Topic 5.1: Communities & Ecosystems

1

Objectives of today’s class….• Learn the basic language of ECOLOGY– Ecology, ecosystem, population, species,

community• Learn about energy flow in ecosystems

Kick-off: Inquiry Activity

In groups of 2-3, you have five minutes to….• Choose a location and write it down, then• Make a list of all of the types of organisms,

including plants, humans, animals, insects etc that you have seen in a specific location.

Inquiry Activity

• Make a diagram that shows how the organisms that you listed interact with each other.

• Who eats who/what?• Where do these organisms live?

Think About It

• 1. Which organisms on your list provide energy or nutrients to the others?

• 2. What would you expect to happen if all the plants in your diagram died? EXPLAIN your answer.

• 3. Why is it difficult to make accurate predictions about changes in communities of organisms?

5.1.1 What is ecology?

• Ecology is the scientific study of interactions among organisms and between organisms and their environment

• Etymology (word Root): eco comes from the Greek oikos which means house.

The Biosphere

The biosphere contains the combined portions of the Earth in which all life exists, including land, water and air or atmosphere.

It extends 8 km above the Earth’s surface and as far as 11 km below the surface of the ocean.

5.1.1 Within the Biosphere are levels of organization

5.1.1 Definitions (you must know these!)

Species: – A group of individuals who can reproduce and

produce fertile offspring.

Populations– Members of the same species who live together in

the same time and place.

5.1 Community vs. Population

A community is assemblage of different populations that live together in a defined area

A population is a group individuals that belong to the same species and live in the same area

5.1.1 Ecosystem

An ecosystem is a collection of all organisms that live in a particular place, which includes the non-living, or physical, environment

5.1.1 Habitat: Definition

Habitat is the environment in which a species normally lives or

the location of a living organism.

Challenge: 2 minutes

1. What did you eat for breakfast?2. What were the ingredients?3. Where did the energy for the ingredients

come from?.....

So what does this have to do with energy?

Connecting 5.1.2 and 5.1.9

1. True or False: Sunlight is the main energy source for all life on Earth:

2. Producers are autotrophs: an organism that synthesizes its organic molecules from simple inorganic substances.

TRUE!

which means they can make their own food from sunlight or chemicals in the environment.

• The process that converts sunlight, water and carbon dioxide into energy is called.

2: Trophic Levels, Food webs and good chains

5.1.2 – 5.1.8

Data Based Question: Pop Quiz!• You have 10 min.

• You may NOT use class notes.

• You may refer to your command term definitions.

From S. Taylor, i-biology 2012

Trophic levels of organisms: Autotrophs/ Producers

Food energy is most commonly produced from light energy through photosynthesis

Some autotrophs can produce food energy without light, instead using chemicals like hydrogen sulfide. These autotrophs use a process called chemiosynthesis.

Trophic levels: Heterotrophs/ Consumers (and decomposers)

Organisms that rely on other organisms for food are called heterotrophs or consumers.

Complete the chart for the different types of consumers and what they eat.

5.1.3 Three Types of HeterotrophConsumer Detritivore Saprotroph

Ingests other organic matter that is living or recently killed

An organism that ingests non-living organic matter

An organism that lives on or in nonliving organic matter, secreting digestive enzymes into it and absorbing products of digestion

Herbivores, carnivores

Worms, scavengers (shrimp, vultures)

Fungi and bacteria

5.1.14 So what do decomposers do?

Saprotrophic bacteria and fungi (decomposers)

recycle nutrients (organic matter and other

essential elements) in an ecosystem

Food Chains vs. Food Webs

5.1.4 Food Chain

light

5.1.5, 6, 7 Food Webs & Trophic Level

• Trophic Level:

5.1.10 Feeding Relationships

Energy flows through an ecosystem in one direction from the sun or other inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)

• The arrows in a food chain (or food web) indicate the direction of energy flow

• Trophic relationships within communities tend to be complex and web-like

Syllabus Topic 5.1.8

• Create your own food web with 5 to 10 organisms.

• You must use names, common names (red oak) are OK, “tree” is not.

• OBJECTIVE 3: “Analyse, comment, compare, constuct, deduce, derive, design”

Click here

Data-based question: ‘Fishing down the Food web…’

A recurring pattern of declining mean trophic level of fisheries landings, termed “fishing down the food web,” is thought to be indicative of the serial replacement of high-trophic-level fisheries with less valuable, low-trophic-level fisheries as the former become depleted to economic extinction. An alternative to this view, that declining mean trophic levels indicate the serial addition of low-trophic-level fisheries (“fishing through the food web”), may be equally severe because it ultimately leads to conflicting demands for ecosystem services. PNAS February 28, 2006 vol. 103 no. 9

The number in [ ] is the point value for the question

Take out your food web

• Double check the arrows, are they going in the direction of energy flow?

• Label all the trophic levels

3: Ecological Pyramids

5.1.12 Ecological Pyramids

An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or web.

5.1.12 Energy Pyramid

Biology Update!

• The “rule of 10” was based on aquatic ecosystems.

• It still generally applies… but…• Recent studies have shown that energy

efficiency can range from 0.05% to 20%.

Calculating energy efficiency

33 kJ

Only 4 kJ of the original energy available to the bullock is available to the next stage, which might be humans. The efficiency of this energy transfer is:efficiency = 4⁄100 × 100 = 4%

How can we improve efficiency?

Food production is more efficient if the food chain is short, because a higher percentage of energy is available to the top trophic level.

5.1.11

• True or False:• Energy transformations are 100% efficient

FALSE!

5.1.12 The Shape of Energy Pyramids

• A pyramid of energy shows the flow of energy from one trophic level to the next in a community.

• The units of pyramids of energy are, therefore, energy per unit area per unit time, for example, kJ m–2 yr–1

A sample Energy Pyramid

Working With Data (WWD)

5.1.13

Unlike the one way flow of energy, matter is recycled within and

between ecosystems. These are called

biogeochemical cycles

Syllabus Check!

• Compare your notes to the syllabus.• Do you have information for all of the topics?• Rate your understanding 0-3 for each topic0: What? Was I even here for this?1: some of these words sound familiar2: I feel pretty comfortable with this, but I might need

to look something up3: Hooray! I could definitely explain this to the class.