Which radioactive isotope is most often used when determining the age of fossil bones found in sediments deposited during the holocene epoch?

In 1980, a group of scientists from The University of California at Berkeley found an unusually high concentration of iridium in a rock layer thought to be 65 million years old. Iridium is rare on Earth, but is sometimes found in meteorites.

In children with infant respiratory distress syndrome (IRDS), the walls of the alveoli cling to each other and make them difficult to inflate. It is common in babies born prematurely.

Which of these describes a quantitative observation? A) an observation of the phenomenon itself B) an observation of the relative size of something OC) an observation of an effect the phenomenon has D) an observation that has a number associated

Puppies and kittens generally receive the coccidian protozoa from where? Walking in new areas Their mothers A contaminated kennel area Their littermates

If a white dwarf adds material from a nearby red giant, what is the result?

Suppose a bolt of lightning starts a fire in a forest. The fire sweeps through the forest and burns away accumulations of brush and deadwood. What is the most likely effect of the fire on the forest community?

What impact does 2-d diversity have on a company?

How can acid rain affect biodiversity in a pond?

Which of the following would be categorized as a cultural ecosystem service of forests?

Natural selection can lead to formation of a new species which is called?