The correct answer is option Energy is lost at each trophic level.
In a Ecological pyramid, the energy is transferred from the producer to the consumer level. The ecological pyramid is triangular in  structure, this is because the number of organism on each successive trophic level is less than the preceding one or the one below it. 
The reason of this shape of ecological pyramid is on subsequent trophic level, the amount of energy transferred is only 10%. The rest of the energy is dissipated in the environment in the form of heat. As only 10% of total energy is transferred to the subsequent level, The amount of energy reaching to tertiary consumer is very less that it cannot meet the energy demand of next level. 
 
        
                    
             
        
        
        
An isotope of any element is the same, with a variation in the neutrons of the nucleus.
The mass number change but the atomic number doesn't.
In this case, protium, deuterium, and tritium are all hydrogen isotopes.
Protium is 1H or Hydrogen-1 is without neutrons.
Deuterium is 2H  or Hydrogen-2 has one neutron.
Tritium is 3H or Hydrogen-3 has two neutrons.
 
        
             
        
        
        
Answer: Option D 
Explanation:
The practice which has been prevailing from a long time is considered as culture.Farming is also a type of culture which is being practiced from a longer period of time in the society.
The farming is also a type of culture which was invented somewhere and started spreading from there to other places.
This practice helped mankind  in providing food and resources to the people of nation.
 
        
             
        
        
        
Answer:
Alcohol fermentation
Explanation:
When oxygen availability is low, the cell can't perform aerobic respiration to breakdown glucose. Instead, anaerobic respiration must be performed. This occurs in cells which consume large amounts of energy, such as muscle cells. Anaerobic respiration produces much less energy than aerobic respiration
One type of anaerobic respiration formed by yeast is called alcohol fermentation (also called ethanol fermentation). This begins with glycolysis, where one molecule of glucose is broke down into 2 molecules of pyruvate. The energy from this reaction generates 2 molecules of ATP, and converts NAD+ to NADH. 
Then, the two molecules of pyruvate are further broke down into 2 acetaldehydes (releasing two molecules of carbon dioxide as a by-product). These two molecules of acetaldehyde are then converted into tw molecules of ethanol, using the H ions from NADH, converting it back to NAD+. See the attached picture
This process is taken advantage of to brew beer and wine. 
 
        
                    
             
        
        
        
<span>Proteins have a very high molecular weight and cannot be present as macro molecules in the glomerular blood. Before even reaching the blood, they are well masticated and processed to simple amino acids and other nitrogenous compounds like urea, uric acid etc. (in the digestive system itself). They are eliminated from the body while glomerular filtration through urine. The glomerular blood thus becomes free from such compounds before leaving the kidney.</span>