Energy and Ecosystems

Question 1

What is an ecosystem?

Answer 1

All the biotic and abiotic factors in a particular area.

Question 2

What are primary producers?

Answer 2

Primary producers are organisms that make their own glucose

Question 3

What are primary/secondary/tertiary consumers?

Answer 3

Primary = feeds on producers
Secondary = feeds on primary consumers
Tertiary = feeds on secondary consumers

Question 4

What is biomass?

Answer 4

• The mass of living material of the organism or tissue
• The chemical energy that is stored within the organism or tissue

Question 5

How can biomass be measured?

Answer 5

• The dry mass (biomass after all water removed) of an organism or tissue (in a given area)
• The mass of carbon that an organism or tissue contains
• The mass of carbon that a sample (i.e. an organism or tissue) contains is generally taken to be 50% of the dry mass of the sample

Question 6

How can the chemical energy store in biomass be estimated?

Answer 6

Calorimetry

Question 7

What are the units for biomass?

Answer 7

mass/area (kg/m2)

Question 8

What is GPP?

Answer 8

Gross primary production (GPP) is the chemical energy store in plant biomass, in a given area or volume.

Question 9

What is NPP?

Answer 9

Net primary production (NPP) is the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account.

Question 10

How is NPP calculated?

Answer 10

NPP = GPP - R
OR
N = I - (F + R)

Question 11

Units for gross primary/secondary productivity.

Answer 11

energy or mass/area/time (kJ/m2/y OR kg/m2/y)

Question 12

What is a trophic level?

Answer 12

Trophic levels describe the position of an organism in a food chain, web or pyramid.

Question 13

What are decomposers?

Answer 13

Decomposers break down dead plant and animal material (in the process gaining the chemical energy still stored in the dead matter).

Question 14

How do decomposers break down organic matter?

Answer 14

• Secreting digestive enzymes onto the surface of the dead organism
• These enzymes break down the dead matter into small soluble food molecules
• These molecules are then absorbed by the decomposers

Question 15

What is the importance of decomposition?

Answer 15

Helps to release organic nutrients back into the environment (eg. the soil) which are essential for the growth of plants and other producers.

Question 16

How is production affected by farming practices?

Answer 16

Increase the efficiency of energy transfer in order to increase the total amount of energy available for human consumption.
1. Reducing the energy lost to other organisms
- pests reduce the energy available for the growth
- reduces NPP
- in turn reduces energy available for humans
- simplify food web by removing pests
- chemical pesticides (insecticides and herbicides )
- biological pesticides (e.g. toads that kill caterpillars, parasitic wraps, pathogens)
2. Reducing energy loss through respiration
- restricted movement
- heated environments, to reduced energy today during homeostasis
- increased biomass so increased NPP