Question 1

Which of the following best explains why lipids are grouped together as a class of biological molecules?

Accepted Answer

They are all hydrophobic and mostly insoluble in water.

Question 2

A dehydration reaction joins two glucose molecules to form maltose. If the formula for glucose is $$\mathrm{C_6H_{12}O_6$}$$, what is the formula for maltose?

Accepted Answer

$$\mathrm{C$$_{12}$$H_{22}O$$_{11}}$

Question 3

Which of the following statements about phospholipids is correct?

Accepted Answer

Their hydrophilic heads face outward and hydrophobic tails face inward in a bilayer.

Question 4

Glucose and fructose are both monosaccharides with the formula $$\mathrm{C_6H_{12}O_6$}$$, but they differ in the arrangement of their atoms. What type of isomers are they?

Accepted Answer

Structural isomers

Question 5

Which of the following best describes the role of cholesterol in animal cells?

Accepted Answer

It is a precursor for steroid hormones and a component of cell membranes.

Question 6

A region of a polypeptide is rich in the amino acids valine, leucine, and isoleucine. Where would you expect this region to be located in the folded protein, and why?

Accepted Answer

On the interior, because these amino acids are hydrophobic.

Question 7

Which bonds are primarily responsible for stabilizing the secondary structure of a protein?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 8

A single amino acid substitution in the primary structure of hemoglobin can cause sickle-cell disease. Which property of proteins does this illustrate?

Accepted Answer

The primary structure determines the overall shape and function of a protein.

Question 9

Which of the following best describes the difference between DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 10

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The sugar-phosphate backbone is on the outside, and the nitrogenous bases are on the inside.

Question 11

A cow is given antibiotics to treat an infection, and then a vet gives the animal a drink of 'gut culture' containing various prokaryotes. Why is this necessary?

Accepted Answer

Antibiotics kill beneficial gut prokaryotes needed for digestion.

Question 12

Which of the following best explains why human sex hormones are considered lipids?

Accepted Answer

They are hydrophobic molecules derived from cholesterol.

Question 13

Which of the following is a correct complementary DNA strand for the sequence $$5'	ext{-}TAGGCCT	ext{-}3'$$?

Accepted Answer

$$3'	ext{-}ATCCGGA	ext{-}5'$$

Question 14

Which of the following best describes a dehydration reaction in the formation of biological polymers?

Accepted Answer

A water molecule is removed to form a bond between monomers.

Question 15

Which of the following is a function of proteins in living organisms?

Accepted Answer

Catalyzing biochemical reactions as enzymes

Question 16

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The overall shape resulting from interactions between multiple polypeptide subunits

Question 17

Which of the following is a correct description of a phosphodiester bond?

Accepted Answer

A covalent bond between the 3' OH of one nucleotide and the 5' phosphate of the next

Question 18

Which of the following would most likely cause a protein to denature?

Accepted Answer

A significant change in pH or temperature

Question 19

Which of the following best explains why unsaturated fats are liquid at room temperature?

Accepted Answer

They have one or more double bonds causing kinks in the fatty acid chains.

Question 20

Which of the following is a correct statement about the directionality of nucleic acids?

Accepted Answer

The 5' end has a free phosphate group, and the 3' end has a free hydroxyl group.

Carbon Atoms and Large Biological Molecules

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