Question 1

Which of the following best describes an element in biological terms?

Accepted Answer

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

Question 2

Water ($$\mathrm{H_2O}) is $$considered a compound because:

Accepted Answer

It is formed by a fixed ratio of two different elements.

Question 3

Which property of water allows it to moderate temperature on Earth?

Accepted Answer

High heat of vaporization

Question 4

Why is carbon considered the backbone of organic molecules?

Accepted Answer

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

Question 5

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

Accepted Answer

Nitride ($$-\mathrm{N$$^{3-}$$})$$

Question 6

Which type of chemical bond is primarily responsible for the structure of DNA base pairs?

Accepted Answer

Hydrogen bonds

Question 7

A scientist discovers a bacterium that appears to use arsenic instead of phosphorus in its DNA backbone. What is the most scientifically sound approach to this claim?

Accepted Answer

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

Question 8

Which element is found in both proteins and nucleic acids, and is essential for their structure?

Accepted Answer

Nitrogen

Question 9

What is the main reason water is considered a 'universal solvent'?

Accepted Answer

Its polar nature enables it to dissolve many ionic and polar molecules.

Question 10

Which of the following best explains why ice floats on water?

Accepted Answer

Hydrogen bonds in ice create an open lattice structure, making it less dense than liquid water.

Question 11

Which of the following is a correct statement about valence shells and chemical bonding?

Accepted Answer

Atoms form chemical bonds to fill their valence shells.

Question 12

Which bond type is the weakest among those commonly found in biological molecules?

Accepted Answer

Van der Waals interaction

Question 13

Carbon-14 dating is useful in biology because:

Accepted Answer

It tracks the decay of radioactive carbon-14 to estimate the age of once-living material.

Question 14

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

Accepted Answer

Oxygen

Question 15

Which scenario best illustrates evaporative cooling in biological systems?

Accepted Answer

Sweating causes water to evaporate from the skin, removing heat from the body.

Question 16

Which functional group is found in amino acids and is essential for protein structure?

Accepted Answer

Amino ($$-\mathrm{NH_2$})$$

Question 17

Which of the following statements about science and retraction is most accurate?

Accepted Answer

Retraction is a sign that science is self-correcting and open to new evidence.

Question 18

Which element is required in trace amounts for nerve function and communication in humans?

Accepted Answer

Potassium

Question 19

Which of the following best explains why silicon is less suitable than carbon as the backbone for life in water-rich environments?

Accepted Answer

Silicon-based molecules are less stable and less versatile in water.

Question 20

A molecule contains only hydrogen, carbon, and oxygen. Which macromolecule could it NOT be?

Accepted Answer

A protein

The Chemicals of Life: Elements, Bonds, Water, and Carbon in Biology

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