Ch 4: Energy and Matter in Ecosystems

Question 1

What is the original source of energy for all ecosystems?

Answer 1

The sun. Energy is essential for a system to do work. Energy can’t be recycled like matter, but must be supplied continuously

Question 2

What are some types of energy?

Answer 2

• solar energy: energy transmitted from the sun in the form of electro-magnetic radiation
• radiant energy: transfer of heat from a hot object by infared rays
• heat energy: transferred by a difference in temperature
• ultraviolet light
• geothermal energy: heat generated from the Earth’s core

Question 3

How do living organisms use the Sun’s energy?

Answer 3

Producers (autotrophs) possess special organelles called chloroplasts that contain the pigment chlorophyll. This pigment is able to absorb most of the wave lengths in sunlight (photosynthesis)

They turn this energy into high energy chemical bonds during the synthesis of organic materials from basic inorganic ingredients taken in from the environment. Energy is therefore stored in these chemical bonds and releseased when they are broken

Question 4

What is the chemical formula for photosynthesis and what is its role?

Answer 4

the role of photosynthesis is as the process producers use to transform the Sun’s energy into chemical energy

Question 5

Why are producers significant?

Answer 5

Producers are significant in an ecosystem as they are depended upon by organisms that can’t produce their own nutrients- they ensure the survival of non-autotrophs and therefore encourage biodiversity

Question 6

How is NPP calculated?

Answer 6

GPP - amount required by producers for cellular respiration

Question 7

How do consumers obtain energy?

Answer 7

• consumers obtain their energy from the food they eat
• herbivores extract energy stored in chemical bonds by cellular respiration

Question 8

What is the process of cellular respiration?

Answer 8

1. mechanical and enzyme action break down food. Enzymes digest cellulose and breaks down the chemical bond between individual glucos molecules making up the cellulose
2. series of chemical reactions extract energy in glucose bonds to form adenosin triphosphate (ATP) which provides cells with energy

Question 9

What is ATP useful for?

Answer 9

• synthesis
• growth and repair
• reproduction
• mechanical and chemical work
• temperature maintanenance

Question 10

How is the transfer of energy and matter modelled?

Answer 10

Through food chains and webs- qualitative and predictive models

• each link in the chain is called a trophic level (trophic=feeding)
• each organism in the chain feeds on and obtains its energy and matter from the preceding one. Energy and matter are therefore transferred progressively from one trophic level to the next

Question 11

What is the difference between a food chain and a food web?

Answer 11

a food chain is weher one occupying a trophic lebel is consumed by a higher trohpic level organism creating a chain where energy and matter is passed to progressively higher levels. Food webs show how different organisms feed on each other, interconnecting food chains in an ecosystem and showing the transfer of energy through an ecosystem

Question 12

What does a generalised food chain look like?

Question 13

What is the general amount of energy that ends up being passed to the next trophic level and where does the remainder go?

Answer 13

only about 10% of the energy at one trophic level is passed on to the next level. The remaining 90% is lost to hte surrondings as heat energy and chemical energy in waste.

• producers in the ocean have some of the highest trophic efficiencies i.e. the te of zooplankton feeding on phytoplankton can be more than 40

Question 14

What is the purpose of an ecological pyramid and what does it show?

Answer 14

to provide quantitative relationships between trophic levels of a community

• members of organisms involved
• the biomass (amount of organic matter)
• amount of energy transferred from one to the next

Question 15

What does a pyramid of numbers measure?

Answer 15

the number of animals at each trophic level, the width indicated the relative number of organims at each trophic level

• an inverted pyramid of numbers results when more organisms occupy the trophic level above the preceding level

Question 16

What does a pyramid of biomass measure?

Answer 16

the total mass (amount of dry organic matter) of organisms at each level. It can be at one particular time or as a rate (i.e. gm-2year-1)

• usually pyramidal but can sometimes be inverted i.e. the biomass of certain herbivorous organisms is larger than the biomass of the plants that they feed on because of the plants they feed on are smaller and have a shorter life cycle

Question 17

What does a pyramid of energy measure?

Answer 17

the rate at which energy is transferred from one trophic level to another. Expressed in kJm-2y-1.

• always pyramidal as only some of the energy stored in a tropgic level goes to the next trophic level
• higher the trophic efficiency, steeper the sides-ocean ecosystem would have steeper sides then a terrestrial ecosystem

Question 18

How does matter get recycled?

Answer 18

the difference between energy and matter is that while the sun provides a constant, external supply of energy, the total matter that exists on our planet is a fixed resource and therefore must be recycled

INSERT PIC OF MODEL

Question 19

What are the main components of nutrient cycling models?

Answer 19

• a biological component that follows how the element cycles through organisms
• a geochemical component showing how the element cycles through soil, rocks, water and the atmosphere

Question 20

What are the main similarities between the carbon and the nitrogen cycle?

Answer 20

• both have sinks in the ocean (both have organisms that can be pulled down and fixed)
• naturally occuring form is unusable and needs to be fixed
• bacteria involved in both: cyanobacteria involved in fixation
• in both cycles, carbon and nitrogen are passed though food chains, carbon as glucose and nitrogen as proteins