Compare and contrast a character”versus a variant

General Biology 

 Compare and contrast a “character” versus a “variant (or trait)”.A pea plant with a Tt genotype is crossed to a plant with a tt genotype. What percentage of the offspring do you expect will be dwarf? What is a transgenic organism? Give one example.What is a stem cell? Give two examples of how stem cells may be used to treat human disorders.Briefly describe the method of gene therapy to treat ADA-deficiency?  Briefly describe the four stages that led to the first primitive cells?What is chemical selection?What is a molecular clock? What are molecular clocks used for?Define “horizontal gene transfer.”List the key physical factors of the environment. Which is usually the most important factor that affects the distribution of organisms.What is the Greenhouse effect? How have humans affected this phenomenon and how has it impacted the Earth’s environment?What is Leibig’s law of the minimum?  Give an example.Briefly describe the carbon cycle.

 Briefly describe the three levels of biodiversity. Compare and contrast four hypotheses regarding species diversity and ecosystem function.