BIOLOGY 2 Marks Questions

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.

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

1. Lobefins are the fish with stout and strong fins, that could move on land and go back to water, they must have lived about 350 mya and were thought to be extinct.
2. In 1938, a Coelacanth (lobefin) was caught in South Africa.
3. Though no specimens of these are left with us, they evolved into the first amphibians.
4. These were the ancestors of modern day frogs and salamanders.

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.

1. Presence of free oxygen in present day atmosphere.
2. Existence of living organisms.

• Mammals are endothermic vertebrates.
• Have hair and fur on the body.
• Have mammary glands.

1. Darwin’s finches.
2. Australian marsupials.

• Amino acids were found.
• Miller created in a laboratory scale, the conditions similar to the primitive earth.
• Electric discharge using electrodes was created in a closed flask containing CH₄, NH₃, H₂, and water vapour at 800°C.
• The production of organic compounds supported the chemical evolution that preceded the formation of life on earth.

1. The characteristics which enable some population or individuals to survive better in natural conditions (foods, climate, physical factors) would outbreed others (survival of the finest).
2. Thus, those organisms, which are better fit or adapt well will survive and get selected by nature, which furthers their evolution. This is called natural selection.

• Differential reproduction: The phenomenon in which all organisms who reach reproductive stage reproduce with varying degree of success, some reproduce more offsprings and some reproduce only few and other reproduce none depending upon their degree of fitness.

• Reproductive isolation: The biological phenomenon in which the individual belonging to same species reproduce among themselves, to maintain the species integrity. Both these terms are used in reference to natural selection.