Abiotic vs Biotic Factors

Abiotic vs Biotic Factors

Middle School

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Learning Objectives

• Define biotic and abiotic factors and tell them apart in an ecosystem.

• Find examples of biotic and abiotic factors in different environments.

• Explain how living and non-living things in an ecosystem affect each other.

• Understand how resources and abiotic factors decide which organisms can live somewhere.

Key Vocabulary

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Ecosystem

A community of interacting living organisms and their non-living physical environment.

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Biotic Factors

The living or once-living components of an ecosystem, such as plants, animals, and fungi.

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Abiotic Factors

The non-living chemical and physical parts of an ecosystem that affect organisms.

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Ecology

The scientific study of the relationships between different organisms and their surrounding environment.

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Habitat

The specific natural home or environment where a particular plant or animal lives.

What is an Ecosystem?

• Ecology studies how living things interact with their environment.

• An ecosystem includes all living and non-living things in an area.

• Everything is connected, from the smallest bacteria to the largest animal.

Multiple Choice

Based on the definition, what does an ecosystem include?

• Only the non-living things in a place.

• The study of how organisms interact with their environment.

• A group of interacting organisms and the non-living things in a particular place.

• Only the living organisms in a place.

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Biotic Factors: The Living Parts

• Biotic factors are all the living or once-living parts of an ecosystem.

• This includes producers, consumers, decomposers, and even microorganisms within other organisms.

• Organisms interact, like a squirrel using a tree for shelter and food.

• The predator-prey relationship, like a hawk hunting a squirrel, is key.

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Multiple Choice

Which of the following is the best example of an interaction between two biotic factors?

• A squirrel digging in the soil.

• A squirrel drinking water from a puddle.

• A squirrel being hunted by a hawk.

• A squirrel breathing in air.

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What Are Abiotic Factors?

• Abiotic factors are all non-living substances and conditions in an environment.

• They were never alive and affect the survival of living organisms.

• Common examples are air, water, soil, sunlight, and temperature.

• Other factors include salinity, minerals, humidity, clouds, and pollution.

Multiple Choice

Which list contains only abiotic factors?

• Mushrooms, bacteria, wind, and air.

• Sunlight, soil, trees, and water.

• Air, wind, soil, and temperature.

• Temperature, pollution, and fish.

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How Factors Interact

• Non-living factors determine which organisms can survive in an ecosystem.

• For example, deserts and tundras support different life due to extreme temperatures.

• Living organisms can also cause changes to their non-living environment.

• For instance, grass growing in a river can slow the current’s speed.

Multiple Choice

How can a biotic factor, like grass, change an abiotic factor, like a river?

• By drinking all the water from the river.

• By making the river water salty.

• By turning the river into soil.

• By slowing the river's current, which can change its temperature and oxygen levels.

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What Is a Habitat?

• A habitat is the natural home where an organism lives.

• It is a specific part of a much larger ecosystem.

• A squirrel's habitat in a forest may be in the trees.

• A worm's habitat in the same forest is in the soil.

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Multiple Choice

What is the relationship between an ecosystem and a habitat?

• They are not related in any way.

• They are the same thing.

• An ecosystem is the specific home of an organism within a larger habitat.

• A habitat is the specific home of an organism within a larger ecosystem.

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Common Misconceptions About Biotic and Abiotic Factors

Misconception	Correction
Dead things like fallen leaves are abiotic.	They are biotic because they were once living.
Abiotic factors are less important than biotic factors.	Abiotic factors are essential for the survival of all living things.
Only animals are considered biotic factors.	Biotic factors include plants, fungi, and bacteria.

Multiple Choice

A gardener notices that their plants are not growing well. They have already ensured the plants are free of insects (biotic). Which abiotic factor should they investigate to understand why the plants are struggling?

• The number of bees visiting the flowers.

• The presence of rabbits in the garden.

• The composition and pH of the soil.

• The number of worms in the soil.

Multiple Choice

A scientist is describing an environment. Which statement correctly classifies a factor of that environment?

• The mushrooms growing on a log are an abiotic factor.

• The average annual rainfall is a biotic factor.

• The competition between two bird species for nesting sites is a biotic interaction.

• The minerals within the rocks are a biotic factor.

Multiple Choice

A new factory is built near a forest, and it releases a lot of pollution into the air, an abiotic factor. What is a likely long-term effect on the biotic factors in the forest ecosystem?

• The trees and animals will immediately adapt and become healthier.

• The number of predators will increase instantly.

• The pollution will have no effect on the living organisms.

• The health and population of plants and animals may decline due to the poor air quality.

Multiple Choice

If a prolonged period of cloudy weather (abiotic change) reduces the growth of plankton (biotic producers) in the ocean, what is a probable outcome for the ecosystem?

• The ocean temperature will rise significantly.

• The ocean water will become saltier.

• The populations of fish that eat plankton will increase due to a new food source.

• The populations of fish and other animals that depend on plankton for food will likely decrease.

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Summary

• An ecosystem is a community of living and non-living things.

• Biotic factors are the living parts; abiotic factors are the non-living parts.

• All factors in an ecosystem are interconnected and affect one another.

• A habitat is an organism's specific home within an ecosystem.

Poll

On a scale of 1-4, how confident are you about differentiating between biotic and abiotic factors?

• 1

• 2

• 3

• 4