Question 1

Which of the following best describes why carbon is considered the most abundant element in cells?

Accepted Answer

Carbon can form up to four covalent bonds, allowing for complex molecules.

Question 2

A molecule of methane ($$CH_4) is $$formed when one carbon atom bonds with four hydrogen atoms. What type of bonds are present in methane?

Accepted Answer

Four non-polar covalent bonds

Question 3

Which of the following statements about the periodic table and biological abundance is correct?

Accepted Answer

Elements with high abundance in cells are mostly found in the first three rows of the periodic table.

Question 4

Which of the following best explains why water ($$H_2O) is a $$polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

Question 5

A sodium atom ($$Na) $$has one valence electron. When it reacts with chlorine ($$Cl$$), what type of bond is formed and why?

Accepted Answer

An ionic bond, because sodium donates an electron to chlorine.

Question 6

Which of the following biomolecules is primarily responsible for storing genetic information?

Accepted Answer

Nucleic acids

Question 7

Refer to the periodic table provided. Which element is most likely to form three covalent bonds in biological molecules?

Accepted Answer

Nitrogen ($$N)$$

Question 8

Which of the following best describes the difference between polar and non-polar covalent bonds?

Accepted Answer

Polar covalent bonds involve unequal sharing of electrons, while non-polar covalent bonds involve equal sharing.

Question 9

A phosphate group is shown making five bonds in a biological molecule. What property of phosphorus allows this?

Accepted Answer

Phosphorus can expand its valence shell to accommodate more than eight electrons.

Question 10

Which of the following is NOT a characteristic of living organisms according to the course definition?

Accepted Answer

Ability to form ionic bonds with all elements

Question 11

Which of the following best explains why oxygen is highly reactive in biological systems?

Accepted Answer

Oxygen has six valence electrons and tends to form two covalent bonds to achieve a stable octet.

Question 12

Which of the following statements about the chemical behavior of atoms is correct?

Accepted Answer

The chemical behavior of an atom is determined by the electrons in its outermost shell.

Question 13

A molecule contains a bond with a difference in electronegativity of 0.9. According to the scale, what type of bond is this?

Accepted Answer

Polar covalent bond

Question 14

Which of the following best describes the role of lipids in cells?

Accepted Answer

Lipids are a major component of cell membranes and energy storage.

Question 15

Which of the following is a correct statement about covalent bonding in the molecule $$NH_3 ($$ammonia)?

Accepted Answer

Nitrogen forms three covalent bonds with hydrogen atoms.

Question 16

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

Accepted Answer

Water is polar and can surround and separate the positive and negative ions.

Question 17

Which of the following is a real-life example of a non-polar covalent bond?

Accepted Answer

The bond between two hydrogen atoms in $$H_2$$

Question 18

Which of the following best describes the relationship between electronegativity and bond type?

Accepted Answer

A large difference in electronegativity leads to ionic bonds, while a small or zero difference leads to covalent bonds.

Question 19

Which of the following is NOT a function of proteins in living organisms?

Accepted Answer

Storing genetic information

Question 20

A scientist is designing an experiment to test the effect of a new drug on cell growth. Which of the following is the best example of a control in this experiment?

Accepted Answer

A group of cells that does not receive the drug

Fundamental Concepts in General Biology: Atoms, Biomolecules, and Chemical Bonds CHP 3

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