What is one example of an index fossil?
1. a rock
2. a tooth
3. a trilobite
4. a meteor

Astudent reads the following text in a science book: scientific evidence tells us that the cause of earths four seasons is the tilt of earth as it revolves around the sound the student is instructed to illustrate this information in a science book. how will the student illustrate winter in the northern hemisphere? a.earths northern hemisphere will tilt away from the sun. b. earths northern hemisphere will tilt toward the sun. c.earths orbit will be farther away than from the sun d. earths southern hemisphere will tilt away from the sun.

If this person had son,what,sex chromosome did they give their son? a.x b.y c.neither d.we need more information to know for sure

If a dna molecule has 100 nucleotides and 22 of them are cytosine, how many thymines does it have?