Spontaneous generation, the hypothetical process by which living organisms develop from nonliving matter. Jan Baptista van Helmont, a seventeenth century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. Answer : (a)

The same structure developed along different directions due to adaptations to different needs. This is divergent evolution and these structures are homologous. Homology indicates common ancestry. Answer : (d)

Mutation theory can not explain the phenomenon of MIMICRY (i.e. the resemblance between mimic and model), protective coloration and relationship between position of nectaries in flowers and length of proboscis of insects that pollinates them. Answer : (a)

Answer : (c)

Archaeopteryx was first described as the 'missing link' between reptiles and birds in 1861 – and is now regarded as the link between dinosaurs and birds Answer : (a)

Organs that are not anatomically similar structures though they perform similar functions. Hence, analogous structures are a result of convergent evolution - different structures evolving for the same function and hence having similarity Answer : (b)

Sympatric speciation is the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region. Answer : (a)

"Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success. Answer : (a)

Coevolution occurs when two or more species reciprocally affect each other's evolution. Coevolution is the process by which two or more species evolve in same time by exerting selection pressures on each other. Examples of coevolutionary systems include host and parasites, predators and prey, and mutualistic or symbiotic interactions. Commensalism is an association between two organisms in which one benefits and the other derives neither benefit nor harm. An example is the Cattle Egret. As large grazers move through the grass, they stir up insects. Cattle Egrets follow them and get a banquet. The large grazers are neither helped nor harmed by the presence of the birds. population benefits from the interaction but population is not affected by the interaction In case of Coevolution there is no selection pressures on each other. Answer : (d)

A homologous structure is an organ, system, or body part that shares a common ancestry in multiple organisms. This definition is found in evolutionary biology and uses the meaning of having a similar structure or origin. Homologous organs are defined as the organs of different animals that are having a similar structure but differ in their functions Answer : (d)

The genetic diversity has three different sources: mutation, recombination and immigration of genes. Mutation is the driving force of genetic variation and evolution. Answer : (c)

The four key points of Darwin's Theory of Evolution are: the origin of species; traits are passed from generation to generation; survival of the fittest; and only the survivors of the competition for resources will reproduce (high efficiency of reproduction). Answer : (d)

Pelvic girdle and hind limbs are vestigial in aquatic mammals like whales. Answer : (a)

Evolution for Darwin was gradual, slow and continous. Branching descent and natural selection is key concept of evolution. Answer : (b)

According to Hardy-Weinberg's principle says that allele frequencies in a population are stable and is constant from generation to generation. The gene pool (total genes and their alleles in a population) remains a constant. This is called genetic equilibrium. Five factors are known to affect Hardy-Weinberg equilibrium. These are gene migration or gene flow, genetic drift, mutation, genetic recombination and natural selection. Answer : (c)

Process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation. Darwin’s finches represent one of the best examples of this phenomenon. Another example is Australian marsupials. A number of marsupials, each different from the other evolved from an ancestral stock, but all within the Australian island continent. When more than one adaptive radiation appeared to have occurred in an isolated geographical area (representing different habitats), one can call this convergent evolution Answer : (b)

The essence of Darwinian theory about evolution is natural selection. The fitness, according to Darwin, refers ultimately and only to reproductive fitness. Hence, those who are better fit in an environment, leave more progeny than others. These, therefore, will survive more and hence are selected by nature. He called it natural selection and implied it as a mechanism of evolution. some organisms are better adapted to survive in an otherwise hostile environment. Adaptive ability is inherited. It has a genetic basis. Fitness is the end result of the ability to adapt and get selected by nature. Answer : (b)

In biology, abiogenesis or the origin of life is the natural process by which life has arisen from non-living matter, such as simple organic compounds. Louis Pasteur by careful experimentation demonstrated that life comes only from pre-existing life. Answer : (c)

Charles Darwin: all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce. Charles Darwin = origin of species. Louis Pasteur by careful experimentation demonstrated that life comes only from pre-existing life. He showed that in pre-sterilised flasks, life did not come from killed yeast while in another flask open to air, new living organisms arose from ‘killed yeast’. Louis Pasteur = Swan necked experiment. deVries believed mutation caused speciation and hence called it saltation (single step large mutation). deVries = mutation theory. Sidney Fox (1950s) showed that splashing amino acids under hot, dry conditions caused them to instantly polymerize into proteins. Fox = protobiosis. Answer : (a)

Answer : (b)

Answer : (c)

During the Mesozoic, or "Middle Life" era, life diversified rapidly and giant reptiles, dinosaurs and other monstrous beasts roamed the Earth. The period, which spans from about 252 million years ago to about 66 million years ago, was also known as the age of reptiles or the age of dinosaurs. Jurrasic age is part of mesozoic era. Answer : (d)

Any population has built in variation in characteristics. Those characteristics which enable some to survive better in natural conditions (climate, food, physical factors, etc.) would outbreed others that are less-endowed to survive under such natural conditions. Another word used is fitness of the individual or population. The fitness, according to Darwin, refers ultimately and only to reproductive fitness. Hence, those who are better fit in an environment, leave more progeny than others. These, therefore, will survive more and hence are selected by nature. He called it natural selection and implied it as a mechanism of evolution. Those that can better-adapt, survive and increase in population size. Answer : (d)

Louis Pasteur devised the experiment. He heated an infusion sealed in a vessel with a S-shaped or "Swan neck", let it cool, and then broke of the tip of the vessel. This allowed fresh air to enter, but any particulate matter was trapped in the bend of the neck. This demonstrated that certain germ particles in the air caused the spoiling of the broth, disproving spontaneous generation Answer : (a)

Adaptive convergence is the phenomenon by which living beings facing the same environmental pressure problems and undergoing genetic variability and natural selection incorporate similar analogous organs and structures solutions into their bodies during evolution. Answer : (a)

Reproductive isolation : the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences. Answer : (a)

The bottleneck effect is an extreme example of genetic drift that happens when the size of a population is severely reduced. Events like natural disasters (earthquakes, floods, fires) can decimate a population, killing most individuals and leaving behind a small, random assortment of survivors. The original drifted population becomes founders and the effect is called founder effect. Polydactylic dwarfs suffer from Ellis–van Creveld syndrome which is the result of founder effects in isolated human populations in Amish. Although relatively rare, this disorder does occur due to lack of genetic variability. Answer : (d)

Ecological isolation is a type of reproductive isolation in which mating is prevented because of the separation of species resulting from the difference in their habitat. Answer : (c)

Giant tortoise, Darwin's finches and marsupials of Australia, all are examples of adaptive radiation. Answer : (d)

Darwinism is an evolutionary theory proposed by Charles Robert Darwin. He believed that evolution is a gradual, rather than a sudden biological event. One of the main objections to natural selection was that there are gaps between forms in nature that could not be crossed if evolution was powered by natural selection alone. Answer : (d)

In biology, an atavism is a modification of a biological structure whereby an ancestral genetic trait reappears after having been lost through evolutionary change in previous generations. Answer : (c)

Pelycosaurus- It is also called as mammal like reptiles. They developed during late carboniferous and reached their apex in the early part of the Permian remaining the dominant land animals for some 40 million years. Answer : (b)

Any population has built in variation in characteristics. Those characteristics which enable some to survive better in natural conditions (climate, food, physical factors, etc.) would outbreed others that are less-endowed to survive under such natural conditions. Another word used is fitness of the individual or population. The fitness, according to Darwin, refers ultimately and only to reproductive fitness. Hence, those who are better fit in an environment, leave more progeny than others. These, therefore, will survive more and hence are selected by nature. He called it natural selection and implied it as a mechanism of evolution. Answer : (a)

Microspheres are microscopic, firm spherules which form on the cooling of hot saturated solutions of proteinoids. They were first reported in 1959 by Sidney Fox, K. Harada, and J. Kendrick who proposed that microspheres might represent a significant early stage in precellular evolution. Answer : (d)

In 1953, S.L. Miller, an American scientist created similar conditions in a laboratory scale. He created electric discharge in a closed flask containing CH4, H2, NH3 and water vapour at 800°C. He observed formation of amino acids. In similar experiments others observed, formation of sugars, nitrogen bases, pigment and fats Answer : (b)

Lamarckism, a theory of evolution based on the principle that physical changes in organisms during their lifetime—such as greater development of an organ or a part through increased use—could be transmitted to their offspring. Lamarckism did not put variations under consideration being responsible for the rate of survival of organisms. Answer : (b)

Adaptive radiation is the rapid diversification of an ancestral population into several ecologically different species, associated with adaptive morphological or physiological divergence. It leads to speciation. Answer : (d)

Modern Synthesis/Synthetic Theory/Evolutionary Synthesis also suggests that evolution is not only due to natural selection acting on variation; other major effects — such as genetic drift — may also contribute to the evolution of organisms. You may remember that genetic drift occurs when the genetic makeup of a population changes because individuals leave the population. Charles Darwin defined natural selection as the "principle by which each slight variation , if useful, is preserved". The concept was simple but powerful: individuals best adapted to their environments are more likely to survive and reproduce Answer : (d)

The mechanism that Darwin proposed for evolution is natural selection. Because resources are limited in nature, organisms with heritable traits that favour survival & reproduction will tend to leave more offsprings than their peers , causing the traits to increase in frequency over generations. Darwinian variations are heritable; are small and directional Answer : (d)

In population genetics, the Hardy–Weinberg principle, also known as the Hardy–Weinberg equilibrium, model, theorem, or law, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences Answer : (a)

The central idea of Lamarckism is that the characterisitcs acquired by an organism during a lifetime in response to environmental conditions are passed onto their offspring. Answer : (b)

Archaeopteryx lived in the Late Jurassic around 150 million years ago, in what is now southern Germany, and also Portugal, during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now Answer : (a)

Arrhenius (1908) proposed the theory of directed panspermia. The salient features are: i) They assumed the presence of advanced civilization on other planets in our galaxy. ii) Life on earth and many other planets were infected from these advanced civilized planets. Answer : (d)

A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Answer : (a)

The thorn and tendrils of Bougainvillea and Cucurbita represent homology. Answer : (d)

When plants occur at two or more distant places of the world which are separated by overland's or oceans hundreds or thousands of kilometres apart. Such a distribution is called discontinuous or disjunct distribution. The three genera of lungfishes show discontinuous distribution, as they occur in three different continents. Answer : (c)

In a diploid, p and q represent the frequency of allele A and allele a. The frequency of AA individuals in a population is simply p2. Similarly of aa is q2, of Aa 2pq. Hence, p2 + 2pq + q2 = 1. Answer : (a)

Interspecific hybridization is the crossing of two species from the same genus. Mule is the result of a donkey stallion mating with a female horse. Answer : (d)

Genetic drift describes random fluctuations in the numbers of gene variants in a population. Genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time. These variations in the presence of alleles are measured as changes in allele frequencies. Answer : (a)

According to de Vries' mutation theory, living organisms can develop changes to their genes that greatly alter the organism. These changes are passed down to the next generation, and lead to the development of new species. Once a new species has evolved, it becomes fixed and stops changing. Answer : (b)