A biogeochemical cycle corresponds to the uninterrupted movement of atoms of chemical elements on the planet, which are essential for the maintenance of life on Earth. This recycling of elements occurs through the interaction between living beings and the environment.
a) Living beings, chemical reactions and abiotic components
b) Microorganisms, electrical discharges and geological transformations
c) Physical transformations, inorganic components of the earth's surface and human activities
d) Climatic elements, ecosystems and biological evolution
You living beings participate in numerous transformations in biogeochemical cycles, which are formed by successive chemical reactions for the natural movement of chemical elements between the biosphere and the abiotic components, that is, between living beings and the environment.
Biogeochemical cycles are essential for the maintenance of life on the planet, as they allow chemical elements flow naturally between earth systems: atmosphere, hydrosphere, lithosphere and biosphere.
(FATEC/2016) Biogeochemical cycles are essential for the existence and perpetuation of known life forms. Among these cycles, five of them have a greater flow of matter and their elements make up more than 95% of the mass that makes up living beings. These cycles are:
a) water, oxygen, calcium, sulfur and cesium.
b) water, carbon, nitrogen, phosphorus and sulfur.
c) hydrogen, helium, oxygen, nitrogen and sulfur.
d) water, hydrogen, carbon, phosphorus and cesium.
e) helium, lithium, beryllium, boron and carbon.
Of the 118 known chemical elements, only about 30 elements are essential to living things.
Regarding the composition of living beings, more than 95% corresponds to the elements carbon (C), oxygen (O), nitrogen (N), hydrogen (H), sulfur (S) and phosphorus (P). In addition, water () is also a common component and main constituent.
With respect to types, classify the following biogeochemical cycles into gaseous (1) and sedimentary (2).
For a biogeochemical cycle to occur, the existence of a reservoir of the chemical element is essential, that is, an environment in which it is available in large quantities.
Gaseous biogeochemical cycles are those with the main reserve of the element in the atmosphere, as in the carbon, oxygen and nitrogen cycle.
Sedimentary biogeochemical cycles are those with the main reserve of the element in the Earth's crust, as in the cycle of calcium, sulfur and phosphorus.
The nitrogen cycle corresponds to the reaction circuit that distributes the chemical element nitrogen through nitrogenous compounds between the environment and living beings.
a) biological fixation, physical fixation, assimilation and fertilization
b) absorption, nitration, nitrosation and excretion
c) fixation, ammonification, nitrification and denitrification
d) nitromarking, conservation, stabilization and dispersion
Fixation: transformation of nitrogen gas from the atmosphere into ammonia;
Ammonification: decomposition of nitrogen compounds and production of ammonia;
Nitrification: conversion of ammonia into nitrite and later into nitrate;
Denitrification: conversion of nitrates into nitrogen gas, which is released into the environment.
The chemical species that are part of the nitrogen cycle are:
Nitrogen gas () present in the atmosphere, which is converted into ammonia (
) in the fixation step and also ammonia is produced in the decomposition of nitrogen compounds in the ammonification process.
Subsequently, the nitrification step converts ammonia to nitrite () and then into nitrate (
).
Finally, nitrogen is returned to the atmosphere by converting soil nitrates into nitrogen gas (), in the absence of oxygen, or also as nitrous oxide (
).
(UFPR 2021) About the biogeochemical cycles, which allow the interaction of elements with the environment and with living beings, mark the correct alternative.
a) Legume roots such as beans, soybeans and peas have the ability to associate with nitrogen-fixing bacteria.
b) Global warming is due to the reduction in the rate of oxygen in the atmosphere and the increase in sulfur dioxide emissions.
c) Cyanobacteria are capable of degrading inorganic matter and making phosphorus available to other living beings.
d) The main way to incorporate atmospheric nitrogen () in organic molecules is through foliar absorption during photosynthesis.
e) The preservation of forests contributes to the reduction of the greenhouse effect, as it guarantees the capture of atmospheric CO2 through the respiration of plants.
Fixative bacteria associated with legume roots are capable of biological nitrogen fixation.
genus bacteria rhizobium and azobacter convert nitrogen from the air () into ammonia (
) breaking the molecule with the enzyme nitrogenase. These beings are usually inserted in the nodules of the roots of plants, mainly legumes.
(PUC-RS/2018) The figure below is a partial representation of the nitrogen cycle.
I. The number 1 represents nitrogen fixation.
II. The numbers 2 and 3 represent steps in the denitrification process.
III. The numbers 2 and 3 are mediated by prokaryotic organisms.
IV. The number 4 represents the nitrification process.
I. CORRECT. Nitrogen fixation corresponds to the conversion of molecular nitrogen into ammonia.
II. WRONG. The conversion of ammonia to nitrite and then to nitrate is part of the nitrification step.
III. CORRECT. Bacteria are prokaryotic beings and at this stage the nitrifying bacteria act to produce nitrogen compounds that can be assimilated by plants.
IV. WRONG. It is represented that plants assimilate the product in nitrification, which in this case are nitrates.
Photosynthesis and chemosynthesis are the processes that, in nature, transform carbon dioxide into organic matter.
The return of this gas to the atmosphere takes place through cellular respiration, decomposition and the burning of fuels.
The water cycle or hydrological cycle corresponds to the cycling of a substance essential for the survival of living beings on Earth.
Consider the stages of the cycle (column 1) and relate them to their descriptions (column 2).
( ) Step in which water in the gaseous state returns to the liquid state.
( ) Stage in which water is absorbed by the soil and the formation of underground reservoirs occurs.
( ) Stage in which water from the hydrosphere passes into the atmosphere by changing from a liquid to a gaseous state.
( ) Stage in which rain occurs, that is, the release of condensed water vapors.
( ) Stage in which excess water is released by the leaves of plants through the transformation of liquid water into water vapour.
( ) Step in which water in the solid state changes to the gaseous state without passing through the liquid state.
At evaporation water from the hydrosphere passes into the atmosphere by changing from a liquid to a gaseous state.
At sublimation water in the solid state changes to the gaseous state without passing through the liquid state.
At condensation water in the gaseous state returns to the liquid state.
At precipitation rain occurs, that is, the release of condensed water vapors.
At infiltration the water is absorbed by the soil and the formation of underground reservoirs occurs.
At perspiration Excess water is released by plant leaves through the transformation of liquid water into water vapour.
