Question 1

Which property of carbon most directly explains its ability to form a wide variety of complex molecules essential for life?

Accepted Answer

Its ability to form four covalent bonds with other atoms.

Question 2

Organic chemistry is primarily concerned with compounds containing which element?

Accepted Answer

Carbon

Question 3

Which of the following best describes a hydrocarbon?

Accepted Answer

A molecule containing only carbon and hydrogen atoms.

Question 4

Carbon atoms can form double bonds with other carbon atoms. What is a consequence of this type of bonding?

Accepted Answer

All bonds around the double-bonded carbons are in the same plane.

Question 5

Which of the following is true about cis-trans isomers?

Accepted Answer

They differ in the spatial arrangement of atoms around a double bond.

Question 6

Enantiomers are important in biology because:

Accepted Answer

They are mirror images and can have very different effects in organisms.

Question 7

Which functional group is most likely to make a molecule behave as a base in water?

Accepted Answer

Amino group

Question 8

A molecule with the formula $$\mathrm{C}_6\mathrm{H}_{12}$$ could be which of the following?

Accepted Answer

A cycloalkane

Question 9

Which statement best explains why fats are energy-rich molecules?

Accepted Answer

They have long hydrocarbon chains with many nonpolar carbon-hydrogen bonds.

Question 10

Which of the following molecules is classified as an organic molecule found in organisms and is used as a reactant in photosynthesis?

Accepted Answer

Carbon dioxide ($$\mathrm{CO}_2)$$

Question 11

Which of the following best describes the difference between structural isomers and cis-trans isomers?

Accepted Answer

Structural isomers differ in the arrangement of atoms; cis-trans isomers differ in the spatial arrangement around a double bond.

Question 12

Methamphetamine exists as two enantiomers with very different effects. What does this illustrate about enantiomers?

Accepted Answer

Enantiomers can have dramatically different effects in biological systems.

Question 13

Which of the following is NOT a major element commonly found in organic molecules essential for life?

Accepted Answer

Calcium (Ca)

Question 14

Which statement about the valence of carbon is correct?

Accepted Answer

Carbon has a valence of 4, allowing it to form four covalent bonds.

Question 15

Which of the following best explains why organic molecules can be so diverse?

Accepted Answer

Carbon can form single, double, and triple bonds with a variety of elements.

Question 16

Which of the following is a correct statement about the structure of urea ($$\mathrm{CO(NH_2$)_2}$$)?

Accepted Answer

Each carbon atom forms both single and double covalent bonds.

Question 17

A molecule has the same molecular formula as another but differs in the covalent arrangement of its atoms. What type of isomer is this?

Accepted Answer

Structural isomer

Question 18

Which of the following statements about functional groups is correct?

Accepted Answer

Functional groups are directly involved in chemical reactions and determine molecular function.

Question 19

Testosterone and estradiol are both steroids with four fused rings, but they differ in their chemical groups attached to the rings. What does this difference illustrate?

Accepted Answer

Chemical groups attached to a carbon skeleton can dramatically affect molecular function.

Question 20

Which of the following is a direct result of the double bond in a cis-trans isomer?

Accepted Answer

The double bond restricts rotation, causing different spatial arrangements.

Carbon and the Molecular Diversity of Life: Study Guide

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