Question 1

Which of the following statements best explains why carbon is considered the backbone of organic molecules?

Accepted Answer

Carbon can form up to four covalent bonds, enabling a variety of molecular shapes such as straight chains, branched chains, and rings.

Question 2

A pharmaceutical company is testing two drugs that are enantiomers of each other. Which of the following is most likely true about these drugs?

Accepted Answer

They have similar physical properties but may interact differently with biological molecules, leading to different effects in living organisms.

Question 3

Which functional group is correctly matched with its composition?

Accepted Answer

Carboxyl group: $$\mathrm{C+O+O+H}$$

Question 4

Which process is responsible for joining two monosaccharides to form a disaccharide, and what is a byproduct of this reaction?

Accepted Answer

Condensation (dehydration) reaction; water is produced

Question 5

A patient is diagnosed with sickle-cell disease, which is caused by a single amino acid substitution in hemoglobin. What is the most direct consequence of this mutation at the protein level?

Accepted Answer

The protein's primary structure is altered, which can disrupt its overall shape and function.

Question 6

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids contain double bonds and are liquid at room temperature.

Question 7

Which of the following statements about ATP is correct?

Accepted Answer

ATP releases energy when a phosphate group is removed, forming ADP.

Question 8

Which of the following best explains why enzymes are considered biological catalysts?

Accepted Answer

They speed up chemical reactions without being consumed by lowering the activation energy.

Question 9

A researcher is studying a molecule with the formula $$\mathrm{C_6H_{12}O_6$}. $$She finds that it can exist as glucose, fructose, or galactose. What term best describes these molecules?

Accepted Answer

Isomers

Question 10

Which of the following is a correct pairing of a polysaccharide and its biological function?

Accepted Answer

Starch – energy storage in plants

Question 11

Which of the following best describes the structure of a phospholipid and its role in cells?

Accepted Answer

It has a hydrophilic head and hydrophobic tails, forming the cell membrane bilayer.

Question 12

Which of the following changes is most likely to cause denaturation of a protein?

Accepted Answer

Increasing temperature or changing pH

Question 13

Which of the following is true about DNA and RNA?

Accepted Answer

DNA contains thymine, while RNA contains uracil.

Question 14

A scientist discovers a new organism whose cell walls contain chitin. Based on this information, to which group could this organism most likely belong?

Accepted Answer

Fungi

Question 15

Which of the following best describes the directionality of DNA strands?

Accepted Answer

One strand runs from $$5' to$$ $$3'$$, and the complementary strand runs antiparallel from $$3' to$$ $$5'.$$

Question 16

Which of the following is a purine found in nucleic acids?

Accepted Answer

Adenine

Question 17

Which of the following best explains why cellulose is difficult for most animals to digest?

Accepted Answer

Most animals lack the enzymes to break the specific glycosidic bonds in cellulose.

Question 18

Which of the following best describes the role of chaperonins in cells?

Accepted Answer

They help proteins fold into their correct three-dimensional shapes.

Question 19

Which of the following is a correct sequence of information flow in a cell?

Accepted Answer

DNA $$\rightarrow$$ mRNA $$\rightarrow$$ amino acids (protein)

Question 20

Which of the following best describes the difference between a polymer and a monomer?

Accepted Answer

A monomer is a single building block, while a polymer is a large molecule made of repeating monomers.

Carbon and the Molecular Diversity of Life & The Structure and Function of Large Biological Molecules

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