Answer: billions of types of proteins
Answer:
Scientist count the world humans population with an organization called The United Nations Population Division (UNPD),
Explanation:
Which keeps track of the world population, projects that the world's human population will hit 7 billion on Halloween Day 2011. Admittedly, that is just an estimate: There's no way to know exactly how many people are alive at any given moment, and the true date that humanity's ranks will surpass 7 billion could come in the weeks or months before or after Oct. 31. Nonetheless, the UN's guess is the best there is.
The three examples of stimulus include;
1. Hit the skin with a needle or pin is a good example of stimulus. The sudden removing of the hand is the response.
2. When somebody bangs a door you jump if you were unaware because of the sound. The jumping is the response to a stimulus.
3. Holding a hot plate we fling hand away from it. The stimulus here is holding the plate while removal of the hand is the response.
Stimulus is the change or cause in an organism's surrounding which causes the organisms to react.
