Plays a major part in the various cycles of nature (water cycle, carbon cycle and nitrogen cycle)
In the lowest layer, the Earth’s atmosphere consists of:
Layers of the Atmosphere
Highest layer (80km/50mi to about 700km/450mi)
The thermal structure of the Earth’s atmosphere is the result of:
complex interaction between the electromagnetic radiation from the sun;
radiation reflected from the Earth’s surface and
molecules and atoms in the atmosphere.
Temperature is higher because of collisions between ultraviolet photons and atoms of the atmosphere
Mesopause – base of the thermosphere
Ionosphere – acts as reflector of radio waves.enabling radio transmissions to “hop” between widely separated points on the Earth’s surface.
Layers of the Atmosphere
Temperature decreases with altitude of 50km/31mi to 80km/50mi.
Temperature ranges from 0 o C/32 o F to below -100 o C/212 o F
found on top of the stratosphere
Production of ozone (O 3 ) from oxygen molecules (O 2 )
Layers of Atmosphere
Temperature decreases with altitude of 10km/6mi to 50km/31mi.
Temperature ranges from -60 o C/-140 o F to near 0 o C/32 o F
better absorber of UV radiation than ordinary oxygen atom
prevents lethal amounts of UV from reaching the Earth’s surface
the mark between the stratosphere and troposphere and marks the influence of the Earth’s warming effects
Layers of the Atmosphere
The lowest level of the atmosphere (altitude from 0-10 km)
With temperature of 15 0 C by the Earth, which in turn is warmed by infrared and visible radiation.
Carbon and oxygen found in organism are ultimately returned to the atmosphere via the carbon-oxygen cycle.
Phases of Photosynthesis
Light Reaction/Light Dependent Phase
The first phase of photosynthesis involves reactions that occur only in light and require chlorophyll.
In these light reactions, water molecules are split and energy stored for later use.
The whole series takes place in split second.
Light Reaction Is absorbed by Chlorophyll a (energy carrier) Becomes energized chlorophyll that supplies energy to Split H 2 O and Add P 2H O 2 ADP (energy carrier) Trapped by NADP released forming ATP- stores energy (H acceptor) Forming NADPH2 For use in the dark reaction
Dark Reaction CO2 Combines with RDP, a 5-C sugar in the chloroplast(CO2 acceptor) To form a very unstable 6-C sugar This splits quickly and forms 2 PGA, a 3-C compound Combines with 2H supplied by NADPH2 from the light reaction (energy supplied by conversion of ATP to ADP) forms PGAL H2O Can be used as nutrient or converted to RDP Glucose Used to combine with CO2 and By combining 2 molecules of PGAL and substituting H for a phosphate
Cellular Respiration: Chemical Reaction
C 6 H 12 O 6 + O 2 CO 2 + H 2 O + Energy
Cellular Respiration: Three Reactions
Takes place in the cytosol and not in the organelles
Does not require the use of oxygen
Glucose is converted to ATP
2. Kreb’s cycle
Takes place in the matrix of the mitochondria
Requires the use of oxygen and releases carbon dioxide
3. ATP synthesis/ ETC
Takes place in the inner membrane of the mitochondria
Requires the use of oxygen
These reactions pump H+ across the membrane creating a gradient
As H+ enters the matrix, ATP is formed.
ATP Synthesis/ Electron Transport Chain
Energy Produced in Cellular Respiration
In Glycolysis = 2 ATP
In Krebs Cycle = 2 ATP
In ATP synthesis/ ETC = 34 ATP
Total = 38 ATP
From 38 ATP, the 2 ATP are used to transport products of glycolysis into the mitochondria.
Therefore: 36 ATP are produced for the whole process
Types of Respiration
1. Aerobic respiration
Stage which requires molecular oxygen
Water and carbon dioxide are given off and energy is released.
2. Anaerobic respiration
Do not require oxygen to regenerate NAD
Occurs outside mitochondria
Organisms depend on glycolysis to generate ATP and on fermentation to generate NAD.
Product of this reaction is ethanol.
This alcohol is formed whenever fruits are processed into wine through fermentation.
Comparison of Photosynthesis and Respiration
1. Occurs only in the chlorophyll-bearing cells of plant.
2. Needs the presence of light
3. Water and Carbon dioxide are used.
4. Oxygen is given off as a waste product.
5. Food is built or synthesized.
6. The weight of the plant is increased
7. Energy is stored.
1. Occurs in every living plant and animal cell.
2. Occurs at all times.
3. Water and Carbon dioxide are given off as waste products.
4. Oxygen is used in the process.
5. Food is destroyed to release its energy.
6. The weight of the plant is decreased.
7. Energy is released.
One of the basic elements that compose proteins. Proteins are the structural components of all living things.
All organisms are made up of proteins. Growth of plants will be limited if there is not enough nitrogen in the soil.
About 78% of the atmosphere is nitrogen gas (N2) but in this state, nitrogen cannot be used by organisms.
1. Nitrogen fixation
Conversion of Nitrogen (N 2 ) to ammonia (NH 3 ) or ammonium (NH 4 )
Before nitrogen can be made available to plants and animals, it must first be fixed by nitrogen-fixing bacteria .
-found in nodules of legumes (soybean, mongo, pea).
when these bacteria die, ammonia or ammonium is released and used by other bacteria as energy source.
Small portion of gaseous nitrogen is fixed in the air by lightning and the fixed nitrogen is brought down to the soil by rain.
Ammonia and ammonium is converted to nitrites (NO 2 ) by nitrifying bacteria in the soil. Some of these bacteria convert nitrites to nitrates (NO 3 ).
When ammonia and nitrates that are released in the soil are dissolved in soil water, they are absorbed by roots of plants and become incorporated into plant proteins .
these plant proteins are then eaten by animals by which animal proteins are formed.
Metabolic wastes (urea, uric acid) and remains of plants and animals are broken down by decomposers releasing ammonia or ammonium in the process.
Nitrates not used by plants are converted by denitrifying bacteria to nitrogen gas which is released to the atmosphere