NCERT Solutions for Class 12 Biology Chapter 6: NCERT Solutions for Class 12 Biology Chapter 6 Evolution explains how life on Earth began and changed over time. This chapter discusses important topics like the origin of life, different theories of evolution, and the evidence that supports these ideas.
It also explains processes like natural selection, genetic drift, and how new species are formed. These solutions are written in a simple way to help students understand the concepts better. By practicing these, students can prepare well for their board exams and entrance tests like NEET.NCERT Solutions for Class 12 Biology Chapter 6 PDF
Here is the NCERT Solution for Class 12 Biology Chapter 6 Evolution: Chapter 6 of Class 12 Biology focuses on the concept of evolution, the process by which species change over time. The chapter discusses various theories, evidence, and mechanisms that explain how life on Earth has evolved over millions of years. 1. Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.Answer:
According to Darwin’s theory, organisms with beneficial traits survive better in their environment. In the case of bacteria, when antibiotics are used, most bacteria die, but a few with mutations that make them resistant survive. These resistant bacteria multiply quickly because there’s less competition after the sensitive bacteria die. Over time, this leads to a population of antibiotic-resistant bacteria. These bacteria can also share their resistance genes with others, making the problem worse. 2. Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.Answer:
A fascinating fossil discovery related to dinosaurs reveals their evolution during the Jurassic era. This finding helped scientists understand how reptiles evolved and how mammals and birds emerged. Recently, fossils like Confuciusornis , an ancient bird from China, sparked debates about how birds evolved from dinosaurs. 3. Attempt giving a clear definition of the term species.Answer:
A species is a group of organisms that can interbreed and produce healthy, fertile offspring. 4. Trace the various components of human evolution.Answer:
Human evolution involved changes in brain size, body posture, diet, and physical features over time. The stages are as follows:Human Stage | Brain Size | Posture | Diet | f |
---|---|---|---|---|
Dryopithecus africans | - | Ape-like, knuckle-walking | Leaves, fruits | Equal arms and legs, large canines |
Ramapithecus | - | Semi-erect | Nuts, seeds | Large molars, small canines |
Australopithecus africanus | 450 cm³ | Fully erect | Herbivorous | Used tools, lived on trees |
Homo habilis | 735 cm³ | Fully erect | Carnivorous | First to make tools |
Homo erectus | 800–1100 cm³ | Fully erect | Omnivorous | Used advanced tools for hunting |
Homo sapiens fossils | 1650 cm³ | Fully erect | Omnivorous | Developed culture, made art |
Homo sapiens sapiens | 1200–1600 cm³ | Fully erect | Omnivorous | Highly intelligent, modern humans |
Answer:
Yes, some animals, like dolphins, show self-consciousness. They recognize themselves in mirrors and communicate using unique whistles and movements. Other self-aware animals include chimpanzees, parrots, crows, and orangutans. 6. List 10 modern-day animals and their corresponding ancient fossils.Answer:
Modern Animal | Fossil Name |
---|---|
Horse | Eohippus |
Man | Ramapithecus |
Elephant | Moeritherium |
Whale | Protocetus |
Fish | Arandaspis |
Giraffe | Palaeotragus |
Dog | Leptocyon |
Camel | Protylopus |
Tetrapod | Ichthyostega |
Bat | Archaeonycteris |
Answer:
Start by tracing outlines of animals and plants from books or magazines. Use encyclopedias and the internet for more examples. Begin with simple drawings, gradually adding details like leaves, flowers, or feathers. 8. Describe one example of adaptive radiation.Answer:
Adaptive radiation occurs when one species evolves into several different species to adapt to various environments or food sources. A good example is Darwin’s finches on the Galapagos Islands. From a common ancestor, finches developed different beak shapes based on their diets, such as seed-eating, insect-eating, and even blood-sucking. 9. Can we call human evolution adaptive radiation?Answer:
No, human evolution isn’t considered adaptive radiation. Although humans evolved from a common ancestor, this evolution didn’t lead to the formation of multiple new species. Adaptive radiation refers to the diversification of one species into many, which isn’t the case for humans. 10. 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.Answer:
The evolution of the horse began during the Eocene era with Eohippus and progressed as follows:Eohippus → Mesohippus → Merychippus → Pliohippus → Equus
Key evolutionary traits: