Chapter 9

Which of the following is not a basic feature of all living things on Earth? a. consumption of energy b. sexual reproduction c. mutation d. sensitivity to environment e. organic molecules

The original definition of "habitable zone" included which of the following? a. surface temperature of a planet in the range of \(273-373 \mathrm{K}\) b. presence of surface water c. known existence of life-forms d. Sun-like central star e. availability of carbon

The original definition of "habitable zone" included which of the following? a. surface temperature of a planet in the range of \(273-373 \mathrm{K}\) b. presence of surface water c. known existence of life-forms d. Sun-like central star e. availability of carbon

You find a polymer that contains the nucleobases \(A, G,\) and \(C . W h a t\) kind of molecule can it be? a. only DNA b. only RNA c. either DNA or RNA d. an amino acid e. DNA, RNA, or an amino acid

Which of the following is/are true of nucleotides? Choose all that apply. a. Each is a combination of a sugar molecule and a phosphate. b. They are components of DNA. c. They are components of RNA. d. They are polymers linked to other polymers by nucleobases. e. They are proteins.

The pattern of nucleobases in a strand of DNA is TGCAACG. When the strand splits for reproduction, which nucleobases will attach, in what sequence? a. TGCAACG b. CATGGTA c. CGTTGCA d. GCAACGT e. ACGTTGC

The sequence of bases in DNA directs which function? a. regulating oxygen synthesis b. building proteins c. facilitating mutations d. regulating reproduction e. regulating metabolism

The results of the Miller-Urey experiment supported which of the following conclusions about the early Earth? a. Life on Earth was inevitable. b. All available carbon would have been converted into organic molecules. c. The molecules produced in the experiment represented the specific molecules that formed life on Earth. d. Life was easy to produce. e. Amino acids and organic compounds would have formed readily.

Which of the following statements about natural selection is not true? a. Different traits are more favorable in different environments. b. Natural selection can lead to better adaptation of an organism to the environment. c. Traits that enhance the probability of reproduction tend to prolif- erate d. Less adaptive traits die out in one generation. e. Natural selection may begin with a random genetic change.

Which of the following terms does not describe a process that can affect the frequency of a gene in a population? a. migration b. mutation c. genetic drift d. natural selection e. replication

Which of the following is/are examples of traits that can be tied to heredity? Choose all that apply. a. Men who shave their heads as cultural norm also shave their sons' heads. b. The tallest sibling in a family produces taller children than his siblings do. c. Pancreatic cancer runs in a family. d. \(A\) child, whose parents both lack a specific antigen in their blood, also lacks that antigen. e. A chameleon can change its skin color at will.

Which of the following statements about lateral gene transfer is/are not true? Choose all that apply. a. It occurs only in reptiles. b. It occurs only in microorganisms. c. It occurs only asexually. d. It represents a two-way sharing of genes. e. It occurs within one generation.

Which of the following characteristics accurately describe Earth's first life forms? Choose all that apply. a. self-replicating b. single-celled c. multicellular d. aerobic e. anaerobic

Which of the following accurately describe(s) the Drake equation? Choose all that apply. a. It tells us exactly which kinds of stars can harbor planets with life. b. It calculates the true probability of extraterrestrial life. c. It names the factors that contribute to the total probability of life elsewhere. d. It provides a way to gauge how knowledge of the various factors is progressing. e. Its value has not changed since it was first conceived.

Why is the 21 -cm line believed to be a prime candidate for the wavelength an extraterrestrial would send or recognize if sent? Choose all that apply. a. It is radiated by hydrogen, the most abundant element in the Universe. b. It falls in the radio part of the spectrum, whose long wavelengths are most likely to travel unimpeded over large distances. c. An advanced civilization would be aware of its relevance. d. It is definitive proof of water and therefore life. e. It is easier to detect than all other frequencies.

True/False: In calculating the habitable zone for the Sun, astronomers assume that life on Solar System planets requires water. If a planet orbiting at \(1 \mathrm{AU}\) from a Sun-like star had life based on a molecule with much higher melting and boiling points, the habitable zone for that star would be significantly farther from the star than the Sun's is.

True/False: All known living things on Earth contain carbon.

What are the distinguishing characteristics of organic molecules?

Some moons of planets outside the habitable zone in our Solar System appear to have liquid water on or below their surfaces. What are the possible sources of the heating required to produce this environment

Why are very hot stars not good candidates for highly evolved life?

What sources of energy other than sunlight have been discovered for extremophiles on Earth?

Describe how DNA differs from RNA in structure and function.

Discuss the importance of time in abiotic synthesis.

As the environment changes, how does natural selection help a particular species adapt?

What is meant by the term "Cambrian explosion"?

Why do astronomers believe that radio wavelengths are the most likely means of interstellar communication?

What is the Fermi paradox?

To date, what evidence is there for the existence of life beyond Earth?

Some people believe that evolution is only a theory and that there are other equally valid theories for the creation of different species on Earth. How would you respond to that claim?

How would it change your religious or philosophical views if the existence of intelligent extraterrestrial life were confirmed? if it were conclusively refuted?

What is the minimum length of time for sending a message and receiving a reply from an extraterrestrial on a planet 23 light-years away?

Assume that an RNA molecule has 144 nucleotides and that there are 4 different nucleotides. How many attempts will it take to produce one of these molecules, if it must be built from individual nucleotides one at a time?

Imagine that life that evolved on an exoplanet is based on 6 unique nucleotides instead of 4. An RNA molecule on that planet requires 138 nucleotides built from those 6 kinds of nucleotides. Building the RNA from individual nucleotides, how many attempts will it take to be sure to produce the necessary one?

Assume that the RNA molecule needed for life has 144 nucleotides, but it can be constructed out of a specific combination of 16 -nucleotide subunits. Both can be built from 4 basic nucleotides. How many different combinations of the 16 -nucleotide molecules are there?

A fast-rotating planet with an albedo of 0.4 orbits a star that has a luminosity 0.8 times that of the Sun at 0.5 AU. What are the inner and outer boundaries for the habitable zone? Is the planet in the habitable zone?