Hello Students. Are you Searching for NCERT Solutions for Class 12 Biology Chapter 7? If yes then you are most welcome to NCERTian. Here we have provided you with the complete Question and Answers of Chapter 7: Evolution. These solutions are written by expert teachers and faculties keeping the need of students in mind.
| Chapter | 7. Evolution |
| Subject | Biology |
| Class | Twelve |
| Category | NCERT Solutions for Class 12 |
Our NCERT Solutions for Class 12 Biology is a great resource for students preparing for boards or competitive exams, such as the NEET. These Biology Class 12 Solutions are made by expert faculties, keeping the latest curriculum in mind. Besides helping students with understanding the concepts of Biology, these solutions are also helpful in writing accurate answers that are vital to score full marks in examinations. On this page, we have given the Class 12 Biology Chapter 7: Evolution Solutions.
NCERT Solutions for Class 12 Biology Chapter 7
Evolution Solutions
Q1) Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.
Darwinian selection theory states that individuals with favourable variations are better adapted than individuals with less favourable variation. It means that nature selects the individuals with useful variation as these individuals are better evolved to survive in the existing environment. An example of such selection is antibiotic resistance in bacteria. When bacterial population was grown on an agar plate containing antibiotic penicillin, the colonies that were sensitive to penicillin died, whereas one or few bacterial colonies that were resistant to penicillin survived. This is because these bacteria had undergone chance mutation, which resulted in the evolution of a gene that made them resistant to penicillin drug. Hence, the resistant bacteria multiplied quickly as compared to non-resistant (sensitive) bacteria, thereby increasing their number. Hence, the advantage of an individual over other helps in the struggle for existence.
Q2) Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Answer) 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.
Q3) Attempt giving a clear definition of the term species.
Answer) Species can be defined as a group of organisms that can interbreed under natural conditions and produce fertile offsprings.
Q4) Try to trace the various components of human evolution (Hint : Brain size and function, skeletal structure, dietary preference, etc.).
Answer)
| Name | Brain capacity | Posture | Food | Features |
|---|---|---|---|---|
| Dryopithecus africans | … | Knuckle walker | Soft fruit and leaves | Canines large, arms and legs are of equal size |
| Ramapithecus | … | Semi-erect (more man-like) | Seeds, nuts | Canines were small while molars were large. |
| Australopithecus africanus | 450 cm3 | Full erect posture, height (1.05 m) | Herbivorous (ate fruits) | Hunted with stone weapons, lived at trees, canines and incisors were small |
| Homo habilis | 735cm3 | Fully erect posture, height (1.5 m) | Carnivorous | Canines were small. They were first tool makers. |
| Homo erectus | 800-1100 cm3 | Fully erect posture, height(1.5-1.8 m ) | Omnivorous | They used stone and bone tools for hunting games. |
| Homo neanderthalnsis | 1300-1600 cm3 | Fully erect posture, height (1.5-1.66 m) | Omnivorous | Cave dwellers, used hides to protect their bodies, and buried their dead |
| Homo sapiens fossilis | 1650 cm3 | Fully erect posture with height (1.8 m) | Omnivorous | They had strong jaw with teeth close together. They were cave dwellers, made paintings and carvings in the caves. They developed a culture and were called first modern men. |
| Homo sapiens sapiens | 1200-1600 cm3 | Fully erect posture, height (1.5-1.8 m ) | Omnivorous | They are the living modern men, with high intelligence. They developed art, culture, language, speech, etc. They cultivated crops and domesticated animals. |
Q5) Find out through internet and popular science articles whether animals other than man has self-consciousness.
Answer) 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.
Q6) List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.
Answer)
| Animals | Fossils |
|---|---|
| Man | Homo Sapiens |
| Dog | Leptocyon |
| Chimpanzee | Dryopithecus |
| Elephant | Moerithers |
| Horse | Eohippus |
| Gorilla | Dryopithecus |
| Camel | Protylopus |
| Whale | Protocetus |
| Fish | Arandaspis |
| Octopus | Belemnite |
Q7) Practise drawing various animals and plants.
Answer) Students can solve themselves
Q8) Describe one example of adaptive radiation.
Answer) Adaptive radiation is an evolutionary process that produces new species from a single, rapidly diversifying lineage. This process occurs due to natural selection. An example of adaptive radiation is Darwin finches, found in Galapagos Island. A large variety of finches is present in Galapagos Island that arose from a single species, which reached this land accidentally. As a result, many new species have evolved, diverged, and adapted to occupy new habitats. These finches have developed different eating habits and different types of beaks to suit their feeding habits. The insectivorous, blood sucking, and other species of finches with varied dietary habits have evolved from a single seed eating finch ancestor.
Q9) Can we call human evolution as adaptive radiation?
Answer) 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.
Q10) 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 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.
That’s it. These were the solutions of NCERT Class 12 Biology Chapter 7 – Evolution. Our team hopes that you have found these solutions helpful for you. If you have any doubt related to this chapter then feel free to comment your doubts below. Our team will try their best to help you with your doubts.