Test: Theories of Organic Evolution - NEET MCQ

Hugo de Vries (1848-1935) proposed mutation theory for the formation of new species. He came to conclude this theory while working on Oenothera lamarckiana evening primrose. According to him, new species are not formed by continuous variations but by sudden appearance of variations which he assigned as mutations. He stated that these mutations are heritable and persist in successive generations.

Survival of the fittest or Natural selection : In struggle for existance, only those organisms survive which possess the most useful variations. This has been called 'Natural selection' by Darwin and 'Survival of fittest' by Spencer.

Lamarckism states that an organism can pass on to its offspring physical characteristics that the parent organism acquired through use or disuse during its lifetime.its principle revolves around the fact that the characteristics inherited itself would be passed on.

Philosophie zoologique is an 1809 book by Jean-Baptiste Lamarck in which he outlines his theory of evolution now known as Lamarckism. In the book, Lamarck named two supposed laws that would enable animal species to acquire characteristics under the influence of their environment. The two laws are as followed :

a) Law of use and disuse theory that defines the change in the body structure over the course of evolution.

b) The second law states that the change in the body structure must be inherited.

So, the correct answer is option B.

August Weismann, a German scientist formulated his famous 'Theory of continuity of germplasm' in 1886, on experimenting with mice. His theory states that inheritance in multicellular organisms takes place by means of germ cells i.e. egg and sperm cells only.

The term "survival of the fittest" was first used by the Victorian naturalist Herbert Spencer as a metaphor to help explain natural selection, the central element of Charles Darwin's revolutionary theory of evolutionary change, first published in 1859 in his famous book, The Origin of Species by Means of Natural Selection.

These are examples of artificial selection 'Artificial selection' is a process in which the breeder choose to perpetuate only those forms that have certain desirable inheritable characteristics. The other three options are incorrect as mutation is a sudden change in DNA sequence due to mutagenic agents such as chemicals and radiations. Natural selection is a gradual process by which biological traits become either more or less common in a population as a function of the effect of the changing environment. Reverse evolution or devolution is a notion that species can change into more primitive forms over time. 

The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.

Charles Darwin traveled on the HMS Beagle on December 27, 1831. He went on board in Devonport and traveled for 5 years.
So, the correct option is, 'Beagle'.

Evolution is the change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes that are passed on from parents to offspring during reproduction.

So, the correct answer is 'Genetic variations were not found among members of a population'.

On the Origin of Species, published on 24 November 1859, is a work of scientific literature by Charles Darwin which is considered to be the foundation of evolutionary biology. Darwin's book introduced the scientific theory that populations evolve over the course of generations through a process of natural selection.

There were many scientists and scholars that influenced Charles Darwin: 
1) Thomas Malthus wrote essays about populations and carrying capacities for the environment. Malthus was an economist and his ideas about overpopulation, disease, and the struggle to survive influenced Darwin. 
2) Charles Lyell influenced Darwin. Lyell was a geologist who came up with the idea of uniformitarianism, which means that the same processes that were at work in the past are at work in the present. Lyell was the first geologist to come up with an estimate of the great age of the earth, based on the processes of erosion.
3) Alfred Russel Wallace also influenced Darwin. Quite independently, he came up with the same idea of evolution by natural selection. Darwin got his "Origin of Species" to the publisher first.
Apart from that, Darwin was also influenced by Georges Cuvier and Charles Lamarck.
Therefore, the correct answer is option D.

If the population of a species is transferred to the more suitable environment, then it will show  protection against enemies. Populations are groups of individuals belonging to the same species that live in the same region at the same time. Population density is a measure of the number of organisms that make up a population in a defined area. In the suitable environment, the species of the population becomes more strong to fight with enemies and protect themselves.

So, the correct answer is option B.

The Darwinian theory considers a driving force in evolution, the adaptation to the environment derived from the combined effect of the natural selection and the random mutations. The Darwinian theory of natural selection does not say anything about the origin of variations or the processes in which they are carried out in nature.
So, the correct answer is 'Variations'

According to the fossil records, snakes used to have a complete set of forelimbs and hindlimbs about 150 million years ago. The gene that signals the limbs development in snakes is the Sonic hedgehog gene. According to a recent study, a trio of mutations occurred in this gene about 100 million years ago and thus making it less likely to expressed. So, the mutations made the gene to be eradicated completely and hence, the snakes don't have limbs or legs.

Hence, the present day limbless snakes with long slender body developed from the limbed ancestors. Also, due to continued disuse of limbs and stretching of their body to suit their creeping mode of locomotion, legs were lost during the course of evolution.

So, the correct answer is B.

Boring of pinna (external ear) and nose of Indian women is never inherited to the next generations although they have been bored for thousand of years, it is not explained by Lamarckism.

The ancestors of giraffe were bearing a small neck and fore­limbs and were like horses. But as they were living in places with no surface vegetation, they had to stretch their neck and forelimbs to take the leaves for food, which resulted in the slight elongation of these parts, it is explained by Lamarckism.

The ancestors of stag were not having so much speed in running, but as they needed protection from other animals of that time they started running, due to which present speed were achieved by the stag, it is explained by Lamarckism. 

Therefore, the correct answer is option A.

Germplasm is living hereditary assets, for example: seeds or tissues that are kept up with the end goal of creature and plant reproducing , protection and other research employment. Germplasm accumulation is vital for the support of organic decent variety and sustenance security.

Ernest Haeckel is the scientist who had contributed much to genetic evolutionary studies. He is the one who described: "Ontogeny recapitulates phylogeny".

The theory of natural selection states that the organisms which are able to cope up with the surrounding are able to survive to a larger extent. This ability was termed as "survival of fittest" by Charles Darwin. It is more commonly used today in other contexts, to refer to a supposed greater probability that "fit" as opposed to "unfit" individuals will survive some test. In these contexts, "fit" refers to "most well adapted to the current environment" which differs from common notions of the binary 'fit' and 'unfit'. Darwin first used Spencer's new phrase "survival of the fittest" alongside "natural selection" in the fifth edition of On the Origin of Species, published in 1869, intending it to mean "better designed for an immediate, local environment". He explained natural selection leading to the survival of the fittest.
Therefore, the correct answer is option D.

The concept of sudden genetic change which breeds true in a species is represented as a mutation. Any sudden or spontaneous change in character which is inheritable is known as mutation. It is defined as the changing of the structure of a gene, resulting in a variant form which may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes.
So, the correct answer is option D.

Mutations can be induced by several methods. The three general approaches used to generate mutations are radiation, chemical and transposon insertion.
In addition to X-rays, other types of radiation treatments that have proven useful include gamma rays and fast neutron bombardment. These treatments can induce point mutations (changes in a single nucleotide) or deletions (loss of a chromosomal segment).
Chemical mutagens work mostly by inducing point mutations. Point mutations occur when a single base pair of a gene is changed. These changes are classified as transitions or transversions. Two major classes of chemical mutagens are routinely used. These are alkylating agents (such as ethyl methane sulphonate (EMS), ethyl ethane sulphonate (EES) and base analogs (5-bromouracil and 2-aminopurine).
Therefore, the correct answer is option D.

Mutations are permanent changes in the DNA. However most mutations are neutral; they either make no change in the expression of any gene, or the changes made do not affect the function of any gene product.

Mutation can be defined as a sudden heritable change in the genetic material of any organism.The cause of mutation is Changes in DNA, Changes in chromosome and  Changes in gene.For example, during cell division, the cell makes a copy of its DNA and sometimes the copy is not quite perfect. That small difference from the original DNA sequence is a mutation. Mutations can also be caused by exposure to specific chemicals or radiation. These agents cause the DNA to break down.

Mutations are the main cause for the evolutionary changes. In this, there will be a sudden or induced change in the sequence of DNA. This mutated gene whether dominant or recessive if selected by nature, through natural selection, spreads to other generations. 

Sexual reproduction involves the formation and fusion of gametes.
This requires formation of gametes with meiosis in diploid organisms or meiosis taking place in zygote if the organism is haploid. Due to meiosis, only 50% of the genetic material is passed to the next generation and fusion of gametes results in a unique combination of the genome.
While asexual reproduction results in offsprings with exact genetic material as their parent reducing chances of variations.
So, the correct option is 'Sexual reproduction'.

Darwinism is an evolutionary theory proposed by Charles Robert Darwin, an English Naturalist. He believed that evolution is a gradual, rather than a sudden biological event. His theory was based on several facts, observations and inferences. They are 1) overproduction, 2) constancy in population, 3) struggle for existence, 4) natural selection.
The prodigality of production or overproduction: Every organism tends to increase its population in large proportions. For example, Paramecium divides by binary fission at the rate of three to four times a day. At this rate, the volume of all the paramecia equals to 10,000 times that of the earth at the end of the 9000th generation in the absence of any check.
Constancy in population: However, such an abnormal increase is not noticed in the population of any species in nature as the offspring die in large number before reaching the reproductive age. It is true that the food and the other sources do not increase in the same proportion as that of the population.

Struggle for existence: As the food sources are limited, severe competition exists among the members of a population. Darwin called it a struggle for existence.

Natural selection: The organisms with less reproductive success are not represented in future generations, however, fit they may be in the struggle for existence. This is called the Natural selection. Herbert Spencer called this phenomenon Survival of the fittest.

Darwinism failed to explain the mechanism by which variations occur. Thus Darwin faced the criticism "DARWINISM EXPLAINS THE SURVIVAL OF THE FITTEST BUT NOT THE ARRIVAL OF THE FITTEST".

So, the correct option is 'It does not explain variations with heredity'

Hugo de Vries, a Dutch botanist proposed mutation theory to explain the mechanism of evolution. His theory was published in 1901 in his book "Die Mutation Theorie". He performed experiments on the evening primrose.
According to him, mutations are sudden and heritable changes which are subjected to natural selection. The frequency of a mutated gene in the population is expected to increase if the gene is selected by nature.

It is a long-standing observation that most mutations are recessive. That is, they do not lead to visible phenotypic effects when in heterozygous combination with the wild-type allele.
Recessive disease mutations are much more common than those that are harmful even in a single copy, because such "dominant" mutations are more easily eliminated by natural selection.

Neo-Darwinism is a modified version of Darwin’s theory, that regards evolution as a change in gene frequencies due to mutation, natural selection considered as the most important, although not the only cause for such changes.

Lamarckism or theory of use and disuse has been disproved in this case. It states that animals acquired characteristics after using certain physical traits constantly.