Lesson 6- The Evolution of Cells, Organisms, and Microorganisms
There are three theories of the origin of life on Earth. The first is that it arrived in the form of extraterrestrial sources; the other is that it originated as a heterotroph, and the last that is originated as an autotroph. We had scientist explore this theories of life and find evidence of how the life started on Earth. But till this day do we really know how life was started we can only go off the evidence that we read about in book.
There is yet no evidence to support or contradict panspermia; although the majority view holds that panspermia especially in its form is unlikely given the challenges of survival and transport in space. There are also important issues of the atmosphere, and may be responsible for epidemic outbreaks, new diseases, and the genetic novelty necessary for macroevolution. Panspermia does not necessarily suggest that life originated only once and subsequently spread through the entire Universe, but instead that once started, it may be able to spread to other environments suitable for replication.
The mechanisms proposed for interstellar panspermia are hypothetical and currently unproven. Panspermia can be said to be both interstellar between star systems and interplanetary between planets in the same star system, and its transport mechanisms may include radiation pressure and lithopanspermia (microorganisms in rocks).
Deliberate directed panspermia from space to seed Earth or sent from Earth to seed other solar systems have also been proposed. One new twist to the hypothesis is that it proposes that plasmodia magnetic fields ejected from the magnetosphere may move the few spores lifted from the Earth’s atmosphere with sufficient speed to cross interstellar space to other systems before the spores can be destroyed. Then transfer of material is well documented, as evidenced by meteorites of Martian origin found on Earth.
Earth is where all of us live in. Earth is the 3rd Planet from the sun, as well as the 5th largest planet in our solar system. As far as humans know Earth is unique in the Solar System as being the only planet which is able to support life in all its forms: from basic micro-organisms to highly sophisticated human beings. There are many reasons why this happens. In this Research paper I will be ...
Space travel may also be a way of transport mechanism for cross-pollination in our solar system or even beyond. However, space agencies have implemented sterilization procedures to avoid planetary contamination.
In experiments, scientists have showed that the electrical discharges of lightning, radioactivity, and ultraviolet light caused the elements in the early Earth atmosphere to form the basic molecules of biological chemistry, such as nucleotides, simple proteins, and ATP. It seems likely, then, that the Earth was covered in a hot, thin soup of water and organic materials. Over time, the molecules became more complex and began to collaborate to run metabolic processes. Eventually, the first cells came into being, These cells were heterotrophy, which could not produce their own food and instead fed on the organic material from the primordial soup. (this heterotrophy gives this theory its name).
The anaerobic metabolic processes of the heterotrophy released carbon dioxide into the atmosphere, which allowed for the evolution of photosynthetic autotrophy, which could use light and CO2 to produce their own food. The autotrophy released oxygen into the atmosphere. For most of the original anaerobic heterotrophy, oxygen proved poisonous. The few heterotrophies that survived the change in environment generally evolved the capacity to carry out aerobic respiration. Over the subsequent billions of years, the aerobic autotrophy and heterotrophy became the dominant life-forms on the planet and evolved into allof the diversity of life now visible on Earth.
Atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth’s gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation. A. Nitrogen – 78% – Dilutes oxygen and prevents rapid burning at the earth’s surface. Living things need it to make proteins. Nitrogen cannot be used directly from the air. The Nitrogen ...
Concepts in Biology (2008) Svante Arrhenius, I quoted him on the Panspermia information.