AST 248: The Search for Life in the Universe

TYPE YOUR ANSWERS.

1. Explain why the greenhouse effect of the Earth's atmosphere is not the true reason a car's interior heats up on a sunny day. What experiment shows that the explanations for each phenomenon are not the same? You may have to do a google or literature search to answer this question. The greenhouse effect of the Earth's atmosphere is due to the transparency of the atmosphere to visible light and its opaqueness to infrared light. The greenhouse effect of a greenhouse or a car is due to the air inside being heated by sunlight and simultaneously being trapped, not able to exchange its heat with the outside. An experiment is to make a greenhouse out of a material that is transparent to both visible and infrared light; it is found that its interior heats up the same as it would if it were made of glass, which is transparent to visible light and opaque to infrared light.
2. What are the major reasons why some planets retain atmospheres and others might not? a. mass (gravity) of planet (both for retention and outgassing) b. magnetosphere (which shields planet from solar winds)
3. What are the essential differences between the Lamarckian and Darwinian views of evolution? The Lamarckian view suggests that organisms are spontaneously created and evolve to greater complexity as individuals during their lives. Individuals evolve. The Darwinian view suggests that organisms arise from parent organisms and don't evolve during their lives, but populations slowly change due to natural selection during reproduction. Populations evolve, not individuals.
4. Give three reasons why it has been decided by most biologists that single-celled prokaryotic organisms should be divided into two domains, bacteria and archaea. Ribosomes of bacteria differ from those of archae and eukaryotes; tRNA structures differ; archael cell walls do not contain peptidoglycan, cellulose or chitin; cell membranes differ fundamentally.
5. Give three examples of selectivity as it pertains to life found on Earth. Examples of selectivity: restriction to 20 amino acids, restriction to 100,000 proteins, restriction to 4 bases, restriction to left-handed amino acids.