BIOLOGY M.C.Q (1 Marks)

4. Evidence from DNA extracted from sex chromosomes, autosomes and mitochondria.

2. Hydrocarbons

Explanation:

In the early decades of the twentieth century, J.B.S. Haldane and Alexander Oparin independently set forth similar ideas concerning the conditions required for the origin of life on Earth. Both suggested that organic molecules could be formed from non organic materials in presence of an external energy source and that the primitive atmosphere was reducing and contained Ammonia and water vapour, among other gases.

Oparin suggested that organic compounds could have undergone a series of reactions leading to more complex molecules. He proposed that the molecules formed colloid aggregate or coacervates, in an aqueous environment. Haldane hypothesized that the oceans served as a huge cooking pot, powered by the sun or lighting, chemical reactions could occur in an aqueous environment to form a huge diversity of organic compounds.

Haldane coined the term 'prebiotic soup' that consisted of an abundance of methane, ammonia and water. The first organic molecules thought to have formed was Hydrocarbon chains, which were composed solely of hydrogen atoms bonded to carbon atoms. Hydrocarbons provided the foundation framework for the formation of more complex organic molecules, such as simple amino acids.

1. Highly genetically variable individuals.

3. Divergent evolution

Explanation:

The structures which are similar in their morphology, anatomy, genetics and embryology but dissimilar in their function are called as homologous organs. Many mammals have similar limb structures. The flipper of a whale, the wing of a bat, and the leg of a cat are all very similar to the human arm.

Divergent evolution is the accumulation of differences between groups, which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments, which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection.

4. Convergent evolution

Explanation:

When two animals/plants belonging to two distinct lineages of evolution, exhibit similarities with respect to adaptation to a certain environmental condition is called convergent evolution.

Example, wings of birds and insects, they have different structures internally but perform the same function, that is adaptation to aerial habitat.

3. Proconsul

Explanation:

In 1948, Leakey reported skull of Proconsul africanus.

2. Lichens.

Lichens do not possess roots and hence air is their primary source for most elements. They will not grow in the areas that are polluted. So, lichen is used as a reliable indicator of atmospheric pollution.

1. 22.5km

Explanation:

Moving from centre to surface, earth can be divided into three major layers namely; the core, the mantle and the crust. Core is the deepest and hottest layer of earth; the outer core consists of iron-nickel alloy along which small amount of heavy metals while the inner core is made up mostly of iron.

The higher temperature, 7000-9000°F keeps the outer core in liquid state while higher pressure on inner core keeps it in solid state despite the high temperature conditions. Thickness of outer and inner core is 2259km and 1221km respectively.

Mantle is 2900km thick layer wherein most of the earth’s internal heat is located. The outer most layer of earth is crust; it is 22.4km thick and forms the only habitable part of earth. It comprises continents (lithosphere) and ocean basin (hydrosphere) that support life.

3. Disappearance of tail.

Explanation:

Tail in present day man is a vestigial organ. All chordates including man have a well developed post anal tail. Change in diet brought about changes in dental and facial make up and other anatomical changes and development of voice were important events during evolution of man.

Disappearance of tail was a minor anatomical improvement that finally lead to bipedal locomotion and upright posture.

3. 180 million years ago.

Explanation:

The first small dinosaurs appeared during Triassic period (225 million years ago) of Mesozoic era. This makes option D incorrect as dinosaurs did not appear 500 million years ago.

Jurassic period (180 million years ago) is marked by diversification of dinosaurs; large dinosaurs dominated the earth. This makes option C correct.

The asteroid impact at the end of Cretaceous period around 60 million years ago caused mass extinction of dinosaurs thereby eliminating them. Asteroid hit increased the metal iridium concentration on earth. This makes options A and B incorrect as dinosaurs were extinct by 50 and 10 million years ago.

3. Coccyx, nictitating membrane, vermiform appendix, ear muscles.

3. Speciation through reproductive isolation.

4. Frogs evolved from gilled ancestors.

1. Convergent evolution : Eyes of octopus and mammals; Divergent evolution : Bones of forelimbs of vertebrates.

Explanation:

Divergent evolution : Bones of forelimbs of vertebrate Convergent evolution : Eyes of octopus and mammals.

Divergent evolution means similar organs have same structural plan and found in similar organisms, diverge along different evolutionary lines and Convergent evolution means organisms with different ancestry converge together due to similar environment or habitat and evolve similar organs.

So, the correct answer is 'convergent evolution:eyes of octopus and mammals; divergent evolution:bones of forelimbs of vertebrates.

4. Neanderthal human.

4. Gymnosperms are dominant plants and first birds appear.

2. Weismann

1. Phylogenetic

Explanation:

Arm and leg of man and horse are examples of homologous organs. A homologous structure is an example of an organ or bone that appears in different animals, underlining anatomical commonalities demonstrating descent from a common ancestor.

In other words, its when very different animals have bones that appear very similar in form or function and seem to be related. So, we can say there is a phylogenetic relationship between man and horse.

4. Homo erectus was preceded by Homo habilis.

4. Age of Mammals and Modern flora.

Explanation:

The most recent era of geologic time, from about 65 million years ago to the present is called a Cenozoic era.

The Cenozoic Era is characterized by the formation of modern continents and the diversification of mammals and plants.

A Cenozoic era is known as the age of mammals and modern flora because the largest land animals have been mammals during that time and formation and diversification of moderns flora took place.

1. Yes, because we share a common ancestor.

Explanation:

Neanderthal mans are not the direct ancestors of humans. But obviously we share a common ancestry. Human evolutionary tree consist of branches.

1. Oparin and Haldane.

4. Cro-magnon man.

4. Lamarckism was wrong in inheritance of acquired characters.

1. Divergent evolution.

2. Fingernails.

2. The collision of earth with large meteorites.

Explanation:

Huge meteorites struck earth somewhere around modern Mexico. These meteorites were rich in Iridium an element rare on earth. Strike of meteorites brought in a number of drastic changes in environment and climate and set in huge forest fires. All of these changes might be associated with mass extinction at the end of Mesozoic era. However, an alternative view is that meteorites did strike earth, and mass extinction had happened before the strike of meteorites and meteorites strike was not the cause of mass extinction. Exactly what happened, we still do not know.

1. Directional

3. Electron-spin resonance method.

4. Darwin

1. Parapithecus

Explanation:

Origin and evolution were about 30-35 million years ago.

Originated from Egypt

The oldest and the most primitive is Parapithecus.

4. Essay on Population by Malthus.

1. 6000

Explanation:

The sun is 4.6 billion years old. It is largely composed of hydrogen and helium. The surface of the sun is called photosphere. The photosphere gives off the sun's energy in forms of heat and light. Sunspots on the photosphere are cooler and darker than the surrounding area.

The temperature at the surface of the sun is about 60000C. The temperature rises from the surface of the sun inwards towards the very hot center of the sun, where it reaches about 15,000,000 centigrade.

The temperature of the sun also rises from the surface outward into the solar atmosphere. The uppermost layer of the solar atmosphere, called corona, reaches temperatures of million of degrees.

4. Hydrogen and methane

Explanation:

The primitive earth is thought to be highly reducing in nature due to the absence of oxygen. Hydrogen and methane predominated the atmosphere and caused the condensation of various biomolecules. This theory was forwarded by Oparin and Haldane which accounts for the chemical evolution of life.

It was proved by Urey and Miller through an experimental set-up that mimicked the primitive earth conditions and resulted in the formation of amino acids.

Hence, the correct answer is 'Hydrogen and methane'.

1. Convergent evolution.

2. Darwin

Explanation:

Darwin's finches (also known as the Galapagos finches) are a group of about fifteen species of passerine birds. They often are classified as the subfamily Geospizinae or tribe Geospizini. It is still not clear to which bird family they belong, but they are not related to the true finches.

They were first collected by Charles Darwin on the Galapagos Islands during the second voyage of the Beagle. All are found only on the Galapagos Islands, except the Cocos finch from Cocos Island.

2. Adaptive radiation

Explanation:

The evolutionary term descent with modification is most often associated with human evolution, but it is actually a more general term than that would suggest. Simply put, descent with modification means that traits are passed down from generation to generation and sometimes undergo changes or modifications over time.

These changes may be caused by Natural Selection or even a mutation of DNA. The term became popular when Charles Darwin used it in his book The Descent of Man.

Adaptive radiation is an evolutionary pattern whereby a single ancestral form diversifies into several or many related forms. Adaptive radiation is a subset of the theory of descent with modification, expressing evolution within closely related forms rather than new designs.

3. Evolutionary divergence.

Explanation:

Speciation that occurs when one population becomes geographically separated from the rest of the species and subsequently evolves by natural selection and /or genetic drift is known as allopatric speciation. 

Allopatric speciation is the most common method of speciation and accounts for almost all evolution of new animal species.

Differentiation of species is a wrong option because individuals show differentiation not species. Isolation is not related to maintenance or extermination of species.

3. Mesozoic

1. Individuals mate selectively.

1. Eyes of octopus and mammals - Bones of forelimbs of vertebrates.

Explanation:

Convergent evolution creates "analogous structures" that have similar from or function but were not present in the last common ancestor.

eg:- eye of octopus & mammals.

Divergent evolution is accumulation of differences between closely related populations within a species, adding to specification.

It creates homologous structure that have similar structure different function.

eg :- bones of forelimb of vertebrates.

2. Cretaceous

Explanation:

Flowering plants (angiosperms) arose close to the beginning of the Cretaceous and became more abundant as the period progressed. The Late Cretaceous was a time of great productivity in the worlds oceans, as borne out by the deposition of thick beds of chalk in western Europe, eastern Russia, southern Scandinavia, the Gulf Coast of North America, and western Australia.

The Cretaceous ended with one of the greatest mass extinctions in the history of Earth, exterminating the dinosaurs, marine and flying reptiles, and many marine invertebrates. Thus, option B is correct. Angiosperm were not arose in carboniferous period, triassic period and tertiary period.

1. Exoskeleton

2. Cloud of gas and dust.

Explanation:

Approximately 4.6 billion years ago, the solar system was a cloud of dust and gas known as a solar nebula. Gravity collapsed the material in itself as it began to spin, forming the sun in the center of the nebula.

With the rise of the sun, the remaining material began to clump up. Small particles drew together, bound by the force of gravity, into larger particles. The solar wind swept away lighter elements, such as hydrogen and helium, from the closer regions, leaving only heavy, rocky materials to create smaller terrestrial worlds like Earth.

So, earth like other planets formed from cloud of gas and dust.

3. Neolithic

Explanation:

The cultural evolution of man is described in following stages – Palaeolithic, Mesolithic, Neolithic. Neolithic age is the most recent in which man developed agriculture, manufactured pottery and clothes.

3. Australopithecus ramidus

Explanation:

Australopithecus ramidus is the most ape like hominid ancestor, who walked upright and is considered to be missing link between hominids and apes. It is the oldest and most primitive of hominin fossil dating back to 4.4 million years.

2. History and development of race along with ariations.

1. Sedimentary rocks.

Igneous rocks are formed from lava and hence no fossil can be found in them. Metamorphic rocks can be made from igneous or sedimentary rocks. Hence, ‘a’ is the correct answer.

3. Devonian period

Explanation:

Upper (i.e. more recent) Devonian sediments contain fossil remains of salamander-like amphibians (or labyrinthodonts) that were often quite large, with short necks and heavy, muscular tails.

4. Divergence

Explanation:

Homology refers to evolution of organisms in different directions from a common ancestry i.e., divergence. It leads to development of homologous organs that are adapted to perform different functions and have different appearance but share common basic structural plan and origin.

Divergent evolution is the accumulation of differences between groups, which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments.