BIOLOGY M.C.Q (1 Marks)

1. Plantigrade

Explanation:

In terrestrial animals, plantigrade locomotion means walking with the podials and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals.

The other options are digitigrade, walking on the toes with the heel and wrist permanently raised, and unguligrade, walking on the nail or nails of the toes (the hoof) with the heel/wrist and the digits permanently raised.

1. Mesozoic

1. The arm of a human, wing of a bird.

1. Convergent evolution.

3. 4.5 to 5 billion

Explanation:

The solar system was formed around 4.6 billion years ago out of the collapse of a dense cloud composed of dusts and gases.

By studying several things, mostly meteorites and using radioactive dating techniques, specifically looking at daughter isotopes, scientists have estimated that the solar system is 4.6 billion years old.

1. Trilobites

Explanation:

Trilobites were the dominant species during the Cambrian Period, 540 to 490 million years ago. They are a fossil group of extinct marine arthropods that form the class Trilobita.

They finally disappeared in the mass extinction at the end of the Permian about 250 million years ago. 

2. Herbert Spencer.

1. Small isolated population.

3. Biogenetic law.

4. Adaptive radiation.

3. 96

Explanation:

The gene is autosomal recessive lethal, the heterozygous individuals carrying one copy of the affected allele and one of wild type allele will serve as carriers.

If the genotype of homozygous individuals for the recessive lethal gene is qq and that of homozygous individuals for wild-type gene is pp then the genotype of heterozygous individuals will be pq.

According to the question, the frequency of a recessive lethal allele is (q = 0.4). Frequency of wild-type allele : p = 1 - q,i.e.,1 - 0.4 = 0.6

Hardy Weinberg law states that the sum of all genotype frequencies is represented as the binomial expansion of the square of the sum of p and q. This sum is equal to one. ( p + q )² = p² + 2pq + q² = 1.

Hence, the frequency of carrier genotype in total population (2pq) = 2 × 0.6 × 0.4 = 0.48.

And the number of carriers in the population of 200 is = 0.48 × 200 = 96.

4. All of the above.

Explanation:

The primitive reducing atmosphere of earth was rich in water vapour, carbon monoxide, carbon dioxide and hydrogen. Absorption of infrared radiation by green house gases (CO₂​ and CH₄​) imparted high temperature to primitive earth.

The high temperature, UV light and lightening facilitated reaction between above-mentioned elements. Oxygen did not occur in the free state as the prevailing reduced substances immediately combined with it to form oxides (iron oxides, silicon oxides).

Abundant hydrogen combined with free oxygen, nitrogen and carbon to form water, ammonia, methane and cyanides.

4. Optimum utilization of resources.

Explanation:

Darwin finches occupy different niche with in the same geographical area and the distribution is primarily decided by the differences in diet of birds.

2. Homo erectus is the ancestor of man.

1. Pectoral fins of a fish and forelimbs of a horse.

4. Pre-cambrian

Explanation:

Geological Time scale is the vast expanse of geological time has been separated into eras, periods, and epochs.

All geologic time before the beginning of the Paleozoic era is known as Precambrian era. This includes about 90% of all geologic time and spans the time from the beginning of the earth, about 4.5 billion years ago, to 544 million years ago. It is the largest span of time in Earth's history. 

4. Sidney Fox and Oparin

Explanation:

Coacervates were non-living colloidal aggregates of proteins and polysaccharides but did not have the ability to reproduce nor they developed a covering membrane of lipids.

Oparin and Sydney Fox held that large organic molecules synthesized abiotically on the primitive earth.

These molecules later came together spontaneously and due to intermolecular attraction formed large colloidal aggregates called coacervates.

3. Peking man, Heidelberg man, Neanderthal, Cro-magnon.

3. Remarkable increase in the brain size.

4. Adaptive radiation

Explanation:

In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges and opens environmental niches. Thus, option D is correct.

Adaptive convergence is a form of evolution in which two unrelated (or distantly related) species evolve very similar forms due to similar selective pressures. Thus, option C is wrong.

Genetic drift or allelic drift is the change in the frequency of a gene variant (allele) in a population due to random sampling. Thus, option B is wrong.

Speciation is the evolutionary process by which new biological species arise. Thus, option A is wrong.

4. Non-evolving

Explanation:

The Hardy-Weinberg principle assumes that the allele and genotype frequencies in a large population will remain constant from generation to generation in the absence of evolutionary influences like mate choice, mutation, selection, genetic drift, gene flow, and meiotic drive.

Hardy-Weinberg Equations:

p² + 2pq + q² = 1

p + q = 1

{p = frequency of the dominant allele in a population}

{q = frequency of the recessive allele in a population}

4. Melanization of peppered moth in industrial areas.

1. Cro-Magnon man

Explanation:

Homo sapiens is the parent species to which modern man belongs. It evolved from Homo erectus in Africa. Homo sapiens developed three subspecies- Neanderthal man, Cromagnon man and Modern man. The most primitive of these three, the Neanderthals, lived 30,000 to 100,000 years ago. This was followed by Cromagnon man, who lived around 20,000 to 50,000 years ago.

4. Convergent evolution.

3. Nitrogen

Explanation:

The atmosphere of earth is a layer of gases surrounding the planet and it is retained by the earth's gravity. The atmosphere protects life on earth by absorbing ultraviolet solar radiation, warming the surface through heat retention and reducing temperature extremes between day and night.

The gases in earth's atmosphere include: nitrogen-78%, oxygen-21%, argon-0.9%, carbon dioxide-0.03%. Water vapour and other gases exist in small amounts as well.

Nitrogen dilutes oxygen and prevents rapid burning at the earth's surface. Living things need it to make proteins. Nitrogen cannot be used directly from the air. The nitrogen cycle is nature's way of supplying the needed nitrogen for living things.

4. Anaerobic because early atmosphere contained.

Explanation:

In any case scientists are sure that the primordial atmosphere contained no free oxygen (O₂​) and therefore ozone could not exist either. So, in primordial atmosphere, when the living organism evolved the respiration process was anaerobic, because early atmosphere contained little or no oxygen. Thus, option D is correct.

In primordial atmosphere, the respiration process was not aerobic. Thus, option B and C are wrong.

In primordial atmosphere, the respiration process was not anaerobic as it released more energy. Thus, option A is wrong.

1. Origin of life from non-living substances.

Explanation:

How life originated we do not know. In the present earth life comes from pre-existing life but in primitive earth theory of abiogenesis says that life originated from nonliving entities. Prefix 'A' means non, Bio refers to life and genesis means synthesis or production i.e., synthesis or production of life from something nonliving.

2. Chemoheterotrophs.

1. High temperature, volcanic storms, reducing atmosphere containing CH₄, NH₃ etc.

2. G. Lemaitre

Explanation:

Georges Lamaitre was a Belgian priest, astronomer and a professor of physics. He is considered the father of the Big Bang theory. According to the theory, the expansion of the observable universe began with an explosion of a single particle at a definite point in time.

Earlier versions of the 'Big Bang theory' had the universe originating from a singularity, this has been replaced by the idea that the universe originated from literally nothing at all.

1. Water to land.

3. The young ones are protected inside the mother's body and are looked after they are born leading to more chances of survival.

Viviparity is considered to be more evolved because the young ones are protected inside the mother's body and are looked after they are born leading to more chances of survival.

2. 32%

Explanation:

According to the Hardy Weinberg law, the allele and genotype frequencies in a population remain constant in the absence of factors responsible for evolution. It states that the sum of all genotype frequencies can be represented as the binomial expansion of the square of the sum of p and q.

This sum is equal to one : ( p + q )² = p² + 2pq + q² = 1.

"p" is the frequency of the dominant allele, and "q" is the frequency of the recessive allele. The "2pq" in the equation shows the frequency of heterozygotes in the population.

According to question, if it is a recessive disease then "p" is the frequency of normal dominant allele, "q" will be the frequency of disesease causing recessive allele and "2pq" will be the frequency of carrier individual.

In the question the frequency of disease causing recessive allele is given i.e q = 80% or o.8.

If p + q = 1 then, p = q - 1 => 1 - 0.8 = 0.2 or 20%.

Thus, the frequency of carrier will be = 2 × p × q => 2 × 0.8 × 0.2 = 0.32 or 32%.

1. Convergent evolution

Explanation:

Convergent evolution occurs in an unrelated group of organisms. It is the development of similar functional structures but in unrelated groups.

The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography is called adaptive radiation. Natural selection is the basis of evolution.

2. Wallace

1. Adaptive convergence

Explanation:

When different groups of animals show similar adaptations due to similar environmental conditions, it is called convergent evolution, which is caused by adaptive convergence.

4. Phylogeny

4. Amphibian

Explanation:

Amphibians are absent in Galapagos islands as they could not leave the mainland and travel to the island by crossing saline water.

3. Water

Explanation:

Firstly there is no water on the moon which is the first and foremost requirement for the life. Life first started on the earth because of water and if no water we can imagine no life. Air is also required to breathe and no air is on the moon or we can say that oxygen is required by human beings to breathe is not enough on the moon for the survival.

3. Latimeria

Explanation:

Latimeria is a genus of West Indian Ocean coelacanth (Latimeria chalumnae) and Indonesian coelacanth (Latimeria menadoensis).

Living fossil is a living species or clade of an organism that appears to be similar to a species otherwise known only from fossils. Latimeria is one such living fossil.

2. 1600

Explanation:

Atmosphere is the layer of air enveloping the earth at the height of around 1600 km and it consists of many gases. The major components of the atmosphere are nitrogen, oxygen and water vapour. The minor components are argon and carbon dioxide, the trace components include inert gases like methane.

The atmosphere protects us from meteors and harmful solar radiation and warms the earth's surface by heat retention. Earth's atmosphere has primary five layers, referred to as spheres. From the lowest to the highest layer, they are the troposphere, stratosphere, mesosphere, thermosphere and exosphere.

These five distinct layers have been identified using thermal characteristics, chemical composition, movement and density.

2. Mutation

4. Convergent evolution.

Organs having different origin but similar function are called analogous. Wings of butterfly and of birds look alike. They 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.

2. Pleistocene

Explanation:

The first Homo sapiens have evolved in the Pleistocene Epoch.

This time period began about 2.6 million years ago and lasted till 1,700 years ago. By the end of this period, the Homo sapiens were present all over the world.

1. Chemosynthesis

Explanation:

Scientists have developed a theory that describes how the very first microscopic life on primitive Earth could have evolved as a result of a series of chemical reactions. This theory is called chemosynthesis, and it describes the chemical evolution of cellular life.

Chemosynthesis, process in which carbohydrates are manufactured from carbon dioxide and water using chemical nutrients as the energy source, rather than the sunlight. It starts when random molecules in the atmosphere of primitive earth form simple organic molecules with energy provided by ultra violet light, radiation and other energy sources.

The chemosynthesis theory implies that the development of life is probable wherever the proper physical and chemical conditions are in place.

1. Biogenesis theory

Explanation:

Biogenesis means life comes from pre existing life, as in modern earth. Now life comes from pre-existing life only but life actually evolved from non living components abiogenetically.

2. Shortening of jaws.

1. Jurassic

Explanation:

The dominant animals during the Jurassic period were dinosaurs.

2. 25 × 106 year back.

3. Pre-existing variation in the population.

Adaptive radiation is related to evolution of different designs for a single organ according to varied needs of different groups. Transduction is related to transfer of viral or bacterial genetic material. Divergent evolution is related to homologous organs.

Hence, option ‘c’ is correct.