Question

topics I picked

Fossils of transitional form support Darwin's theory of evolution

Mutation and sexual reproduction produce the genetic variation that makes evolution

Conditions on early earth made the origin of life possible

What were the three most profound topics that you have learned in chapters 13 - 15? How does this information help support the theory of evolution and piece together a time line of living organisms from beginning until now? How would you describe evolution to someone that has not taken a college biology course? Provide an explanation for each of your topics.

Answer 1

According to Darwins theory of evolution which is 'descent with modification' , all organisms are related through descent from to their ancestors lived in past. The present form of life has modified from ancestral form by natural selection over a long period of time. This indicate all organisms are evolved from a common ancestor which can be represented as a single tree of life. A transitional fossil is the one that howa trait common to both ancestral group and the descendant group derived from it.The fossil of Archaeopteryx which exhibited combinations of traits of both dinosaur and birds indicate that there existed a common ancestor for birds and reptiles.

In a population all individuals are not similar but they exhibit differences in their physical traits (for example colour, height etc are different among organisms of same species). This phenotypic differences are due to changes in genotype or genetic make up (or changes in alles or genes ). VAriations in a population occur by these changes in genes facilitated by mutation and sexual reproduction. New genotype can be produced by mutation (error in copying DNA) that occur naturally. In sexual reproduction combinations of alleles are formed increasing possibility of variation among population. Thus mutation and sexual reproduction cause variation and allow the selection of individuals with better character, such genetic changes are accumulated over time leading to formation of new species leading to evolution.

The conditions of earth was also evolved over time allowing existence of life to diversification of species. Earth was highly reduced in the begining without any oxygen.Abiotic synthesis of snall organic molecules which polymerised eventually, forming pro cells or probionts. Self replicating molecules and prokaryotes are evolved , eventually by photosynthesis atmosphere has oxygenic and eukaryotes are evolved.

As a whole the changes in earths atmosphere and evolution of organisms occured in parellel. As complex multicellular organisms evolved, they accumulated changes over time giving rise to newer species . Mutatin and sexual reproduction facilitated these. Thus geological time scle reflect these processes and its pattern .

Evolution include the exploration of how life originated in earth, diversified into many kind and forms that we see around and how the organisms are adapting to changing environmnet. Evolution describe why monkeys show similarity in features with man, and why human are quite different from other organisms.