Evolution — BIOLOGY STD 12 Science — Question

1. Fossils help in tracing the organic evolution in following ways:

1. Fossils represent modes of preservation of ancient species.
2. Fossils help in establishing evolutionary traits among organisms and their ancestors.
3. Fossils help in establishing the time period in which organisms lived.
4. Fossils provide good evidence of the structure and lifestyle of animals (and even plants) from the past.
5. They provide a record of the remains of long-extinct species.

2. Miller Urey Experiment:

Miller and Urey were two scientists who believed Oparin and Haldane and wanted to prove their theory. So, they performed the famous ‘Miller- Urey experiment’ in the lab.

• They replicated the environmental and atmospheric conditions that may have existed in the primitive earth in their lab by taking gases like methane, ammonia, hydrogen and water vapour in a closed vessel.
• When they came back to check the results of their experiment after a week, they detected the presence of amino acids, nitrogen bases, fats, and sugar.
• With these results, the theory of gradual chemical evolution was accepted.
• This experiment gave the other scientists to piece the remaining pieces together.