Science Tests and You: A series of information sheets designed to improve the transmission of
scientific knowledge.
Volume 3, Issue 1
In order to ensure success in the upcoming science test on Interactions in the
Environment, you should direct your review on the following areas. These can be found
throughout Unit 1 of your most excellent textbook: “Investigating Science and
Technology 7”.
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1.1
1.2
1.3
2.1
2.2
2.3
3.1
3.2
3.3
Interactions of Biotic and Abiotic Elements
The Roles of Producers
Producers and Consumers
The Transfer of Energy in and Ecosystem
Cycling Matter
Interactions and Changes in Ecosystems
Succession, Recovery, and Renewal in Natural Communities
The Environment impact of Humans
Sustainable Human Communities
Happy Studying
Definitions
Biotic – A living thing in an ecosystem (eg. frog, snake grass)
Abiotic – A non-living thing in an ecosystem (eg. Wind, water, rocks)
Nutrients – The components of food that your body converts into energy
Habitat – A place that provides living things with oxygen, water, food, shelter, and anything else they
need for survival.
Producers – Plants are called producer because they produce their own food to supply the matter and
energy they need to survive.
Photosynthesis – A chemical reaction that takes place in the leaves of green plants when the Sun’s
light is present.
Chlorophyll – The green colour/compound in most leaves that is needed in the chemical reaction for
photosynthesis.
Populations – Are groups of individuals that belong to the same species and live in the same area at
the same time
Species – The most closely related groups of living things in an ecosystem.
Community – made up of populations of different species.
Consumers – Organisms that have to “Consume” other biotic elements to survive.
Herbivores – Animals that eat plants.
Carnivores – Animals that eat meat.
Omnivores – Animals that eat both meat and plants.
Prey – An animal that is hunted for food.
Predator – An animal that hunts and consumes prey.
Scavengers – Consumers that feed off of the remains of dead animals
Detritivores – Consumers that feed of waste (snails and earthworms)
Organic Matter – Matter derived from living things, such as animal waste and dead insects.
Decomposers – Consumers that break down dead plants nad animals into smaller pieces (fungi,
bacteria)
Bacteria – Microscopic living organisms that function as decomposers
Food Chain – A visual way of showing the feeding interaction between producers and consumers. A
food chain always begins with a producer.
Primary Consumers – Eat producers. They are the first level of consumers in a food chain.
Secondary Consumers – Carnivores and Omnivores that eat the primary consumers.
Tertiary Consumers – Carnivores and Omnivores that eat secondary consumers.
Energy Pyramid – A type of graphic representing the amount of energy transferred in a food chain.
Food Web – A series of interconnected food chains.
Cycle – The over-and-over-again movement of matter from abiotic elements into biotic elements and
back to abiotic elements.
Cycling of Matter – A series of steps in a cycle that allow abiotic elements to be used over and over
again.
Native Species – Biotic elements that occur naturally in a given area.
Introduced Species – A biotic element that was brought to an environment where it did not live
before.
Bioinvasion – A term used to describe the introduction of foreign species into native ecosystems.
Invasive Species – An introduced species that interferes with the natural ecosystem.
Sustainability – An ecosystems ability to continue to support biotic elements.
Succession – The natural replacement of one community of living things by another.
Primary Succession – The formation of a new community where no community existed
Pioneer Species – Plants and plant-like species that are part of succession.
Secondary Succession – When a community has been destroyed or disturbed by natural
occurrences or human activities.
Climax Community – A natural community that has undergone several changes and eventually
becomes stable. These communities undergo changes more slowly over long periods of time.
Toxic Substances – A chemical that can cause harm or death to living things.
Section Summaries
1.1
Interactions of Biotic and Abiotic Elements
- Biotic elements have five basic needs for survival
o Oxygen (Colourless, odorless gas in Earth’s atmosphere. Oxygen helps your body
release and use energy from the food that you eat)
o Water (Your body is about 70% water. Animals must take in clean water to
survive. Plants need water to make food)
o Food (You need food to get the nutrients your body needs. Nutrients include
carbohydrates, fats, proteins, vitamins, and minerals)
o Energy (Oxygen, water, and nutrients from food interact in your body to produce
energy)
o Suitable Habitat As a living thing, you must live in a place where you can obtain
everything you need to survive)
- Plants use sunlight, soil and water to grow. Animals use leaves, branches, trees, or soil for
shelter and other living things for food. These are examples of interations of biotic elements in
ecosystems.
1.2
The Roles of Producers
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The Sun is an essential abiotic element in most ecosystems.
The two forms of energy from the Sun are light and heat
Plants interact with the Sun to produce their own food through photosynthesis.
Through photosynthesis, producers combine carbon dioxide from the air and water from
the soil. This combination forms a sugar product called glucose and a waste product
oxygen.
Roles of producers
- They produce oxygen (waste product from photosynthesis)
- They supply food (berries, leaves, nuts etc.)
- The provide shelter (Insects/Squirrels live in trees, beavers use branches etc.)
Biotic elements in ecosystems can be defined as Populations, Species and Communities. (SEE
DEFINITIONS FOR EACH) Have a look at figure 1.19 (pg.20) and the paragraph on pg. 21
1.3
Producer and Consumers
- Animals cannot make their own food and must consume other living things to get nutrients
(Herbivores, Carnivores, Omnivores)
- A food chain shows the feeding interaction among producers and consumers
Acorn  Squirrel  Fox
- Detritivores (consumers of waste) and Decomposers (consumers that break down dead plants
and animals) are essential to ecosystems since they connect the biotic elements of ecosystems to the
abiotic elements.
2.1
The Transfer of Energy in an Ecosystem
- Food chains show how energy is transferred in an ecosystem. (primary, secondary, tertiary
consumers)
- At each step in the food chain, less energy is available to the next consumer (study the energy
pyramid on page 39)
- A group of interconnected food chains is called a food web. In other words, a leaf may be
eaten by either a rabbit, or a deer, and a wolf eats both the rabbit and the deer, and other
animals.
2.2
Cycling of Matter
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2.3
Decomposers break down organic matter in order to recycle the basic elements. These
are then reabsorbed by biotic elements. Decomposers are the engines of Earth’s recycling
program for nutrients.
Review the steps that show the continuous cycling of matter (figure 2.11 pg. 45) to help
understand the cycling of matter.
Interactions and Changes in Ecosystems.
- The supply of resources in ecosystems is limited. This controls the size of populations of biotic
factors.
- There are other limiting factors that also control the size of abiotic populations such as:
available food, climate, suitable habitat, number of predators.
- Ecosystems change for a variety of reasons. The flow of energy and the cycling of matter
affect the interaction of producers, consumers and decomposers.
- Abiotic factors can affect an ecosystem. For example, a lack of rainfall may cause the number
of producers to decrease. As a result there will be less food for primary consumers.
- Bioinvasion by an introduced species with no natural enemies will also affect an ecosystem,
since the introduced species will compete for resources.
- An ecosystem is sustainable when it can maintain the balance of needs and resources over
time.
- Scientists study the impact of modern human lifestyles on ecosystems. In 1987, the United
Nations stated the human activity must not interfere with the ability of ecosystems to sustain
themselves.
3.1
Succession, Recovery, and Renewal in Natural Communities
- Ecosystems change in predictable ways known as succession. This is the natural
replacement of one community by another.
- Primary succession is the formation of a new community where no community had
existed. For example, on a newly formed volcanic island the plants that appear first, and that can
survive the tough conditions, are part of primary succession. These new plants are called pioneer
species.
- Secondary succession occurs when a community has been destroyed or disturbed by
natural occurrences or human activity. As a result, a new community appears.
- When a community reaches a relative stability (in other words, changes occur very slowly and
are not very significant) the community is called a climax community.
- Ecosystems will recover after major catastrophic events, such as volcanoes, floods etc.
Fireweed, for example, is one of the first plants to establish itself after a fire. (figure 3.6 pg 65)
- Human activity, however, can make it harder for ecosystems to recover or renew.
3.2 The Environmental Impact of Humans
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3.3
Many modern human technologies have affected the quality of air and water for all living
things.
Burning fossil fuels for heating, transportation and industry pollutes the air
Humans drink a lot of water. This additional competition for fresh water can impact
ecosystems.
Humans dump toxic chemicals into water systems. This can be harmful to ecosystems
and to humans that drink the water.
Humans build on habitats. Destruction of habitats means fewer producers available to
make food and support the basic needs of living things.
Humans use landfill sites to dispose of waste. In 2007, the city of Toronto disposed of
441 350 tonnes of solid waste to landfill sites every day. Although this is a very large
amount, it is less than it has been in the past due to recycling programs.
Sustainable Human Communities.
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A sustainable human community is one that more closely models an ecosystem.
Energy comes from renewable resources such as solar, wind.
Waste products are broken down and re-used.
There are costs associated with using sustainable technologies. At first, at can be
financially expensive because very few people are doing it. As more people use the
technology, the financial cost is reduced.
However, there are other costs, such as the environmental and social cost that is
associated with using sustainable technologies. These must also be considered, so that
we do not have such a harmful impact on ecosystems.