MB 10 Intro

What organisms are autotrophs?

Almost all plants are autotrophs; the only nutrients they require are water and minerals from the soil and carbon dioxide from the air. Specifically, plants are photoautotrophs, organisms that use light as a source of energy to synthesize organic substances. Photosynthesis also occurs in algae, certain other protists, and some prokaryotes (i think this also makes them autotrophic).

How does photosynthesis go about nourishing the entire living world?

An organism acquires the organic compounds it uses for energy and carbon skeletons by one of the two major modes: autotrophic nutrition or heterotrophic nutrition.

What are autotrophs?

Autotrophs are "self-feeders" (auto-means "self," and trophos means "feeder"); they sustain themselves without anything derived from living beings. Autotrophs produce their organic molecules from CO2 and other inorganic raw materials obtained from the environment. They are the ultimate source of organic compounds for all nonautotrophic organisms, and for this reason, biologists refer to autotrophs as the "producers" of the biosphere.

What are some of the types of alternative fuels that are coming from plants and algae?

Biofuels from crops such as corn, soybeans, and cassava have been proposed as a supplement or even replacement for fossil fuels. To produce "bioethanol," the starch made naturally by the plants is simply converted to glucose and then fermented to ethanol by microorganisms. Alternatively, a simple chemical process can yield "biodiesel" from plant oils. Either product can be mixed with gasoline or used alone to power vehicles. Some species of unicellular algae are especially prolific oil producers, and they can be easily cultured in containers such as the tubular plastic bags.

How do heterotrophs obtain their organic material?

Heterotrophs obtain their organic material by the second major mode of nutrition. Unable to make their own food, they live on compounds produced by other organisms (hetero- means "other"). Heterotrophs are the biosphere's consumers.

The main product of fossil fuel combustion is CO2, and this combustion is the source of the increase in atmospheric CO2 concentration. Scientists have proposed strategically situating containers of these algae near industrial plants, or near highly congested city streets. Why does this arrangement make sense?

I believe this arrangement makes sense because the algae can utilize the CO2 in order to produce even more and more fuels, at the same time removing the CO2 away from the atmosphere, which will in turn lessen the green house effect. Situating containers of algae near sources of CO2 emissions makes sense because algae need CO2 to carry out photosynthesis. The higher their rate of photosynthesis, the more plant oil they will produce (this is a win win win situation!). At the same time, algae would be absorbing the CO2 emitted from industrial plants or from car engines, reducing the amount of CO2 entering the atmosphere.

What is the life on earth powered by?

Life on earth is solar powered. The chloroplasts of plants capture light energy that has traveled 150 million kilometers from the sun and convert it to chemical energy that is stored in sugar and other organic molecules. This process is called photosynthesis.

How did the fossil fuels that we use today in our cars and other things come about?

The Earth's supply of fossil fuels was formed from remains of organisms that died hundreds of millions of years ago. In a sense, then, fossil fuels represent stores of the sun's energy from the distant past. Because these resources are being used at a much higher rate than they are replenished, researchers are exploring methods of capitalizing on the photosynthetic process to provide alternative fuels.

What are the two stages of photosynthesis?

The light reactions, in which solar energy is captured and transformed into chemical energy; and the Calvin cycle, in which the chemical energy is used to make organic molecules of food.

What are some forms of heterotrophic consumption?

The most obvious form of heterotrophic consumption ("other feeding") occurs when an animal eats plants or other animals. But heterotrophic nutrition may be more subtle. Some heterotrophs consume the remains of dead organisms by decomposing and feeding on organic litter such as carcasses, feces, and fallen leaves; they are known as decomposers. Most fungi and many types of prokaryotes get their nourishment this way. Almost all heterotrophs, including humans, are completely dependent, either directly or indirectly, on photoautrotrophs for food-and also for oxygen, a by-product of photosynthesis.

Why should we be researching biofuels?

The rate of fossil fuel use by humans far outpaces its formation in the earth: Fossil fuels are a nonrenewable source of energy. Tapping the power of sunlight by using products of photosynthesis to generate energy is a sustainable alternative if cost effective techniques can be developed. It is generally agreed that using algae is preferable to growing crops for this purpose because this use of cropland diminishes the food supply and drives up food prices.