SAT II Biology M : Molecular Biology

Study concepts, example questions & explanations for SAT II Biology M

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Example Questions

Example Question #1 : Macromolecules

Asparagine is an example of an amino acid. If you put asparagine and other amino acids together in a chain, you would get what organic compound?

Possible Answers:

A protein

A lipid 

A carbohydrate

A nucleic acid

Correct answer:

A protein

Explanation:

Amino acids are the building blocks of proteins, so when they are put together in a chain, you will get a protein.

Example Question #1 : Macromolecules

Which of the following macromolecules is made up of amino acids?

Possible Answers:

Sucrose

Trigylcerides

Lactase

Glucose

Deoxyribonucleic acid

Correct answer:

Lactase

Explanation:

A macromolecule made of amino acids is a protein. Lactase, the enzyme that aids in lactose digestion, is the only protein on the list. Sucrose and glucose are carbohydrates. Deoxyribonucleic acid is DNA, a nucleic acid. Triglycerides are a type of lipid.   

Note: You can identify an enzyme (which is a protein) by the fact that its name ends in "-ase."

Example Question #1 : Macromolecules

Carbohydrates represent important macromolecules in the biochemical pathways of many organisms. 

Which of the following is/are monosaccharide(s)?

I. Glucose
II. Fructose
III. Maltose

Possible Answers:

II and III

I, II, and III

I only

I and II

I and III

Correct answer:

I and II

Explanation:

Glucose and fructose are monomeric saccharides, or monosaccharides. The carbon to hydrogen to oxygen  ratio exists in a 1:2:1 pattern indicative of a monomeric saccharide. The molecular formula of glucose and fructose is . Maltose is a disaccharide composed of two molecules of glucose.

Example Question #2 : Macromolecules

Disaccharides, such as maltose, are produced when two monosaccharides undergo a dehydration synthesis reaction.

Which of the following formulas represents a disaccharide?

Possible Answers:

Correct answer:

Explanation:

The disaccharide maltose is formed by the dehydration synthesis reaction of two glucose monomers. When simply adding the two glucose monomers together, it may be thought that the summation of the two  will be the chemical formula of maltose. However, this does not account for the dehydration synthesis reaction in which one oxygen atom and two hydrogen atoms disappear. After accounting for these molecules the chemical formula for maltose will be represented by .

Example Question #2 : Macromolecules

Polysaccharides are considered sugar moieties that include 3 or more monomeric saccharides together.

Which of the following is/are polysaccharide(s)?

I. Glycogen
II. Starch
III. Cellulose

Possible Answers:

I and II

II and III

I, II, and III

I and III

I only

Correct answer:

I, II, and III

Explanation:

Glycogen, starch, and cellulose are all polysaccharides composed of many glucose monomers linked together.

Example Question #4 : Macromolecules

Animals and plants store glucose in saccharide polymers. 

Which of the following is the polymer form of storage in plants and animals, respectively?

Possible Answers:

Plants: chitin

Animals: glycerol

Plants: sucrose

Animals: maltose

Plants: starch

Animals: glycogen

Plants: glycogen

Animals: glycogen

Plants: cellulose

Animals: glucose

Correct answer:

Plants: starch

Animals: glycogen

Explanation:

The sugar polymer form in which plants store energy is starch, whereas with animals, it is glycogen. While the other answers may in fact be sugar molecules involved in energy metabolism, they do not represent the primary sugar polymer storage molecule. Therefore the correct form of storage for plants is starch. And the correct form of storage for animals is glycogen.

Example Question #2 : Macromolecules

In which of the following molecular forms do animals store energy?

Possible Answers:

Lipids only

Glycogen and peptidoglycan

Lipids and glycogen

Peptidoglycan only

Glycogen only

Correct answer:

Lipids and glycogen

Explanation:

Both lipids (fat) and glycogen (made up of glucose molecules) store energy in animals. Lipids are used for long-term energy storage while glycogen, found in the liver and muscles, is used for short-term energy storage. Peptidoglycan is the molecule that makes up the bacterial cell walls.

Example Question #2 : Macromolecules

Plants often have a waxy covering on the outside of their leaves to prevent water loss. This waxy covering probably contains mostly which organic compound?

Possible Answers:

A carbohydrate

A protein 

A nucleic acid

A lipid

Correct answer:

A lipid

Explanation:

Major lipid groups include fats, steroids, and waxes. Because the question references a "waxy covering," we know that the plant covering must be composed of lipids.

Example Question #2 : Macromolecules

Which organic compound serves as stored energy for living things?

Possible Answers:

Proteins 

Lipids

Carbohydrates 

Nucleic acids

Correct answer:

Lipids

Explanation:

Lipids make up the bulk of fat in animal tissues and thus stores energy.

Example Question #3 : Macromolecules

Phospholipids are an essential component of the phospholipid bilayer necessary to the cell.

Which of the following correctly represents a phospholipid subunit with the corresponding polarity?

Possible Answers:

Fatty acid tail: polar

Phosphate tail: polar

Fatty acid head: nonpolar

Phosphate head: nonpolar

Fatty acid tail: nonpolar

Correct answer:

Fatty acid tail: nonpolar

Explanation:

A phospholipid generally consists of a phosphate head (polar) and a fatty acid tail (non-polar).

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