IB Environmental systems and societies Topic 4.3A Phytoplankton and Macrophhytes Revision Notes (SL/HL)

IB Environmental systems and societies Topic 4.3A Phytoplankton and Macrophhytes Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Phytoplankton: The Microscopic Base of Aquatic Food Webs

Definition

Phytoplankton

Phytoplankton are microscopic organisms capable of photosynthesis

Phytoplankton are microscopic, photosynthetic organisms that drift in the sunlit surface layer of oceans, seas, and freshwater, called the euphotic zone.
As autotrophs, they use sunlight, carbon dioxide, and dissolved nutrients to make organic matter by photosynthesis.
They make up only about 1% of Earth's photosynthetic biomass but carry out nearly 50% of global photosynthesis, producing about half of the world's oxygen.
Main groups
1. Diatoms: single-celled algae with silica shells.
2. Dinoflagellates: some bioluminescent, others toxic or symbiotic.
3. Cyanobacteria (blue-green algae): photosynthetic bacteria, not true algae.

Common Mistake

Not all producers are plants.
Most phytoplankton are microorganisms, and cyanobacteria are bacteria, not plants.

Why Phytoplankton Matter Globally

They form the base of marine food webs, feeding zooplankton, fish larvae, and filter feeders.
They help regulate climate by taking up CO₂ and moving it to the deep ocean (the biological carbon pump).
They underpin commercial fisheries by feeding the higher trophic levels we harvest.
They form seasonal blooms visible from space that drive patterns of ocean productivity.

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Definition

Paywall

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Note

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Tip

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Phytoplankton: The Microscopic Base of Aquatic Food Webs

Definition

Phytoplankton

Phytoplankton are microscopic organisms capable of photosynthesis

Phytoplankton are microscopic, photosynthetic organisms that drift in the sunlit surface layer of oceans, seas, and freshwater, called the euphotic zone.
As autotrophs, they use sunlight, carbon dioxide, and dissolved nutrients to make organic matter by photosynthesis.
They make up only about 1% of Earth's photosynthetic biomass but carry out nearly 50% of global photosynthesis, producing about half of the world's oxygen.
Main groups
1. Diatoms: single-celled algae with silica shells.
2. Dinoflagellates: some bioluminescent, others toxic or symbiotic.
3. Cyanobacteria (blue-green algae): photosynthetic bacteria, not true algae.

Common Mistake

Not all producers are plants.
Most phytoplankton are microorganisms, and cyanobacteria are bacteria, not plants.

Why Phytoplankton Matter Globally

They form the base of marine food webs, feeding zooplankton, fish larvae, and filter feeders.
They help regulate climate by taking up CO₂ and moving it to the deep ocean (the biological carbon pump).
They underpin commercial fisheries by feeding the higher trophic levels we harvest.
They form seasonal blooms visible from space that drive patterns of ocean productivity.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 4.3A Phytoplankton and Macrophhytes Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Phytoplankton: The Microscopic Base of Aquatic Food Webs

Why Phytoplankton Matter Globally

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Phytoplankton: The Microscopic Base of Aquatic Food Webs

Why Phytoplankton Matter Globally

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account