If life exists on Mars, what form is it likely to be?

The function of enzymes is to

For an element to have no charge, which must be equivalent in number?

Two studies were carried out to determine if children in daycare got more ear infections than children who stayed at home. The first study compared ear infection rates in 50 Canadian girls ages 1 to 2, half of whom attended daycare and half of whom stayed home. The second study compared ear infection rates in 1000 Swedish boys ages 3 to 4, half of whom attended daycare and half of whom stayed home. The results of these two studies differed greatly. Which of the following is LEAST likely to be the cause of such differences?

The periodic table displays the elements arranged according to

If you were to dissect a plant into smaller and smaller units, what is the smallest unit that would still be considered alive?

Which of the following types of chemical bonds involves the sharing of electrons?

A(n)  _____  is a charged atom.

A polar covalent bond is formed by

You have the following known facts: Smoking causes accumulation of materials in the lungs, thereby decreasing oxygen-absorbing capability of the lungs. Long-term smoking causes more accumulation of materials in the lungs. Decreased lung capacity increases the workload of the heart. Which of the following hypotheses can you make from these observations?