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