Answer:
Niacin (Ans. A)
Explanation:
Nicotinamide adenine dinucleotide (NAD) is known as important cofactor which help in carrying electrons from one reaction to another reaction in the cellular respiration process.
Cells are able to restore performed compounds which are containing a pyrimidine base precursor vitamin for the synthesis of NAD: nicotinamide, nicotinic acid, and nicotinamide riboside.
These elements are taken up from the diet whos containing vitamin B3. Nicotinamide, and nicotinamide riboside both can be absorbed from the gut. Niacin or vitamin B3 also produced within cells with the help of cellular digestion of NAD+.
It's some change in the conditions around the organism, which the organism can detect and respond to. A change in temperature, more light, or something physically poking the organism are examples.
Answer
The main reason being the amount of food available.
Explanation:
Think of it this way:
If an animal is trying to find food but another species is looking for the same prey then its going to be increasingly difficult for the species to find prey and if there's not enough of the prey species then the population of the predator to go down.
That is why its considered a limiting factor.
There was no life on Earth for the first billion years because the atmosphere was not suitable for life. Earth's first atmosphere had lots of water vapor but had almost no oxygen. Later, frequent volcanic eruptions put several different gases into the air.
