Keep in mind that this is Grade 8.
I needed to answer these four questions in paragraph form.

1. Biology is a natural science that studies the structure, function, growth, and evolution of living organisms. These organisms can include fungi, plants, animals, humans, micro-organisms, etc.
2. Biology has been involved of in the discovery of many major discoveries, such as the discovery of evolution, the discovery of extinct species and many more.
2/3. Biology has mainly had a significant effect in medical breakthroughs. There have been medical breakthroughs as a result of the discovery of infectious micro-organisms, discovery of the essential minerals, nutrients and vitamins in foods, the discovery of the role of oxygen, the discovery of the structure and importance of proteins, and the discovery of the structure and function of DNA and RNA. These discoveries have made it possible to classify and treat many diseases and disorders.
4. There are many branches of science related to Biology. Some major branches include Agriculture (the science of farming), Anatomy (the science of bodily structure), Ecology (the science of the ecosystem), Chemistry (the science of substances of matter), Oceanography (the science of the physical and biological properties of the sea) and many more.
We had two classes to work on this.
Are these good answers?
(EDIT) Fixed #4 and improved #3.
(EDIT #2) Fixed #1