10 grams $$80 \times \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = 10$$

pH = 5 $$\text{pH} = -\log_{10}(1 \times 10$$^{-5}$$) = 5$$

Carboxyl group ($$\text{R–COOH})$$

Question 1

Which of the following statements best describes the relationship between atomic number and element identity?

Accepted Answer

The atomic number is the number of protons, and is unique for each element.

Question 2

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much will remain after 30 years?

Accepted Answer

10 grams $$80 	imes \frac{1}{2} 	imes \frac{1}{2} 	imes \frac{1}{2} = 10$$

Question 3

Which of the following best explains why water has a high heat capacity?

Accepted Answer

Hydrogen bonding between water molecules requires more energy to break.

Question 4

What is the main difference between a saturated and an unsaturated fatty acid?

Accepted Answer

Saturated fatty acids contain only single bonds in their hydrocarbon tails, while unsaturated fatty acids contain one or more double bonds.

Question 5

Which of the following is a correct balanced chemical equation for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 6

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ mol/L. What is its pH?

Accepted Answer

pH = 5 $$	ext{pH} = -\log_{10}(1 	imes 10$$^{-5}$$) = 5$$

Question 7

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

Accepted Answer

Enzymes lower the activation energy, speeding up reactions without being consumed.

Question 8

Which of the following is an example of a decomposition reaction?

Accepted Answer

$$AB \rightarrow A + B$$

Question 9

What is the primary function of glycogen in the human body?

Accepted Answer

Main storage polysaccharide for energy

Question 10

Which of the following statements about electrolytes is correct?

Accepted Answer

Electrolytes are soluble inorganic substances whose ions conduct electricity in solution.

Question 11

Which functional group acts as an acid, releasing H+ to become R–COO–?

Accepted Answer

Carboxyl group ($$	ext{R–COOH})$$

Question 12

Which of the following best describes the structure of DNA?

Accepted Answer

Paired strands coiled in a double helix with thymine as a nitrogenous base

Question 13

Which of the following is a property of water that is essential for life?

Accepted Answer

Water has a high heat capacity, allowing it to stabilize temperature.

Question 14

Which of the following is a correct description of a buffer system?

Accepted Answer

A buffer system stabilizes pH by neutralizing acids or bases.

Question 15

Which of the following is a correct example of a reversible reaction?

Accepted Answer

$$A + B \rightleftharpoons AB$$

Question 16

Which of the following is NOT a function of proteins in the human body?

Accepted Answer

Energy storage

Question 17

Which of the following best describes the process of dehydration synthesis?

Accepted Answer

A reaction that joins monomers to form polymers by removing water.

Question 18

Which of the following is a correct description of ATP?

Accepted Answer

ATP is a nucleotide with three phosphate groups held together by high-energy bonds.

Question 19

Which of the following statements about phospholipids is correct?

Accepted Answer

Phospholipids form micelles in water due to their hydrophilic heads and hydrophobic tails.

Chapter 2: The Chemical Level of Organization - Study Notes

Study Guide - Practice Questions