Energy of Ecosystems

Question 1

Concept of energy in ecosystems

Answer 1

• Energy is the capacity to do work
• Except for deep sea hydrothermal ecosystem, sun is the only energy source for all Earth’s ecosystems.
• Less than 60% of total incident solar radiation is synthetically active radiation.
• Solar energy is transformed into mechanical and heat energy during metabolic activities.

Question 2

Components of energy flow in ecosystem

Answer 2

Radient energy Chemical energy
Sun ———————- Producers ————————
(Metabolism)
Consumers/Decomposers

Question 3

In ecological energetics we consider:

Answer 3

• Quanitity of energy reaching an ecosystem per unit of area per unit time
• Quantity of energy trapped by green plants and converted to a chemical form
• Quantity and path of energy flow from green plants to organisms of different trophic levels over a period of time in a known area (energy flow from producers to consumers)

Question 4

Ecosystem follows the first and second law of thermodynamics

Answer 4

• Energy may be transformed from one form to another but can niether be created nor destroyed
• Processes involving energy transformation does not occur spontaneously unless there is degradation of energy from non random to random form

Question 5

What is ATP and what is it used for?

Answer 5

• Energy stored in organic molecules, transferred via cell respiration into ATP
• Used to support cell metabolisim: building and breaking down molecules, homeostasis and growth

Question 6

What are inefficiencies in the tranfer of energy?

Answer 6

• Toxic waste organic molecules are excreted
• Some ingested material is absorbed and egested
• Some parts of an organism remain uneaten

Question 7

Define ‘food chains’, ‘food webs’ and ‘cellular respiration’.

Answer 7

Food chains: linear sequence of organisms starting with a producer and ending with a predator
Food webs: a series of food chains which are interconnected at various trophic levels
Cellular respiration: conversion of chemical energy into a form cells can use. Releases heat when organic molecules are converted to ATP

Question 8

What is the 10% law?

Answer 8

Only 10% of the energy from organic matter is stored as flesh. The remaining is lost during transfer.

Question 9

What is a trophic level and how is energy lost?

Answer 9

Tophic level: position of the organism in a food chain

Energy is lost as heat from respiration, is not consumed or as feces

Question 10

Define ‘standing crop’ and ‘pyramid of energy’

Answer 10

Standing crop: each time a trophic level has a certain mass of living material at a particular time
Pyramid of energy: any calculations of energy content, biomass or numbers has to include all organisms at that trophic level