Chapter 3.2-Energy, Producers, and Consumers

Every living thing needs energy for growth, reproduction, and its own metabolic processes (processes by which food is converted into the energy and products needed to sustain life). If there is no energy, there are no life functions. Organisms can't create energy by themselves, so they can only use energy from other sources. On Earth, sunlight is a vital energy source for many living things.

Not so long ago, researchers found out that there are other energy sources for life. Autotrophs are organims that are able to capture energy from sunlight or chemicals and use it to produce their own food. They use solar or chemical energy to make food by putting together inorganic compounds into complex organic molecules. Autotrophs are also called primary producers because they store energy in forms that make it available to other organisms that eat them. HINTS: auto means "by itself. Trophikos means "to feed." so autotroph means "self feeder."

Most primary producers use the sunlight through the process of photosynthesis. Photosynthesis captures light energy and uses it to power chemical reactions that convert carbon dioxide and water into oxygen and carbohydrates. If there were no photosynthetic producers like trees, there wouldn't be enough oxygen for humans to breathe.

Biologist found organisms around volcanic vents on the deep ocean floor. There was no light for photoshythesis, so the scientists were trying to find out what the primary producers were. These orgainisms used chemosynthesis. It is a process which chemical energy is used to produce carbohydrates. Chemosynthetic organisms are mostly found in deep ocean floors, but several types of producers have been found in other parts of the bioshere such as hot springs.

Consumers such as animals, fungi and many bacteria can't directly use energy from the environment as primary producers. They are also called heterotrophs because they must get energy and nutrients from other organisms by eating them. There are many different types of consumers. Below:

• Carnivores-eat meat
• Herbivores-eat plants
• Scavengers-eat food killed by other animals. ex. vultures
• Omnivores- eat both plants and animals
• Decomposers-they "feed" by chemically breaking down organic matter. The decay caused by decomposers is part of the process that produces detritus-small pieces of dead and decaying plant and animals.
• Detritivores- digest decomposers that live on detritus particles. They chew or grinds them into even smaller pieces. ex. mites, snails, shrimp, crab, worms
  

Organisms in nature usually don't stay inside the categories ecologists placed them in. For example, herbivores that eat different plant parts often have various ways of getting food. Most birds don't eat leaves. That is because seeds and fruits are easy to digest while leaves are difficult to digest. Also, some carnivores such as hyenas will try to scavenge if they get a chance.
Photosynthesis

Carbon dioxide +Water +Light Energy = Carbohydrates+Oxygen

Chemosynthesis

Chemical Energy-Carbon dioxide+Hydorgen sulfide+Oxygen = Carbohydrates+Sulfur compounds