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Ncert Solutions For Class 12 Chapter 7

Ncert Solutions For Class 12 Biology Chapter 7 Pdf Download

Adda 247 provides NCERT Solutions for Class 12 Biology chapter 7. NCERT Solutions for Class 12 Biology chapter 7 which is for the students who want to go ahead in life and achieve great marks in their examinations. The NCERT Solutions for class 12 are provided by the teachers who are experts of their subjects. The solutions are set according to the rules formulated by the NCERT class 12 biology and in the language that can be understood by every student. By these reading the solutions students can build up a strong base easily. The NCERT class 12 Biology solutions covers the chapters 1 to 16 with the important questions and the answers in a detailed way.

Examinations can be threatening for some people, a proper learning of the concepts is the key to crack the examination. Students rely on the solutions of the NCERT provided by Adda 247. The solutions are formulated by the experts of the subjects who have tremendous knowledge in their subjects.

These NCERT Solutions of class 12 chapter 7 help the students to get familiarized with the textbooks. The students can access the solutions anywhere while browsing the web easily. The solutions are very precise and accurate.

 

NCERT Solutions for Class 12 Biology Chapter 7 – Evolution

 

The chapter provides information about Evolution. Evolutionary biology is the study of history of life forms on earth. The process of gradual modification of simpler forms into the present complex forms over millions of years is called evolution. Charles Darwin concluded that existing living forms share similarities to varying degrees not only among themselves but also life forms that existed millions of years ago. Alfred Wallace stated that all the existing life forms share similarities and shares some common ancestors which are present at different periods in the history of earth.



Download Full PDF of Class 12 Biology Chapter 7

 

Features of the NCERT Solutions for Class 12 Biology Chapter 7 – Evolution

 

NCERT Solutions for class 12 biology chapter 7 have been answered based on the important information on the question.

  • The columns are used wherever necessary.
  • Solutions are solved point wise and accurately answered point to point.

 

The important question of Ncert Solutions Class 12 Biology Chapter 7

 

Question 1. Explain antibiotic resistance observed in bacteria in light of Darwinian selection theory.

Answer:

  • 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.

 

Question 2.  Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.

Answer:  Paleontology is the field of science the helps us to understand about evolution by the use of fossils.

Fossils of dinosaurs were found that have revealed the evolution of reptiles in Jurassic period. Two unusual fossils recently found in China which brings the controversy over the evolution of birds. Confuciusornis lived during the Cretaceous period in China is the genus of the primitive bird.

 

Question 3. Attempt giving a clear definition of the term species.

Answer: Species can be defined as a group of organisms, which have the capability to interbreed in order to produce fertile offspring and do not breed with members of other species.

 

Question 4. Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)

Answer: The various components of human evolution involve the age of appearance, brain capacity, posture, locomotion, height, body hairs, dietary preferences, skeletal structure, cranium structure etc. A summary of human evolution based on these components is as follows:

 

Name of the Organisms Brain capacity in cm Posture Dietary preferences Some other features
1. Dryopithecus   not known Bent, ape-like Soft fruits and leaves Equal sized arms and legs, large canines
2. Ramapithecus not known Semi-erect, more man-like seeds and nuts Large molars, small canines
3. Australopithecus 500 Fully erect Herbivorous Small canines, hunted with stones
5. Homo habilis 650-800 Fully erect Carnivorous Toolmakers with small canines
6. Homo erectus 900 Fully erect Omnivorous Used tools made of stones and bones
7. Homo neanderthalnsis 1400 Fully erect Omnivorous Cave dwellers used to hide their bodies
8. Homo sapiens 1200-1600 Fully erect Omnivorous Highly intelligent, social

 

Question 5. Find out through internet and popular science articles whether animals other than man has self-consciousness.

Answer:  Self-consciousness is defined as the awareness of oneself. Other than man there are some animals which are self-conscious. These include dolphins, elephants, chimpanzees, apes and monkeys. Self-consciousness in animals can be studied using the mirror test. When chimpanzees were exposed to the mirror for the first time they were threatened. However on repeated exposure they started looking into the mirror and grooming, picking their nose, making faces, etc.

 

Question 6. List 10 modern-day animals and using the internet resources link it to a corresponding ancient fossil. Name both.

Answer: The modern day animals and their ancient fossils are listed in the following table.

Animal Fossil
Man Ramapithecus
Horse Eohippus
Dog Leptocyon
Camel Protylopus
Elephant Moerithers
Whale Protocetus
Fish Arandaspis
Tetrapods Icthyostega
Bat Archaeonycteris
Giraffe Palaeotragus

 

Question 8. Describe one example of adaptive radiation.

Answer:  Adaptive radiation refers to the process in which the individuals belonging to a rapidly diversifying group, diverge from their lineage to form new species. Adaptive radiation works on the theory of natural selection. One example of adaptive radiation is Darwin’s finches of Galapagos island. These finches were formed from a single diversifying species that came on this geographical region accidentally. The new species diversified and got adapted to the conditions present on this habitat. The different finches developed different eating habits and accordingly developed different beak structures. This further led to their evolution through adaptive radiation

 

Question 9. Can we call human evolution as adaptive radiation?

Answer:  No, we cannot call human evolution as adaptive radiation.

Adaptive radiation is the diversifying of organisms from a single species due to various factors such as competition for resources, isolation in a different environment, etc.

Human evolution was a gradual process of anatomical, physiological and changes that took place over a long period of time. The humans did not diversify into many species from a common ancestor. They rather enhanced over the period of time, suiting best according to their current environment.

 

Question 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 horse started with Eohippus during Eocene period. It involved the following evolutionary stages.

(i) Gradual increase in body size

(ii) Elongation of head and neck region

(iii) Increase in the length of limbs and feet

(iv) Gradual reduction of lateral digits

(v) Enlargement of third functional toe

(vi) Strengthening of the back

(vii) Development of brain and sensory organs

(viii) Increase in the complexity of teeth for feeding on grass

The evolution of horse is represented as

(i) Eohippus

It had a short head and neck. 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. The molars were short crowned that were adapted for grinding the plant diet.

(ii) Mesohippus

It was slightly taller than Eohippus. It had three toes in each foot.

(iii) Merychippus

It had the size of approximately 100 cm. Although 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.

(iv) Pliohippus

It resembled the modern horse and was around 108 cm tall. It had a single functional toe with splint of 2nd and 4th in each limb.

(v) Equus

Pliohippus gave rise to Equus or the modern horse with one toe in each foot. They have incisors for cutting grass and molars for grinding food.

 

FAQs on NCERT Solutions for Class 12 Biology Chapter 7

 

What are the advantages of referring NCERT Solutions for class 12 Biology chapter 7?

Students referring the ncert solutions for class 11 biology chapter 7 pdf download by Adda 247 find the solutions helpful during the exams. The solutions are prepared by the experts in an interactive manner keeping in mind the students. The students’ perspective is kept in mind while preparing the solutions. It helps in completing the syllabus on time and also provides notes for the revision prior to the exam.

 

What are the advantages of referring NCERT in competitive exams like JEE and AIPMT? 

Most of the competitive exams like NEET, JEE etc. follow the basic NCERT books for designing their question papers. NCERT serves as the base for every book prepared for NEET and JEE. The competitive exams are based on the CBSE syllabus applied in XI and XII classes and NCERT books strictly follow CBSE syllabus. In addition to this, NCERT books play an important role in clearing out the theoretical concepts. Every topic given in NCERT books is explained in such a way to help students make their basics and fundamentals strong and clear.

 

How To Use NCERT Solutions For Class 12 Biology?

  1.  Study the chapter topic wise and understand the various concepts.
  2.  First, try to solve the questions by yourself and then look at the solutions.
  3.  Use them as a reference guide while revising the chapter.
  4.  If you get stuck at any question, you can check the step by step solution from the PDF from ncert solutions for class 11 biology chapter 2 pdf download by Adda 247.

 

Is it mandatory to solve all the NCERT questions mentioned at the end of each chapter?

The questions and answers mentioned in NCERT textbooks at the end of each chapter are quite important not only for examination but also for understanding the concepts in a better way. These questions aim to test the students’ understanding and learning over the topics that they have learned in the chapter.

Solving the NCERT exercise problems will help to

  • clear all the concepts and formulae you learned in a chapter
  • get comfortable with different types of questions that might be asked in exams
  • get enough practice which is key to succeed in Mathematics exam
  • improve your accuracy and speed

 

What are the important concepts covered in the Chapter 7 of NCERT Solutions for Class 12 Biology?

The concepts involved in the chapter 4 of NCERT Solutions are –

7.1 – Origin of Life
7.2 – Evolution of Life Forms – A Theory
7. 3- What is the Evidence for Evolution?
7.4 – What is Adaptive Radiation?
7.5 – Biological Evolution
7.6 – Mechanism of Evolution
7.7 – Hardy – Weinberg Principle
7.8 – A Brief Account of Evolution
7.9 – Origin and Evolution of Man

 

These concepts are created by the faculty at Adda 247. The solutions are available at Adda 247 in the PDF format which can be downloaded by the students.

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