Question 1

Which of the following best describes an element?

Accepted Answer

The smallest unit of matter that is indivisible by chemical means.

Question 2

Water is considered the 'universal solvent' because:

Accepted Answer

Its polar nature allows it to dissolve both ionic and many polar non-ionic substances.

Question 3

Which property of water allows it to moderate Earth's climate and regulate temperature in living organisms?

Accepted Answer

High heat of vaporization

Question 4

Why is carbon considered the backbone of virtually all organic molecules?

Accepted Answer

It can form up to four covalent bonds, allowing for diverse and complex structures.

Question 5

Which of the following is NOT a functional group commonly found in biological molecules?

Accepted Answer

Hydroxide ($-O^-$)

Question 6

A sodium atom ($Na$) transfers an electron to a chlorine atom ($Cl$) to form table salt ($NaCl$). What type of bond is formed?

Accepted Answer

Ionic bond

Question 7

Which of the following statements about hydrogen bonds is TRUE?

Accepted Answer

They help stabilize the structure of proteins and DNA.

Question 8

Why does ice float on water?

Accepted Answer

Hydrogen bonds in ice create a lattice structure that is less dense than liquid water.

Question 9

Which element is essential for the structure of nucleic acids and is often found in the 'backbone' of DNA and RNA?

Accepted Answer

Phosphorus ($P$)

Question 10

A scientist claims to have discovered a bacterium that can use arsenic instead of phosphorus in its DNA backbone. What is the most scientifically valid response to this claim?

Accepted Answer

Conduct follow-up studies to test and potentially refute the claim.

Question 11

Which of the following best explains why water is a liquid at room temperature and pressure?

Accepted Answer

Hydrogen bonding between water molecules increases cohesion and raises the boiling point.

Question 12

Which of the following elements is most abundant in living organisms?

Accepted Answer

Carbon ($C$)

Question 13

What is the main reason why knowing the elements present in living organisms is important for biology?

Accepted Answer

It helps us understand the chemical reactions and processes essential for life.

Question 14

Which of the following is a correct statement about van der Waals interactions?

Accepted Answer

They occur between non-polar molecules and are weaker than hydrogen bonds.

Question 15

Which of the following best describes a compound?

Accepted Answer

A combination of two or more elements in a fixed ratio.

Question 16

Which of the following elements is found in proteins and is essential for their structure?

Accepted Answer

Sulfur ($S$)

Question 17

Which property of water is most important for evaporative cooling in living organisms?

Accepted Answer

High heat of vaporization

Question 18

Which of the following is a real-world application of radioactive isotopes in biology?

Accepted Answer

Dating ancient fossils using Carbon-14 decay rates.

Question 19

Which of the following best explains why carbon-based molecules are more versatile than silicon-based molecules for life?

Accepted Answer

Carbon can form four stable covalent bonds, allowing for complex and diverse structures.

Question 20

Which of the following is a multi-step problem: If a molecule contains carbon, hydrogen, oxygen, and nitrogen, which macromolecules could it potentially be a part of, and which functional groups would you expect to find?

Accepted Answer

It could be a protein or nucleic acid, and you would expect to find amino ($-NH_2$), carboxyl ($-COOH$), and phosphate ($-OPO_3$) groups.

Chemical Elements, Compounds, and Molecules: Foundations of Life

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