$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which of the following statements best describes an isotope?

Accepted Answer

An atom of a given element that differs in the number of neutrons in its nucleus.

Question 2

A radioactive isotope of phosphorus is used to label DNA in a bacterial culture. Which property of radioactive isotopes makes this possible?

Accepted Answer

They release energy during radioactive decay, which can be detected.

Question 3

Which of the following best explains why water is an excellent solvent for many biological molecules?

Accepted Answer

Water molecules have two polar covalent bonds, allowing them to interact with charged and polar substances.

Question 4

A scientist is studying a molecule that contains carbon, hydrogen, and oxygen in a 1:2:1 ratio. This molecule is most likely a:

Accepted Answer

Carbohydrate

Question 5

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is two or more atoms held together by chemical bonds, while a compound is a molecule composed of more than one element.

Question 6

Which type of chemical bond is responsible for the complementary base pairing in DNA?

Accepted Answer

Hydrogen bonds

Question 7

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 8

Which of the following best explains why phospholipids are essential for cell membrane structure?

Accepted Answer

They have both hydrophilic heads and hydrophobic tails, allowing them to form bilayers in aqueous environments.

Question 9

Which of the following reactions is an example of dehydration synthesis?

Accepted Answer

The formation of a peptide bond between two amino acids, releasing a water molecule.

Question 10

A patient is found to have a blood pH of 7.1. Which of the following statements is most accurate?

Accepted Answer

The blood is slightly acidic, and buffers are needed to restore normal pH.

Question 11

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers prevent drastic changes in internal pH by absorbing or releasing H$$^+$$ ions.

Question 12

Which of the following statements about proteins is correct?

Accepted Answer

Proteins are composed of amino acids linked by peptide bonds.

Question 13

Which of the following is a function of carbohydrates in cells?

Accepted Answer

Forming the backbone of nucleic acids.

Question 14

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 15

Which of the following best explains why salts are important in biological systems?

Accepted Answer

They dissociate into electrolytes, which are essential for electrical signaling and enzyme function.

Question 16

A scientist adds a base to a solution, causing the pH to increase from 7 to 9. By what factor did the hydrogen ion concentration decrease?

Accepted Answer

By a factor of 100

Question 17

Which of the following best describes a nonpolar covalent bond?

Accepted Answer

A bond formed by the equal sharing of electrons between atoms with similar electronegativities.

Question 18

Which of the following is a real-life example of a hydrolysis reaction in the human body?

Accepted Answer

The breakdown of dietary proteins into amino acids during digestion.

Question 19

Which of the following statements about nucleic acids is correct?

Accepted Answer

Nucleic acids are composed of nucleotides, each containing a phosphate, a pentose sugar, and a nitrogenous base.

Question 20

A mutation causes a change in the side group of an amino acid in a protein. Which of the following is the most likely consequence?

Accepted Answer

The protein's three-dimensional shape and function may be altered.

Ch 2. The Chemistry of Microbiology: Foundations for Life

Guida di studio - Domande di pratica