(1.1) Diatoms are marine organisms with unique cell walls that contain the element silicon. Which of the following are two common elements found in the cells of diatoms?

(1.1) Besides nitrogen, the DNA base guanine is made of which of the following elements?

(1.1) Structures called microtubules are found in the cytoplasm of most eukaryotic cells. Microtubules are made up of proteins and help shape and support the cell. Which of the following elements are most abundant in microtubules?

(1.1) Some types of organic fertilizers are made from animal products such as bone. These fertilizers are added to soil to provide a source of nutrients for plants. Which of the following elements is expected to be most abundant in organic fertilizers made from animal products?

(1.1) The graph shows the percent by mass of six common elements in the human body. What are elements 5 and 6?

(1.1) Carbohydrates, lipids, proteins, and nucleic acids are organic molecules essential for life. Which of the following elements makes the large structures of these organic molecules possible?

(1.1) Peptidoglycan is a compound in the cell walls of many bacteria. Which of the following elements are most abundant in peptidoglycan?

(1.1) Many farm animals eat hay, which is made by cutting and drying plants such as ryegrass and timothy grass. Scientists analyzed the composition of hay after it was cut and again after it was dried. The amounts of which common biological elements would have decreased the most as the hay dried?

(1.2) Fructose, sucrose, and starch are all examples of

(1.2) The table provides information about the composition and function of four important molecules in living organisms. Which of the molecules in this table is a carbohydrate?

(1.2) Which group of organic compounds contains fatty acids?

(1.2) The diagram shows the basic structure of a cell’s plasma membrane. What is the primary function of lipid molecules in the plasma membrane?

(1.2) Plant species such as the sesame plant and the coconut palm have large amounts of lipids in their seeds. Which of the following is the most likely function of these lipids?

(1.2) Cellulose is a compound found in plants. It is made of a long chain of molecules with ringed structures. The molecules contain mostly carbon, hydrogen, and oxygen atoms in a ratio of approximately 1 carbon : 2 hydrogen : 1 oxygen. To which category of biological molecules does cellulose belong?

(1.2) Part of a carbohydrate molecule is shown. What is the building block of this carbohydrate?

(1.2) An altered form of the structural protein collagen causes a condition in which bones are weak and break easily. Which of the following are components of collagen?

(1.2) A cell membrane has a double layer of molecules. These molecules are made up of a phosphorus-containing “head” and two long, fatty acid “tails.” Which of the following best explains why the molecules are classified as lipids?

(1.2) When proteins are broken down, phenylalanine is sometimes produced. Phenylalanine contains the elements carbon, nitrogen, hydrogen, and oxygen. Phenylalanine is which type of compound?

(1.2) Collagen is found in connective tissue throughout the human body. Collagen is made of three amino acid chains that are twisted around one another. Which of the following best explains why collagen is classified as a protein?

(1.3) Some bacteria produce cellulase, a substance that speeds up the breakdown of cellulose in plant cell walls. Cellulase is an example of which of the following?

(1.3) Which of the following best describes how enzymes affect chemical reactions?

(1.3) Secretions from the pancreas contain compounds called lipases. Lipases increase the rate of digestion of lipids. Lipases are an example of which of the following?

(1.3) Skin cells and liver cells contain different sets of enzymes. Which of the following conclusions can be made based on this information?

(1.3) Many enzymes are found in the cytoplasm of human body cells. These enzymes would be expected to function optimally at which of the following temperatures and pH values?