Q: A solution has a pH of 4. What is the hydrogen ion concentration $$[H^+] in $$moles per liter?

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

Question 1

Which of the following best explains why water is a liquid at room temperature, while other similar-sized molecules are gases?

Accepted Answer

Water molecules form hydrogen bonds due to their polarity.

Question 2

A patient is found to have a blood pH of 7.1. Which of the following best describes the change in hydrogen ion concentration compared to normal blood pH (7.4)?

Accepted Answer

The hydrogen ion concentration is about $$2^{0.3} (or $$roughly 2 times) higher, since each 0.3 pH unit change is about a doubling or halving of [H+].

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 4

A molecule of sodium chloride (NaCl) is formed when sodium donates an electron to chlorine. What type of bond is formed between the resulting ions?

Accepted Answer

Ionic bond

Question 5

Which of the following best describes the process of hydrolysis?

Accepted Answer

A water molecule is added to break a polymer into monomers.

Question 6

Which of the following is a property of water that is critical for maintaining body temperature homeostasis?

Accepted Answer

Water has a high heat capacity, allowing it to absorb and retain heat.

Question 7

A solution has a pH of 4. What is the hydrogen ion concentration $$[H^+] in $$moles per liter?

Accepted Answer

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

Question 8

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH by absorbing or releasing $$H^+$$ ions.

Question 9

Which of the following is true regarding the structure of a phospholipid?

Accepted Answer

It contains a glycerol, two fatty acids, and a phosphate group.

Question 10

A protein is denatured when:

Accepted Answer

Its three-dimensional structure is disrupted, causing loss of function.

Question 11

Which of the following best explains why glucose and sodium chloride (NaCl) dissolve differently in water?

Accepted Answer

NaCl dissociates into ions due to water's polarity, while glucose dissolves without dissociation.

Question 12

Which of the following is a correct statement about the pH scale?

Accepted Answer

A solution with pH 5 has 100 times more $$[H^+]$$ than a solution with pH 7.

Question 13

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A compound contains atoms of more than one element, while a molecule may contain atoms of only one element.

Question 14

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

Accepted Answer

Long-term energy storage in the form of glycogen in animals.

Question 15

Which of the following best describes the process by which ATP releases energy for cellular work?

Accepted Answer

ATP is hydrolyzed to ADP and a phosphate group, releasing energy stored in the bond.

Question 16

Which of the following is a correct match between a biomolecule and its monomer?

Accepted Answer

Carbohydrate — monosaccharide

Question 17

Which of the following best describes the role of enzymes in chemical reactions?

Accepted Answer

Enzymes lower the activation energy, speeding up reactions.

Question 18

Which of the following is a property of saturated fatty acids?

Accepted Answer

They contain only single bonds between carbon atoms.

Question 19

Which of the following best describes the structure of DNA?

Accepted Answer

Two strands of nucleotides held together by hydrogen bonds between complementary bases.

Question 20

Which of the following is an example of a polar covalent bond?

Accepted Answer

The bond between oxygen and hydrogen in a water molecule

Chapter 2: The Chemical Level of Organization – Structured Study Notes

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