Biology 2 Marks Questions

The organs which have same basic structural design and development origin but differ in their uses and functions are called homologous organs. The forelimbs of some animals have similar anatomical structure. They possess humerus, radius, ulna, carpals, metacarpals and phalanges in their forelimbs, e.g., forelimbs of man, whales, bats, cheetah, indicates that they have common ancestors, thus supporting organic evolution.

Embryology, anatomy, palaeontology and biogeography provided evidences for organic evolution.

Lamarck’s theory of evolution states that use and disuse of an organ can bring about a change in that organ which is then acquired and passed on to the next generation, e.g., the long neck of giraffe was explained by Lamarck, as an outcome of these animal to stretch their neck constantly to eat the leaves from the upper branches of the trees.

The sum total of all the allelic frequencies of a stable population is one.
The factors which affect Hardy-Weinberg's equilibrium are as follows:

1. Gene migration/ gene flow.
2. Genetic drift.
3. Mutation.
4. Genetic recombination.
5. Natural selection.

The disturbance in genetic equilibrium in a population, would result in evolution.

1. Convergent evolution.
2. Convergent evolution.
3. Convergent evolution.
4. Divergent evolution.

1. There are inheritable variation among the members of a population.
2. Many more individuals are produced each generation that can survive and reproduce.
3. Individuals with adaptive characteristics are more likely to be selected to reproduce by the environment.
4. Gradually, over long periods of time, a population can become well adapted to a particular environment.
5. The end result of organic evolution is many different species, each adapted to specific environments.

Methane, carbon dioxide, ammonia and water vapour.

1. Homo erectus.
2. Neanderthal man.
3. Homo habilis.
4. Dryopithecus and Ramapithecus.

Earth was supposed to have been formed about 4.5 billion years back in the solar system of our milky way galaxy. Its surface was covered with water vapour, methane, carbon dioxide and ammonia released from molten mass.
Subsequently, the ozone layer was formed. fu it cooled, the water vapour fell as rain and filled all depressions to form oceans and other water bodies.

Pelycosaurs and Therapsids.

1. All vertebrate embryos develop a row of gill slits, which are functional only in fish and tadpole larva and not in other vertebrates.
2. Notochord is present in all vertebrate embryos.

Such similarities indicate that they have descended/ evolved from a common ancestor.