There are many external forces, substances or condition which affect the living organisms in one or the other way. They are considered as factors. These entire factors combine together to form an environment.

In atmosphere, the nitrogen is present in large quantity about 78%. In our body, nitrogen is about 3%. During inspiration we take $O _2$ with various gases and nitrogen is one of them. During exhalation, the nitrogen comes out with $CO _2$.

Green house gases (e.g. CO$ _{2}$, CH$ _{2}$, CFCs etc.) are increasing in the atmosphere due to human and natural activities. These gases trap the heat(infra-red radiation) reflected by the earth. This heats up the atmosphere(leads to an increase in earth's temperature). This phenomenon is called global warming which occurs due to green house effect.

Biome is an interaction between various communities of organisms and the environment they live in. These communities of organisms dwell in similar geographical, climatic and other biotic factors.

The environmental conditions in these region are favourable and hence species have become diversified.

Sulphur shower : In the month of May, on hills the  yellow Pollen grains of Pinus Plants are Produced in lot of number and are scattered in air.

Acclimatization is the development of a favourable morphological and physiological response to a change In environment.

The organisms that use external heat to maintain their body temperature are termed as ectotherms while those maintaining their body temperature using the metabolic heat are termed as endotherms (mammals and aves). Among the given options, Blue jay (aves) is endotherms. 

At the molecular level even living things are fundamentally made up of all the elements that make non-living matter. There have been attempts to make these molecules and their integration to create life by scientists but none of them has been successful yet. Hence, it is often believed that there is a vital force that can not be created by us that gives organisms characteristics of life. 

Animals with constant body temperature are called homoootherms. They have insulating coat to check the loss of body heat. This coat consists of hair in most mammals, blubber (subcutaneous fat) in whales and perspiration cools down the body of these animals when required.These are also termed endothermic as they regulate their body temperature by physio;logical means and maintain more or less constant internal temperature. Poililotherms are cold-blooded animals which are unable to regulate their body temperature which changes with change in temperature of environment e.g. fish, frog, lizard. They are also called as ectothems.

Tropical rainforests are disappearing fastly from India due to deforestation, habitat loss and fragmentation. These forests are of extreme value since they contain the maximum biodiversity.  

Topography means the physical features of a place such as hills, plains, slopes, rocks, valleys,etc. The topography affects the distribution of organisms directly or indirectly by influencing other factors, such as light intensity, wind velocity nature of sol, rainfall water currents or wave action. 

The sun's surface emits about 63 million watts of energy per square meter. By the time it reaches the Earth, after traveling 150 million kilometers, or 93 million miles, it has dimnished to 1,370 watts per square meter which are equal to thousand of kilocalories.

Osmocoformers are the organisms that change the osmotic concentration of their body with the change in ambient conditions. Their body fluids are in osmotic balance with the environment For many marine invertebrates the osmolarity and ionic concentrations of their body fluids are similar to those of the sea water in which they live. 

Photosynthesis is a process that converts $CO _2$ into organic compounds and starch (carbohydrate) using energy from sunlight. $O _2$ is also released during this process.

The UNEP (United Nations Environment Program) has passed many environmental conservation acts. To create awareness of the condition, to encourage participation on public level, developing International Environmental Law etc. are its objectives.

Aquatic organisms are used to a certain range of temperature in the water-body where they live. A sudden marked change in this temperature can be dangerous for them. It affects breeding of aquatic animals. The eggs and larvae of various animals are particularly susceptible to temperature changes.