Biology Chapter 6: Evolution

Study Notes

Origin of Life

Evolutionary Biology explores the history of life forms on Earth, encompassing changes in flora and fauna over millions of years.
Understanding evolution requires knowledge of the Earth's origin and the early universe, including the formation of stars and galaxies.
The universe is around 20 billion years old and consists of vast clusters of galaxies containing stars and gas clouds.
The Big Bang theory describes the origin of the universe through a massive explosion that caused expansion and cooling, leading to the formation of hydrogen and helium.

Formation of Earth

Earth formed approximately 4.5 billion years ago as part of the Milky Way galaxy.
Early Earth lacked an atmosphere and was covered by water vapor, methane, carbon dioxide, and ammonia from its molten surface.
Ultraviolet rays from the sun caused water to break apart into hydrogen and oxygen, allowing H2 to escape and enabling chemical reactions that formed the first water bodies.
The ozone layer developed, and as Earth cooled, rain filled depressions to create oceans.

Emergence of Life

Life is thought to have arisen approximately 4 billion years ago, about 500 million years after Earth’s formation.
The idea of "panspermia" suggests that life, or its building blocks, may have originated from outer space, with early Greek philosophers proposing that spores traveled between planets.
Historically, spontaneous generation was believed to cause life to arise from decaying matter, but this was debunked by Louis Pasteur, who showed that life emerges only from existing life.
Pasteur's experiments illustrated that organisms arose from exposure to air rather than spontaneous generation.

Chemical Evolution

Russian scientist Oparin and British scientist Haldane theorized that life began from pre-existing non-living organic molecules, leading to a process called chemical evolution.
Conditions on early Earth included high temperatures, volcanic activity, and a reducing atmosphere rich in methane (CH4) and ammonia (NH3).
In 1953, S.L. Miller demonstrated these conditions in a laboratory by creating an environment with CH4, H2, NH3, and water vapor exposed to electric discharge at 800°C, simulating early Earth’s conditions.

Description

Explore the fascinating concepts of evolution in Biology Chapter 6. This quiz covers the origin of life, evidences for evolution, and the adaptation of various life forms on Earth. Test your understanding of evolutionary biology and the historical context of life on our planet.