Ecosystems: Energy and Matter Transfers

Flashcards about energy and matter transfers, autotrophs, heterotrophs, trophic levels, energy pyramids, and the carbon cycle based on lecture notes.

Give some examples of photoautotrophs.

Cyanobacteria, clover, algae (like giant kelp), and pine trees.

Give some examples of chemoautotrophs.

Sulfur-oxidizing, nitrogen-oxidizing, and iron-oxidizing bacteria.

Why are oxidation reactions important in living organisms?

Oxidation reactions release energy, making them useful for living organisms.

How do photosynthetic organisms use light?

They oxidize water molecules via photolysis to donate electrons and hydrogen ions, releasing oxygen gas.

How do chemoautotrophs obtain energy?

They obtain energy from oxidation reactions without needing light.

How do iron-oxidizing bacteria obtain electrons?

Iron-oxidizing bacteria, like Mariprofundus ferrooxydans, takes iron(II) and removes an electron to transform it into iron(III).

What are heterotrophs?

Organisms that use carbon compounds obtained from other organisms to synthesize their own carbon compounds.

Give some examples of heterotrophs.

Zooplankton, sheep, fish, and insects.

What happens when heterotrophs consume food?

They digest proteins into amino acids, lipids into fatty acids, and DNA/RNA into nucleic acids, then assimilate these to build their own molecules.

How do cells release energy?

Oxidation of carbon compounds, such as glucose.

Do autotrophs carry out cellular respiration?

They also need to use organic molecules they've synthesized as an energy source.

What are the main trophic levels?

Producers, primary consumers, secondary consumers, and tertiary consumers.

What does 'trophic level' indicate?

The number of organisms the energy in the system has flowed through.

What units are used to show how much and how fast energy flows from one trophic level to the next?

Kilojoules per square metre per year (kJ m⁻² yr⁻¹).

Why is each level in an energy pyramid smaller than the one before?

Energy is lost between levels, organisms cannot create energy, they can only transfer it inefficiently.

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

Not all of an organism is swallowed, not all food swallowed is absorbed, some organisms die without being eaten, and there is heat loss due to cellular respiration.

Why is there heat loss to the environment in both autotrophs and heterotrophs?

Due to conversion of chemical energy to heat in cell respiration.

Why is heat generated during cellular respiration?

The transfer of energy from one form to another is not 100% efficient. Chemical reactions result in generating heat.

What happens to the number of organisms and biomass at each successive stage in food chains?

There are fewer or smaller organisms at each successive stage due to energy losses.

What is primary production?

It is the accumulation of carbon compounds in biomass by autotrophs, the mass of carbon per unit area per unit of time, or grams per metre squared per year: g m² yr-1.

What is secondary production?

Accumulation of carbon compounds in biomass by heterotrophs.

What molecules along the food chain cannot contribute to the accumulating biomass?

Carbon dioxide is lost from organisms during cellular respiration, and waste products including urea are excreted.

How is carbon recycled in ecosystems?

Photosynthesis, feeding, and respiration.

Tell me about the carbon cycle and photosynthetic autotrophs

Photoautotrophs take carbon dioxide from the atmosphere and convert it into carbohydrates.

Describe the role of carbon dioxide in the carbon cycle.

Carbon dioxide is absorbed by photoautotrophs, consumers use the carbon, and cellular respiration releases carbon dioxide back into the environment.

What is a carbon source?

An organism that is a net producer of carbon dioxide.

What is a carbon sink?

An organism that absorbs and holds more carbon than it releases.

What happens during combustion?

Release of carbon dioxide into the atmosphere during combustion of biomass, peat, coal, oil and natural gas.