Select the correct statement from the following given options.
(a) Darwinian variations are small and directionless
(b) Fitness is the end result of the ability to adapt and gets selected by nature
(c) All mammals except whales and camels have seven cervical vertebrae
(d) Mutations are random and directional
(b) Fitness (survival of the fittest) is a result of selection and proliferation of only those organisms which were most suitably adapted to the environment and get selected by nature.
Jurrassic period of the Mesozoic era is Characterised by
(a) radiation of reptiles and origin of mammal-like reptiles
(b) dinosaurs become extinct and angiosperms appear
(c) flowring plants and first dinosaurs appear
(d) gymnosperms are dominant plants and first birds appear
(d) Jurassic period is the second geological period of Mesozoic era. In this period, the gymnosperms were dominant and the plants included fems, cycads, Ginkgo, bushes and conifers. Among animals, important invertebrates included ammonites, corals, brachiopods, bivalves and echinoids. Reptiles dominated the vertebrates and the first flying reptiles the pterosaurs appeared. The first primitive bird, Archaeopteryx, also made its appearance.
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
(d) Homo sapiens sapiens is the modern man evolved about 25000 years ago. The direct ancestor of the living man was the Cro-magnon (Homo sapiens fossilis), discovered in 1868 from Cro-magnon rocks of France by 'Mac Gregor' from Holocene epoch. Cro-magnon was emerged about 34000 years ago. It is believed that Cro-magnon man was somewhat more intelligent and cultured than the man of today.
Which one of the following sequences was proposed by Darwin and Wallace for organic evolution?
(a) Variations, natural selection, overproduction, constancy of population size
(b) Overproduction, variations, constancy of population size, natural selection
(c) Variations, constancy of population size, overproduction, natural selection
(d) Overproduction, constancy of population size, variations, natural selection
(b) Through living organisms tend to multiply geometrically, the number of individuals of a species tend to remain constant over a long period of time. Out of heterogenous population (due to the variation) best adapted individuals are selected by nature.
Industrial melanism is an example of
(a) defensive adaptation of skin against ultraviolet radiations
(b) drug resistance
(c) directional selection due to smoke from industries
(d) protective resemblance with the surroundings
(c) Industrial melanism is an example of directional selection. Changing enviroment leading to changes in the phenotypic/genotypic constitution of a population.
The homologous organs are those that show similarity in
(a) size (b) origin
(c) function (d) apprearance
(b) Homologous structures are those which have the same embryonic origin and basic structure, though they may or may not perform the same function.
Occurrence of endemic species in South-America and Australia is due to
(a) these species have been extint from other regions
(b) continental separation
(c) there is no terrestrial route to these places
(d) retrogressive evolution
(b) Seas separating the continents form barriers to free intercontinental movement causing evolution of organisms independently in these continents leading to endemism. Endemic species are those species which are found in a restricted area of the world.
Genetic drift is change of
(a) gene frequency in same generation
(b) appearance of recessive genes
(c) gene frequency from one generation to next
(d) None of the above
(c) Genetic drift is defined as any random change, either directed or undirected in frequency of an allele within a population over time i.e., from one generation to next.
Thorn of Bougainvillea and tendril of Cucurbita are examples of
(a) analogous organs
(b) homologous organs
(c) vestigial organs
(d) retrogressive evolution
(b) Thorns of Bougainvillea and tendrils of Cucurbita are homologous organs. These are modified branches and are axillary in position. It means axillary branches in Bougainvillea are modified into thorns for protection from borrowing animals and in Cucurbita they are modified into tendrils for climbing.
The analogous organs have almost similar appearance and perform the same function but these develop in totally different groups and are totally different in their basic structure and development origin. The phyllode of Ruscus or cladode of Asparagus are analogous to leaves of other plants.
Adaptive radiation refers to
(a) adaptations due to geographical isolation
(b) evolution of different species from a common ancestor
(c) migration of members of a species to different geographical areas
(d) power of adaptation in an individual to a variety of environments
(b) Adaptive radiation is the development of different functional structures from a common ancestral form.