transfer of energy and matter

ecology topic

Ecosystem definition

Communities interacting with each other and the abiotic factors of their environment

2 ways ecosystems can vary

Size and complexity

TRFs are very complex, deserts are simple

How does energy enter and exit an ecosystem (open system)

Enters via sunlight but is then converted into chemical energy by plants and stored in plant tissues. It flows through the ecosystem when it’s passed onto primary consumers who ingest the plant and then passed onto secondary consumers when they eat the primary ones. It leaves when an organism with stored energy leaves the ecosystem such as migrating birds

How does matter enter and exit an ecosystem

Enters when an organism enters the ecosystem via things like migration and leaves when organisms leave like when matter is washed away on the beach or dead matter like timber is taken away

Closed system definition+ example

A system where matter can only be recycled and can’t enter or exit but energy can leave and enter. Earth is an example

Sunlight as a source of energy and how energy then moves through an ecosystem 

The sun provides light energy which is converted into chemical energy by plants in photosynthesis and stored in the tissues of plants. It is passed onto consumers when the ingest the plant

How do ecosystems (+examples) with no sunlight gain energy

Examples include deep sea volcanic vents and deep caves. They rely on bacteria to generate their own energy from chemical processes

Difference+ similarity between laws and theories 

Laws are observed patterns of data but don’t aim to explain why this pattern is occurring

Theories aim to understand why phenomena are happening

Both can be used to make predictions

What is a useful generalisation

A law or idea that applies to most things but there are some exceptions

What do the arrows in a food chain represent

Transfer of energy

What do food webs show?

The interactions between different food chains

What happens to inorganic nutrients?

They are converted into carbon compounds and stored in plant tissues. Because the supply of inorganic nutrients is finite the inorganic nutrients need to be released. This can only happen when the plant dies and decomposers can decompose the dead matter

Decomposition definition and what does it allow to happen

The breakdown of dead organisms and living organisms waste

It enables nutrient cycling 

Types of decomposers and what they do

Detritivores begin the process by breaking apart dead plant tissue

Saprotrophs then release an enzyme which break down organic molecules into inorganic nutrients. These are then released into the soil and absorbed by other organisms like trees and the saprotrophs also absorb some.

What do producers have to make 

Carbon compounds

E.g. glucose, lipids, amino acids

How is chemical energy passed onto primary consumers

The primary consumer ingests the plant and absorbs the carbon compounds which contain chemical energy 

How are carbon compounds used in consumers?

Used as fuel in respiration or to build up animal tissue 

What 2 things do food chains show?

Feeding relationships between organisms and transfer of biomass 

What is a mode of nutrition

The way an organism gains its organic molecules or carbon compounds to fuel respiration

What form of energy do organisms need to survive?

ATP

How is ATP transferred to an organism

by respiration

Where does ATP come from?

Carbon compounds such as carbohydrates

2 main modes of nutrition

Autotrophy heterotrophy

Photo autotrophs

These are photosynthetic organisms which use light energy to fix carbon dioxide in the air into organic molecules such as carbohydrates 

Chemo autotrophs 

These use energy from the oxidation of inorganic molecules instead of light energy such as iron

How can the organic molecules produced be used?

To produce macromolecules which are needed to produce cells and tissues like proteins and lipids

What is an anabolic reaction 

A reaction where larger molecules are produced from smaller ones

How do photo autotrophs actually produce carbon compounds in depth?

Light energy is used to release electrons:

It’s either used to break down water molecules by the process of photolysis into oxygen, hydrogen ions and electrons

Or it’s used to excite the electrons in photosynthetic pigments so that they are released

The electrons and hydrogen ions are then used in the production of ATP and reduced coenzymes

These are then used in the production of carbon compounds during light independent photosynthetic reactions

How do chemo autotrophs actually produce carbon compounds in depth?

Electrons are released through oxidation of inorganic molecules. An example is the oxidation of Fe(II) into Fe (III)

The donated electrons are used in ATP production

How do heterotrophs gain their carbon compounds?

Through ingestion of matter of other organisms. They digest the tissues and then build up new molecules such as proteins and nucleic acids. The new carbon molecules are assimilated into the bodies of the heterotroph ready for the next trophic level.

Types of heterotrophs

Consumers, detritivores, saprotrophs

What are the functions of life

Metabolism 

Reproduction

Homeostasis (maintenance of internal environment within tolerable conditions)

Growth

Response

Excretion

Nutrition

By product of respiration

Heat

What are carnivorous predators of the tertiary consumers called

Quaternary consumers

What do pyramids of energy represent+ unit

The energy present in the organisms at each trophic level

kJ/m2/year

How much energy is roughly transferred to the next trophic level

10%

Why is energy lost at each trophic level

Incomplete digestion- some is egested as faeces

Lost as heat energy in respiration 

Lost in the excretion of waste products of metabolic reactions like urea, water and co2

Not every part of the organism is eaten

What is the remaining energy that is not lost to the environment used for in organisms

Fuelling life processes

Stored in carbon compounds in tissues

Role of decay organisms in energy loss

Break down matter that couldn’t be digested e.g. faeces

Decompose dead organisms which weren’t eaten by consumers

Decompose parts of an organism which couldn’t be eaten

ways heat is lost to the environment

Respiration 

Other cellular reactions which use ATP

Decomposition

What process causes heat loss to occur

Respiration

Why does biomass decrease so much at each trophic level

Only 10% of energy is transferred to each trophic level, so primary consumers have to eat a lot of producer biomass to have enough energy to survive and so on

Primary production

This is the accumulation of carbon molecules in the biomass of autotrophs

secondary production

The accumulation of carbon molecules in the biomass of heterotrophs

Why does primary production increase in certain biomes

There are more optimum conditions for photosynthesis such as sunlight hours and rainfall so faster primary production 

Unit for measuring the rate of primary production 

Biomass per unit area/ volume per year

G/m2/year or m3 if it’s an aquatic biome

How is some of the energy lost when heterotrophs consume carbon compounds

Respiration when it’s lost as co2

Excretion of metabolic waste products like water and urea

How is secondary production calculated

Subtracting respiratory losses from the energy stored in the biomass that was ingested 

Organic carbon

This is carbon stored in the biomass of living organisms such as in proteins and carbs

inorganic carbon

This is carbon in the atmosphere like CO2 or dissolved in the ocean as hydrogen carbonate ions

What 2 things do carbon cycle diagrams show?

Carbon stores eg sinks

Processes of carbon transfer eg dissolving and photosynthesis 

What is a carbon sink

a carbon store

3 examples of carbon sinks

Plants

Peat

Ocean

What is a carbon source

Something which releases carbon

2 examples of carbon sources

Plant material that is burned

Decaying organisms

What causes a net uptake of carbon dioxide

When rate of photosynthesis is higher than rate of respiration 

Ways co2 is released

Combustion of fossil fuels (coal oil and gas)

Combustion of peat (plant material which didn’t fully decompose due to acidic and waterlogged conditions)

Combustion of plant matter (e.g. wood)

Example of a major interaction between auto and heterotrophs

Photosynthetic organisms produce oxygen and take in co2 in photosynthesis. This causes a huge production of oxygen and a huge removal of co2.

The opposite applies for organisms who respire aerobically 

mineral elements that are cycled through ecosystems

Nitrogen 

Phosphorus 

Potassium

Calcium