IB Environmental systems and societies Topic 1.2B Negative Feedback Loops Revision Notes (SL/HL)

IB Environmental systems and societies Topic 1.2B Negative Feedback Loops Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Definition

Negative feedback loops

Negative feedback loops are processes where the output of a system acts to reduce or reverse changes, helping the system maintain stability.

Negative Feedback: How Systems Hold Themselves Steady

Feedback is any process in which the output of a system loops back to influence its own operation.
Negative feedback loops counteract change, keeping a system near stability and equilibrium.
They underpin homeostasis in living systems and equilibrium in ecological and planetary systems, preventing extreme swings that could threaten survival.

Note

Negative feedback loops are usually drawn as systems diagrams, with storages, flows, and an arrow that feeds the output back to reverse the change.
Positive feedback and tipping points are covered in 1.2C.

How Negative Feedback Works

A system starts in equilibrium, with inputs and outputs balanced.
A disturbance upsets the balance, for example a change in temperature, population size, or resource availability.
The system responds in a way that reduces or reverses the initial change, restoring stability.
As a result the system fluctuates around an average condition rather than drifting steadily away from it.

Predator-Prey Cycles: Feedback in Populations

Example

When prey numbers rise, predators have more food and their population grows.
As predator numbers rise, more prey are eaten, so prey abundance falls.
With less prey available, predator numbers then decline through food scarcity.
Fewer predators let the prey population recover, and the cycle repeats.
This ongoing cycle keeps both populations near a long-term average.

Climate and Body Temperature: Feedback That Cools

Cloud Feedback in the Hydrological Cycle

Higher temperatures increase evaporation, which drives more cloud formation.
Clouds reflect incoming solar radiation because of their high albedo, which reduces heating.
As the planet cools, evaporation and cloud formation fall again, so the feedback holds temperature within narrow limits.

Temperature Regulation in the Human Body

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

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

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 nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

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

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

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 nisi ut aliquip ex ea commodo consequat.

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.

Unlock the rest of this chapter with a free account

Definition

Negative feedback loops

Negative feedback loops are processes where the output of a system acts to reduce or reverse changes, helping the system maintain stability.

Negative Feedback: How Systems Hold Themselves Steady

Feedback is any process in which the output of a system loops back to influence its own operation.
Negative feedback loops counteract change, keeping a system near stability and equilibrium.
They underpin homeostasis in living systems and equilibrium in ecological and planetary systems, preventing extreme swings that could threaten survival.

Note

Negative feedback loops are usually drawn as systems diagrams, with storages, flows, and an arrow that feeds the output back to reverse the change.
Positive feedback and tipping points are covered in 1.2C.

How Negative Feedback Works

A system starts in equilibrium, with inputs and outputs balanced.
A disturbance upsets the balance, for example a change in temperature, population size, or resource availability.
The system responds in a way that reduces or reverses the initial change, restoring stability.
As a result the system fluctuates around an average condition rather than drifting steadily away from it.

Predator-Prey Cycles: Feedback in Populations

Example

When prey numbers rise, predators have more food and their population grows.
As predator numbers rise, more prey are eaten, so prey abundance falls.
With less prey available, predator numbers then decline through food scarcity.
Fewer predators let the prey population recover, and the cycle repeats.
This ongoing cycle keeps both populations near a long-term average.

Climate and Body Temperature: Feedback That Cools

Cloud Feedback in the Hydrological Cycle

Higher temperatures increase evaporation, which drives more cloud formation.
Clouds reflect incoming solar radiation because of their high albedo, which reduces heating.
As the planet cools, evaporation and cloud formation fall again, so the feedback holds temperature within narrow limits.

Temperature Regulation in the Human Body

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 1.2B Negative Feedback Loops Notes

Negative Feedback: How Systems Hold Themselves Steady

How Negative Feedback Works

Predator-Prey Cycles: Feedback in Populations

Climate and Body Temperature: Feedback That Cools

Cloud Feedback in the Hydrological Cycle

Temperature Regulation in the Human Body

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

Negative Feedback: How Systems Hold Themselves Steady

How Negative Feedback Works

Predator-Prey Cycles: Feedback in Populations

Climate and Body Temperature: Feedback That Cools

Cloud Feedback in the Hydrological Cycle

Temperature Regulation in the Human Body

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

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