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Hindi Question English Question Answers Marks Category Manage
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Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Why or why not
Geographical isolation prevents transfer of genes between two species. In self-pollinating plant, pollen is transferred from the anther of one flower to the stigma of the same flower or of another flower of the same plant. It does not require any external agent for pollination, neither is it dependant on another plant for pollination. So, geographical isolation cannot affect the speciation of a self-pollinating plant.
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An example of homologous organs is (a) our arm and a dog’s fore-leg. (b) our teeth and an elephant’s tusks. (c) potato and runners of grass. (d) all of the above.
(d) All of the Above. As in all cases the basic internal structure and origin of the organs are the same though they differ functionally. For example, elephant's tusk is a modified incisor. So, origin is the same but the function is different. Tubers of potato and grass runners are both stem modifications but functions are different, hence these are homologous organs.
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In evolutionary terms, we have more in common with (a) a Chinese school-boy. (b) a chimpanzee. (c) a spider. (d) A bacterium
(a) In evolutionary terms, we have more in common with a Chinese school boy. Because both belong to the same species Homo sapiens. Chimpanzees and humans both have a common ancestor but are two different species.
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A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
Children with light-coloured eyes can either have LL or Ll or ll genotypes. Let us assume that the children have LL (both dominant alleles) genotype. This is possible only when both parents are also of the LL genotype. If the children with light-coloured eyes have ll genotype, then their parents will also have ll genotype. Therefore, it cannot be concluded whether light eye colour is dominant or recessive.
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Explain the terms analogous and homologous organs with examples.
Homologous organs are similar in origin (or are embryologically similar) but perform different functions. Forelimbs of frog, lizard, pigeon, bats, whales, horses and humans have the same basic structural plan but different functions. For example, the wings help in flight whereas human forearm helps in various activities. Homologous organs The organs which have similar functions but are different in their structural details and origin are called analogous organs. For example, the wings of a bird and a bat are similar in function, but this similarity does not mean that these animals are more closely related. The basic structure of the wings of insects is different from that of a bird and a bat but similar in function. Also, on careful observation we will find that the wings of a bat are just the folds of skin that are stretched between its fingers whereas the wings of birds are present all along the arm. Similarly, fins of fishes and flippers of whales are also examples of analogous organs. Therefore, these organs are analogous organs.
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