Q: A solution has a pH of 4. What is the concentration of hydrogen ions ($$[H^+]) in $$this solution?

$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which property of water allows plants to transport water from their roots to their leaves without expending energy?

Accepted Answer

Cohesion and adhesion

Question 2

A molecule of methane ($$CH_4) is an $$example of which type of chemical bond?

Accepted Answer

Nonpolar covalent bond

Question 3

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Hydrogen bonds in ice create a lattice that makes it less dense than liquid water.

Question 4

Which of the following statements about electronegativity and bond type is correct?

Accepted Answer

A difference in electronegativity between 0.5 and 2.0 results in a polar covalent bond.

Question 5

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

Accepted Answer

Quick energy source and structural support

Question 6

A solution has a pH of 4. What is the concentration of hydrogen ions ($$[H^+]) in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 7

Which of the following best describes the structure of a phospholipid in a cell membrane?

Accepted Answer

A hydrophilic head and two hydrophobic tails

Question 8

Which of the following is true about the formation of a peptide bond?

Accepted Answer

It is formed by a dehydration reaction between the carboxyl group of one amino acid and the amino group of another.

Question 9

Which of the following best explains why table salt ($$NaCl) $$dissolves easily in water?

Accepted Answer

Water is polar and stabilizes the ions formed from $$NaCl.$$

Question 10

Which of the following is a correct statement about the secondary structure of proteins?

Accepted Answer

It involves hydrogen bonding between backbone atoms, forming alpha helices and beta sheets.

Question 11

A patient is diagnosed with a genetic disorder that affects the structure of their hemoglobin protein. Which level of protein structure is most likely directly affected by a single amino acid substitution?

Accepted Answer

Primary structure

Question 12

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

Accepted Answer

Saturated fatty acids contain only single bonds between carbon atoms, while unsaturated fatty acids contain one or more double bonds.

Question 13

Which of the following is a property of water that helps moderate Earth's climate?

Accepted Answer

High specific heat

Question 14

Which of the following best explains why cellulose is not digestible by humans?

Accepted Answer

Humans lack the enzyme to break the $$\beta-1$$,4 glycosidic bonds in cellulose.

Question 15

Which of the following is the correct general formula for a monosaccharide?

Accepted Answer

$$C_nH_{2n}O_n$$

Question 16

Which of the following best describes the backbone of a nucleic acid polymer?

Accepted Answer

A sugar-phosphate chain held together by phosphodiester bonds

Question 17

A scientist is studying a molecule that is highly water soluble, tastes sweet, and has the formula $$C_6H_{12}O_6$. Which class of biomolecule is this most likely to be?

Accepted Answer

Carbohydrate

Question 18

Which of the following is a real-life consequence of water's high heat of vaporization?

Accepted Answer

Evaporation of sweat cools the human body efficiently.

Question 19

Which of the following best explains why carbon is the backbone of biological molecules?

Accepted Answer

Carbon can form up to four covalent bonds, allowing for diverse molecular structures.

Question 20

Which of the following is a correct statement about hydrogen bonds?

Accepted Answer

They form between the partial positive charge of hydrogen and the partial negative charge of another atom.

Biology Unit 1: The Chemistry of Life – Elements, Water, and Biological Molecules

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