Introduction. The question "Are we alone?" is oneof the most profound questions in all of science. But if we are tolook for life beyond Earth, we must first understand what life isand the conditions under which it can exist. The theory ofevolution, which is the unifying theory underlying modern biologyand medicine, explains the tree of life shown in the diagram andprovides important insights into issues of extraterrestriallife
2)there is competition for survival among the individuals of thepopulation
3)the population will tend to grow with time
4)the population will ultimately overwhelm its environment, causingthe environment to collapse
The second of the two "undeniable facts" is that individuals in apopulation of any species vary in many heritable traits (traitspassed from parents to offspring), so that no two individuals areexactly alike. This fact is important to understanding evolutionbecause it means that __________.
1)individuals can recognize their friends and family
2)the number of heritable traits must increase from one generationto the next
3)some individuals possess traits that make them better able thanothers to compete for food and other resources
4)all individuals in a population have an equal chance to surviveand reproduce
1)the population will grow larger and larger in number
2)all individuals of the population will tend to look more and morealike
3)heritable traits that enhance survival will become progressivelymore common in succeeding generations
4)the individuals of the population will reproduce at younger andyounger ages
|Human population has been rapidly growing overthe past few centuries.|
|Species often show unique adaptations that aresuited to the specific environment in which they live and might bedetrimental in other environments.|
|Genetic comparisons show that the DNA ofclosely related species is more similar than that of more distantlyrelated species.|
|Over time, bacteria tend to acquire resistanceto antibiotic drugs.|
2)The discovery that there are organisms on Earth with genomesquite different from those of known organisms.
3)The discovery of microbial life on Mars that uses a differentgenetic molecule than DNA.
4) The discovery of fossils of human-like primates dating to a timebefore the earliest dinosaurs existed