Function of an enzyme is to lower reaction's activation energy and to increase speed of a reaction, but to make it happen, enzyme and substrate must fit spatially. The shape of an enzyme is essential to make enzyme-substrate complex - if active site of an enzyme doesn't fit to substrate, there won't be a enzyme-catalised reaction.
The answer to this is passive hyperemia.
It was the plants around us. They give us air to breath. It was to help us breath so we can live.
Answer:
Composition: mostly hydrogen and helium gas
Mass: 1.989 × 10³⁰ kg
Explanation:
Sun is a star at the center of the solar system. It is mostly composed of Hydrogen and Helium gases. Fusion of Hydrogen into Helium in the core powers the sun. Huge amount of heat and light energy is liberated. The mass of the Sun is 1.989 × 10³⁰ kg. Sun is a Population I star.