Question 1

Which of the following best explains why a sodium atom (Na) forms a cation when it reacts with chlorine (Cl) to form table salt (NaCl)?

Accepted Answer

Sodium loses an electron to achieve a stable electron configuration, resulting in a net positive charge.

Question 2

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 3

A solution is prepared by dissolving 18 g of glucose (C$$_6H$_{12}O$_6) in $$enough water to make 0.5 L of solution. What is the molarity of the solution? (Molar mass of glucose = 180 g/mol)

Accepted Answer

$$0.2\ \mathrm{M}$$

Question 4

Which emergent property of water allows a pond to remain liquid under a layer of ice during winter, supporting aquatic life?

Accepted Answer

Expansion upon freezing

Question 5

A biologist is studying a protein that denatures when the pH drops below 6. Which property of water and biological systems is most relevant to maintaining the protein's function?

Accepted Answer

The presence of buffers that maintain a stable pH

Question 6

Which of the following best describes the difference between a dehydration reaction and a hydrolysis reaction in biological systems?

Accepted Answer

Dehydration reactions build polymers by removing water; hydrolysis reactions break polymers into monomers by adding water.

Question 7

Which functional group is present in all amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group ($$-\mathrm{COOH})$$

Question 8

Which of the following best explains why lipids do not dissolve in water?

Accepted Answer

Lipids are nonpolar and hydrophobic, so they do not interact favorably with water molecules.

Question 9

A DNA molecule is composed of two strands running in opposite directions. Which term best describes this arrangement, and what is the base pairing rule for adenine?

Accepted Answer

Antiparallel; adenine pairs with thymine

Question 10

Which of the following is a trace element required by humans and is essential for the proper functioning of the thyroid gland?

Accepted Answer

Iodine

Question 11

Which of the following best describes the role of weak interactions, such as hydrogen bonds and van der Waals forces, in biological molecules?

Accepted Answer

They help stabilize the three-dimensional structure of large molecules like proteins and DNA.

Question 12

Which of the following statements about the Miller-Urey experiment is correct?

Accepted Answer

It demonstrated that organic molecules could be synthesized abiotically under conditions thought to resemble those of early Earth.

Question 13

Which of the following best distinguishes a saturated fat from an unsaturated fat at the molecular level?

Accepted Answer

Saturated fats have only single bonds between carbon atoms, while unsaturated fats have one or more double bonds.

Question 14

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$\ \mathrm{M}. $$What is the pH of this solution?

Accepted Answer

$$5$$

Question 15

Which of the following best describes the difference between a nucleotide and a nucleoside?

Accepted Answer

A nucleoside consists of a nitrogenous base and a sugar, while a nucleotide also contains a phosphate group.

Question 16

Which of the following is a correct pairing of a functional group and its property?

Accepted Answer

Phosphate group ($$-\mathrm{PO}_4$$^{2-}$$): contributes negative charge and can transfer energy

Question 17

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

Accepted Answer

Hydrogen bonds between water molecules absorb heat when they break and release heat when they form, buffering temperature changes.

Question 18

Which of the following best describes the primary structure of a protein?

Accepted Answer

The sequence of amino acids in a polypeptide chain

Question 19

Which of the following statements about DNA and RNA is correct?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 20

A scientist is analyzing a carbohydrate and finds that it is composed of many glucose units joined by $$\alpha-1$$,4 and $$\alpha-1$$,6 glycosidic bonds. Which carbohydrate is the scientist most likely studying?

Accepted Answer

Glycogen

BSC2010 Exam #1 Study Notes: Chapters 2-5 (Chemical Context of Life, Water and Life, Carbon and Molecular Diversity, Biological Macromolecules)

Study Guide - Practice Questions

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