l. Which of the following does not correctly describe optical isomers? a. The tw
ID: 52343 • Letter: L
Question
l. Which of the following does not correctly describe optical isomers?
a. The two forms are considered mirror-images of each other.
b. The two forms are called D and L.
c. They occur when only three different atoms or functional groups are attached to a central carbon.
d. Amino acids are one example of optical isomers.
e. Two of the above are incorrect
2. Which of the following statements concerning protein structure is incorrect?
a. The secondary structure of proteins involves bonding between R groups to form
alpha helices and beta sheets.
b. The tertiary structure of proteins can be maintained by ionic bonding, which occurs between a positively charged anion and a negatively charged cation.
c. The quaternary structure of proteins involves the interaction of multiple proteins or polypeptide chains.
d. Two of the above are incorrect
e. All of the above are incorrect
3. Which of the following statement is incorrect?
a. Fats are only hydrophobic.
b. Phospholipids and cholesterol are both hydrophobic and hydrophilic.
c. Fats and phospholipids can be membrane components.
d. Two of the above are incorrect
e. None of the above are incorrect
4. Which of the following statements correctly describes the differences between a carbohydrate and a hydrocarbon?
a. Both are composed of carbon, oxygen, and hydrogen.
b. Both contain carbonyl and hydroxyl functional groups.
c. Both can be hydrophilic and hydrophobic.
d. All of the above are correct
e. None of the above are correct
5. Which of the following correctly orders the steps of the scientific method?
a. observations - experimentation - hypothesis - conclusions
b. observations - hypothesis - conclusions - experimentation
c. observations - hypothesis - experimentation - conclusions
d. hypothesis - observations - conclusions - experimentation
e. hypothesis - observations - experimentation - conclusions
6. You want to radioactively label proteins to study. This is done by growing cells in the presence of the radioactive element. Cells then use that radioactive element when making different macromolecules. Which element would you want to use so only proteins will be radioactive?
a. sulfur
b. phosphorus
c. oxygen
d. carbon
e. nitrogen
7. Which of the following statements does not accurately describe hydrogen bonding?
a. Hydrogen bonding occurs between an atom with a partial positive and an atom with a partial negative charge.
b. Hydrogen bonding holds together the secondary structure of proteins and nucleic acids.
c. Hydrogen bonding is involved in maintaining the tertiary structure of proteins.
d. two of the above are incorrect
e. All of the above are correct
8. Which of the following correctly describes a saturated fatty acid?
a. The absence of a double bond confers a bent structure, resulting in a more solid consistency.
b. The absence of a double bond confers a linear structure, resulting in a more liquid consistency.
c. The absence of a double bond confers a linear structure, resulting in a more solid consistency.
d. The presence of a double bond confers a linear structure, resulting in a more solid consistency.
e. The presence of a double bond confers a bent structure, resulting in a more liquid consistency.
9. Based on the phylogenetic tree, which statement below is correct?
a. Archaea and Eukarya are closer together than Bacteria and Eukarya.
b. Bacteria and Archaea are closer together than Archaea and Eukarya.
c. Bacteria and Eukarya are closer together than Archaea and Bacteria.
d. None of the above are correct
Explanation / Answer
1. c. They occur when only three different atoms or functional groups are attached to a central carbon.
Optical isomers occur when four different atoms or functional groups are attached to a central carbon (chirality). Most of the amino acids are chiral and examples of optical isomers (but not all amino acids).
2. A. The secondary structure of proteins involves bonding between R groups to form alpha helices and beta sheets.
The interaction of R groups signifies the tertiary structure of a protein.
3. a. Fats are only hydrophobic.
Not only fats, but all lipids are hydrophobic, that include, oils, waxes etc.
4. c. Both can be hydrophilic and hydrophobic.
Eg: cellulose contains hydrophobic sites
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