NEET Important Chapter - Evolution

This article includes the important topics of the chapter Evolution as per the NEET syllabus for Biology. This article will make topics easy to understand for students who are preparing for NEET as it contains the  main and important topics for thorough preparation and last-minute revision. 

This article gives information on all important topics and provides insight into the exam pattern. By revising this document, students can recall all the answers to some of the important questions related to the chapter such as what is evolution, how did life origin on earth, what is bigbang theory, what is the theory of life forms evolution, what all are the evidences of the evolution, what is adaptive radiation, what is biological evolution, what is mechanism of evolution, explain Hardy-weinberg principle, a brief explanation of evolution, how did man’s origin take place on earth and how he has evolved till now.

Important Topics of Evolution

• Origin of Life

• Evolution of Life Forms - A Theory

• What are the Evidence of Evolution

• What is Adaptive Radiation

• Mechanism of Evolution

• Hardy-Weinberg Principle

• A Brief Account of Evolution

• Origin and Evolution of Man

Important Concepts

Origin of Life

The stars we see in the sky started their life around millions of years ago. The origin of life has been explained by a theory called the Big-Bang theory. According to this theory, the sun exploded and threw some small particles. After many years, when these particles obtained a normal temperature, there was no presence of molecular oxygen to break down the reactions; so it led the molecules to fuse, like H₂ fused with O to form H₂O. When the process continued, the origin of life took place. S.L. Miller during 1953 explained this theory through an experiment.

Evolution of Life Forms - A Theory

During the nineteenth century, many doubts and debates arose on the evolution of life. Later, Charles Darwin concluded those by showing the similarities between the life forms present now and also the organisms that lived millions of years ago. He also said that some of the changes that the organisms have undergone are the reasons they have survived till now.

What Is the Evidence of Evolution?

• It indicates paleontological evidence which signifies that life forms have made an appearance at various instances in the earth’s history, which covers fossils, rocks from sediments, etc.

• Ernst Heckel put forward the embryological support for evidence which was based upon the examination of some traits during the embryonic stages that carried on in all vertebrates that are not found in adults. 

• The idea was disapproved by Karl Ernst von Baer as he notes that embryos do not go through the adult phases of different animals

• Divergent evolution is used to refer to the animals having the same structure developed alongside distinctive guidelines because of variations to specific needs. The structures are referred to as homologous, wherein homology represents not unusual ancestry. For example - The tendrils and thorns of Cucurbita and Bougainvillea imply homology

• Convergent evolution refers to the same structure having evolved into different structures, thereby displaying similarity. This is why convergent evolution results in analogous structures.  Examples of analogy – Dolphins and Penguins’ flippers

• It was indicated that entities in a blended population may want to adapt higher, continue to exist and reason, and grow within the size of the population. But, none of the variants got worn out absolutely.

• An example of evolution by means of anthropogenic action is the appearance of resistant cells or entities in months or years as against centuries.

• Through these proofs or evidence it was also specified that evolution in the context of determinism is not a directed process, rather it is a stochastic process based on the entities of chance mutation and chance events in nature.

What Is Adaptive Radiation?

• It is a process of evolution of different species in specific geographical regions that radiate to other geographical areas. Example: Australian marsupials and Darwin’s finches

• Entities are better tailored to survive in an otherwise opposed environment because the adaptive capability is inherited; it being a genetic foundation, while fitness is the outcome of the ability to conform and as a result getting decided on by way of nature.

• Two key concepts of the Darwinian principle of evolution are branching descent and herbal choice

Biological Evolution 

Organic evolution is the trade in inherited tendencies over successive generations in populations of organisms. Evolutionary modification of traits occurs when variation is brought into a population by using gene mutation or genetic recombination or is removed by herbal choice or genetic waft.

Mechanism of Evolution

There are five key mechanisms that motivate a population, a group of interacting organisms of a single species, to showcase a trade in allele frequency from one era to the subsequent. Those are evolution by mutation, genetic waft, gene waft, non-random mating, and herbal choice 

Hardy-Weinberg Principle

• This precept states that allele frequencies in a populace are stable and are regular from generation to technology, the gene pool remains steady. This is referred to as genetic equilibrium, where the sum overall of all allelic frequencies is 1.

• In a diploid, let x and y represent A and a, allele frequency. The allele a, probability with a frequency of x, pops up on both the chromosomes of a diploid individual is simply the probability product.

• 5 elements affecting Hardy-Weinberg precept are – gene glide, genetic glide, genetic recombination, mutation and natural selection

• While the original drifted population will become founders, the impact is referred to as founder impact

A Brief Account of Evolution

Evolution is the manner of change in all styles of lifestyles over generations, and evolutionary biology is a look at how evolution takes place. Organic populations evolve via genetic adjustments that correspond to changes inside the organisms' observable traits.

Origin and Evolution of Man

Cutting-edge or modern humans originated in Africa beyond 200,000 years and evolved from their maximum possibly latest commonplace ancestor, Homo erectus, which means 'upright man' in Latin. Homo erectus is an extinct species of human that lived between 1.9 million and 135,000 years in the past.

Solved Examples from the Chapter

1. Explain antibiotic resistance located in micro organisms in light of Darwinian choice ideas.

Ans: As per Darwin's statement, the environment selects entities with favourable versions, these entities are capable of surviving. While a population of bacteria is attacked with the aid of a specific antibiotic, sensitive micro-organism have a tendency to perish. Other micro-organism possessing favourable mutations turn resistant even within the presence of antibiotics and those live to tell the tale, thriving, and rapidly multiplying as the alternative competing bacteria have died out. For that reason, the range of microorganisms is at an upward push. In addition to this, they mass transfer these genes, proof against microorganism, to different microorganisms. Consequently, microorganisms immune to antibiotics broadly spread across making the whole populace grow to be antibiotic-resistant.

Key point to remember: The environment selects entities with favourable versions and these entities are capable of surviving. This is the natural selection process proposed by Darwin.

2. Are we able to call human evolution as adaptive radiation?

Ans: Human evolution can be called adaptive radiation as adaptive radiation is an evolutionary process which offers an upward push to new species from a single, not unusual ancestor, but within the case of human evolution. Even though we share a common ancestor, we humans have gone through an eventual however revolutionary alteration inside the ingesting options, shape of frame and many others. The evolution of humans now does not consist of diversification and radiating into exceptional species, which in fact is a distinguishing function of adaptive radiation.

Key point to remember: Adaptive radiation: “A rapid increase in the number of species with a common ancestor, characterised by great ecological and morphological diversity”. 

Solved Problems of Previous Year Questions

1. Which one of the following is incorrect about the characteristics of protobionts (coacervates and microspheres) as envisaged in the abiogenic origin of life? 

1. They were able to reproduce 

2. They could separate combinations of molecules from the surroundings 

3. They were partially isolated from the surroundings 

4. They could maintain an internal environment 

Ans: (b) They could separate combinations of molecules from the surroundings 

A protobiont is a mixture of abiotically produced organic molecules surrounded by a membrane or a membrane-like structure. Protobionts showcase some of the homes related to life, such as easy duplicate, metabolism and excitability, in addition to the maintenance of inner chemical surroundings special from that in their surroundings. It has been suggested that they are a key step to the starting place of life on earth. Experiments by Sidney W. Fox and Aleksandr Oparin have validated that they'll be fashioned spontaneously, in situations just like the environment notion to exist on an early earth.

Trick to remember: Protobionts- “An aggregation of organic molecules, surrounded by a membrane, that abiotically coalesces into resemblances of living matter; thought to be the precursors of prokaryotic cells”.

2. An example of Industrial melanism is 

a) Neo Darwinism 

b) Natural selection 

c) Mutation 

d) Neo Lamarckism 

Ans: b) Natural selection 

In some arthropods the evolutionary effects like industrial melanism are prominent. Here the industrial pollution affected the environment and it resulted in dark pigmentation. 

The light colored liches grown on the trees and there lived white colored-peppered moths which were directly visible to the predators, during industrialization the atmosphere affected by sulphur dioxide pollution led to vanishing of lichens and the moths also were darkly pigmented which led to merging of their body colour with the tree colour so that the predators were not able to identify the moths. This was called natural selection.   

Trick to remember: Natural selection is the process in which nature or the environment selects the species which are fit to survive. 

3. Which is the most common mechanism of genetic variation in the population of a sexually reproducing organism? 

a) Transduction 

b) Chromosomal aberrations 

c) Genetic drift 

d) Recombination 

Ans: (d) Recombination 

Homologous recombination is a tremendous supply of variability. During meiosis in sexual organisms, homologous chromosomes go over and alternate genetic fabric. It is a system by way of which pieces of DNA are broken and recombined to supply new combinations of alleles. This recombination technique creates genetic variety at the level of genes that displays differences inside the DNA sequences of various organisms.

Trick to remember: In sexually producing organisms, half of the chromosomes come from the father and another half from the mother. Both  of these combine in the zygote. So the recombination of two types of chromosomes takes place, which leads to genetic variation. 

Practice Questions

1. Which one of the following is regarded as the direct ancestor of modern man? 

a) Homo erectus 

b) Ramapithecus 

c) Homo habilis 

d) Cro-magnon man  

Ans: (a) Homo erectus 

All through human evolution, several species and subspecies roamed on this planet and lived together and also in all likelihood exchanged genes, therefore, obscuring the exact lineage which ultimately evolved into present day human beings. However, Homo erectus that lived around the middle Pleistocene are regarded as the direct line that developed into cutting-edge guys. The most important subspecies of Homo erectus are Java guy, Peking guy and Heidelberg man.

2. The homologous organs are those that show similarity in 

a) Size 

b) Origin 

c) Function 

d) Appearance 

Ans: (b) Origin 

Homologous structures have the same embryonic origin and basic structure, though they may or may not carry out the identical feature. Homologous systems show that the animals which own them have no unusual ancestry and show evolution by divergence from the ancestral kind. Vestigial organs are those which have ceased to be of any use to their possessor. However, nonetheless the era after technology in a reduced form. They are retrogressive organs but were properly advanced and useful within the ancestors.

Conclusion

This article contains all important information pertaining to the NEET exam, essential for all NEET 2022 aspirants. It can be really helpful for a quick and effective preparation and revision. It covers all the important concepts, topics and questions from previous year NEET question papers. This article gives you detailed information on all the important topics with respect to the NEET exam. Test your knowledge by trying to solve the practice questions on your own.