The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion. Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages
Pesticide use can be very harmful beacause too much of them can cause the crops to go bad, and kill bees which help spread pollen and enhance the crops.
<span>Both photoautotrophs and chemoautotrophs synthesize organic compounds from (inorganic) carbon dioxide, a process known as carbon fixation. Photoautotrophs get the energy to perform these reactions from light. Chemoautotrophs get it from electron donors such as hydrogen sulfide and ammonia. Cyanobacteria, by contrast, convert nitrogen from the atmosphere into ammonia, a process known as nitrogen fixation.</span>
Using Punnett Squares, you can predict the genotypes and phenotypes of the offspring<span> of a cross between a homozygous (purebred) tall pea plant and a homozygous (purebred) short pea plant.</span>
Decomposers, as the name suggests, decompose dead plants or animals into simple compounds. They feed on dead producers from the first levels or consumers from other three levels. Breaking them down, decomposers release nutrients that producers can use.
In an ecosystem with four levels, the first level are producers, such as plants and algae. On the second trophic level, there are primary consumers, herbivores that eat plants, for example, a deer, a rabbit, a grasshopper. The next trophic level belongs to secondary consumers that eat herbivores, for example, a wolf, a fox. The highest level is tertiary consumers that eat carnivores, for example, a bear, an eagle.
