If a radioactive substance's half-life is 20 years, how much of a 40-gram sample will be left after 60 years? A. 5 grams B. 10 grams C. 20 grams D. 30 grams

What does the cell have to do before division begins?

Choose one concrete example of a cells response after its signal has been received and describe it.

a balloon filled with water is placed in a microwave until it bursts. Name two different physical changes that occur during this reaction

The Sun is A. a very small star. B. a medium-sized star. C. the largest star in the universe. D. the same size as all the other stars.

Why is it hotter in in a attic compared to a bacement

What does natural selection act on

Where does cellular respiration occur? In the cytoplasm In the mitochondrion < - - In the cell membrane In the chlorophyll

People generally know that citrus fruits are good food sources of vitamin C, but there are plenty of non-citrus sources as well. What are some of the non-citrus foods are good sources of vitamin C?

what is the presence of different genes on the same chromosome, is it linkage?, diploid?, haploid?, autosome?, or chromosome theory

Which of the following statements about hormones are correct? (A) Hormones can be peptides, steroids, or amino acid derivatives. (B) Hormones can stimulate the synthesis of target proteins through the activation of specific genes.