Section 3.2- Energy, Producers, and Consumers.

Section 3.2- Energy, Producers, and Consumers.

Vocabulary-

Autotroph: and organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer.

Primary producer: the first producer of energy-rich compounds that are later used by other organisms.

Photosynthesis: a process used by plants and other autotrophs to capture light and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches.

Chemosynthesis: a process in which chemical energy is used to produce carbohydrates.

Heterotroph: an organism that obtains food by consuming other living things; also called a consumer.

Consumer: an organism that relies on other organisms for its energy and food supply; also called a heterotroph.

Carnivore: and organism that obtains energy by eating animals. Ex: snakes, dogs, cats, river otter.

Herbivore: an organism that obtains energy by eating only plants. Ex: cows, caterpillars, and deer.

Scavenger: and animal that consumers the carcasses of other animals. Ex: king vulture.

Omnivore: and organism that obtains energy by eating both plants and animals. Ex: humans, bears, pigs, white-nosed coati.

Decomposer: an organism that breaks down and obtains energy from dead organic matter. Ex: bacteria and fungi. The decay caused by decomposers is part of the process that produces detritus- small pieces of dead and decaying plant and animal remains.

Detritivore: an organism that feeds on plant and animal remains and other dead matter. Ex: mites, snails, shrimp, crabs. Commonly digest decomposers that live on, and in, detritus particles.

Primary Producers-

• Living systems operate by expending energy
• Organisms need energy for growth, reproduction, and their own metabolic processes.
• Sunlight is the ultimate energy source.
• For some organisms, chemical energy stored in inorganic chemical compounds serves as the ultimate energy source for life processes.
• Only algae, certain bacteria, and some plants can capture energy from sunlight or chemicals and convert it into forms that living cells can use. (Those organisms are called autotrophs).
• Autotrophs use solar or chemical energy to produce “food” by assembling inorganic compounds into complex organic molecules. Also called primary producers.
• Primary producers are the first producers of energy-rich compounds that are later used by other organisms.
• So, primary producers and essential to the flow of energy through the biosphere.

Energy From the Sun-

·         The best known and most common primary producers harness solar energy through the process of photosynthesis. (See photosynthesis definition).

• Photosynthesis adds oxygen to the air and removes carbon dioxide, so without photosynthetic producers, the air would not contain enough oxygen for people to breathe.
• Plants are the main photosynthetic producers on land.
• Algae fill that role in freshwater ecosystems and in the sunlit upper layers of the ocean.
• Photosynthetic bacteria (cyanobacteria) are important primary producers in ecosystems such as tidal flats and salt marshes.

Life Without Light-

• Deep-see ecosystems depend on primary producers that harness chemical energy from inorganic molecules such as hydrogen sulfide.
• Those organisms carry out a process called chemosynthesis. (See chemosynthesis definition).
• Chemosynthetic organisms are not only found in the deepest, darkest ocean. Some chemosynthetic bacteria live in harsh environments, like deep-sea volcanic vents or hot springs.

Comparing Photosynthesis and Chemosynthesis-

            Plants use the energy from sunlight to carry out the process of photosynthesis. Other autotrophs, like sulfur and bacteria, use the energy stored in chemical bonds in chemosynthesis. So, in both processes, energy-rich carbohydrates are produced.

Consumers-

  

• Animals, fungi, and many bacteria cannot directly harness energy from the environment as primary producers do. They are known as heterotrophs, which are also called consumers. (See heterotroph and consumer definitions).

Types of Consumers-

• Carnivores, herbivores, scavengers, omnivores, decomposers, and detritivores. (See definitions).

Beyond Consumer Categories-

• Categorizing consumers is important, but the categories don’t often express the real complexity of nature.
• For example, herbivores that eat different plants parts often differ greatly in the ways they obtain and digest their food because seeds and fruits are rich in energy and nutrients and easy to digest, while leaves are poor in nutrients and hard to digest.
• Organisms in nature often don’t stay inside the categories ecologists place them in.
• For instance, some animals described as carnivores, will scavenge if they get a chance. and many aquatic animals eat a mixture of algae, bits of animal carcasses, and detritus particles.
• So the categories make a good place to start talking about ecosystems, but it is important to expand on this topic by discussing the way that energy and nutrients move through ecosystems.