Origin and Evolution of Life Notes, Questions Answers and MCQs

origin and evolution of life notes

In this article, you will understand the topic "origin and evolution of life" in a very easy way. We are going to provide you the notes of this chapter, along with questions answers and MCQs which will help you ace in your class 11 or class 12 exams. 

Origin and evolution of Life PDF download link is provided at the end of this article. You can either download this free pdf for offline use or read content of the PDF online here.

Some Basic Terms related to origin and evolution:


Life we are living and people around us in today's world were not same like this before. We have evolved a lot and continuously evolving. After bearing various hurdles, challenges, numerous eras, phases, and a great deal of hardship, mankind has reached this level. 

Basically, life on our planet has been changing and evolving for a long time. A long, long time ago, the Earth looked a whole lot different than it does now, and creatures had to adapt to their surroundings in order to survive. Over time, some species became extinct, while others evolved and developed into what we see today. 

According to the Theory of Organic Evolution from a Common Ancestor, many contemporary organisms evolved from much simpler ancestral forms. This theory actually suggests that the organic evolution is the process of gradual change. “All living creatures on Earth derive from a common ancestor with modifications,” according to the organic evolution theory.

The characteristics of organisms have changed in the past, are changing today, and will continue to change in the future. 

Some of these changes happened slowly over hundreds or thousands of years, but others happened much more quickly, like with the black peppered moth or pesticide-resistant insects.

Let's go back in time to before the creation of the Earth!

The Origin of Universe

Life as we know it, had its existence after the earth was formed, with the atmosphere and galaxy 20 billion years ago. Back then, there was nothing but darkness and gas. Big Bang Theory is the most widely accepted explanation for the origin of life and the universe. Imagine, a very huge explosion that took place 20 billion years ago gave birth to the cosmos. Fantasy or reality, the universe came to be, and as the effects of the explosion settled, temperatures cooled and gases like hydrogen and helium filled the empty spaces, shaping the galaxies we see today.

Universe Big Bang Theory

It took billions of years for the perfect recipe of water vapor, methane, carbon dioxide, and ammonia to come together and create our planet. Back then, there was just air and wetness, with no sign of life yet. 

In the presence of sunlight, the process was accelerated and electrical molecular connections were formed and broken, giving the earth its new look. And after millions of years of the stabilization of atmosphere, the first spark of life emerged on earth, marking the start of the life on our planet.

Life's origin

There are numerous theories regarding earth's life beginning. Some scientists believed life began as a particle from space, while another group said life arose from non-cellular materials such as mortal matter. 

The latter perspective was known as an automated generation idea, that was subsequently abandoned.

In 1953, Oparin and Haldane suggested life from non-living substances such as proteins and RNA. This was followed by an evolutionary hypothesis suggesting that the atmosphere on earth may lead to the creation of life molecules from non-living molecules. 

Few scientists conducted similar experiments. However, as the first life started, they began to look differently. It laid the foundation for development.

Hope you have grasped fundamental facts regarding origin and evolution of life. Now, these answered questions will assist you expand knowledge.

Origin and evolution of life question Answer PDF:

1. Explain life's chemical genesis or Oparin idea.

Ans: Alexander Oparin in 1923 and JBS Haldane in 1928, both scientists backed biology hypothesis and published Oparin Holdane theory.

Thus life initially originated from basic living creatures. At the beginning of the world's surface, the earth was covered by an ancient climate or air conditioning that produced several gases such as CO2, CO, SO2, SO3, N2, NO2, N2O5, H2S, CH4, H2O, etc. Most of the gases were the significant energy sources, such as sunshine or sunlight, radioactive material energy, and volcanic eruption energy. This solution changed cyanobacteria or blue algae's early life.

Conclusion: Life started from the simplest combination at the beginning, but not as today.

2. What's evidence of evolution? Discuss.

Ans: Evidence of evolution is:
1. Anatomical evidence for comparison or morphological feature.
(A) Homologus organs 
b) Same organs 
c) Linking animals

2. Model character evidence.
3. Paleontological or fossil research evidence.
4.Physiological or biochemical evidence
5. Genetics evidence.

A) Homologus organs: 
These are the organs of the same origin and form but differing in morphology and function. Using homologous organs, animals may trace the common ancestor. For example: funny animals' frontal bones, Radio-ulna, carpels, metacarpels, and phallenges.

The genesis of the bones in the animals above is the same, but the structure varies only in their natural order and roles owing to various mutations. So having the same root characteristics showed that in the beginning all vertebrates may have the same origin.

B) Similar organs: they are organs of distinct origin, anatomy and appearance, but have the same functions. 

Birds - pre-modification
Butterfly wings - thoracic annex.

C) Organs: Now are the organs used to work in the past, but these days are not completely functioning.

(Link): A link or missing link is a character represented by animals of two or more groups. E.g. Jurassic reptile or extinct Archaeopteryx bird is an excellent illustration.

2. Evidence of foetal character: the foetus is responsible for embryo development, all vertebrate embryos exhibit normal character.
A. One central eye for listening.
B. Two basic hearts' presence.
C. Pharyngeal gill respiratory slits.
D. Mail and tail availability.
3. Paleontological or fossil research evidence:

Paleontology involves studying extinct fossils. Fossil research offers clear, direct proof of evolution. They assist track facts of genesis and development, connections, increasing problems, etc. Archeological evidence indicates to gradual development throughout time. Animals are better preserved as fossils than plants.

3. Discuss Darwinism.

Ans: Charles Darwin (1809-1882) was a naturalist, prolific English author. After graduating almost five years, he sailed across Britain on his HM Beagle voyage. And between 1835-1855 he travelled throughout the European and Indian Ocean for almost 20 years. He gathered numerous animal species during his trip. Another young scientist, Sir Alfred Wallace, also studied the variety of bird beaks in the Malayan peninsula. In 1858, Darwin and Wallace produced a written species list that became the world's best-selling book. In 1859, Darwin published a dissertation on evolution theory, termed evolution theory. Similarly, in 1871, he released The Descent of Man, one of the world's second best-selling novels.

1. Animals are extremely reproductive, yet their numbers are nearly constantly unchanged.
2. The current battle.
3. Diversity, genetics.
4. Natural choice
5. Species origin.

1. Animals are extremely prolific, but constant:
All animals have a high lifecycle reproduction rate. For example: one pair of eggs lay around 6-7 eggs, each egg group has a yield of 130-150 eggs, hatching on the 10th and 14th day and starting to reproduce. So, till the first parent remains, the housefly number is likely to be 191 x 10 increased to 18 digits.
If every generation of houseflies continues their life cycle, then only houseflies that have not yet occurred will govern it in the world to come. Although the fertility rate is extremely high, it is nearly always consistent with many variables in people.

2. The fight for survival: increasing the number of animals immediately increases competition between particular and internal species. Through such contests, a food chain is created in which the process of eating and diet continues. As a consequence, only those creatures that continue their life cycles can battle the struggle for existence, particularly food and space.

3. Genetics: Animals that battle for survival continue their life cycles. Among those species with a very good diversity, all others will automatically continue the life cycle as a gene.
Natural Choice or Power Survival (Spencer): surviving animals that battle for existence.

MCQs from origin and evolution of life:

  1. Why did it take millions of years for life to appear on Earth after the planet had formed?

  • The planet had cooled down enough to sustain life.
  • The planet had warmed up enough to sustain life.
  • Life on Earth could begin only when seedlings arrived on our planet from other worlds.
  • It took millions of years for RNA to replace DNA.

2. Who proposed that the first form of life could have come from per- existing non- living organic molecules?
    a. Alfred Wallace
    b. oparin and Haldane
    c. Charles Darwin
   d. Louis Pasteur

3. Universe originated
  1. 10-20 billion years ago
  2. 1-2 billion years ago
  3. 500-700 million years back
  4. 250-500 million years ago
4. Oxygen in atmosphere has been formed by _____
a) Evaporation of water
b) Metabolism of microorganisms
c) Decaying organisms
d) Photosynthesis of blue green algae

5. Which of the following is the generally recognised hypothesis about the beginning of life on earth?
  • Cosmozoic theory
  • Theory of spontaneous generation
  • Theory of Chemical evolution
  • Theory of special creation

6. When the first living cell appeared
  • 4.6 billion years ago .
  • 3.8 billion years before now
  • about 2.6 billion years ago
  • Approximately 2 billion years ago

7. Which were the first cells to develop?
  • Photoautotrophs.
  • saprotrophs
  • chemoautotrophs
  • chemoheterotrophs

8. Which is the oldest geological time period among the following?
  • Cambrian 
  • Permian 
  • Jurassic 
  • Quaternary

9. The experiment which stated that recreated circumstances that were believed to exist on the early Earth is
  • Experiment Hershey–Chase
  • Experiment Geiger–Marsden
  • Experiment Miller–Urey
  • Experiment with Schiehallion

10. Evolution, according to Darwin, is ___
  • sluggish, gradual, and ongoing process.
  • procedure that begins abruptly yet ends abruptly.
  • A sluggish and irregular procedure.
  • A gradual, abrupt, and discontinuous process.

11. The process through which various creatures develop similar characteristics in nature is referred to as .
  • Drift in genetics 
  • Cultivated selection
  • Diffusion of evolution
  • Convergent evolution 

  1. Option a - The planet had cooled down enough to sustain life.
  2. Option b - Oparin and Haldane.
  3. Option a - 10-20 billion years ago.
  4. Option d - Photosynthesis of blue-green algae.
  5. Option c - Theory of Chemical evolution.
  6. Option b - 3.8 billion years before now.
  7. Option a - Photoautotrophs.
  8. Option a - Cambrian.
  9. Option c - Experiment Miller–Urey.
  10. Option a - Sluggish, gradual, and ongoing process.
  11. Option d - Convergent evolution.

We have also uploaded Biomolecules Notes PDF in our website. So you can check that out as well.  Hope this Origin of Life Notes and Question answers PDF has been useful to you.

To read this content offline, click "Download PDF" button. Wait for the PDF preview to load. Then, click the download symbol or "save" button and choose the download location.

Download PDF
Please wait..

Download our Android Apps for Offline NEB Notes!

Install from Play Store