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Xam Idea Class 12 Biology Chapter 7 Solutions: Evolution

Xam Idea Class 12 Biology Solutions for Chapter 7 ‘Evolution’ are about one of the most mysterious concepts of the formation of life on earth. The origin of life on earth can be discovered only after finding the history of the origin of the universe, the planets, and the stars. With the help of our Xam Idea solutions, you would understand how chemical evolution or the formation of biomolecules leads up to the first cellular formation of life.

Xam Idea Class 12 Biology Solutions are created by our subject matter experts as per the latest CBSE Class 12 board exams syllabus. We have provided solutions to all the 196 questions of the chapter. This includes questions based on various topics of the chapter like adaptive radiation, Darwin’s theory, the significance of the study of fossils, Miller’s experiment, and if evolution is a process or end result of a process. We have also discussed topics like the origin of life, theories on the evolution of life forms, the evidence for evolution, adaptive radiation, biological evolution and mechanism of evolution in depth.

Xam Idea solutions provided by Instasolv are one of the best solutions for preparing for Class 12 CBSE board exams. Evolution is a complex and challenging topic with lots of theories and explanations. The key to learning it effectively is by referring to our solutions that are designed by the finest academic experts. Our well-organized, accurate, and engaging answers would definitely help you enhance your scores in the exams.

Important topics for Xam Idea Class 12 Biology Solutions Chapter 7: Evolution

Origin of Life: After the formation of the planet Earth, it took around 500 million years for life to the origin. There were many different theories on the formation of life on earth:

  • Many scientists had a conception that life came from other planets. Greeks had a theory that a part of life called spores was transferred from other planets.
  • The theory of spontaneous origin suggested that life had appeared from the dead and decaying matters.
  • The life that emerged from the pre-existing life was experimentally proved by Louis Pasture thereby, banishing the theory of spontaneous.
  • The formation of life appeared by chemical evolution and life was first formed from the pre-existing non-living organic molecules like proteins and RNA as suggested by Oparin and Haldane.

Experimental representation of Miller’s experiment: In 1953, Miller experimented to prove that the origin of life on earth is due to chemical evolution. The experiment represents that:

3 billion years ago the first non-cellular forms of life originated. They were giant molecules like polysaccharide, protein, RNA, etc.

The cellular formation of life was single-cell originated in water.

Biogenesis: Biogenesis means the first form of life appeared slowly through evolutionary forces from non-living molecules.

Evidence of Evolution: Several proofs provide evidence that the evolution of life has taken place on earth. They are:

  • Paleontological evidence: Palaeontology is a scientific study of the history of life on the earth based on fossils. Fossils are remains of single-cellular living things, bacteria, fungi that have been replaced by aged rock sediments. Fossils help in understanding the different aspects of the existence of a living organism.
  • Homologous Organs: It can be defined as the organs that have a similar basic structure and different functions for different animals. For example, humans, frogs, flippers, and whales have a similar basic structure but different functions.
  • Analogous structures: They are the opposite of homologous organs. It can be defined as organs that have similar functions and different anatomy and origin. For example, potatoes and sweet potatoes both have the same function of food storage but different origins.
  • Biochemical evidence: Biochemical means changes that occur at the molecular level in organisms over a period of time. These biochemical changes share some common structural similarities between ancestors and diverse organisms.

Darwin’s Theory of Evolution: The theory of evolution by Darwin is based on the two vital concepts that are “descent with modification” and “natural selection.” The theory of natural selection was based on:

  • Limited natural resources and Overpopulation: Each year there is a struggle of resources as the population is more as compared to resources available.
  • Survival to the fittest: Here the word “fittest” is not related to the human being’s fitness but, it is related to the ability to survive and reproduce.
  1. Competition for resources
  2. Struggle for existence

Brief Account of evolution: The first cellular form of life existed on the planet earth about 2000 million years ago.

  • Single-celled organisms converted to multi-celled organisms.
  • 500 million years ago invertebrates were evolved.
  • 350 million years ago jawless fish were formed.
  • The organisms started to conquer from water to land. They evolved into first amphibians.
  • Reptiles were evolved from amphibians. They had different shapes, sizes, and could lay eggs.
  • A few reptiles evolved into birds and a few into mammals.
  • Mammals were more intelligent in noticing and avoiding danger.

Exercise Discussion for Xam Idea Class 12 Biology Solutions Chapter 7: Evolution

Chapter 7 Evolution has a total of 196 questions in it. The questions are categorized into 4 parts: they are very short question answers, short question answers and long question answers. Each category is further divided into two parts: PYQ (past years questions) and OIQ (objective inventory questionnaires).

Very Short Question Answers 

  • It consists of a total of 79 questions out of which 30 questions fall under the PYQ section and the rest 49 questions fall under the OIQ section. 
  • Very short QA section covers very simple and direct questions like definitions. 
  • Questions are based on topics like the genetic drift, Hardy-Weinberg’s evolution theory, gene migration, biochemical evolution, convergent evolution, and spontaneous generation theory.

Short Question Answers Part I & II

  • Part I consists of a total of 66 questions from which 30 questions belong to the PYQ category and 33 questions belong to the OIQ category. 
  • Part II consists of a total of 31 questions from which 23 questions belong to the PYQ and 8 questions belong to the OIQ. 
  • The complexity of the question asked in this section increases as compared to a very short QA. 
  • Questions are based on topics like Miller’s experiment, adaptive radiation, mass extinction of species, Darwin’s theory of natural selection, reproduction & reproductive isolation, and paleontological evidence.

Long Question Answers 

  • It consists of a total of 23 questions from which 19 questions belong to the PYQ category and 4 questions belong to the OIQ category. 
  • It covers the most complex and twisted questions of the chapter.
  •  Questions covered under this section are: Lamarck’s theory of evolution, evidence of evolution from comparative anatomy and morphology, Miller’s and Urey’s experiment, industrial melanism, homologous organs, founder effect, Oparin and Haldane hypothesis, and Vries theory of mutation.

Why Use Xam Idea Class 12 Biology Solutions Chapter 7: Evolution by Instasolv?

  • Xam Idea Class 12 Biology Solutions by Instasolv are free of cost and easily accessible to the students on our website.
  • All these solutions are as per the latest CBSE Class 12 syllabus for Biology. 
  • Instasolv’s solutions would help you boost your confidence and tackle any type of questions asked in exams whether it be CBSE or NEET.
  • Our solutions would help you strengthen your weaker topics by solving all your doubts related to Evolution instantly.