Biochemical systems

Question 1

what is the role of carbon and carbon dioxide?

Answer 1

Carbon has 2 main functions in living organisms:
structural component of organic molecules
important element in chemical energy storage

In the atmosphere, carbon mainly exists as carbon dioxide- used by plants in photosynthesis.

Carbon dioxide is a greenhouse gas and therefore traps heat in the atmosphere.

Question 2

respiration equation

Answer 2

C6H12O6 + 6O2 –> 6CO2 + 6H2O

Question 3

when does carbon fixation occur?

Answer 3

during the process of photosynthesis when plants remove carbon dioxide from the atmosphere to make carbohydrates.

Question 4

photosynthesis equation

Answer 4

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 5

how is carbon removed from the atmosphere?

Answer 5

since it is very soluble, large amounts are removed when it dissolves in the oceans

CO2 + H2O –> HCO3 - + H +

Question 6

other methods of carbon being removed from the atmosphere

Answer 6

sedimentation
weathering and precipitation

Question 7

role of termites in carbon cycle

Answer 7

Termites digest cellulose in plant material, breakig it down and releasing carbon dioxide in the process back to the ecosystem.

Question 8

role of fungi in carbon cycle

Answer 8

Fungi are decomposers that break down dead material for use as food, converting it into fungal biomass and making it available for return to the food chain.
- Decomposition process releases some carbon dioxide into the atmosphere and can result in the breakdown of complex organic molecules.

Question 9

role of dung beetles in carbon cycle

Answer 9

Dung beetles make it possible for carbon to re-enter the food chain when the larvae feed on the cow manure and make it available to decomposers.

Question 10

human activity on the carbon cycle

Answer 10

Anthropogenic activity affects the carbon cycle and the amount of carbon stored in carbon sinks.

humans burn fossil fuels –> deplete fossil fuel reserves –> increased global warming and air pollution

Question 11

role of nitrogen

Answer 11

Green plants use nitrogen to build their own protein molecules

Nitrogen becomes readily available for primary producers only when it is converted from dinitrogen gas into ammonia.

Nitrogen exists in inorganic forms (ammonia, nitrate) and organic forms (amino and nucleic acids)

Question 12

what is nitrogen fixation?

Answer 12

reduces nitrogen to ammonium ions or ammonia; catalyzed by nitrogenase; nitrogen-fixing bacteria carry out the process

Question 13

how can lightning fix atmospheric nitrogen?

Answer 13

high energy discharge can combine nitrogen and oxygen. The nitrogen oxides that are formed may dissolve in rainwater to form weakly acidic solutions.

Question 14

equations to show lightning on nitrogen fixation

Answer 14

N2 + O2 –> 2No2 + H2O –> 2HNO3

N2 + O2 –> 2NO2 + H2O –> 2HNO2

Question 15

what is nitrification?

Answer 15

converts ammonium compounds to nitrate with the subsequent release of energy for the bacteria involved; nitrate forming bacteria combine ammonia and oxygen to form nitrites

Question 16

what is denitrification?

Answer 16

denitrifying bacteria break down nitrates into nitrogen and nitrous oxide

Question 17

humans on the nitrogen cycle

Answer 17

Use of fertilizers adds nitrogen compounds to the soil (accounts for large amount of nitrogen fixation annually).

Cultivation of leguminous crops increases the amount of nitrogen fixing microorganisms in soil.

Burning fossil fuels increases the concentration of nitrous oxide and ammonia in the atmosphere

Increase in nitrate runoff in aquatic systems result in eutrophication and pollution

Question 18

role of phosphorus

Answer 18

ATP is responsible for energy transfer reactions at the cellular level.

Phosphate is incorporated into the backbone of nucleic acids DNA and RNA
- important for genetics

High concentrations of phosphorus promotes lush growth of algae and vegetation

Question 19

how are phosphates transported?

Answer 19

in the aqueous form

Question 20

where is most phosphorus found?

Answer 20

in sedimentary rocks

Question 21

human activities on phosphorus cycle

Answer 21

Commercial synthetic fertilizers
Mining of deposits of calcium phosphate
Large amounts of sulphuric acid to convert phosphate rock into superphosphate fertilizer
Cutting tropical rainforest
Agricultural runoff

Question 22

what is evaporation?

Answer 22

water transforms from liquid to gas and rises into the atmosphere

Question 23

what is condensation?

Answer 23

water vapor rises into the atmosphere, forming clouds and fog; cools down to decrease in temperature

Question 24

what is precipitation?

Answer 24

water vapor returns to earth as rain, snow or sleet

Question 25

what is runoff?

Answer 25

water which falls back to the surface of earth and enters different water bodies

Question 26

what is infiltration?

Answer 26

water on the surface seeps down intk the ground to form aquifers

Question 27

what is transpiration?

Answer 27

plants absorb water from the soil

Question 28

describe process of carbn cycle

Answer 28

Photosynthesis: Plants absorb carbon dioxide (CO2) from the atmosphere and convert it into organic compounds (like glucose) using sunlight.

Respiration: Organisms, including plants and animals, release CO2 back into the atmosphere by breaking down organic compounds for energy.

Decomposition: Dead organisms and waste products are broken down by decomposers, releasing stored carbon into the soil and atmosphere as CO2 or methane (CH4).

Combustion: Burning fossil fuels or biomass releases stored carbon into the atmosphere as CO2, contributing to atmospheric carbon levels.

Question 29

steps of the nitrogen cycle

Answer 29

Nitrogen Fixation: Atmospheric nitrogen (N₂) is converted into ammonia (NH₃) by nitrogen-fixing bacteria or through industrial processes and lightning.

Nitrification: Ammonia is converted into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by nitrifying bacteria in the soil.

Assimilation: Plants absorb nitrates from the soil and use them to create proteins and other organic nitrogen compounds. Animals obtain nitrogen by consuming plants or other animals.

Ammonification: When plants and animals die or excrete waste, decomposers convert organic nitrogen back into ammonia.

Denitrification: Denitrifying bacteria convert nitrates back into nitrogen gas (N₂), releasing it into the atmosphere, completing the cycle.

Question 30

stages of the phosphorus cycle

Answer 30

Weathering: Phosphate rocks break down through weathering, releasing phosphate (PO₄³⁻) into the soil and water.

Absorption by Plants: Plants absorb phosphate from the soil and use it to form organic compounds, such as DNA and ATP.

Consumption: Animals obtain phosphorus by eating plants or other animals. Phosphorus moves through the food chain as organisms consume each other.

Decomposition: When plants and animals die, decomposers break down their bodies, returning phosphorus to the soil in the form of phosphate.

Sedimentation: Phosphate may eventually wash into bodies of water, where it settles and becomes part of sedimentary rock, potentially being uplifted over time and restarting the cycle.