What role do bacteria play in the nitrogen cycle?

A meteorite is determined to be 4.5 billion years old. It now has 78 atoms of lead-206. Assuming no loss of daughter isotopes, how many atoms of uranium-238 did the meteorite have to begin with? The half-life of uranium-238 is 4.5 billion years.

Living things need a constant supply of energy, even though many of the chemical reactions they undergo release energy. Why is this true?

Light travels fastest through A. air. B. water. C. metal.

A father with myotonic dystrophy has three daughters who are all carriers of the mutant allele and two sons who are unaffected noncarriers.

Which of the following is not considered to be a rock? coal sandstone pumice lava

Identify each statement as a hypothesis, theory, or law. Higher air pressure causes fuel to burn at a faster rate.

Which sequence represents the correct levels of organization for multicellular organisms

Which statement best compares and contrasts lipids and carbohydrates? Both are used for tissues, but only carbohydrates are used for tissue growth. Both are used for energy storage, but only carbohydrates are used for long-term energy storage.

What is another name for lane d in the diagram

This is the energy stored as adipose tissue:.