1. Ch. 3 The Biosphere

2. 3-1 What Is Ecology?
Ecology- the study of interactions among organisms and between organisms and their environment.

3. 3-1 What Is Ecology?
Biosphere- the combined portions of the planet in which all life exists, including land, water and air.

4. 3-1 What Is Ecology?
To understand relationships within the biosphere, ecologists study events and organisms that range from a single individual to the entire biosphere.

5. 3-1 What Is Ecology?
Species- organisms so similar that they can breed and produce fertile offspring.
Populations- one species that lives in the same area.
Communities- many different species that live in the same area.

6. 3-1 What Is Ecology?
Ecosystem- all the organisms in a particular place together with their nonliving environment.
Biome- group of ecosystems that have the same climate and similar communities.

7. 3-1 What Is Ecology?
Scientists conduct ecological research using three basic approaches:
1) observing
2) experimenting
3) modeling

8. 3-2 Energy Flow Sunlight is the main energy source for life on Earth.
Some types of organisms can use the energy stored in inorganic chemical compounds.

9. 3-2 Energy Flow
Autotrophs(producers)- use energy from the environment to make their own food.
Photosynthesis- the process of converting light energy into carbohydrates (food).

10. 3-2 Energy Flow
Chemosynthesis- the process of using chemical energy to produce carbohydrates (food).

11. 3-2 Energy Flow
Heterotrophs(consumers)- organisms that rely on others for their energy and food supply.
Herbivores- plant eaters
Carnivores- meat eaters
Omnivores- plant and meat eaters
Detritivores- eat dead matter (plant and animal remains)

12. 3-2 Energy Flow
Decomposers- bacteria and fungi that break down organic matter.
Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs and then to heterotrophs.

13. 3-2 Energy Flow
Food chain- a series of steps in which organisms transfer energy by eating and being eaten.
Food web- complex interactions linking various food chains in an ecosystem together.

14. 3-2 Energy Flow
Trophic level- one level in a food chain or food web (1st trophic level-producers, 2nd trophic level- consumers, etc.)
Ecological pyramid- shows the relative amounts of energy or matter within each trophic level.

15. 3-2 Energy Flow
Only about 10% of the energy available within one trophic level is transferred to organisms at the next trophic level!
Biomass- total amount of living tissue within a given trophic level.

16. 3-3 Cycles of Matter
Unlike the one-way flow of energy, matter is recycled within and between ecosystems.
Biogeochemical cycles- elements, compounds and other matter passed between organisms in different parts of the biosphere.

17. 3-3 Cycles of Matter The Water Cycle
Evaporation- process by which water changes from liquid to gas.
Transpiration- water evaporating from the leaves of plants.

18. 3-3 Cycles of Matter
Nutrients- all the chemical substances that an organism needs to sustain life.
All living organisms need nutrients to build tissues and carry out essential life functions.

19. 3-3 Cycles of Matter
Nitrogen fixation- process by which certain bacteria convert atmospheric nitrogen into ammonia, nitrates, and nitrites to be used by producers to make proteins.
Denitrification- process by which some soil bacteria convert nitrates into nitrogen gas.

21. 3-3 Cycles of Matter
Primary productivity- the rate at which producers can create organic matter.
Limiting nutrient- substance that is scarce or cycles slowly, limiting an ecosystem.

22. 3-3 Cycles of Matter
Algal bloom- a large increase in algae and other producers when an aquatic ecosystem receives a large amount of a limiting nutrient (i.e., runoff from heavily fertilized field).