Question

biology 211 fall 2025
page 2 of 18
part i. answer all questions on the optical scan sheet provided. (50 points total)

1. which of the following statements is/are false?
2. prokaryotes use ribosomes for translation
3. all eukaryotes are multicellular
4. eukaryotic cells arose by endosymbiosis
5. cells in all three domains divide by mitosis

a. 1 and 3
b. 2 and 4
c. 3 and 4
d. 1, 2, and 3
e. 1, 2, and 4

1. which of the following organic molecules stores the most potential energy?

a. oleic acid (c₁₈h₃₄o₂)
b. glucose (c₆h₁₂o₆)
c. pyruvate (c₃h₄o₃)
d. ethane (c₂h₆)

1. which of the following is essential for a biological reaction to be spontaneous?

a. endothermic (positive δh)
b. exothermic (negative δh)
c. endergonic (positive δg)
d. exergonic (negative δg)
e. both b and d

1. below is the structure of the amino acid methionine. which chemical group

represents the r group?
\ce{ch3-s-ch2-ch2-\overset{\ce{nh2}}{\ce{c}}-h}
\ce{cooh}
a. -h
b. -nh₂
c. -cooh
d. -ch₂-s-ch₂-ch₃

Explanation:

Question 1

1. Analyze each statement:

• Statement 1: Prokaryotes do use ribosomes for translation (true).
• Statement 2: Not all eukaryotes are multicellular (e.g., yeast is a unicellular eukaryote), so this is false.
• Statement 3: Eukaryotic cells are thought to have arisen by endosymbiosis (true).
• Statement 4: Prokaryotes (in two domains) divide by binary fission, not mitosis; only eukaryotes (third domain) use mitosis, so this is false.
• So false statements are 2 and 4.

• Potential energy in organic molecules is related to the number of C - H bonds (more bonds mean more energy). Oleic acid is a fatty acid with a long hydrocarbon chain, glucose is a sugar, pyruvate is a 3 - carbon molecule, and ethane is a small hydrocarbon. Fatty acids have more C - H bonds per gram than sugars, and oleic acid is a fatty acid with a long chain, so it stores the most potential energy.

• A spontaneous reaction has a negative $\Delta G$ (exergonic). Exothermic reactions (negative $\Delta H$) can contribute, but the key for spontaneity is negative $\Delta G$ (exergonic). Also, exothermic (negative $\Delta H$) reactions tend to be spontaneous, and exergonic (negative $\Delta G$) is the definition of a spontaneous reaction. So both B (exothermic, negative $\Delta H$) and D (exergonic, negative $\Delta G$) are essential for spontaneity in many cases (since $\Delta G=\Delta H - T\Delta S$; a negative $\Delta H$ helps, and negative $\Delta G$ is the criterion).

Answer:

B. 2 and 4

Question 2