During which period of the Paleozoic Era did the largest mass extinction occur? A. Permian B. Devonian C. Cambrian D. Carboniferous

An elongated tailbone occurs rarely in some newborn children, What does the presence of a tailbone indicate?. a) That the tail will grow in length as the child grows. b) That our early ancestors were tailed primates.

Does mars have an atmosphere at night

Which of the following describes a solution that contains a buffer? A. Acetic acid is added to the solution, and the pH of the solution becomes lower. B. Distilled water is added to the solution, and the pH of the solution does not change. C.

3. What characteristic is shared by birds, salamanders, and sharks?

How do plants respond to different environmental stimuli?

you are running an experiment trying to figure out how water affects plant growth for three orchid plants you recently bought. The orchids are the same species and you will place the plants next to eachother in the same windowsill.

The living world is organized in levels. Biotic and abiotic factors also can be arranged into levels of biological organization. Put the words below in order from the least complex to the most complex

Which of the following, when taken up by the cell, binds to the repressor so that the repressor nolonger binds to the operator? A) ubiquitin B) inducer C) promoter D) repressor E) corepressor

Which of these organisms would be a producer? A. fish B. grasshopper C. flower D. snake

A 75 year old man need a replacement heart valve. he lives alone and cares for himself. is a mechanical or biological heart more suited for him