Biology Test 35

When Pangea broke apart the World’s climate changed, the continents were separated and the flow of oceanic currents and winds got altered. The continents shifted the surface of Earth which thus brought about huge changes in rock formation, climate, fossils etc.

According to theory of special creation, the different life forms that exist today have been created by super natural power.

The cretaceous period took place about 140 to 65mya. The major events that took place in this period- flowering plants became plentiful, first of many insects and birds appeared, break up of Pangea, first modern day mammals also appeared during this period.

According to Darwin, fitness is the ability of an individual to survive and reproduce in its own environment. This fitness depends on the number of offspring it produces comparing to the other individuals of its own species. So, natural selection is based on Survival of the fittest. Individuals that are able to reproduce more than others are naturally selected first because these individuals will produce large number of off-springs thus will pass on more of their genetic material than the less fit individuals.

The origin of homo sapiens in Africa and then radiating out to other places is suggested by maximum variations found in mitochondrial DNA of Africans and Variations in Y chromosome. 
Greatest mitochondrial DNA variation are seen amongst the African populations. These variations keep on decreasing in number as we move further away from Africa. The variations in Y chromosome suggests that almost little or zero interbreeding took place between homo erectus and homo sapiens after they migrated.

Neanderthal man is the first known to have buried their dead. They also followed empathy, had medicine. They were considered to be better painters than talkers. Neanderthal would hunt the animal, kill it and cut of the animals hide and use the hide to protect their own body.

Ape have a body with long trunk and longer arms than the legs. their center of gravity is high in the trunk. Whereas, the modern man has shorter arms than legs and their center of gravity is in pelvis.

Archaeopteryx lithographica is a connecting link between reptiles and birds. It has both reptilian and avian characteristics. Reptilian character- Wing claw, toothed beak and long tail. Avian character- Wings with contour feathers.

Reproductive isolation is the most important for speciation because these isolating mechanisms ensure that the species remain distinct in nature. These mechanisms may be either prezygotic or postzygotic.