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Ecology and Conservation - Biotic and Abiotic Factors

Grade 6IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Ecology is the study of how living organisms interact with each other and their non-living environment.

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Abiotic Factors are the non-living physical and chemical parts of an ecosystem. Examples include sunlight, temperature, wind, soil type, and the availability of water (H2OH_2O), oxygen (O2O_2), and carbon dioxide (CO2CO_2).

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Biotic Factors are the living components of an ecosystem. This includes all animals, plants, fungi, protists, and bacteria, as well as their interactions like predation and competition.

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An Ecosystem is formed by the interaction of a community of biotic factors with the abiotic environment.

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Limiting Factors are abiotic or biotic factors that restrict the size of a population. For example, a lack of H2OH_2O in a desert limits the number of plants that can grow.

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The levels of organization in ecology are: Individual →\rightarrow Population →\rightarrow Community →\rightarrow Ecosystem →\rightarrow Biosphere.

📐Formulae

Population Density=Total Number of Individuals (N)Land Area (A)\text{Population Density} = \frac{\text{Total Number of Individuals (} N \text{)}}{\text{Land Area (} A \text{)}}

6CO2+6H2O+light energy→C6H12O6+6O26CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2

Total Ecosystem=Biotic Factors+Abiotic Factors\text{Total Ecosystem} = \text{Biotic Factors} + \text{Abiotic Factors}

💡Examples

Problem 1:

A scientist is studying a 5 km25 \text{ km}^2 section of a forest and counts 150150 pine trees. Calculate the population density of the pine trees and identify if the trees are biotic or abiotic factors.

Solution:

Population Density = 150 trees5 km2=30 trees/km2\frac{150 \text{ trees}}{5 \text{ km}^2} = 30 \text{ trees/km}^2. The trees are biotic factors.

Explanation:

To find the density, we divide the total number of individuals by the area. Since trees are living organisms, they are classified as biotic.

Problem 2:

In a tropical rainforest, the temperature remains around 27∘C27^\circ C and the annual rainfall is approximately 2000 mm2000 \text{ mm}. Are these measurements biotic or abiotic factors? How do they affect the plants?

Solution:

These are abiotic factors. They provide the necessary H2OH_2O and warmth for high rates of photosynthesis.

Explanation:

Temperature and precipitation are non-living physical conditions, making them abiotic. They act as the environment in which biotic factors (plants) must survive.

Problem 3:

Identify the gas represented by O2O_2 and explain why it is an abiotic factor essential for fish.

Solution:

O2O_2 represents Oxygen. It is abiotic because it is a non-living chemical molecule.

Explanation:

Fish require dissolved O2O_2 in the water to perform cellular respiration, which allows them to produce energy from food. Even though it is essential for life, the gas itself is non-living.

Biotic and Abiotic Factors - Revision Notes & Key Formulas | IB Grade 6 Science