Which best describes a tetrad?
o a. a diploid cell
o b. four chromatids
o c. two gametes
o d. a haploid cell

Which kind of worm has a closed circulatory system? a planarian b fluke c pinworm d an earthworm

How many autosomes are in this human karyotype? how many sex chromosomes?

Describe how viruses and bacteria can be used as biological weapons. what are some of the potential threats and potential benefits? do you agree with the use of viruses and bacteria as biological weapons? why or why not?