1. the movements of energy and nutrients through living systems are different because (1 point)

energy flows in one direction, and nutrients recycle.
energy is limited in the biosphere, and nutrients are always available.
nutrients flow in one direction, and energy recycles.
energy forms chemical compounds, and nutrients are lost as heat.

2. which of the following depends on bacteria? (1 point)

conversion of dead organic matter to fossil fuel
photosynthesis
dissolution of phosphates from rock
nitrogen fixation

3. which of the following is a correct statement? (1 point)

decomposition is an important part of only two of the three nutrient cycles.

the nutrient cycles contain paths of elements through the living world but not through the
nonliving world.

living organisms are able to convert inorganic forms of carbon, nitrogen, and phosphorus
into organic forms.

the atmosphere represents an important reservoir for organic forms of carbon and nitrogen.

4. because of biogeochemical cycling (1 point)

human activity has no effect on elements, chemical compounds, and other forms of matter.
living organisms are not limited by any one nutrient.
nutrients are circulated throughout the biosphere.
many nutrients do not reach toxic concentrations in the biosphere.

1. The correct answer is the first option: energy flows in one direction, adnd nutrients recycle. Think of a fly. When a fly is eaten by a frog, the energy from the fly goes into the frog. When the frog is eaten by a larger animal, then the energy from the frog goes into the larger animal. It's never the other way around (the energy from the larger animal doesn't go into the consumed frog, and the energy from the frog doesn't go into the consumed fly). However, the nutrients from these insects and animals are recycled, because the larger animal can use nutrients from both the frog and the fly. 2. The correct answer is nitrogen fixation. Nitrogen fixation is a chemical process in which nitrogen from the atmosphere is converted into organic compounds. This usually occurs with the help of certain microorganisms, which are bacteria. 3. The correct answer is the third option. Something is organic simply when carbon is covalently bonded to the atoms of other elements, a process which certain living organisms are able to do. 4. The correct answer is the third option. Biogeochemical cycling is a type of pathway that allows chemical substances to move through different spheres. This is why our actions on earth affect things like the atmosphere (for example the use of hairspray, and how it adds to the deterioration of the ozone layer).