Chapter 2.2 – Nutrition and Energy Flow

1. The ultimate source of energy for life is the SUN

2. Plants use the sun’s energy to manufacture food in a process known as PHOTOSYNTHESIS

Where Does Earth’s Energy Come From?

1. An organism that can make its own food is called an AUTOTROPH

2. Autotrophs are also called PRODUCERS because they provide the entire food chain with energy

3. Plants and algae are the most common type of autotroph and they make their own food using photosynthesis

Autotroph

1. An organism that cannot make its own food is called a HETEROTROPH

2. Heterotrophs obtain energy by eating other organismsa) Heterotrophs are also known as CONSUMERS

because they get energy from other organisms.

Heterotroph

1. An HERBIVORE is a heterotroph that feeds only on PLANTS

a) E.g. cows horses, zebras, squirrels

Herbivore

1. A CARNIVORE is a heterotroph that feeds only on other heterotrophs (meat, insects, etc)

a) E.g. Lions, sharks, wolves

Carnivore

1. An OMNIVORE is a heterotroph that feeds on BOTH plants and animals

a) E.g. Humans, bears, raccoons, skunks

Omnivore

1. A SCAVENGER is a heterotroph that does not kill for food but eats already dead animals

a) E.g. Vultures, insects, crabs

Scavenger

1. DECOMPOSERS break down and release nutrients from dead organisms (recycle)

a) E.g. Bacteria, fungus

Decomposer

1. A FOOD CHAIN is a simple model that shows how matter and energy moves through an ecosystem

2. producers consumers decomposersa) Arrows on a food chain show the direction

ENERGY is moving

Food Chain

1. Each step in a food chain is called a TROPHIC LEVEL

2. Trophic levels include:a) Producers – autotrophs that produce their own foodb) Primary Consumers – heterotrophs that eat

autotrophsc) Secondary Consumers – heterotrophs that eat

primary consumersd) Tertiary Consumers – heterotrophs that eat

secondary consumers

Trophic Levels

Food Web

1. Most of the time food chains are too simple and don’t show all of the feeding relationships in an ecosystem

2. A FOOD WEB is a complex model of interconnected food chains that shows all of the feeding relationships in an ecosystem

10% Rule

1. As energy moves up the food chain, 90% of it is lost as HEAT

2. Only 10% of energy moves up to the next level

a) The 90% that is lost is used up by the organism for metabolism and movement; only 10% is stored in its tissues

Nutrient Cycles

1. Matter and nutrients must be recycled in all ecosystems; matter is not unlimited like energy from the sun

2. Nutrient cycles:a) Water Cycleb) Carbon Cyclec) Nitrogen Cycle

1. All life depends on water. Water moves around the Earth in a cycle

2. EVAPORATION: liquid water changes into water vapor (liquid gas)

3. CONDENSATION: water vapor changes to liquid water (gas liquid)

4. PRECIPITATION: water falls from the atmosphere back to Earth (rain, snow, etc.)

5. RUNOFF: gravity causes all water to eventually flow back to oceans or lakes

6. TRANSPIRATION: plants lose water vapor through their leaves7. Animals breathe out water vapor in every breath and also return

water through urine and sweat

The Water Cycle

The Carbon Cycle

1. All life is based on the Carbon moleculesa) Carbon atoms form the backbone for proteins,

carbohydrates, fats, and other important life molecules

2. Autotrophs convert CARBON DIOXIDE (CO2) and water into sugars through the process of photosynthesis

3. Plants and animals break down the sugars and release CO2 back into the atmosphere

The Carbon Cycle

1. A large amount of CO2 dissolves in and out of the oceans

2. Decomposers return the carbon of dead plants and animals back to the atmosphere

3. When plants and animals die and are quickly buried, over millions of years, the carbon in their bodies can be converted into FOSSIL FUELS

4. When fossil fuels are burned CO2 is released back into the atmosphere

The Nitrogen Cycle

1. 78% of the air is Nitrogen (N2)

2. Plants cannot use nitrogen in this form3. Bacteria in the roots of plants can “fix”

atmospheric nitrogen by turning it into a usable form for plants

4. Animals get nitrogen by eating plants5. Animals return nitrogen to the soil through

urination and death/decay6. Man-made fertilizers also give nitrogen to plants