All things on Earth can be classified into one of two categories

BIOTIC ABIOTIC

insects

fungi

bacteria

plants

birds

mammals

reptiles

amphibians

fish

substrate

precipitation

temperature

sunlight

wind

disturbances (fire, hurricanes)

nutrients

BIOLOGY = the study of living things

What things make something “living” vs. “nonliving”?

1. reproduction (DNA)

2. movement

3. metabolism

4. growth

5. stimulus response to the environment

atoms

molecules

cells

subatomic particles

tissues

organs

organ systems

organisms

populations

communities

ecosystems

biosphere

Earth

Hierarchy of Life

ecosystem

community

population

organism

a community of species combined with their abiotic (nonliving) environment

any single life form

a group of interacting organisms of the same species that occupy a specific area at the same time

populations of all the different species occupying a particular place at the same time

E = energy

The single most essential requirement for living things.

Without it, cells cannot work and all biological processes stop.

ENERGY FLOW IN BIOLOGICAL SYSTEMS

What is the ultimate source of energy for living things on Earth?

The ultimate source of energy for life on Earth is the sun

CO2

H2Oyields sugar + O2

photosynthesis converts the radiation E of the sun into chemical bond E stored in sugar (glucose)

Captured E from the sun is stored in the chemical bonds of glucose

Living things access this stored E by breaking these bonds during metabolism

RESPIRATION

Living organisms are either:Living organisms are either:

AUTOTROPHS

HETEROTROPHS

so….

• energy comes to our planet from the sun

• is converted into chemical bond energy by photosynthetic organisms

• is accessed for use by organisms through aerobic or anaerobic respiration

- all life is linked in food chains and webs -

Green plants are called producers because they “produce” food for the rest of the planet

The sun = E source

Primary consumers eat producers (green things).They are also known as herbivores (“herb eaters”).

Secondary consumers eat primary consumers.They are also known as carnivores (“meat eaters”).

FOOD CHAIN

secondary consumer

primary consumer

tertiary consumer

primary producer

tertiary consumer

secondary consumer

primary consumer

primary producer

FOOD PYRAMID

tertiary consumer

secondary consumer

primary consumer

primary producer

DECOMPOSERS…turning a food chain into a food cycle

• feed on dead producers and consumers• are necessary for the renewal of life because they recycle nutrients and biological molecules making them available to be used again by producers

Energy flows along the chains in one direction from the sun.

At each link in the chain, there is energy loss.

tertiary consumer

secondary consumer

primary consumer

primary producer

10%

10%

10%

Only about 10% (5%-20% range) of the E stored in biological mass at onelevel of the food pyramid is converted to biological mass at the next level

The other 90% of energy is lost in transfer – largely as heat

Why should we care about food chains and

food webs ??

In the 1800’s, sea otters were hunted to near extinction

The main food of sea urchins = kelp

kelp creates kelp forests critical habitat: providing food and shelter for hundreds of marine species

Sea Otter Sea Urchins Kelp forestall species dependent

on kelp forest

As Sea Otter population recovered, this trend was reversed

The main food of sea otters = sea urchins

1. Understanding food webs allows us to better understand and predict how impacts to ecosystems will influence all species.

sea algaeAdelie penguins

krill

As global warming diminishes Antarctic sea ice, the algae that inhabit the substructure of the sea ice disappear.

In turn, krill that feed on the algae decline, leaving little food for the penguins that feed on krill.

2. They allow us to trace the movement of materials through ecosystems

foodwebs are often used to trace the bioaccumulation of toxins in wildlife

Methylmercury is absorbed by algae and plankton in the ocean and biomagnifies/ bioconcentrates as it moves up the food chain.

Life on Earth is sustained by:

1. the flow of E from the sun through living things by their feeding interactions

2. the cycling of matter (the atoms and molecules needed for survival) through the biosphere