ASU BIO181 General Biology I Practice Exam 97Q

ASU BIO181 GENERAL

BIOLOGY I PRACTICE

EXAM 97Q

Question 1: A researcher changes only the pH of a growth medium and measures

bacterial growth rate. What is the independent variable?

Choices:

1) Bacterial growth rate 2) pH of the growth medium 3) Incubation time 4) Number of bacterial cells at the end

Correct Answer: pH of the growth medium

Explanation: The independent variable is the factor deliberately manipulated by the researcher; here that factor is pH.Page 1

Question 2: Which observation best supports the conclusion that an organism

maintains homeostasis?

Choices:

1) Its DNA sequence changes each day 2) Its internal temperature remains within a narrow range despite environmental changes 3) It increases in mass throughout its life 4) It produces o�spring

Correct Answer: Its internal temperature remains within a narrow range despite

environmental changes Explanation: Homeostasis is the regulation of internal conditions within a relatively stable range despite external change.

Question 3: An atom has 6 protons, 6 neutrons, and 8 electrons. What is its net

charge?

Choices:

1) 2+ 2) 2- 3) Neutral 4) 8-

Correct Answer: 2-

Explanation: Six protons contribute +6 and eight electrons contribute -8, giving a net charge of -2.Page 2

Question 4: Which type of chemical bond forms when two atoms share pairs of

electrons?

Choices:

1) Ionic bond 2) Hydrogen bond 3) Covalent bond 4) Van der Waals interaction

Correct Answer: Covalent bond

Explanation: A covalent bond forms through the sharing of electron pairs between atoms.

Question 5: Why can ionic compounds dissociate in water?

Choices:

1) Water is nonpolar 2) Water molecules form covalent bonds with every ion 3) Water's partial charges can surround and stabilize separated ions 4) Water removes protons from all solutes Correct Answer: Water's partial charges can surround and stabilize separated ions Explanation: Water is polar, so its partial charges interact with cations and anions and help keep the ions separated in solution.Page 3