The half-life of cobalt 60 is 5.3 years. What fraction of a sample remains after 21.2 years?

A.

one half

B.

one quarter

C.

one eighth

D.

one sixteenth

Which of these is a difference between a DNA and an RNA molecule? A. DNA contains nitrogenous bases, whereas RNA contains phosphate groups. B. DNA is usually double-stranded, whereas RNA is usually single-stranded. C.

1) The volume of a balloon is 225 ml. The temperature of the balloon is 20°C. If a scientist drops the temperature by 10°C, what is the new volume?

Which of the following can survive in extreme environments (like high temperature or acidity) ? A) Prokaryotes B) Eukaryotes C) Archaens D) Viruses

Which of the following is most likely to move through the cell membrane by facilitated diffusion?

Louis Pasteur was the final scientist to settle the question of Spontaneous Generation and biogenesis by

A mutation that results in a single amino acid substitution in the active site of an enzyme

Two identical nuclei are form durning___?

If Tyler does not eat a diet that excludes essential amino acids, his cells will not be able to build

Dr. o is playing in her garden again. she needs 1 kg of potting soil for her plants. she has 750g. how much more does she need?

What causes leaves to dry out