Question 1

Which of the following best describes a compound?

Accepted Answer

A substance formed when two or more elements are chemically combined in fixed ratios.

Question 2

Which four elements make up about 96% of living matter?

Accepted Answer

Carbon, Oxygen, Hydrogen, Nitrogen

Question 3

A patient is diagnosed with goiter due to a deficiency in which trace element?

Accepted Answer

Iodine (I)

Question 4

Which subatomic particle is responsible for the atomic number of an element?

Accepted Answer

Proton

Question 5

Given an atom with 17 protons and 18 neutrons, what is its mass number?

Accepted Answer

$$35$$

Question 6

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 7

Which type of chemical bond is the strongest in biological molecules?

Accepted Answer

Covalent bond

Question 8

What is the main mechanism of an ionic bond?

Accepted Answer

Transfer of electrons from one atom to another, resulting in attraction between oppositely charged ions

Question 9

Water is described as a polar molecule. Which property does this polarity confer?

Accepted Answer

Water dissolves many substances, forming aqueous solutions.

Question 10

A buffer system in human blood helps maintain pH by balancing which two ions?

Accepted Answer

$$\mathrm{H^+}$$~and~\mathrm{$$HCO_3$$^-}$

Question 11

Which of the following best explains why DNA strands are stabilized?

Accepted Answer

By hydrogen bonds between base pairs

Question 12

If the pH of a solution decreases from 7 to 5, how does the concentration of $$\mathrm{H^+}$$ ions change?

Accepted Answer

It increases by a factor of 100

Question 13

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

Accepted Answer

NaCl (table salt)

Question 14

A molecule with a specific three-dimensional shape is critical for which biological interaction?

Accepted Answer

Signal transduction between receptors and ligands

Question 15

Which of the following is true about valence electrons?

Accepted Answer

They are crucial for chemical bonding.

Question 16

Which statement best describes a hydrogen bond?

Accepted Answer

A weak bond formed when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

Question 17

Which of the following is NOT a property of water due to its polarity?

Accepted Answer

Water is hydrophobic and repels charged molecules.

Question 18

Which formula correctly represents the calculation of atomic mass?

Accepted Answer

$$	ext{Atomic Mass} = 	ext{Number of Protons} + 	ext{Number of Neutrons}$$

Question 19

Which of the following is a function of buffers in biological systems?

Accepted Answer

Buffers resist changes in pH by accepting or donating $$\mathrm{H^+}$$ ions.

Elements, Compounds, and Chemical Principles in Anatomy & Physiology

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