When did the last mass extinction occur?

O

A. At the beginning of this era.

O

B. At the beginning of this period.

O

C. At the beginning of this epoch.

O

D. At the beginning of this eon.

Explain what process the a cell must use to allow a protein to enter and why?

Assume thymine makes up 15% of the bases in a double-stranded DNA molecule. What percentage of the bases in the molecule will be represented by cytosine? Explain your answer.

How does crossing over ensure that organisms living in isolated populations will have genetic variation?

Both extroverts and introverts are at risk for antisocial behaviors. a. True b. False

Comprehension Questions: Available in 01:14 The nucleus contains protons and neutrons Electrons

Which of the following is a feeding source for fens? aquifers dexfoliants exfoliants nitrates

What system includes oceans, lakes, rivers, and groundwater? a. geosphere b. hydrosphere c. atmosphere d. biosphere

Fungal spores a. are only asexually produced. b. cannot be seen in a light microscope. c. are used to identify fungi. d. are produced by molds but not by yeasts. e. are only produced under harmful environmental conditions

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm.

What's the function of rough er