Three samples of DNA contain the percentages of nitrogenous bases listed in Table 12-2. According to Chargaff's law, which two samples probably belong to the same species? A. cannot tell without data on guanine and thymine
B. 1 and 2
C. 1 and 3
D. 2 and 3

Approximately what portion of the foods that we eat have been genetically modified in some way? a. fewer than 10% b. about 50% c. nearly 100%

Which of the following cell structures is significantly different between gram- positive and gram-negative bacteria?

True or false: (a) the strings of little red dots represent carbohydrates. (b) the model is called a bilayer because there are two main types of molecules present, lipids and proteins. (c) the many black lines represent amino acid tails. (d) this model shows membrane transport. (e) the blue ovals are hydrophobic. (f) the blue ovals represent phospholipid heads.