Question 1

Which of the following correctly describes the location and charge of a neutron within an atom?

Accepted Answer

Located in the nucleus; no electrical charge ($$0)$$

Question 2

A radioactive isotope of phosphorus, $$^{32}P$$, is often used in biological research. Which of the following best explains its use?

Accepted Answer

It can be used to label DNA molecules, allowing researchers to track DNA synthesis in cells.

Question 3

Why do elements in the same group of the periodic table have similar chemical reactivity?

Accepted Answer

They have the same number of valence electrons, which determines their chemical bonding behavior.

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 a covalent bond in a biological molecule?

Accepted Answer

The bond between two hydrogen atoms in a molecule of $$H_2$$

Question 6

Which property of water allows it to move upward through the stem of a plant against gravity?

Accepted Answer

Cohesion and adhesion, resulting in capillary action

Question 7

Hydrogen bonds form between water molecules because:

Accepted Answer

Water is a polar molecule, with partial positive and negative charges attracting each other.

Question 8

Why are hydrogen bonds biologically important?

Accepted Answer

They stabilize the three-dimensional structures of proteins and nucleic acids.

Question 9

Which of the following best explains how molecular polarity influences the solubility of a substance in water?

Accepted Answer

Polar molecules dissolve well in water because water is also polar, allowing for hydrogen bonding.

Question 10

A buffer system in blood helps maintain pH homeostasis. Which equation best represents the bicarbonate buffer system?

Accepted Answer

$$CO_2 + H_2O$$ \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + $$HCO_3$$^-$$

Question 11

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

Accepted Answer

Low heat of vaporization

Question 12

Which scenario best illustrates the concept of capillary action in nature?

Accepted Answer

Water moving from the roots to the leaves of a plant through xylem vessels

Question 13

Which of the following best describes the difference between an acid and a base?

Accepted Answer

An acid donates $$H^+$$ ions, while a base accepts $$H^+$$ ions.

Question 14

If a solution has a pH of $$4$$, how many times more acidic is it than a solution with a pH of $$7$$?

Accepted Answer

$$1000$$ times more acidic

Question 15

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

Accepted Answer

Ice is less dense than liquid water due to the hydrogen-bonded lattice structure.

Question 16

Which of the following is a real-life example of a buffer system maintaining homeostasis?

Accepted Answer

The bicarbonate buffer system regulating blood pH in humans

Question 17

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are involved in forming bonds between atoms, determining the atom's chemical reactivity.

Question 18

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

Accepted Answer

The bond between sodium ($$Na^+) $$and chloride ($$Cl^-) $$ions in table salt

Question 19

Which property of water allows it to moderate temperature changes in organisms and environments?

Accepted Answer

High specific heat

Question 20

Which of the following best explains why salt (NaCl) dissolves easily in water?

Accepted Answer

The polar water molecules surround and separate the positive ($$Na^+) $$and negative ($$Cl^-) $$ions.

Fundamental Chemistry Concepts for Microbiology

Guida di studio - Domande di pratica