MD

Pioneer community	Climax community
It is the first community that appears in a bare area during ecological succession (primary community)	It is the final stable biotic community that appears in an area during ecological succession (final community)
The establishment of the pioneer community is the first step in ecological succession (first seral stage)	The emergence of the stable climax community is the final step in ecological succession (last seral stage)
Pioneer community appears on a previously uninhabited area	Climax community establishes in a previously occupied area by other seral communities
Pioneer community consists of generally small sized species	Climax community consists of species of different sizes that are well adapted to the environment
The species in the community are tolerant to extreme environments	The species in the climax community are comparatively less tolerant to extreme environments
*Pioneer species are generally ‘r-selected’ species that are fast growing, shade intolerant and short lived	Climax species are k selected species that are slow growing, shade tolerant and long lived
Pioneer species are good colonizers but poor competitors	Climax species are poor colonizers but good competitors
Pioneer species are generally with numerous small seeds capable of dormancy, well dispersed by animals or wind, low density, pale, non-durable timber	Climax species are generally with few larger seeds capable of dormancy, well dispersed by animals or wind, low density, pale, non-durable timber
Responsible for soil formation and modifies the environment favoring the colonization of other species of next seral stage	The environment has been modified and made suitable for the emergence of species of climax community by the species of previous seral stages
Pioneer community is replaced by the species of next seral communities	Climax community is a stable community where invasion of other species will not generally happen for a long period
Examples of pioneer species: Lichen in lithosere (rocks), Pioneer community: Phytoplanktons in hydrosere	Examples: Climax species: White spruce (Picea glauca) climax species in the Northern forests of North America. Giant sequoia tree in sequoia forests Climax community: forest

Nitrogen fixation	Nitrification
Nitrogen fixation is the conversion of nitrogen (N2) to ammonia (NH3) or compounds that can be readily utilized by plants for the synthesis of nitrogen containing bio-molecules like amino acids, nucleic acids etc	It is a two step process that converts ammonia (NH3) to nitrate (NO3-)
Nitrogen fixation is the first step in nitrogen cycle that fix atmospheric nitrogen to soil as ammonia (NH3)	Nitrification is a major step in the nitrogen cycle in soil where soil ammonia (NH3) is converted to soil nitrate (NO3-)
Nitrogen fixation occurs by a) biological Nitrogen Fixation, b) non-biological N2 fixation by lightning, volcanic eruptions etc and c) Industrial N2 fixation called Haber-Bosch process. More than 70% of Nitrogen is fixed by biological methods	Nitrification is the biological oxidation of ammonia (NH3) to nitrite (NO2-) and then to nitrate (NO3-) by nitrifying bacteria
The microorganisms involved in Nitrogen fixation are called nitrogen fixers or diazotrophs	The microorganisms involved in Nitrification are called nitrifying bacteria
Nitrogen fixers are either symbiotic or free living. Nitrogen fixers include some bacteria like Rhizobium in symbiotic association with leguminous plants, blue green algae like Anabaena and lichens like Collema.	Nitrification is carried out by two groups of bacteria; nitrite bacteria like Nitrosomonas which converts ammonia (NH3) to nitrite (NO2-) and nitrate bacteria like Nitrobacter that converts nitrite (NO2-) to nitrate (NO3-)

         example of biotic resources: Living organisms and their products

1. The resources have no change of getting depleted or exhausted
2. The resources are present in unlimited or infinite quantities
3. Excessive and improper use may result in their pollution .
4. Example of Inexhaustible resources: Solar energy, (cosmic resources) wind power, hydro power, rain fall (climatic resources)

b) Exhaustible (Depletable):

1. The resources have every chance of getting depleted or exhausted. 
2. The resources have finite supply
3. Excessive and improper use may result in wastage and depletion of the resources.
4. Example of Exhaustible resources: Forests, grassland, fossil fuels, minerals,

Energy is defined as the capacity of a substance or a body to do work. Conventional sources of energy refer to the energy sources that have been traditionally used for many years. These energy sources are non-renewable and likely to be depleted due to its extensive use. Non-conventional energy sources are alternate energy resources to the conventional energy resources but in limited use due to lack of feasible technology.
Conventional vs Non conventional Sources of Energy 

Conventional Energy Resources	Non-conventional  Energy Resources
It refers to the traditional sources of power or energy like firewood, coal, petroleum etc	It refers to recently developed sources of energy from sun, wind, tides etc
Energy sources are non-renewable	Energy sources are renewable
Comparatively expensive to maintain, store and transport	Initial expenditure for energy generation is high but cheaper in the long run
Following established technologies for energy production	Require new feasible technologies; still under research and development
Energy sources which are fixed in nature	Generally energy sources are not be fixed in nature
Available in limited quantity; exhaustible	Available in plenty; inexhaustible
Causes large scale pollution; not eco-friendly	Generally Eco-friendly source of energy
Causes green house effect and major culprit in climate change and has serious health consequences	No such issues as energy source is ecologically safe
At present, widely used energy source	Presently limited use; feasible technologies are yet to be developed
Examples: coal, petrol, diesel, LPG etc	Examples: solar energy, wind energy, hydroelectric power etc

Blood is a fluid connective tissue. It is an extremely complex substance carrying a wide variety of cells and substances to all areas of he body. Blood is often described as seat of the soul since it performs several vital functions of the body . A normal  healthy man has about 5.5 litres of blood.

•      Regulate body temperature. 
•      Maintains a constant pH and water balance 
•      Defence against pH and water balance 
•      Transport digested food materials, respiratory gases and waste materials

• Transport: Plasma transport the digested food products like glucose, amino acids, fatty acids, etc.
• Body immunity: one type of globulins called immunoglobulins act as antibodies. They inactive invading microorganisms and their toxins.
• Prevention of blood loss:  Fibrinogen helps in blood clotting and thus prevents blood loss. During blood clotting the soluble fibrinogen is converted into insoluble fibrin.
• Retention of fluid in blood
• Maintenance of blood pH: Plasma proteins act as acid base buffers and thus maintain the blood pH by neutralizing strong acids and bases.
• Regulation of body temperature: Plasma helps in the uniform distribution of heat all over the body, and in conducting heat to skin for dissipation.

 Gram staining  is a special technique which is used to stain bacteria. This technique was developed by Christian Gram in 1884. The stain  stain used in Gram staining is called Gram stain. Chemically Gram stain is a weakly alkaline solution of crystal violet or gentian violet.

On the basis of cell wall structure and its staining ability with Gram stain, bacteria are grouped into two categories. They are Gram positive bacteria and Gram negative bacteria

Cell wall of Gram positive bacteria	Cell wall of Gram negative bacteria
Cell wall is single layered and primarily made up of peptidoglycan	Cell wall is double layered and with an outer membrane outside to Peptidoglycan layer
Gram positive cell wall retain the primary stain of Gram staining (crystal violet) and appear purple after alcohol treatment	Gram positive cell wall lose the primary stain of Gram staining (crystal violet) after alcohol treatment; and appear pink with counter stain (safranin)
Thick peptidoglycan layer of about 20 to 80 nm	Peptidoglycan layer thin and single layered (about 5 to 10 nm thick)
Periplasmic space is absent	Periplasmic space* is absent
Outer membrane is absent	Outer membrane is present outside to Peptidoglycan layer (about 7.5 to 10 nm thick)
Teichoic acid is present	Generally Teichoic acid is absent
Generally **Porins are absent	Porins are present
Very low lipid content (2-5%)	Very high lipid content (15-20%)
Generally Lipopolysaccharide (LPS) is absent**	Lipopolysaccharide (LPS) is present
Lysozyme degrade peptidoglycan wall cause lysis of cell (sensitive to lysozyme)	Lysozyme cannot degrade Gram negative bacteria as Peptidoglycan is protected by outer membrane (resistant to lysozyme)
Example of Gram Positive Bacteria	Example of Gram Negative Bacteria