Lesson 3.4

Question 1

is a complete path an element or a compound takes
through the four subsystems of Earth—atmosphere, geosphere, hydrosphere, and
biosphere.

Answer 1

biogeochemical cycle

Question 2

The name “biogeochemical” implies the involvement of life (​bio-​), Earth’s
surface (​geo​), and substances (​chemical​) present on Earth. These processes are
essential for the maintenance of life on Earth. Biogeochemical cycles include water,
nitrogen, carbon dioxide, and oxygen cycles.

Question 3

The movement of water from the ocean to the atmosphere to land and back to the
ocean

This movement is aided by the
processes of evaporation, condensation, precipitation, and runoff.

Answer 3

water cycle or hydrologic cycle

Question 4

The sun heats up bodies of water, such as oceans and
rivers, and also moisture from land and vegetation. Water undergoes
_​. It transforms from liquid to gas.

Answer 4

evaporation

Question 5

Also, plants release water
vapor through the pores under the leaves in the process known as
_​.

Answer 5

transpiration

Question 6

These two processes are sometimes coined together to refer
to the process that transfers water from land to the atmosphere called _​.

(evaporation)
(transpiration)

Answer 6

evapotranspiration

Question 7

Lighter water vapor cools as it reaches a certain altitude, and
forms tiny floating droplets. As a result, clouds form. This process is called _.

Clouds are not the only manifestation of _.
Ground-level fog and glasses fogging up in rooms also result from this
process.

Answer 7

Condensation

Question 8

Water cycle is aided by the
processes of _, _, _, and _.

Answer 8

evaporation
condensation
precipitation
runoff

Question 9

is the movement of nitrogen between the four spheres. It
involves the conversion of nitrogen into various forms. Nitrogen, which makes up
approximately 78% of the atmosphere, is essential to life’s protein synthesis.
Organisms can’t use molecular nitrogen directly that is why conversion of this
element into other forms is vital. The nitrogen cycle involves nitrogen fixation,
nitrification, ammonification, and denitrification.

Answer 9

nitrogen cycle

Question 10

is the process of converting atmospheric nitrogen into
biologically available nitrogen (ammonium compounds).

Answer 10

Nitrogen fixation

Question 11

Molecular nitrogen
(N​2
) is a very stable compound due to the strong bond between the two
nitrogen atoms. Hence, the bond requires a large amount of energy to break.
Only a selected group of prokaryotes can carry out reactions that break such
bond. These prokaryotes are called _ _.

Answer 11

nitrogen-fixing bacteria.

Question 12

a process that converts ammonia and ammonium
compounds into nitrite and then to nitrate. Most nitrification process occurs
aerobically (requires oxygen) and is carried out exclusively by prokaryotes.
The nitrates and nitrites are utilized by land plants and algae in water bodies.
Plants, algae, and bacteria then convert the inorganic forms of nitrogen
compounds through different chemical reactions.

Answer 12

Nitrification

Question 13

is the process where fungi and prokaryotes decompose the
dead tissue of organisms and release the inorganic nitrogen back into the
ecosystem as ammonia. It is also known as nitrogen mineralization.

Answer 13

Ammonification

Question 14

involves the process of releasing nitrogen back to the
atmosphere. Through denitrifying bacteria, organic compounds from dead
organisms are converted back to ammonia, nitrate, or molecular nitrogen.

Answer 14

Denitrification

Question 15

The nitrogen cycle involves

Answer 15

nitrogen fixation

nitrification

ammonification

denitrification

Question 16

is a rather complex cycle. Carbon is present in many forms
ranging from compounds found in living organisms to fossil fuels. Carbon, in its
gaseous state in the form of carbon dioxide (CO​2

) and methane (CH​4

), enters the
atmosphere through respiration, combustion or burning of organic compounds,
and diffusion from the ocean.

Answer 16

carbon cycle

Question 17

_ of plants and photosynthetic bacteria and diffusion into the
oceans remove carbon from the atmosphere.

is the process by
which organisms convert carbon dioxide and water from the environment into
glucose and oxygen.

Answer 17

Photosynthesis

Question 18

From the land, carbon reaches the oceans through rivers and
streams in the form of dissolved carbon, organic compounds, or particulates like
calcium carbonate shells.

Question 19

Carbon from dead organisms which are buried in
wetlands, swamps, lakes and deep-sea sediments for a very long period of time is
converted into

Answer 19

​fossil fuels​

Question 20

One unique characteristic of Earth is the presence of free molecular oxygen in its
atmosphere. Simple and complex processes both on the surface and beneath Earth
determine the amount and distribution of O​2. This distribution can be visualized
through the _ _.

Oxygen is distributed among reservoirs including the
atmosphere, oceans, freshwater environments, soils, and groundwater.

Answer 20

oxygen cycle​

Question 21

The major mechanism that produces oxygen gas is _ which occurs in
plants, algae, and in two groups of prokaryotes (cyanobacteria and
prochlorophytes).

Answer 21

photosynthesis

Question 22

also takes place between the atmosphere and the
surface waters.

Answer 22

Diffusion

Question 23

Oxygen is consumed through _, a process which
produces energy for the organisms.

Answer 23

aerobic respiration​

Question 24

Other processes include metabolism and
oxidation.

Answer 25

photosynthesis
Diffusion
aerobic respiration​,
metabolism
oxidation