27. In 1986, a meltdown of a nuclear reactor in the city of Chernobyl, in Ukraine, released highly radioactive chemicals into the atmosphere. As a result, people suffered various forms of cancer because of exposure to these radioactive chemicals. Cancerous cells divide much more often than noncancerous cells and form tumors in the body. (A) The radioactive chemicals burned people’s skin, which increased cell division rates in the people who developed cancer.

(B)The radioactive chemicals polluted people’s food, which changed some people’s ability to digest proteins and caused cancer.

(C) The radioactive chemicals caused structural changes in people’s genes, which changed how proteins functioned in cell division.

(D) The radioactive chemicals polluted people’s drinking water, which caused cells to divide more quickly in the people’s bodies and form tumors.

Rease is an enzyme used by plants to break down urea (a nitrogen-containing compound) into carbon dioxide and ammonia. urease urea > > > carbon dioxide and ammonia ammonia is broken down by plants into a nitrogen source plants need to grow. thus, plants could not use urea as a nitrogen source unless it was first converted to ammonia. in soybean plants there are two different kinds of urease, one produced in the seeds and the other produced in the leaves of the plant. three types of soybean plants were used in a set of experiments: normal soybeans and two mutant strains, one lacking the urease in the seeds only (strain 1) and one lacking urease in the leaves only (strain 2). experiment 1 separate areas in a field were planted with normal, strain 1, and strain 2 soybeans. all types of soybeans appeared to grow, flower, and produce seeds equally well. there were no externally detectable differences among the strains. experiment 2 small pieces of plant leaves of equal weight were obtained from each type of soybean plant and separately placed on media in culture dishes. tissue growing in this way will become an unorganized clump of cells referred to as callus. to provide a controlled nitrogen source, half the tissue samples of each type were placed on media containing urea, and the other half of the samples were placed on media containing ammonia. after 30 days, the weight gain for each of the callus samples was determined. results are shown in the table below.

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water

In cattle a single gene with two alleles determines fur color the fur can be red white or roan roan fur has both red and white hair which of the following statements is true a the allele for roan fur color is dominant over red and white fur color b the allele for red fur color is dominant over white and roan fur color c the roan and white alleles are expressed independently of the other d the red and white alleles are expressed independently of each other