Question 1

Which subatomic particle determines the atomic number of an element and is responsible for its chemical identity?

Accepted Answer

Proton

Question 2

A radioactive isotope of phosphorus ($$^{32}P) is $$commonly used in biological research. What is the main reason for its use in DNA labeling experiments?

Accepted Answer

It allows tracking of DNA molecules due to its radioactive decay.

Question 3

Valence electrons play a crucial role in chemical bonding. Which statement best describes their influence?

Accepted Answer

Elements with the same number of valence electrons have similar chemical properties.

Question 4

Which of the following best distinguishes a molecule from a compound?

Accepted Answer

A molecule consists of two or more atoms bonded together, while a compound consists of two or more different elements bonded together.

Question 5

Which of the following is an example of an ionic bond in a biological system?

Accepted Answer

The bond between sodium and chloride in table salt ($$NaCl).$$

Question 6

Which property of water allows insects like water striders to walk on its surface?

Accepted Answer

Cohesion due to hydrogen bonding

Question 7

Why are hydrogen bonds biologically important in living organisms?

Accepted Answer

They stabilize the three-dimensional structure of proteins and DNA.

Question 8

How does molecular polarity affect the solubility of a substance in water?

Accepted Answer

Polar molecules dissolve well in water because water is also polar.

Question 9

Which equation best represents the function of a buffer in maintaining pH homeostasis?

Accepted Answer

$$HCO_3^- + H$$^+ \rightarrow H_2CO_3$$

Question 10

Which of the following best explains capillary action in plants?

Accepted Answer

It is due to the combination of cohesion and adhesion of water molecules.

Question 11

A scientist observes that water has a high specific heat. What is the biological significance of this property?

Accepted Answer

It enables water to absorb and release large amounts of heat with little temperature change, helping organisms maintain stable internal temperatures.

Question 12

Which of the following is a correct example of a covalent bond in a biological molecule?

Accepted Answer

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

Question 13

Which property of water is most important for the transport of nutrients and waste in living organisms?

Accepted Answer

Excellent solvent abilities

Question 14

Which of the following best describes the role of buffers in blood?

Accepted Answer

Buffers prevent drastic changes in pH by neutralizing excess acids or bases.

Question 15

Which of the following scenarios demonstrates the application of water's solvent properties in a biological context?

Accepted Answer

Salt dissolving in water in the bloodstream to help nerve function.

Question 16

Which equation represents the dissociation of water into ions?

Accepted Answer

$$H_2O \rightarrow H^+ + OH^-$$

Question 17

Which of the following is NOT a unique property of water that supports life?

Accepted Answer

Inability to dissolve polar substances

Question 18

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

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds hold water molecules further apart in the solid state.

Question 19

Which of the following is an example of capillary action in nature?

Accepted Answer

Water moving up the stem of a plant

Question 20

Which of the following best describes the relationship between isotopes and atomic mass?

Accepted Answer

Isotopes have different numbers of neutrons, resulting in different atomic masses.

Fundamental Chemistry Concepts for Microbiology

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