5B Energy Transfer and Nutrient Cycles

Question 1

Biomass

Answer 1

The mass of living material

Mass of carbon that an organism contains or the dry mass of its tissue per unit area per unit time

Question 2

How do you dry a sample of an organism?

Answer 2

Heat at a low temperature and weigh at regular intervals until the mass becomes constant

Question 3

How much carbon is assumed to be in dry mass?

Answer 3

50%

Question 4

GPP

Answer 4

Gross Primary Production- the total amount of chemical energy converted from light energy by plants, in a given area, in a given time

Question 5

Approximately how much of the GPP is lost to the environment when plants respire?

Answer 5

50%

Question 6

What is the amount of GPP lost to the environment when plants respire called?

Answer 6

Respiratory loss

Question 7

NPP

Answer 7

The Net Primary Production

Question 8

What is the equation for NPP?

Answer 8

NPP= GPP - R

Question 9

How do consumers get energy?

Answer 9

Ingesting plant material or animals that have eaten plant material

Question 10

How is energy lost in consumers?

Answer 10

As heat in respiration, egested as faeces

Question 11

What is the equation for the net production of a consumer?

Answer 11

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 12

What is the equation for the % efficiency of energy transfer?

Answer 12

% efficiency = 100 x (net production of trophic level/ net production of previous trophic level)

Question 13

How do you increase the NP of livestock?

Answer 13

Simplify food web, reduce respiratory loss

Question 14

Saprobionts

Answer 14

Microorganisms that feed on the remains of dead plants and animals using extra cellular digestion to break down the remains

Question 15

Saprobiotic digestion

Answer 15

Obtaining nutrients from dead organic matter and animal waste using extra cellular digestion

Question 16

Mycorrhizae

Answer 16

Relationships between fungi and roots of plants. Fungi made of long strands called hyphae which connect to the plant’s roots. This increases the surface area of the plant’s roots

Question 17

Describe what happens during nitrogen fixation

Answer 17

Nitrogen gas in the atmosphere is turned into nitrogen-containing compounds by bacteria. Turns nitrogen into ammonia, which forms ammonium ions in the soil. The bacteria are found inside root nodules of leguminous plants

Question 18

Describe what happens during ammonification

Answer 18

Nitrogen compounds from dead organisms are turned into ammonia by saprobionts which goes on to form ammonium ions

Question 19

Describe what happens during nitrification

Answer 19

Ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants (nitrates). First turn into nitrites then into nitrates.

Question 20

Describe what happens during denitrification

Answer 20

Nitrates in the soil are converted into nitrogen gas by denitrifying bacteria. Under anaerobic conditions

Question 21

Describe the 7 steps of the nitrogen cycle

Answer 21

Phosphate ions are released into the soil by weathering
Phosphate ions are taken into the roots
Phosphorus transferred through the food chain as animals eat plants ect
Plants and animals die, digested by saprobionts
Weathering of rocks release phosphate ions into the sea/ water sources which is taken up by aquatic producers like algae and is passed along the food chain to fish and birds
Guano returns lots of phosphate ions to the land

Question 22

How are nutrients lost?

Answer 22

Plants take them in through the soil. Crops are harvested and they are removed from the field rather than being decomposed

Question 23

Artificial fertilisers

Answer 23

Pure chemicals such as ammonium nitrate

Question 24

Natural fertilisers

Answer 24

Organic matter such as manure, composed vegetables

Question 25

Leaching

Answer 25

Water soluble compounds in the soil are washed away and end up in near by ponds and rivers

Question 26

Eutrophication

Answer 26

The process whereby nutrients build up in water, leading to the growth of large quantities of algae. This results in the death of plants, and the decomposition of dead plant matter causes the oxygen content of the water to fall, killing aquatic organisms

Question 27

Explain the process of eutrophication

Answer 27

Mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers
Large amounts of algae block light from reaching the plants below
Eventually the plants die because they’re unable to photosynthesise enough
Bacteria feed on the dead plant matter. The increased numbers of bacteria reduce the oxygen concentration in the water by carrying out aerobic respiration
Fish and other aquatic organisms die because there isn’t enough dissolved oxygen