Energy Transfer and Nutrient Cycles

Question 1

What is biomass?

Answer 1

-The mass of living material in an organism

Question 2

How can biomass be measured?

Answer 2

-The mass of carbon of an atom that an organism contains
-Dry mass of its tissue per unit area

Question 3

What is gross primary production (GPP)?

Answer 3

-The total amount of chemical energy converted from light energy by plants in a given area

Question 4

What is respiratory loss(R)?

Answer 4

-When GPP is lost to the environment as heat when plants respire

Question 5

How do you calculated net primary production (NPP)?

Answer 5

NPP=GPP-R

Question 6

Why do consumers not store all of the plants chemical energy?

Answer 6

-Not all food is eaten
-Some are indigestible, excreted as faeces
-Some energy lost to environment through respiration or excretion of urine

Question 7

What is net production?

Answer 7

-The energy left stored in the consumers biomass and is available for the next trophic level

Question 8

What is the equation for net production (N)?

Answer 8

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

Question 9

What is the equation for % efficiency of energy transfer?

Answer 9

net production of trophic level/net production of previous trophic level x 100

Question 10

What is a trophic level?

Answer 10

-Each of the stages in a food chain

Question 11

What is the role of saprobionts?

Answer 11

-Feed on the remains of dead plants and animals on their waste products
-Secrete enzymes and digest food externally and absorb the nutrients they need

Question 12

What is mycorrhizae?

Answer 12

-When fungi form a symbiotic relationship with the roots of plants
-Hyphae connect to a plants roots and greatly increase their surface area so that they can absorb more nutrients

Question 13

Occurring during the nitrogen cycle, what is nitrogen fixation?

Answer 13

-When nitrogen gas in the atmosphere is turned into nitrogen-containing compounds

Question 14

Occurring during the nitrogen cycle, what is ammonification?

Answer 14

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

Question 15

What is nitrification?

Answer 15

-When ammonium ions in the soil are changed into nitrogen compounds that can be used by plants (nitrates)

Question 16

What is denitrification?

Answer 16

-When nitrates in the soil are converted into nitrogen gas by denitrifying bacteria-they use nitrates in the soil to carry out respiration and produce nitrogen gas

Question 17

Describe the phosphorus cycle

Answer 17

-Phosphate ions in rocks are released into soil by weathering
-Phosphate ions are taken into plants through roots
-Phosphate ions are transferred through the food chain
-Phosphate ions are lost from animals in waste products
-Saprobionts break down dead plants and animals, releasing phosphates into soil for assimilation
-Weathering of rocks releases phosphates into seas, lakes and rives, these are taken up by aquatic producers
-Waste produced by sea birds (guano) contains lots of phosphate ions

Question 18

What are artificial fertilisers?

Answer 18

-Inorganic
-Contain pure chemicals as powders or pellets

Question 19

What are natural fertilisers?

Answer 19

-Organic matter
-Manure, composted vegetables, crop residues and sewage sludge

Question 20

What is eutrophication?

Answer 20

-Mineral ions leached from fertilised fields stimulate rapid growth of algae
-Large amounts of algae block light from reaching plants below
-Plants die as they can’t photosynthesise enough
-Bacteria feed on dead plant matter, increased bacteria reduce O2 concentration in water
-Fish and other aquatic animals die as their isn’t enough oxygen