C4.2 energy anf transfer quest 2 bio ecology

C4.2 Transfers of Energy and Matter

What are the forms that energy can exist as?

Energy can exist in various forms including light, chemical and heat energy.

What is a food chain?

A sequence of organisms showing feeding relationships and energy flow between species

Trophic level.

an organism's position in a food chain

How is energy transferred between organisms in a food chain?

As chemical energy.

What do the arrows in a food chain or web represent?

The direction of energy flow (or "gets eaten by").

Define "Autotroph."

An organism (producer) that synthesizes organic matter from inorganic matter.

What is the difference between photoautotrophs and chemoautotrophs?

Photoautotrophs use sunlight (photosynthesis), while chemoautotrophs generate energy without sunlight (chemosynthesis).

Define "Heterotroph."

An organism (consumer) that obtains food by consuming organic matter from other organisms.

What is a detritivore?

A decomposer that digests dead organic matter internally via direct consumption (e.g., earthworms).

What is a saprotroph?

A decomposer that digests dead organic matter externally by releasing enzymes and then absorbing nutrients (e.g., fungi).

What is the "10% rule" in energy pyramids?

Only about 10% of energy is passed to the next trophic level; 90% is lost.

What are the three main reasons for energy loss between trophic levels?

1. Material not consumed (bones, hair); 2. Material not assimilated (poop, urine); 3. Cell respiration (lost as heat).

What is the standard unit for measuring energy in an energy pyramid?

kJm−2y−1 (Kilojoules per square meter per year).

What is the difference between GPP and NPP?

GPP (Gross Primary Production) is the total biomass made during photosynthesis; NPP (Net Primary Production) is the biomass remaining after plant respiration losses.

Why is heat considered "lost" energy in an ecosystem?

Once it leaves the body, it cannot be converted back into chemical energy for biological use.

What is the difference between an open and closed system regarding matter?

In an open system, matter can enter/exit (e.g., migration); in a closed system (like Earth), matter must be recycled.

Define "Carbon Sink" and give an example.

A net absorber of CO2, such as plants (photosynthesis) or oceans.

Define "Carbon Source" and give an example.

A net producer of CO2, such as burning fossil fuels or cellular respiration.

What does the "Keeling Curve" show?

The steady increase of atmospheric CO2 levels over time, with seasonal oscillations.

Why does the Keeling Curve show an oscillating (zigzag) pattern?

Seasonal changes: organisms absorb more CO2 during summer/autumn than in winter.

What conditions are required for Peat formation?

Waterlogged soil (wet), high acidity, and low oxygen levels.

How is methane (CH4) produced in nature?

By anaerobic methanogens (archaea) in environments like wetlands or digestive tracts of mammals.

What is the difference between renewable and non-renewable resources?

Renewable resources replenish naturally on a daily basis; non-renewable resources take millions of years to form.

Why are ecosystems considered open systems?

Because both matter (air, water, organisms) and energy (sunlight) can enter and exit the system.

What is the principal source of energy for most ecosystems?

Sunlight.

How is energy passed along a food chain?

Through predation (one organism eating another).

What is chemosynthesis and where does it occur?

A process where organisms gain energy from chemical reactions (using methane or sulfides) rather than light; occurs in deep oceans or isolated caves.

Why are food webs more realistic than food chains?

They represent interconnected networks of feeding relationships rather than a single linear sequence.

Define Carbon Fixing.

The process by which autotrophs synthesize organic compounds (like sugars) from inorganic carbon (CO2).

What is the difference between a Photoautotroph and a Chemoautotroph?

Photoautotrophs use light energy (photosynthesis); Chemoautotrophs use energy from oxidation reactions (chemosynthesis).

How do Heterotrophs obtain their required carbon compounds?

By obtaining and digesting organic molecules from other organisms.

Contrast Saprotrophs and Detritivores.

Saprotrophs use external digestion (secreting enzymes); Detritivores use internal digestion (ingestion).

In which organisms does cellular respiration occur?

In both autotrophs and heterotrophs to release energy via the oxidation of carbon compounds.

What is the standard unit for an energy pyramid?

kj/m2/year

Why is energy transfer between trophic levels inefficient (approx. 10%)?

Due to incomplete consumption, incomplete digestion, metabolic heat loss, and excretion of waste.

How does energy loss restrict the number of trophic levels?

Higher levels must eat more to get enough energy; if hunting cost exceeds energy gained, the level is unviable.

Define Biomass.

The total mass of a group of organisms, consisting of all carbon compounds in their cells and tissues.

What is the formula for Net Primary Production (NPP)?

NPP = Gross Primary Production − Respiration.

What is a Carbon Sink?

A reservoir that stores more carbon than it releases (e.g., a standing forest where photosynthesis > respiration).

List three anthropogenic (human) factors of carbon release.

Burning of biomass, peat, and fossil fuels (coal, oil, natural gas).

What does the Keeling Curve measure?

Atmospheric carbon dioxide concentrations, recorded at Mauna Loa, Hawaii.

Why do CO2 levels fluctuate annually in the Keeling Curve?

Levels drop in summer due to increased photosynthesis and rise in winter when respiration rates are higher.

Why must inorganic nutrients be recycled on Earth?

Because the supply is limited and new elements cannot be created; they must be returned to the environment by saprotrophs.