Energy and Biochemical Cycles - AP Environmental Science

In cellular respiration, glucose and oxygen are used to produce energy, as well as carbon dioxide and water as wastes. Cellular respiration is essentially the opposite of photosynthesis. Do not confuse cellular respiration with respiration (breathing), which is the physiological process of taking air in to receive oxygen, and breathing air out to expel excess carbon dioxide produced during cellular respiration.

Much of the solar energy that enters earth is absorbed by atmospheric molecules or reflected off of surfaces, and a large portion of the energy is unsuitable for photosynthesis. Photosynthesis is powered by light energy that has wavelengths ranging from 400 to 700 nanometers (nm), while sunlight has a wavelength range from 250 to 2500 nm. As a result, only about 1% of available solar energy is used for photosynthetic activity.

Chlorophyll a and b absorb visible light wavelengths in the purple, blue, and red ranges of the visible spectrum of light and reflect visible light in the green range. The green color of leaves is a result of the green visible light being reflected back and isolated from the other visible colors in the spectrum that were absorbed.

During photosynthesis, plants and algae use solar energy to convert carbon dioxide and water to glucose and oxygen. Phosphorus is not involved in the photosynthesis chemical reaction as a reactant or product.

Cellular respiration is the opposite reaction of photosynthesis:

Photosynthesis converts carbon dioxide, water, and solar energy to sugar and oxygen. Respiration uses oxygen and sugars to provide a cell with energy. Water and carbon dioxide are produced as byproducts. Note that the form of energy used in photosynthesis is sunlight, while the form of energy produced during respiration is chemical energy.

Using energy from the bonds in, for example, hydrogen sulfide or methane, and carbon dioxide, deep sea bacteria can produce sugars identical to those produced in plants via photosynthesis. This is incredibly important for life in deep water where there is no light.

The correct response is producer. A producer converts sunlight into food using photosynthesis. This includes plants, algae, and some fungi. They are sometimes refereed to as primary producers or autotrophs. The big take-home point: producers make their own food.

Trophic levels are related to the transfer of energy in the food chain. Predators and members of the "top of the food chain" occupy higher trophic levels, while energy producers occupy the lower levels. The correct order from lowest to highest should be the maple tree, caterpillar, cardinal, king snake, and then the fox.

Trophic level (feeding level) describes the categories of organisms in a community, and the position of an organism in a food chain, defined by the organism's source of energy; includes producers (a photosythetic organism i.e. plants), primary consumers (an organism that feeds on producers; an herbivore), secondary consumers (an organism that feeds on a primary consumer;a carnivore), a tertiary consumer that feeds on other carnivores.

Scavenger, Detritivores and Decomposers are not any level of consumer since neither consumes any kind of living organism. Scavengers consume already dead organisms. Detritivores consume litter and dung. Decomposers break down biomass into nutrients. Only omnivores consume living organisms since they feed on both primary and secondary consumers.

Because of the law of conservation of energy, it cannot be 100% since some of the energy in each trophic level must be consumed by the organisms themselves. The energy is lost as heat through metabolic activities and other day to day expenditures. This number is supported due to the high number of producers and only a slight number of primary consumers in comparison.

Transpiration concerns the process through which water is carried through plants from roots to small pores in leaves, where it evaporates into the atmosphere. Thus transpiration is not a part of the carbon cycle, which concerns the biochemical exchange of carbon.

All of these are biogeochemical cycles:

Carbon cycle - plants and animals consume carbon dioxide and release carbon dioxide during decomposition or respiration, then the carbon dioxide returns to the atmosphere.

Phosphorus cycle - similar to the carbon cycle, plants and animals consume phosphorous and release it during decomposition. Then the phosphorous returns to the ground and waterways by way of bacteria and processes such as mineralization.

Nitrogen cycle - this is the most complicated biogeochemical cycles. This is because it takes place in multiple situations, including: nitrogen fixation, nitrification, denitrification, and ammonification.

Hydraulic cycle - the water cycle. Water evaporates, wind moves air (and water), precipitation occurs.

The Atmosphere is largely the source of Carbon in the Carbon cycle. Plants utilize photosynthesis to convert atmospheric Carbon Dioxide into Glucose. Animals consume this Glucose and store it in their bodies until they die. the Ocean hosts a large amount of dissolved Carbon Dioxide gas and has Calcium Carbonate as a storage place in oceanic organisms like coral.

Although all of the above are part of the nitrogen cycle, the major reservoir for nitrogen is the atmosphere. The atmosphere contains nitrogen gas which cannot be extracted by plants or animals from the atmosphere. From its reservoir in the atmosphere, nitrogen gas is combined with oxygen to form nitrate and carried to Earth dissolved in rain. Nitrogen-fixing bacteria produce ammonia. This is absorbed by plants and other producers and incorporated into biological molecules that are passed through the trophic levels. Nitrate and ammonia are released by excretion or by decomposer bacteria. Other bacteria convert these molecules back to atmoshperic nitrogen, completing the cycle.

A source is an organism or physical body that releases a certain compound or element. Through energy dynamics or physical manipulations of the environment, it reaches the sink. The sink is the receiver of the element and can act as another source for a different organisms or physical body. This is how matter travels in the environment, from pairs of source to sink dynamics.

According to the principles of the Nitrogen cycle, plants can only absorb nitrogen in the form of ammonia. This is achieved by nitrogen-fixing bacteria that convert atmospheric nitrogen into a form usable by plants. Plants excrete nitrogen in the form of waste as nitrates which are absorbed by animals.

The phosphorus cycle does not contain an atmospheric phase, while both the sulfur and nitrogen cycles do.

The reservoir of phosphorus in ecosystems is rock, where it is bound to oxygen in the form of phosphate. As phosphate-rich rocks are exposed and eroded, rainwater dissolves the phosphate. Dissolved phosphate is abosrbed through the roots of plants. Animals eat the plants and after they die decomposers return the phosphorus that remains in the dead bodies back to the soil and water. It may then be reincorporated into rock.

All of the other cycles have at least one atmospheric component in their systems. The carbon cycle incorporates carbon dioxide in the photosynthesis portion of its cycle. The sulfur cycle incorporates gaseous sulfur dioxide when it is released by volcanic eruptions. The water cycle has the condensation of clouds in the atmosphere and the precipitation of those clouds as well. The nitrogen cycle incorporates atmospheric nitrogen gas before it is fixed by cyanobacteria. Only the phosphorus cycle does not have a phosphorus containing compound in the atmosphere that is essential for life on Earth.