Question 1

Which of the following could be built solely from glucose molecules?

Accepted Answer

Starch is a complex carbohydrate made up of glucose molecules linked together in a chain. It can be broken down into glucose for energy. The other choices, fatty acids, DNA, and oils, are composed of different molecules and cannot be directly constructed from glucose only.

Question 2

Monomers that can be commonly made from components in Earth's atmosphere are

Accepted Answer

Amino acids can be synthesized from components found in Earth's atmosphere, as demonstrated by the Miller-Urey experiment, which simulated early Earth conditions and produced amino acids, the building blocks of proteins.

Question 3

Which of the following is the largest in size?

Accepted Answer

Protein is the largest of the options given because it is made up of many amino acids organized into complex structures. Glucose and nucleotides are both relatively small molecules, while carbon atom is a single atom and thus the smallest option given.

Question 4

Which of the following statements is true of proteins,carbohydrates,and nucleic acids?

Accepted Answer

Proteins, carbohydrates, and nucleic acids are all built from a common set of monomers. Proteins are made up of amino acids, carbohydrates are made up of monosaccharides, and nucleic acids are made up of nucleotides. However, they differ in the specific arrangement and type of monomers they use in their structure.

Question 5

A researcher in a laboratory tests a food item and identifies protein in it.The food item must also contain

Accepted Answer

Proteins are made up of amino acids, so finding protein in a food item necessarily means that it also contains amino acids. Glucose is a type of sugar and not necessarily present in all food items. Lipids are fatty acids and also not necessarily present in all food items. Nucleotides are mostly associated with DNA and RNA and not typically found in large amounts in food.

Question 6

Astronauts returning from outer space studied samples taken from their lunar landing.They found that one of their samples was coated with organic compounds.Which of the following statements must be correct about their samples?

Accepted Answer

Organic compounds are defined by the presence of carbon atoms, so the samples must contain carbon atoms.

Question 7

Laura's supervisor provides her with lipids,carbohydrates,proteins,and nucleic acids and asks her to determine their chemical components.Which of the following elements would she NOT expect to find in these items?

Accepted Answer

While iron is an important element in the body, it is not typically found in the chemical components of lipids, carbohydrates, proteins, or nucleic acids. Phosphorus, hydrogen, and nitrogen are all commonly found in these molecules.

Question 8

Macromolecules are typically formed by repetitively adding small monomers together.Which macromolecule is properly matched with the appropriate monomer?

Accepted Answer

A polypeptide is made up of long chains of amino acids, which are the monomers that form the polypeptide. Nucleic acids are made up of nucleotides, polysaccharides are made up of sugars, and triglycerides are made up of glycerol and fatty acids, not cholesterol.

Question 9

Carbon is an example of a(n)

Accepted Answer

Carbon is a chemical element with the symbol C and atomic number 6. It is not a compound or macromolecule, and it is not an amino acid as amino acids are composed of multiple elements including carbon, hydrogen, nitrogen, and oxygen.

Question 10

A scientist observed a chemical that changes to bright red in the presence of organic compounds containing nitrogen and phosphorus.To test this chemical,a set of test tubes each containing a purified sample of one of the following organic compounds is prepared.The chemical is then added to each tube.The test tube containing ________ will always turn bright red.

Accepted Answer

Nucleic acids contain both nitrogen and phosphorus, so adding the chemical to the tube with nucleic acids will always result in a color change to bright red. Proteins, carbohydrates, and phospholipids do not necessarily contain both of these elements, so they may or may not produce a color change.

Question 11

A disaccharide consists of two

Accepted Answer

A disaccharide is a compound consisting of two sugar molecules joined together. Examples of disaccharides include lactose (glucose + galactose) and sucrose (glucose + fructose). Hydrocarbons are compounds consisting of only hydrogen and carbon atoms, not sugars. Fatty acids and amino acids are building blocks for lipids and proteins, respectively, not carbohydrates.

Question 12

The genetic material found in all living things is made of building blocks called

Accepted Answer

The genetic material in all living things is made up of nucleotides, which are the building blocks of DNA and RNA. Monosaccharides are the building blocks of carbohydrates, phospholipids are the building blocks of cell membranes, and steroids are a type of lipid.

Question 13

We use soap to clean ourselves better than we could with water alone.Soaps contain phospholipids that are responsible for the cleansing action.Which of the following statements is the MOST likely explanation for how soaps work?

Accepted Answer

The option C explains that the phospholipid tail attaches to the oily dirt while the phospholipid head interacts with rinse water and carries the dirt (and soap) away with it. This process of emulsification allows the water to mix with oily substances, which are then carried away by the soap molecules, making it the most likely explanation for how soap works.

Question 14

Nucleotides

Accepted Answer

Nucleotides are the building blocks of nucleic acids, which include DNA and RNA. They consist of a nitrogenous base, a sugar molecule, and a phosphate group, and play a crucial role in genetic information transfer and storage.

Question 15

Which of the following pieces of evidence would best demonstrate that a bacterium found on an asteroid originated in outer space?

Accepted Answer

The presence of right-handed amino acids in the bacterium's proteins would be the best evidence that the bacterium originated in outer space. This is because on Earth, virtually all living things use left-handed amino acids to build proteins, while right-handed amino acids are rarely used. The presence of right-handed amino acids in the bacterial proteins would strongly suggest that they originated in a different environment than Earth, such as outer space. The other choices do not directly relate to the origins of the bacterium.

Question 16

Which of the following is an organic compound?

Accepted Answer

Methane (CH₄) is an organic compound because it contains carbon and hydrogen, which are the primary elements in organic chemistry.

Question 17

Which of the following are composed of the same monomers?

Accepted Answer

Starch and cellulose are both composed of glucose monomers. Proteins are composed of different amino acid monomers, DNA is composed of nucleotide monomers, RNA is composed of nucleotide monomers, cellulose is composed of glucose monomers, and cholesterol and sucrose are completely different types of molecules.

Question 18

One of the symptoms of kidney disease is the presence of proteins in a patient's urine.To quickly test for kidney disease using a urine sample,a doctor might add a chemical that causes a color change when

Accepted Answer

Proteins contain nitrogen but not phosphorus. Therefore, adding a chemical that reacts specifically with nitrogen would cause a color change if proteins are present in the urine.

Question 19

The central element found in organic molecules is

Accepted Answer

The central element found in organic molecules is carbon. Organic compounds are compounds that contain carbon and are found in living things. Carbon has four valence electrons, which allows it to form covalent bonds with other atoms, including itself. This allows for the formation of long chains and complex structures that are essential to life.

Question 20

How many different amino acids are used to build proteins?

Accepted Answer

Only 20 different amino acids are used to build proteins.

Quiz 3: Chemistry of Life