NASA has published a list of criteria for identifying fossil bacteria in samples from Mars, as part of a search for evidence of life. Which of the following is good evidence for the presence of bacterial cells?
A. No evidence of water in the surrounding mineral
B. Three-dimensional organization of cells in a starburst pattern
C. Absence of carbon in the material
D. Cell size of 0.5 to 2 microns
Answer: D
You might also like to view...
Why did scientists originally hypothesize that proteolytic enzymes such as pepsin and trypsin are secreted in inactive form?
A) These proteolytic enzymes, in active form, would digest the very tissues that synthesize them. B) They identified the hormone that activates pepsin and trypsin. C) The stomach is too acidic to maintain these enzymes in their active form. D) Pepsin and trypsin have never been isolated in their fully activated form.
Water has an important stabilizing effect on temperature in living organisms and their environments because as water absorbs heat, much of the energy is used to ____ instead of raising the temperature
a. create hydrogen bonds b. create covalent bonds c. break surface tension d. break hydrogen bonds e. create hydration layers
Which of the following is a correct order of arrival in succession?
a. lichens and mosses cottonwood and willow trees Sitka spruce alders b. flowering plants shrubs lichens fir trees c. lichens and mosses alders and hemlock shrubs and grasses Douglas fir d. none of the choices
Phylogenetic trees are organized into groups that share a homologous trait. What are these groups called?
a. bipolar b. monophyletic c. polymorphous d. evolutionary