psammosere is succession on sand 
Halosere is succession in saline marshes 
Lithosere is succession on rocks 
Hydrosere is the succession which begins in water.

coral reefs are also known as tropical rain forest of sea. All three given options that is coral reefs, tropical rain forest and sugarcane fields have high productivity. Coral reefs and tropical rain forest have high diversity and also high rate of productivity. Sugarcane field is an example of artificial ecosystem which have well defined goals and their motive is to obtain high productivity rate. 
Deserts have less diversity and due to high temperature and arid region, their productivity is low.

Tears in eye, HCl in stomach act as physiological barriers to entry of microorganisms. Hcl is an acid that kills the microorganisms in stomach, hair in nose keep dust and microbes away, urine washes microbes from urethra, lysozyme found in tears and saliva, dissolves bacterial cell wall by attacking them.

Robert constanza and his colleagues have put an price tag on nature services of US $33 trillion per year as these fundamental services are taken for granted because they are free.

primary succession is development of community on bare rocks, sand or sea floor. Only a few simple and hardy can grow and form pioneer community. These are short lives and take very long time to develop because development of soil is also involved. It has minimum diversity.

71% carbon is found dissolved in oceans and it helps in regulation of carbon with atmosphere. 4x10¹³ kg of carbon is fixed in the biosphere through photosynthesis annually and most amount of carbon di oxide returns to the atmosphere via respiratory activities of producers and consumers. Atmosphere only contains 1% of total global carbon.

zooplanktons are the examples of primary consumers that is the organisms which obtain their nutrition by eating plants and their products. 

During succession, bacteria along with fungi were the primary colonizer, which helps in breakdown of inorganic compounds to simple ones. 

Smallest ecosystem are known as microsystem. Example: drop of water. 

While large ecosystem like forest, grassland, ocean, biome are known as macroecosystems. 

Omnivorous are the organisms which can eat both plant products as well as animal products. Eg. Crow, cockroaches etc.

the solar radiation which incidents on earth is used by plants for the process known as photosynthesis, but the total percent of light is not useful for plants. Less than 50% of incident solar radiation is PAR which is useful for plants. Out of this 50% plants only use 2-10% of PAR to synthesize their food.

The situation tells that we want to correct myopia. So, far point must go to infinity. 

v = –4 m, u = –∞, P =? 

P = 1/f = 1/v-1/u 

1/-4 – 1/∞ = -.25D

Lyman series it is the transitions from n >= 2 to the n = 1 state, for Balmer series its from n >= 3 to the n = 2 state

For longest wavelength in Lyman

1/λ_l= R(1²)[1/1²-1/2²]

= 4 R / 3

λ_l= 3/4R

For longest wavelength in Balmer

1/λ_b= R(1²)[1/2²-1/3²]

= 5R/36

λ_b= 36/5R

λ_l/λ_b = 5/27

The helical structure of protein is stabilized by hydrogen bonds between amide group of the same peptide chain. These bonds are formed by –NH- group of one unit and oxygen of carbonyl group of the third unit. This H-bonding is responsible for holding helix in a position.

According to Bohr’s model of atom, electrons in atoms are in orbits of differing energy around nucleus. Each energy level has a definite energy associated with it. In each energy level, electrons move in circular orbit around positive nucleus.

Work done (W) = -P_ext (V₂ – V₁) 

= - 3 × (6 – 4) = -6L-atom 

= -6 × 101.32 J ( ∴1 L-atom = 101.32 J) 

= - 607.92 ≈ 608 J