What is an Environment?

Explain how living things interact with biotic and abiotic parts of the environment (for example: predation, competition, natural disasters and weather).

Biotic and Abiotic

Mutualism between clownfish and sea anemone

Look around at the ecosystem around you. Right now, it probably includes humans, bacteria, maybe some small animals (some you can’t see), and maybe even some plants. But what you might not consider is that the non-living things also affect you, like the amount of humidity, the amount of heat, the chair you are sitting in, and the desk where you are sitting.

When we talk about biomes, climates and ecosystems, we’re talking about different ways to describe the living and non-living things around us. Climate determines the type of biome, which in turn determines the ecosystems that can exist. Inside any ecosystem, we can divide everything into two large groups: abiotic and biotic.

The biotic part of the environment is easy to understand: since “bio” means “alive”, you know that these must be the living things in the environment. All animals, plants, bacteria, fungi and protists are part of the biotic part of the environment. We also know that these living things interact with each other. Plants are often known as producers, because they take energy from the sun and turn it into usable energy for animals. Animals are often divided into primary consumers and secondary consumers. The primary consumers eat the producers, and the secondary consumers eat the primary consumers. Some animals can act as primary and secondary consumers, like humans (we can eat plants and animals). Some animals, bacteria and fungi act as decomposers, breaking down dead organic matter so that the producers can reuse it.

So, what is meant by the abiotic part of the ecosystem? It’s the opposite of the biotic, which means that it’s all the non-living parts of the environment. Abiotic includes sunlight, amount of water, amount of shade and the rockiness of the land. But we can take this one step further: the biotic can affect the abiotic and the abiotic can affect the biotic. Animals can drink and use up water; too much sun can kill plants.

There are thousands of ways that the different parts of an ecosystem interact that are all equally important. For example, if the sun kills all the plants that the animals eat, then the animals will die and will not use up the water. There are a lot of different interactions that happen between abiotic and biotic parts of the environment, but there are also several important interactions that happen among the biotic parts of the environment:

Type of relationship Description of relationship First organism in relationship Second organism in relationship
Parasitism When one organism benefits from and harms another organism while it’s still alive Parasite benefits Host harmed
Predation When one organism feeds off another organism by killing it Predator benefits Prey killed
Commensalism When one organism benefits from another organism without harming it or helping it Commensal benefits Host unaffected
Mutualism When two organisms help each other Benefits Benefits
Competition When two organisms try to get the same resources and end up harming each other Harmed Harmed
1. Define the four major roles of the biotic part of the ecosystem in your own words.
2. Differentiate biotic from abiotic.
3. 3. Classify each of the following interactions according to the role that they play:
Ex: Hail injures cattle, answer: abiotic affects biotic
a) A hurricane drives buffalo from their watering hole
b) A snowstorm creates an avalanche that destroys a forest
c) Ice on the north pole reflects sunlight away from Earth
d) A giraffe eats a leaf on a tree
e) Humans drill through rock to find precious metals
Put it together
4. Come up with an example for three of the five interactions in the table.
5. List three biotic and three abiotic factors for a biome of your choice.
Think about it
6. Make a three-way Venn diagram for three of the types of interactions from the chart. For example, you can compare mutualism, parasitism and commensalism: you would need to know how they are all unique, what they all have in common and how each pair (mutualism & parasitism, mutualism & commensalism, parasitism & commensalism) has something in common.
7. What is the Gaia Hypothesis?
8. For each of proteins, carbohydrates and lipids, list their functions in the human body.
9. State the relationship between climate and biomes.
10. Draw a picture showing the four basic needs of living things.
  1. Find an example of a mutualistic relationship from magazines, books, or the internet.
    1. What are the two organisms?
    2. How does each one benefit from the relationship?
  2. Design an experiment to determine whether or not this relationship is actually mutual.
    1. Write out the experiment, including the hypothesis, control and experimental groups.
    2. What result would tell you that it was a mutualistic relationship?
Build Your Own Ecosystem
  1. Come up with an ecosystem of your own. Give it a name and a specific location.
  2. Name at least three abiotic factors and three biotic factors in your ecosystem. You must be specific and include at least one animal!
  3. Describe four relationships between abiotic and biotic factors. For example, if you have a cheetah (a biotic factor) and high temperatures (an abiotic factor) in your ecosystem, then you can write, “High temperatures affect the cheetah by causing it to sleep more”.
  4. For one of the animals in your ecosystem, describe how it meets the four basic needs.