5B - energy transfer and nutrient cycles

Question 1

What is an ecosystem

Answer 1

This is all the organisms living in a particular area and all the abiotic conditions

Question 2

What is a producer

Answer 2

An organism that makes its own food

Question 3

What do plants use and create in photosynthesis

Answer 3

Use energy and co2 to make glucose and other sugars

Question 4

What is biomass and what is it made up of?

Answer 4

• The mass of living material/Chemical energy stored in the plant
• Biological molecules made from glucose eg cellulose

Question 5

What can biomass be measured in terms of :

Answer 5

• The mass of carbon that an organism contains
• The dry mass of its tissue per unit area

Question 6

How do you measure dry mass

Answer 6

1. Sample of organism is dried
2. Weighed at regular intervals
3. Once mass becomes constant all water has been removed
4. Scale up result to give biomass of the total pop

Question 7

How you you estimate the amount of chemical energy stored in biomass

Answer 7

• CALORIMETRY
  1. Burn dry biomass
  2. Energy released is used to heat a known volume of water
  3. Change in temp of water is used to calculate the chemical energy of dry biomass

Question 8

What is energy measured in

Answer 8

Joules
KiloJoules

Question 9

What is GPP

Answer 9

Gross primary production is the total amount of chemical energy converted from light energy by plants in a given area

Question 10

What is R?

Answer 10

This is respiratory loss and is the amount of of GPP lost to the environment as heat when plants respire

Question 11

What is NPP

Answer 11

Net primary production is the remaining chemical energy for growth and reproduction

Question 12

How do you work out primary production

Answer 12

NPP = GPP - R

Question 13

What are the units for primary production?

Answer 13

It is expressed as a rate (total amount of chemical energy in a given area in a given time)
- Kjha^-1yr^-1
- kjm^2yr^-1

Question 14

How is chemical energy lost

Answer 14

• Not all food is eaten to energy not taken in
• Some are indigestible so lost as faeces
• Respiration
• Urine

Question 15

What is the Net production?

Answer 15

The energy that is left after all this is stored in the consumers biomass

Question 16

How do you calculate net production

Answer 16

N = I - (F+R)
N = net production
I = chemical energy in ingested food
F = Chemical energy lost in faeces and urine
R = Energy lost through respiration

Question 17

How do you calculate efficiency of energy transfer

Answer 17

% efficiency of energy transfer = net production of trophic level / net production of previous trophic level x 100

Question 18

When does energy transfer become more efficient

Answer 18

When you move up the food chain as producers contain more indigestible matter than consumers

Question 19

What is a trophic level?

Answer 19

The stages in a food chain

Question 20

What are the two ways to increase efficiency?

Answer 20

Simplifying food webs
Reducing respiratory losses

Question 21

How does simplifying food webs increase efficiency

Answer 21

Using pests to reduce the amount of energy available for crops so less for humans
This gets rid of food chains that dont involve humans so energy losses reduced and NPP of crop increases

Question 22

How does reducing respiratory loss increase efficiency

Answer 22

• Restrict movement of animals movement can increase rate of respiration
  -Keep animals warm so less energy lost by generating body heat

Question 23

What are the 2 things that saprobionts do ?

Answer 23

• Feed on the remains of dead plants and animals and their waste products breaking them down so chemical elements can be recycled
• Secrete enzymes and digest food externally - EXTRACELLULAR DIGESTION so organic molecules are broken into inorganic ions

Question 24

What is saprobiotic nutrition

Answer 24

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

Question 24

What is a symbiotic relationship

Answer 24

Two species live closely together and one or both species depend on each other for survival

Question 25

What is a Mycorrhizae

Answer 25

A type of fungi that forms a symbiotic relationship with the roots of a plants - fungi made up of long thin strands known as Hyphae which connect to the plants roots increasing the SA so they can absorb ions - Hyphae also increase water uptake in turn the fungi obtain organic compounds such as glucose

Question 26

What contains nitrogen

Answer 26

Proteins, Nucleic Acids, Dna, RNA

Question 27

What are the basic stages of the nitrogen cycle

Answer 27

1. Nitrogen Fixation 2. Ammonification 3. Nitrification 4. Denitrification

Question 28

What is the first stage of the nitrogen cycle in detail?

Answer 28

Nitrogen fixation 1. Bacteria ( Rhizobium) turn nitrogen into ammonia which goes to form ammonium ions in solution that can be used by plants 2. The Rhizobium are found inside root nodules of leguminous plants forming a mutualistic relationship

Question 29

How does the bacteria form a mutualistic relationship

Answer 29

The bacteria provide the plant with nitrogen compounds and the plant provides them with carbohydrates

Question 30

What is the second stage of the nitrogen cycle in detail

Answer 30

Ammonification 1. nitrogen compounds from dead organisms are turned into ammonia by saprobionts forming ammonium ions 2. Animal waste such as urine and faeces also contain nitrogen compounds which are turned into ammonium ions

Question 31

What is the 3rd stage of the nitrogen cycle in detail

Answer 31

Nitrification 1. Ammonium ions in the soil are changed into nitrogen compounds that can be used by plants --> NITRATES 2. It is first changed into NITRITES and other nitrifying bacteria turn it into NITRATES

Question 32

What is the 4th stage of the nitrogen cycle in detail

Answer 32

Denitrification 1. Nitrates in soil are converted into nitrogen gas by denitrifying bacteria 2. Happens under anaerobic conditions by using nitrates in soil to carry out resp

Question 33

What compounds contain phosphorus

Answer 33

Phospholipids Dna Atp

Question 34

Where is phosphorus found

Answer 34

Rocks Dissolved in oceans in the form of phosphate ions

Question 35

What is the stages of the phosphorus cycle

Answer 35

1. Phosphate ions released into soil by weathering 2. Phosphate ions taken into plants through roots and mycorihizzae increase rate 3. Ions transferred through food chain 4. Saprobionts break down the organic compounds when plants and animals die releasing phosphate ions into the soil 5. Phosphate ions released from urine and faeces 6. Weathering of rocks are releases phosphate ions into seas, lakes and rivers which is taken up by aquatic producers such as algae 7. Waste produced by sea birds is known as Guano and contains phosphate ions therefore used as a natural fertiliser

Question 36

How are nutrients lost

Answer 36

Harvesting of crops Animals removed from land

Question 37

What are the different types of fertilisers

Answer 37

Artificial - inorganic and contain pure chemicals as powder or pellets Natural - organic and include manure, composted veg, crop residue

Question 38

What is the environmental issue with Fertilisers

Answer 38

Leaching - water soluble compounds in the soil are washed away into ponds and rivers leading to eutrophication

Question 39

What is Eutrophication

Answer 39

1. Mineral ions leached from fertilised fields stimulate rapid growth of algae 2. The algae block lights reaching surface below 3. The plants die as unable to photosynthesise 4. Bacteria feed on dead matter reducing o2 conc by carrying out aerobic resp 5. Aquatic organisms die as not enough dissolved oxygen