Name: __________KEY Exam A_____________ UID: _______________ Exam code: A
BSCI207: Principles of Biology III
Exam 1A – Fall 2025
Instructions:
• Put your name and UID on this first page.
• Read each question carefully and select the BEST answer.
• For multiple choice/fill in blank – put answers on answer sheet – last page
• For free response questions, answer in (and ONLY in) the space provided on the exam. Full credit
will only be given if you SHOW YOUR WORK
• You have 50 minutes for this exam.
Please read and sign that you agree to follow the University of Maryland honor pledge:
“I understand my obligation to uphold the University Code of Academic Integrity and pledge I have not
received or given any unauthorized assistance on this academic exercise.”
Signature Date
Questions 1 – 20 of 50 points
Question 21 of 8 points
Question 22 of 8 points
Question 23 of 9 points
Total of 75 points
Note: For some reason that is beyond me, 90% of the A exam people got problem 4 wrong. My original
solution was to give everyone who took A exam 2 points, mostly because that was easy for me. After
conferring with several students, I have decided to give credit to those who got the problem wrong on either
exam A or B. Those of you who got it right will not get those 2 pts as I had originally indicated. Thanks for
your understanding.
, 1. As biologists, how do we typically think about heat energy? GAE1/Lecture 3 sect.2
a. It drives metabolic reactions, helping organisms make and break chemical bonds
b. It is too small to drive metabolism, but can help reactions happen faster
c. It is not useful in any way for biological processes
d. It drives photosynthetic reactions, leading to the production of ATP
2. (4 pts) For each organism, select which type of metabolism they use (can use more than once).
a-proteobacteria ___b, a_____ a. chemolithoheterotroph
algae ___c , b_____ b. chemoorganoheterotroph
cyanobacteria ___c_____ c. photoautotroph
methanogenic archaea ___a_____ d. photoheterotroph
Lecture 7 section 2 You only had to pick one for each (BOLD) but all accepted answers are noted
3. Phospholipids will self-assemble into ordered membranes. How do they do this and still satisfy the
second law of thermodynamics? Lecture 3 section 3 CC3 Q7
a. The attraction of their opposite charges releases heat and increases entropy.
b. They form chemical bonds, releasing heat to surroundings and increasing entropy.
c. They associate through hydrogen bonds, freeing water molecules and increasing entropy.
d. They bond together, using heat absorbed from the surroundings to increase their entropy.
4. Why did the evolution of enzymes enable organisms to evolve new metabolic reactions?
a. Enzymes added energy to make endergonic reactions become exergonic
b. Enzymes lowered the activation energy of reactions Lecture 3 section 2 CC3 Q6
c. Enzymes enabled non-spontaneous reactions to become spontaneous
d. Enzymes increased the amount of heat released to the environment
5. Becky Cann and Alan Wilson provided new insights on human evolution. Which molecule / gene did
they choose for their work and why did they choose it? GAE2
a. They chose a ribosomal RNA gene because it evolved slowly
b. They chose a ribosomal RNA gene because it evolved quickly
c. They chose a mitochondrial DNA gene because it evolved slowly
d. They chose a mitochondrial DNA gene because it evolved quickly
6. By using the rate of change of this molecule, Cann and Wilson were able to date the origin of the
common ancestor of modern humans. They found the ancestor arose GAE2
a. 2,000 yrs ago b. 20,000 yrs ago c. 200,000 years ago d. 2 million years ago
7. Cann and Wilson also found the common ancestor of modern humans most likely lived in
a. Africa b. Asia c. Europe d. Australia GAE2
8. Which of the following genetic elements change most slowly over time?
a. An intronic sequence of a nuclear gene like thyroid hormone
b. The 1st or 2nd base of a codon for a nuclear gene like thyroid hormone
c. The 3rd base of a codon for a nuclear gene like thyroid hormone
d. The 3rd base of a codon for a mitochondrial gene like cytochrome b
Lecture 5 section 1 and HW2 problem 2.
2
BSCI207: Principles of Biology III
Exam 1A – Fall 2025
Instructions:
• Put your name and UID on this first page.
• Read each question carefully and select the BEST answer.
• For multiple choice/fill in blank – put answers on answer sheet – last page
• For free response questions, answer in (and ONLY in) the space provided on the exam. Full credit
will only be given if you SHOW YOUR WORK
• You have 50 minutes for this exam.
Please read and sign that you agree to follow the University of Maryland honor pledge:
“I understand my obligation to uphold the University Code of Academic Integrity and pledge I have not
received or given any unauthorized assistance on this academic exercise.”
Signature Date
Questions 1 – 20 of 50 points
Question 21 of 8 points
Question 22 of 8 points
Question 23 of 9 points
Total of 75 points
Note: For some reason that is beyond me, 90% of the A exam people got problem 4 wrong. My original
solution was to give everyone who took A exam 2 points, mostly because that was easy for me. After
conferring with several students, I have decided to give credit to those who got the problem wrong on either
exam A or B. Those of you who got it right will not get those 2 pts as I had originally indicated. Thanks for
your understanding.
, 1. As biologists, how do we typically think about heat energy? GAE1/Lecture 3 sect.2
a. It drives metabolic reactions, helping organisms make and break chemical bonds
b. It is too small to drive metabolism, but can help reactions happen faster
c. It is not useful in any way for biological processes
d. It drives photosynthetic reactions, leading to the production of ATP
2. (4 pts) For each organism, select which type of metabolism they use (can use more than once).
a-proteobacteria ___b, a_____ a. chemolithoheterotroph
algae ___c , b_____ b. chemoorganoheterotroph
cyanobacteria ___c_____ c. photoautotroph
methanogenic archaea ___a_____ d. photoheterotroph
Lecture 7 section 2 You only had to pick one for each (BOLD) but all accepted answers are noted
3. Phospholipids will self-assemble into ordered membranes. How do they do this and still satisfy the
second law of thermodynamics? Lecture 3 section 3 CC3 Q7
a. The attraction of their opposite charges releases heat and increases entropy.
b. They form chemical bonds, releasing heat to surroundings and increasing entropy.
c. They associate through hydrogen bonds, freeing water molecules and increasing entropy.
d. They bond together, using heat absorbed from the surroundings to increase their entropy.
4. Why did the evolution of enzymes enable organisms to evolve new metabolic reactions?
a. Enzymes added energy to make endergonic reactions become exergonic
b. Enzymes lowered the activation energy of reactions Lecture 3 section 2 CC3 Q6
c. Enzymes enabled non-spontaneous reactions to become spontaneous
d. Enzymes increased the amount of heat released to the environment
5. Becky Cann and Alan Wilson provided new insights on human evolution. Which molecule / gene did
they choose for their work and why did they choose it? GAE2
a. They chose a ribosomal RNA gene because it evolved slowly
b. They chose a ribosomal RNA gene because it evolved quickly
c. They chose a mitochondrial DNA gene because it evolved slowly
d. They chose a mitochondrial DNA gene because it evolved quickly
6. By using the rate of change of this molecule, Cann and Wilson were able to date the origin of the
common ancestor of modern humans. They found the ancestor arose GAE2
a. 2,000 yrs ago b. 20,000 yrs ago c. 200,000 years ago d. 2 million years ago
7. Cann and Wilson also found the common ancestor of modern humans most likely lived in
a. Africa b. Asia c. Europe d. Australia GAE2
8. Which of the following genetic elements change most slowly over time?
a. An intronic sequence of a nuclear gene like thyroid hormone
b. The 1st or 2nd base of a codon for a nuclear gene like thyroid hormone
c. The 3rd base of a codon for a nuclear gene like thyroid hormone
d. The 3rd base of a codon for a mitochondrial gene like cytochrome b
Lecture 5 section 1 and HW2 problem 2.
2
