13. energy and ecosystems

Question 1

describe the role of producers

Answer 1

photosynthetic organisms that manufacture substances using light energy, water, co2 and mineral ions

Question 2

Describe the role of consumers

Answer 2

Obtain energy by consuming other organisms
primary consumers being first in food chain, secondary next then tertiary.

Question 3

describe the role of sacrobionts

Answer 3

decomposers like fungi and bacteria break down complex materials in dead organisms into simpler ones, which can be absorbed by plants

Question 4

what is biomass?

Answer 4

dry mass (mass of carbon) in a specific area at a given time

Question 5

how is chemical energy store estimated?

Answer 5

calorimetry;
dry sample is burnt in pure oxygen in a sealed chamber surrounded by a water bath. heat from combustion increases temperature of water. This can be used to calculate energy released from the mass in kj/kg-1

Question 6

what % of light energy is used by producers?

Answer 6

1-3%

Question 7

what is the sequence that most nutrient cycles follow?

Answer 7

• Nutrient is taken up by producers as simple (inorganic) molecules.
• producer incorporates the nutrient into complex, organic molecules
• producer is eaten, nutrient is passed onto consumers
• passed along food chain
• when consumers die, saprobionts release nutrient in simple form

Question 8

What are the four main stages of the nitrogen cycle?

Answer 8

ammonification, nitrification, nitrogen fixing and denitrification

Question 9

What are the two stages of nitrification?

Answer 9

ammonium oxidised into nitrite ions, nitrite ions oxidised into nitrate ions

Question 10

what conditions do denitrifying bacteria need

Answer 10

anaerobic process, lack of oxygen

Question 11

give the equation for net primary production

Answer 11

NPP = GPP - R

R = respiratory losses to environment

Question 12

define gross primary production

Answer 12

the chemical energy store biomass, in a given area

Question 13

define net primary production

Answer 13

chemical energy store of biomass after respiratory losses have been accounted for

Question 14

equation for net production of consumers

Answer 14

chemical store ingested - loss by waste + loss from respiration

Question 15

describe the process of ammonification

Answer 15

production of ammonia from organic nitrogen-containing

Question 16

Draw the nitrogen cycle

Answer 16

Use photos online or notes to mark

Question 17

What is released during nitrification?

Answer 17

• oxidation releases energy, used by some bacteria.

Question 18

Why do framers plough soil?

Answer 18

To maintain air spaces for nitrifying bacteria to respirate

Question 19

Draw the phosphorus cycle.

Answer 19

Use photos online or notes to mark.

Question 20

Describe Saprobiontic nutrition. (4)

Answer 20

• HYDROLYSE dead organisms
• enzymes are secreted ONTO organsim, digestion occurs externally
• Products are absorbed into cells, some remains in environment
• ions are secreted as waste

Question 21

What organic compounds can be broken down into mineral ions?

Answer 21

Nucleic acids, amino acids, ATP

Question 22

What is the role of mycorrhizae in the nitrogen cycle?

Answer 22

fungi that associates with plant roots, increases their surface area for absorption of H2O and mineral ions.

Question 23

The relationship between mycorrhizae and plants can be described as…

Answer 23

mutualistic. Fungi receives glucose from roots, roots have an increase surface area.

Question 24

Contrast what natural and artificial fertilisers are made up of.

Answer 24

Natural - organic matter, organisms remains, waste, manure, sewage, food.

Artificial - inorganic matter, powder/palettes maintaining pure chemicals, eg ammonium nitrate.

Question 25

Contrast the effect that artificial and natural fertilisers have on their environment.

Answer 25

Natural - improve soil structure, stability and water retention

Artificial - doesn’t improve soil structure

Question 26

Importance of nitrogen in plants.

Answer 26

• amino acids
• ATP
• nucleotides
  …Needed for metabolic process and DNA

Question 27

Why do artificial fertilisers work faster?

Answer 27

Natural fertilisers require enzyme action, artificial fertilisers are readily soluble.

Question 28

What is meant by leaching?

Answer 28

Pollution of watercourses by nutrients from soil (usually artificial)

Question 29

Describe the 6 steps of eutrophication

Answer 29

• excess fertiliser/ nutrients into body of water (leaching)
• aquatic plants flourish, rapid growth
• rapid algae growth
• algal bloom prevents sunlight from reaching aquatic plants, death
• less oxygen from plants, more released by decomposers
• death of organisms that require oxygen

Question 30

Equation for the net production (of biomass) of consumers
+ unit

Answer 30

N = I - (F + R)

I = chemical energy store in ingested food
F = store lost to environment via waste
R = respiratory losses

KJ per hectare per year

Question 31

when talking about dead matter and waste you must mention…

Answer 31

Urea, proteins, DNA