A crystal contains a radioactive isotope that has a half-life of 20,000 years. You analyze a sample and find that one-eighth of the isotope remains (12.5%). How old is the sample? How many half-lives have passed?

Which statement explains blood presure?

The emerald ash borer is an insect that is thought to have been accidentally brought to the United States from China in shipping containers. It attacks ash trees, eventually killing the trees, destroying an important part of the ecosystem.

Which of the following is NOT natural acquisition of immunity? a. contact with a pathogen b. antibodies passed on from mother to baby through breast milk C. vaccination d. antibodies passed on from mother to fetus through the placenta

Examples of aerial root plants

The plentiful nature of resources in the tropical rainforest reduces competition for them.

What might happen to cells that are exposed to high concentrations of sugar?

Why are the results of genetic crosses shown in punnett squares interpreted as probabilities, not certainties? give some specific reasons?

An electric clothes dryer draws 22 A of current from a 240-V wall outlet. How much power, in watts, does it use?

Which phase do you spell spend time making organelles and completing tasks such as producing proteins

How do you think an ecosystem can be reestablished in an area after a disturbance happens?