excretion

3. Excretion and decomposition

4. Deposition

5. Erosion

6. Sedimentation

7. Absorption

Gross Primary Productivity (GPP)

The total energy captured by producers through photosynthesis

Net Primary Productivity (NPP)

The energy remaining after plants use some for respiration; available for growth.

Biomass

The mass of carbon or dry mass of tissue in an organism or area

Respiratory Loss

Energy lost as heat during cellular respiration in organisms

Nitrification

The process by which bacteria convert ammonia/ammonium to nitrites and nitrates.

Mycorrhizae

Fungi that form a symbiotic relationship with plant roots to improve nutrient absorption

Saprobionts

Organisms that decompose dead organic material, feeding on it to recycle nutrients

Leaching

The process by which water-soluble compounds are washed out of the soil into waterways

Eutrophication

The process by which excess nutrients (especially nitrogen and phosphorus) lead to algae blooms and oxygen depletion in water bodies.

Calorimeter

A device used to measure the energy content of a substance by measuring heat produced.

Nitrifying

Bacteria Bacteria responsible for the conversion of ammonia to nitrites and then nitrates

Leguminous Plants

Plants that form symbiotic relationships with nitrogenfixing bacteria to enrich soil nitrogen

Denitrification

The process by which nitrates are reduced to nitrogen gas, returning nitrogen to the atmosphere.

Fertiliser

A substance containing nutrients like nitrogen, phosphorus, and potassium used to improve soil fertility

Nitrogen Fixation

The conversion of atmospheric nitrogen into ammonia by nitrogen-fixing bacteria

Algal Bloom

A rapid increase in algae population in water bodies, often caused by excess nutrients

Primary Consumers

Organisms that consume producers (plants or algae) in a food chain

Trophic Level

The position an organism occupies in a food chain, such as producer or consumer