NCERT Solutions for Class 12 Biology Chapter 7 “Evolution” is an essential resource for students to understand the different aspects of evolution, including the principles of natural selection, genetic drift, and speciation. The chapter also covers topics such as the history of life on earth, the concept of the tree of life, and the role of evolution in shaping the biodiversity of the planet. These solutions provided by Swastik Classes offer students a detailed and in-depth explanation of the various concepts and theories related to evolution. They also include practice exercises and questions that can help students test their understanding of the subject matter. With the help of these solutions, students can develop a deeper understanding of the principles of evolution, which can be useful in their future studies or careers.
Answers to the class 12 biology questions provided in the exercise might be challenging for students for a number of reasons. One should not omit any NCERT textbook content in order to get the highest possible grade. Use the Swastik Classes’ NCERT answers for biology class 12 as a resource. Important exam-based questions are covered in depth in each chapter.
NCERT SOLUTIONS FOR CLASS 12 BIOLOGY Chapter 7 Evolution – Exercises
Answer the following Questions.
Question1. Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Solution :
In the presence of antibiotic, the bacteria that are sensitive to it will die. However, if there are any mutants in the population, that can somehow survive its effect, they will multiply and increase in numbers. After that, they will live as antibiotic resistant bacteria.
Question2. Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Solution :
Scientists have found the fossil of a 60-million-year-old creature in Morocco, which is the rabbit sized ancestor of the modern day elephant. Paleontologist Emmanuel Gheerbrant discovered the rabbit-size proto-elephant’s skull fragments in a basin 60 miles (100 kilometers) east of Casablanca, Morocco. The creature, called Eritherium azzouzorum, bolsters the case that whole new orders of mammals were already around less than 6 million years after global catastrophe ended the age of reptiles some 65.5 million years ago.
Question3. Attempt giving a clear definition of the term species.
Solution :
Species can be defined as a group of organisms that can interbreed under natural conditions and produce fertile offsprings.
Question4. Try to trace the various components of human evolution (Hint : Brain size and function, skeletal structure, dietary preference, etc.).
Solution :
| Name | Features |
| Dryopithecus | Ape like, canines large, arms and legs are of equal size, ate soft fruits and leaves |
| Ramapithecus | More man-like, canines were small while molars were large, walked more erect, ate seeds and nuts |
| Australopithecus | Man-like, canines and incisors were small, walked upright, hunted with stone weapons, ate fruits, brain capacities were between 400-600cc. |
| Homo habilis | First human like being, canines were small, first tool makers, did not ate meats, brain capacities were between 650-800cc. |
| Homo erectus | Used stone and bone tools for hunting games, ate meat, brain capacity 900cc. |
| Homo neanderthalnsis | Cave dwellers, used hides to protect their bodies, and buried their dead, brain capacity 1400cc. |
| Homo sapiens (Modern human) | Modern man with high intelligence, developed art, culture, language etc., cultivated crops and domesticated animals. |
Question5. Find out through internet and popular science articles whether animals other than man has self-consciousness.
Solution :
Self-consciousness needs to be defined as the mental link or ones awareness of oneself as an individual or of one’s own being, actions, or thought. There are many other than humans, which have self-consciousness such as dolphins, crow, parrot, chimpanzee, gorilla, etc.
Question6. List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
Solution :
| Animals | Fossils |
| Man | Homo Sapiens |
| Dog | Leptocyon |
| Chimpanzee | Dryopithecus |
| Elephant | Moerithers |
| Horse | Eohippus |
| Gorilla | Dryopithecus |
| Camel | Protylopus |
| Whale | Protocetus |
| Fish | Arandaspis |
| Octopus | Belemnite |
Question7. Practise drawing various animals and plants.
Solution :
Draw various animals and plants from the chapter.
Question8. Describe one example of adaptive radiation.
Solution :
Darwin finches of the Galapagos Islands is an example of adaptive radiation. They once had a common ancestor but as time passed they underwent evolution and adapted itself according to their food habitat.
Question9. Can we call human evolution as adaptive radiation?
Solution :
No, human evolution cannot be called adaptive radiation because adaptive radiation is an evolutionary process that produces new species from a single, rapidly diversifying lineage, which is not the case with human evolution.
Question10. Using various resources such as your school Library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal say horse.
Solution :
The evolutionary stages of horse are:
- Eohippus: It appeared in the Eocene period about 52 million years ago. It was approximately the size of a fox (0.4 m), with a relatively short head and neck and a springy, arched back. It had four functional toes and a splint of 1 and 5 on each hind limb and a splint of 1 and 3 in each forelimb.
- Mesohippus: Approx, 40 million years ago in Oligocene period, Mesohippus which was slightly larger than Eohippus about 0.6 metre. It had three toes in each foot.
- Merychippus: In Miocene period the grazer Merychippus flourished. It had the size of approx 1m. It still had three toes in each foot, but it could run on one toe. The side toe did not touch the ground. The molars were adapted for chewing the grass.
- Pliohippus: Around 12 million years in Pilocene period, modern horse Pilohippus emerged. It had a single functional toe with splint of 2nd and 4th in each limb.
- Equus: Pliohippus gave rise to modern horse, Equus. It have one toe in each foot. They have incisors for cutting grass and molars for grinding food.
Conclusions for NCERT SOLUTIONS FOR CLASS 12 BIOLOGY CHAPTER 7 EVOLUTION
NCERT Solutions for Class 12 Biology Chapter 7 “Evolution” provided by Swastik Classes cover the different aspects of evolution, including its principles, history, and role in shaping the biodiversity of the planet. The solutions offer a comprehensive and detailed explanation of the concepts and theories related to evolution. They also provide practice exercises and questions that can help students test their understanding of the subject matter. By using these solutions, students can gain a deeper understanding of the principles of evolution and its importance in biology. The knowledge gained from these solutions can be useful in further studies or careers related to the field of biology. Overall, these solutions are an essential resource for students studying evolution in Class 12 Biology. FAQS
What is evolution, and how does it occur?
Evolution refers to the process of change in the inherited traits of a population over time, leading to the emergence of new species. It occurs through the mechanisms of natural selection, genetic drift, gene flow, and mutation.
What is natural selection, and how does it contribute to evolution?
Natural selection is the process by which organisms that are better adapted to their environment have a higher chance of survival and reproduction, passing on their advantageous traits to their offspring. This process can lead to the emergence of new species and contribute to the evolution of a population.
How does genetic drift contribute to the process of evolution?
Genetic drift is the random fluctuation in the frequency of certain traits in a population, caused by chance events such as natural disasters or genetic mutations. This process can lead to the loss of certain traits or the emergence of new ones, contributing to the evolution of a population.
How does speciation occur, and what are the different types of speciation?
Speciation occurs when a population of organisms becomes reproductively isolated from other populations, leading to the emergence of a new species. This can occur through different mechanisms, such as geographic isolation (allopatric speciation) or through changes in mating behavior or other reproductive barriers (sympatric speciation).
How does the study of fossils provide evidence for evolution?
The study of fossils provides evidence for evolution by revealing the gradual changes in the morphology and traits of organisms over time. By comparing the fossil records of different species, scientists can trace the evolutionary history of different groups and identify transitional forms that bridge the gap between different species. This evidence supports the theory of evolution by providing a physical record of the gradual changes that have occurred over millions of years.
