CHAPTER 2 Biogeochemical Cycles

Question 1

substance composed of single type of atom, meaning that it cannot be broken down chemically to make a simpler substance.

Micro Elements – elements that are required by living organisms in smaller amounts
ex. —

Macro Elements – elements required by living organisms in larger amounts
ex. —

Answer 1

Elements
B, Cu, Mo
C,H,O,N,P,S

Question 2

also known as “nutrient cycles” – pathways for the transport and transformation of matter within four categorical areas that make up planet Earth.

Four Categorical Areas:
GAHB

Answer 2

Biogeochemical Cycles

Question 3

Biogeochemical Cycles Category

Sedimentary Cycles – (Sulfur, Phosphorus, etc.) it’s main reservoir pool is —- and the —— involved in circulation are non- gaseous.
-This cycle are usually very slow as the elements may get locked up in rocks and go out of circulation for long periods.

Answer 3

atmosphere or water.
lithosphere
biogenetic materials

Question 4

Carbon Cycle

It is the —— on the planet Earth as it is the building blocks of organic compounds (carbohydrates, DNA, fats, proteins, etc.) that enables an organisms to live and survive.

In the atmosphere, carbon is attached to some oxygen in a gas called Carbon Dioxide (CO2) which makes up 0.037% of troposphere.

Processes that predominantly produce CO2 are called —– of atmospheric CO2, while those that absorbs CO2 are called —–.

Answer 4

backbone of life
sources
sinks

Question 5

Carbon Cycle

Carbon may constitute about —- of the living
organisms.
It’s the largest constituent in living organisms and the way it moves in the ecosystem involve the participation of the four components of ecosystem: A, B, L (solid), H (water)

Answer 5

40%

Question 6

Carbon Cycle

CO2 is primary coming from —-.
CO2 may directly dissolves in the —–.
It may absorbed by plants in the form of —–.
The main use of CO2 is in —-.
In —–, CO2 goes back to the atmosphere.

Answer 6

atmosphere
hydrosphere
Carbonates
photosynthesis
respiration

Question 7

Steps in Carbon Cycle

1. Green plants absorb CO2 from the atmosphere and produce carbon containing sugars called Photosynthesis.
2. Plant trap the sun’s light energy in a compound called chlorophyll. This energy is converted to a chemical form called adenosine triphosphate (ATP).
3. Then, plants use the energy from ATP to produce sugar (C6H12O6).
4. The process of photosynthesis requires water (H2O) as well as produces water and oxygen (O2).
   6 CO2+ 6 H2O+ sunlight- C6H12O6 + 6O2
5. Animal eat plants to obtain the energy trapped during photosynthesis. As the animals’ bodies breakdown the carbohydrates in the plant tissues, CO2 is released to the atmosphere. This process is called Respiration.
6. The net chemical reaction of respiration is the exact opposite of photosynthesis:
   6O2 + C6H12O6- 6 H2O + 6 CO2
7. Plants respire as well as they breakdown the organic molecules in themselves in order to release the stored energy.
8. Plants and animals also release CO2 to the atmosphere when they decompose or decay. The chemical reaction for this process is the same as the respiration.
9. When dead plants and animals slowly decay under high pressure and high temperatures, they may form pools of energy known as fossil fuels.
10. The chemical process of burning fuel known as combustion is the same as respiration and decomposition:
    6O2 + C6H12O6 - H2O + 6 CO2
11. The decomposer breakdown the dead organic matter and release the carbon dioxide into the air. Decomposers are essential because without them, all of the carbon on the planet would eventually become locked up in dead carcasses and other trash.
12. Decay permits carbon to be released back into the food web.
13. Carbon Dioxide and other gases, such as water vapor are called greenhouse gases. It is the key components of nature’s thermostat.
14. If the cycles generates too much carbon dioxide, the atmosphere will get warmer while reduction of this gas will result to a colder temperature hence, it plays important role in the energy balance on Earth.

Answer 7

1.

Question 8

Carbon Cycle

Answer 8

• PHOTOSYNTHESIS
• CELLULAR RESPIRATION/COMBUSTION
• DECOMPOSITION

Question 9

Oxygen Cycle

Formerly known as “—–”
French chemist Antoine Lavoisier give the name “oxygen”
* Oxygen like Carbon is a basic element of life.
* It is present in large quantities with — in the atmosphere and it is seen in bound state in water and as oxides and carbonates in rocks.
* Photosynthesis became the source of Oxygen.
* Ozone (O3) - it provides protection to life by filtering out the sun’s UV rays by UV radiation

Answer 9

Dephlogisticated air
20.95%

Question 10

Oxygen Cycle

It describes the movement of oxygen within and between its three main reservoirs: the atmosphere, the biosphere, and the lithosphere.

The main driving factor of the oxygen cycle is the photosynthesis therefore, oxygen and carbon cycles are usually linked which called —

Answer 10

oxygen – carbon cycle.

Question 11

Steps in Oxygen Cycle

1. Plants give out oxygen during the process of photosynthesis.
2. Animals and other aerobic organisms take in oxygen to respire.
3. These living beings release CO2 into the atmosphere during the process of respiration. This CO2 is again used by plants for photosynthesis to produce oxygen.

Question 12

Nitrogen Cycle

It is essential element to life as it is a key component of — and —.
It occurs in many forms and is continuously cycled among these forms by a variety of —.
Although, it is abundant in the atmosphere as diatomic nitrogen gas (N2), it is extremely stable, and conversion to other forms requires a great deal of energy.
It is important element for organisms because it is constituent of CHON molecules, DNA molecules and components of enzymes.

Answer 12

proteins
nucleic acids
bacteria

Question 13

Nitrogen Cycle

It’s circulation involves the four components of the earth.
N2 in atmosphere, first get into the hydrosphere, biosphere and lithosphere by natural means of —-.
—– - chemical form of N2 absorbed by plants.

Answer 13

lightning/ photochemical discharge
NH4+ (Ammonium)

Question 14

Nitrogen Cycle

The faster way of conversion of N is through the participation of N fixing bacteria such as Azolobacter.
Plants cannot fix N2 gas nor the Azotobacter bacteria alone.
The fixing takes place when they take an association (—–).
Also, N is form through fertilizer production such as that of (NH4), Sulfate and urea.
N gets exhausted in the soil, that is why they are manufactured in the chemical plant.

Answer 14

symbiotically

Question 15

Steps in Nitrogen Cycle

1. N2 –> NH𝟒^+ or NO𝟑^−
2. NH3 –> NO𝟐^− –> NO𝟑^−
   Nitrosomonas Nitrobacter
   3.
   NO𝟑^− & NH𝟒^+ incorporation into biological tissue
3. NO𝟐^−/NO𝟑^− –> NH 𝟒^+
4. NO 𝟑^− –> N2
   Denitrifying bacteria Pseudomonas

Answer 15

NITROGEN FIXATION
NITRIFICATION
ASSIMILATION
AMMONIFICATION
DENITRIFICTION

Nitrosomonas and Nitrobacter arechemoautotrophic organisms found in soil and water, and are responsible for the oxidation of ammonium to nitrite (Nitrosomonas) and nitrite to nitrate (Nitrobacter).

Question 16

Nitrogen Cycle

Nitrogen Fixation – the process by which gaseous nitrogen (N2) is converted to ammonia (NH3 or NH4+) via biological fixation or nitrate (NO﷐3﷮−﷯) through high energy physical processes. Legumes form nodules on the roots where nitrogen fixing bacteria take N from air and convert it into ammonia (NH3).

Nitrification – is a two- step process which NH3/ NH4+ is converted to NO3-.
1. The soil bacteria Nitrosomonas and Nitrococcus convert NH3 to NO2-
2. Then Nitrobacter, oxidizes NO﷐2﷮−﷯ to NO﷐3﷮−﷯ .
these bacteria gain energy through these conversion, both of which requires oxygen to occur.

Assimilation – the process by which plants and animals incorporates the NO3- and ammonia formed through nitrogen fixation and nitrification. Plants take up these forms of N through their roots, and incorporate them into plant proteins and nucleic acids. Animals are then able to utilize N from the plant tissues. It produces large qualities of organic nitrogen (proteins, amino acid, & nucleic acid)

Ammonification – is the conversion of organic nitrogen into ammonia. The ammonia produced by this process is excreted into the environment and is then available for either nitrification or assimilation.

Denitrification – is the reduction of NO3− to gaseous N by anaerobic bacteria. This process only occurs where there is no oxygen, such as deep in the soil near the water tables. Hence, areas such as wetlands provide a variables place for reducing excess n levels via denitrification processes.

Answer 16

N2-Gaseous Nitrogen
NO3^− Nitrate
NO2^− Nitrite
NH4^+ Ammonium
NH3 Ammonia

Question 17

Phosphorus Cycle

As phosphate (PO4), it makes up an important part of the structural framework that holds DNA and RNA together.
It is important element since it is present structurally in hair, nails, and bones.
It describe the movement of phosphorus movement from land to sediments in the seas and back to the land again.
The Earth’s — serves as the main storage for this element.
In the Earth, the lithosphere serves as the major source of phosphorus, particularly in rocks and minerals.

Answer 17

crust

Question 18

Phosphorus Cycle

—- – breakdown of rocks into minerals releasing phosphorus, which will be absorb by the plants.
Due to weathering and erosion, phosphates enter the freshwater biomes and goes to the ocean. Once in the ocean, the P is collected on continental shelves as —-
After million years of deposition, the crustal plates rise from the sea floor and expose the phosphates on land. Eventually, weathering will release them from rock and cycle’s geochemical phase begins again.
Unlike any cycles, the atmosphere does not play significant role in the movement of P.

Answer 18

Weathering Process
insoluble deposits.

Question 19

Steps in Phosphorus Cycle

Answer 19

1. Weathering
2. Absorption by plants
3. Absorption by animals
4. Decomposition

Question 20

Phosphorus Cycle

Phosphorus may be found in abundance in rocks. Because of this, the phosphorus cycle begins in the earth’s crust. The phosphate salts are extracted from the rocks and washed away into the earth and combine with it.

-Plants absorb phosphate salts that have been dissolved in water. There are relatively low quantity of sulfur in the soil. That is why farmers use phosphate fertilizers on their agricultural land.
-Aquatic plants absorb inorganic phosphorus from the bottom layers of bodies of water. Phosphate salts have an effect on plant growth in aquatic environments because they do not dissolve properly in water.

-Phosphorus is absorbed by animals through plant consumption or by devouring plant-eating animals. When opposed to rocks, plants and animals have a quicker phosphorus cycle.

When plants and animals die, bacteria degrade them. The organic form of phosphorus is transformed into the inorganic form, which is returned to soil and water throughout this process.
Soil and water will end up in sediments and rocks, which will then weather and release phosphorus. As a result, the phosphorous cycle begins once more

Question 21

Sulfur Cycles

It is present in proteins and gives a distinctive odor to many substances.
It is component of amino acid cysteine and present in large number of enzyme systems.
Several groups of prokaryotes utilize and release sulfur
It is collected mostly in rocks and salts or buried deep in the oceanic floors.
It enters the atmosphere through both natural and human sources.
Natural resources (volcanic eruption, bacteria processes, evaporation, or decaying of organisms).
Major form of sulfur comes from minerals and fossil fuels.
The use of fossil fuel for combustion releases a lot of SO2 (sulfur dioxide). it enters plant tissue in form of SO4^(2−).
It enters biosphere and then the organisms that consume them will be acted upon by the decomposers or will lost in atmosphere in the form of H2S (Sulfide).
Decomposition takes place in the presence of oxygen.
n the aquatic system where oxygen is used in the process of decomposition, very little amount of O2 will transform S into sulfate but transforms S into H2S. In this form, it may return back to earth through the rain, upon oxidation into sulfate will be taken up by the plants.
When sulfur enter the atmosphere through human activity, this mainly cause by industrial processes where sulfur dioxide (SO2) and hydrogen sulfide (H2S) gases are emitted on wide scale.
When S gets back to the air, it falls back to the earth in the form of acid rain (4.5 – 5.5 pH).
Short – termed movements of both element is through atmosphere as result of the metabolism of bacteria.
The gases move rapidly in closed cycle from the air to the soil and back.

Question 22

Steps in Sulfur Cycle

1. Sulfur in the atmosphere is mostly present in the form of SO2 ( human activities and natural processes).
   -SO2is followed by H2S released by microbial action on dead decaying living organisms. The anaerobic decomposition results in the release of H2S, which then oxidizes in the air to form SO2.
   -The sulfate-reducing microorganisms (D. desulfuricans, D. vulgaris, T. yellowstonii, D. nigrificans, etc.) involved in the decomposition process are usually anaerobic where they produce H2S from the oxidized form of sulfur.
   -The sulfur in the biosphere through rock and weathering which makes its way to the soil and then the ocean.
   -In the atmosphere, sulfur aids in the cloud formation by increasing the number of cloud droplets and the droplet size to decrease.
   -Sulfur particles, also called aerosols, fallout from the atmosphere to the biosphere.
   -SO2present in the atmosphere reaches the biosphere as the gas dissolves in the rainwater to form weak droplets of sulfuric acid.
   -Besides, chemical weathering in the pedogenesis process also results in the movement of sulfur from rocks to the soil and the water.
   -Weathering also causes the release of sulfur in the air as some of it is converted into sulfate.
   -Once the sulfur reaches the terrestrial and aquatic biosphere, it is taken up by plants and microorganisms.
   -A group of bacteria called the green sulfur bacteria, act as photoautotrophic bacteria, and utilize sulfur as a form of energy.
   -Other microorganisms in the soil also aid in making sulfur available to plants so that it can be taken up with water from the soil.
   -The sulfur taken up by living beings is then used in the formation of biomolecules like proteins and nucleotides.
   In the ocean ecosystem, chemoautotrophic microorganisms utilize sulfur to produce organic compounds in the form of sulfates.
   -The sulfur in the biosphere then circulates through the food chain as the consumers feed on producers and then reach the microbial chains.
   -The sulfur that doesn’t circulate falls into the depths of terrestrial and marine habitats and remains there in the combined form Ferous sulfate (FeS) in rocks.
   -The sulfur in the food chain then undergoes the decomposition process, converting the sulfate into sulfides so that they can be returned back to the atmosphere.
   -Sulfur reducing bacteria act on the organic forms of sulfur to form inorganic forms like hydrogen sulfide (H2S), which is further reduced to S.
   -The sulfur in the lithosphere also releases back to the atmosphere as a result of volcanic activity.

Question 23

Water Cycle

It is the only substance that occurs naturally as solid (ice), a liquid and gas (water vapor).
It also called Hydrologic Cycle describes the continuous movement of water on, above, below the surface of the Earth.
Water cycle is truly a “cycle”, there is no beginning or end.

Question 24

Steps in Water Cycle

Answer 24

Evaporation
Evapotranspiration
Sublimation
Condensation
Precipitation
Run off

Question 25

Water Cyc;e

EVAPORATION
-Water is found in lakes, oceans, swamps, and soil, as well as in all living creatures and plants.
-When heat is applied from the sun, the water molecules become excited and spread out. The loss of density is called ‘evaporation,’ and it sees the water rise into the air forming clouds of water vapor.
-Much less heat energy is required to evaporate the water in locations with lower air pressure and humidity because there is less pressure holding the water molecules together.
-Water from rivers and lakes contains no salt since ocean water evaporates without it, because salt is too heavy and dense to evaporate with the water vapor.

Question 26

Water Cycle

EVAPOTRANSPIRATION
-The uptake of water at the roots, transport of water through plant tissues, and release of vapor by leavesis known as transpiration. Water also evaporates directly into the atmosphere from soil in the vicinity of the plant called the evapotranspiration.
-A large percentage of the water in the atmosphere is produced by this process due to the large areas covered by plants and trees across the planet.
90% (lakes, oceans, and streams) 10% ( various plant life around the world)

Question 27

Water Cycle

SUBLIMATION
-Snow and ice can actually turn into water vapor without first turning into water. This process is called ‘sublimation,’ and it results from low humidity and dry winds.
-This usually occurs at the peaks of mountains or other high-up places, as the lower air pressure means that less energy is needed to sublimate the ice into water vapor.
Components of Sublimation:
(strong sunlight, low temperatures, low air pressure, strong wind, and low humidity)

Question 28

Water Cycle

CONDENSATION
-The water vapor cools in sky when it contact with the cooler air.
-The vapor becomes a cloud which moving air currents and winds.
-If the water vapor cools to anything above zero degrees centigrade, it will condense as water.
-The water vapor will start to condense on the surface of tiny particles of dust and dirt that rose with the vapor during the process of evaporation. These tiny droplets will start to fall into one another and merge, producing a larger droplet.
When a droplet is large enough, gravity will pull it down, leading to the droplet falling out of the cloud and onto the ground below. This process is called ‘precipitation’ or rainfall.
If precipitation occurs in cold or have very low air pressure, then these water droplets can quite often crystallize and freeze. This causes the water to fall as solid ice, known as hail, or as snow.
If the conditions are in between those associated with snow and rain, the droplets will fall as icy cold, half-frozen water commonly referred to as sleet.

Question 29

Water Cycle

PRECIPITATION
The water that has fallen as rain is absorbed into the ground through a process known as ‘infiltration.’
When water infiltrates the soil, it will move in all directions until it either seeps into nearby streams or else sinks known as ‘groundwater storage.
These formations are also known as ‘aquifers’.
When an aquifer becomes too full, it starts to leak out onto the surface, forming what is known commonly as a ‘spring.’
The water be located near a volcano or any source of natural thermal energy, it will form a hot spring.

Question 30

Water Cycle

RUNOFF
After the water has fallen and the soil has become saturated, or the snow has melted, the water follows gravity and falls down any hills, mountains, or other inclines to form or join rivers. This process is known as ‘runoff,’ and it is how water comes to rest in lakes and returns to the ocean. The waterfalls according to the incline of the place from which it is falling, and when several threads of water meet, they form a stream.

Question 31

Steps in Water Cycle

1.Change from Liquid to Gaseous Phase – Evaporation and Transpiration

2. Change from Solid to Gaseous Phase – Sublimation
3. Change from Gaseous to Liquid Phase – Condensation
4. Change from Gaseous to Liquid and Solid Phase – Precipitation and Deposition
5. Return of the water back into the underground reserve – Runoff, Infiltration, Percolation, and Collection

Question 32

Importance of Biogeochemical Cycles

1. They enable the provision of elements to organisms in utilizable forms.
2. Biogeochemical cycles enables the transfer of molecules from one locality to another.
3. They facilitate the storage of elements.
4. They assist in the functioning of ecosystems.
5. They link living organisms with living organisms, living organisms with the non-living organisms, and non living organisms with non living organisms.
6. They help to balance the flow of organics and inorganic substances of our earth.