Energy and Ecosystems

Question 1

Define Population

Answer 1

Group of organisms of the same species, living in the same place at the same time

Question 2

Define Community

Answer 2

All of the organisms, of several or all species, living in one location at one time

Question 3

Define Ecosystem

Answer 3

A balanced biological system where all the organisms and the non-living components with which they interact in a particular location. Energy flow and nutrient cycling within the ecosystem.

Question 4

Define Habitat

Answer 4

The place where an organism live. It provides the correct set of environmental conditions

Question 5

Define Niche

Answer 5

The role of a particular species in its ecosystem, including its microhabitat, feeding and breeding behaviour etc.

Question 6

Define Producer

Answer 6

An organism which uses light energy (or that from the oxidation of minerals) to fix atmospheric CO2 into complex organic molecules (chemoautotroph or photoautotroph

Question 7

Define Consumer

Answer 7

Organism which derives its energy and complex molecules from the tissues of other living things (heterotroph)

Question 8

What is a biotic factor?

Answer 8

A living component of the ecology of an organism

Question 9

What is an abiotic factor?

Answer 9

A non-living components of the ecology of an organism

Question 10

What is a Edaphic factor?

Answer 10

Aspects of the soil which affect the ecology of an organism

Question 11

Describe what a food chain is?

Answer 11

A diagram which shows a simple, un-branched, feeding relationship, usually with only one organism at each position (trophic level)

Question 12

Describe the three trophic levels?

Answer 12

The position of an organism in a food chain
T1 is always a producer, usually a plant
T2 is a primary consumer = a herbivore
T3 is a secondary consumer = a carnivore

Question 13

What three things do food chains not show?

Answer 13

1) All the species at each trophic level (eg insect herbivores), so the calculated efficiency of energy transfer is low.
2) detritivores and decomposers which are often a greater biomass than other consumers
3) omnivores or other species feeding at several trophic levels

Question 14

What type of diagram shows some things a food chain cannot?

Answer 14

a Food web

Question 15

What is the initial energy source for most ecosystems?

Answer 15

The Sun

Question 16

What happens to light energy from the sun?

Answer 16

Light energy is trapped as chemical energy by photosynthesis

Question 17

Define Gross Ecological Efficiency

Answer 17

This is the percentage transfer of the energy from one trophic level to the next

Question 18

Define Photosynthetic efficency

Answer 18

This is a measure of how well a plant is able to capture light energy

Question 19

How do you calculate Photosynthetic efficiency?

Answer 19

(Gross Primary Productivity / Quantity of light energy falling on plant) X100

Question 20

What is the typical value of Photosynthetic Efficiency?

Answer 20

1-2%

Question 21

Whys is the typical value of photosynthetic efficiency typically so low?

Answer 21

1. Much light is reflected from the leaves.
2. Some light passes through the leaves.
3. Some light is absorbed by non photosynthetic parts.
4. Much of the light is of the wrong wavelength (plants absorb blue and red wavelengths best).

Question 22

Define Gross Primary Productivity (GPP)

Answer 22

is the rate of production of chemical energy in organic molecules by photosynthesis in a given area.

Question 23

What is the units for GPP?

Answer 23

kJ m-2 year-1

Question 24

Define Net Primary Production (NPP)

Answer 24

Amount of energy in organic molecules available in plants for herbivores or primary consumers. This represents the potential food available to primary consumers.

Question 25

What is the equation for calculating NPP?

Answer 25

GPP- Respiration =NPP

Question 26

Define Secondary Productivity

Answer 26

The rate at which consumers accumulate energy from assimilated food in biomass in their cells or tissue. Secondary production occurs in heterotrophs, including animals, fungi some bacteria and some Protoctista.

Question 27

Why is there any loss between each trophic level in a food chain? (4)

Answer 27

1. Not all of the tissue is eaten e.g. bones.
2. Some tissues are indigestible so will be present in faeces (Egested).
3. Respiration losses: A lot of food is respired to provide the energy needed for active transport, muscle contraction, keeping warm (especially mammals and birds), etc. This is lost as heat energy.
4. Energy is lost in excretory products such as
   urea.

Question 28

Why are Herbivores less efficient than Carnivores?

Answer 28

1. Much more energy is left in the faeces of a herbivore than that of a carnivore.
2. A lot more energy is used during the digestive process (remember herbivores digest gut bacteria which have digested the cellulose).
3. Carnivores are more efficient because they are able to digest their high protein diets more easily