(A) Hydrophobic (B) Hydrophilic (C) Both A & B (D) Amphipathic (E) All of the answers above are correct.

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1 Biochemistry - Problem Drill 03: Introduction to Biochemistry No. 1 of Based on their affinity for water, molecules are classified into? (A) Hydrophobic (B) Hydrophilic (C) Both A & B (D) Amphipathic (E) All of the answers above are correct. This answer is partially correct and not the best selection. The definition includes that hydrophobic is a type of affinity of the Biomolecules towards water. This answer is partially correct and not the best selection. The definition includes that hydrophilic is also a type of affinity of the Biomolecules towards water. This answer is partially correct and not the best selection. This answer is partially correct and not the best selection. Yes. This is also a type of affinity in which the molecule contains both hydrophilic and hydrophobic parts. E. Correct! This is the right key to the question asked. Because it includes all given in the list of affinities of Biomolecules towards water. Molecules belong to different chemical groups based on their affinity for water. They are hydrophilic (water loving), hydrophobic (water hating), amphipathic (contain both hydrophilic & hydrophobic). The affinity of various Biomolecules towards water is important for their structure and stability in aqueous environment. This is also required for various biochemical reactions which takes place in aqueous solution The correct answer is (E).

2 No. 2 of A nucleotide contains: (A) Base + phosphate group. (B) Base + sugar. (C) Base + sugar + phosphate. (D) Base alone no other groups attached. (E) All of the above By the definition a nucleotide contains a base and a phosphate group. But this option is incomplete. B. Incorrect By the definition a nucleotide contains a base and a sugar. This fits the definition for a nucleoside but not a nucleotide. Again this option is incomplete. C. Correct! Yes. This option includes all aspects of the definition for a nucleotide. By the definition a nucleotide contains a base and a sugar. No one of the options is correct. Review the definition of a nucleotide. A Nucleoside is an organic molecule containing a purine or pyrimidine base and a five-carbon sugar (ribose or deoxyribose). And a nucleotide is an organic molecule containing a purine or pyrimidine base, a five-carbon sugar (ribose or deoxyribose), and one or more phosphate groups. A phosphoester of a nucleoside. The definition for a nucleotide comprises of a sugar, a base (whether a Purine or a Pyrimidine) and a phosphate group. The correct answer is (C).

3 No. 3 of Which of the following bases is not present in DNA? (A) Adenine (B) Guanine (C) Thymine (D) Cytosine (E) Uracil Yes. Present in the DNA. But read the question, it asks for a base which is not present in DNA. Yes. Present in the DNA. But read the question, it asks for a base which is not present in DNA. Yes. Present in the DNA. But read the question, it asks for a base which is not present in DNA. Yes. Present in the DNA. But read the question, it asks for a base which is not present in DNA. E. Correct! No. Uracil is not present in DNA. It is present in the RNA which is one of the differences between RNA and DNA. List the names of the bases present in DNA: Adenine, guanine, Thymine and cytosine. Remembering certain facts like this list of bases is very important in understanding the structure of macromolecules. Memorize them. The correct answer is (E).

4 No. 4 of camp stands for. (A) C protein amplification. (B) Cyclic AMP. (C) Adenosine 3, 5,-cyclic monophosphate. (D) B and C are both correct. (E) None of the above Some of the abbreviations may sound good when guessed. They can however be misleading. This is one of the expansions for camp. But this is not the best option for the question. This is another expansion for camp. But this is not the best option for the question. D. Correct! Yes. This option includes both expansions for camp. No one of the answers is correct. Expand the abbreviation camp. Expand the abbreviation camp, Recall the slide # 31. two expansions are given viz., cyclic AMP and adenosine 3,5-cyclic monophosphate. Try to memorize the expansions of various abbreviations in Biochemistry. Molecules in biochemistry are more complex in their structure and in the names too in most of the cases. Remembering them is important when studying the metabolism. The correct answer is (D).

5 No. 5 of Decarboxylation is a process of removal of: (A) Phosphate group (B) Water molecule (C) Carbon dioxide (D) Electrons (E) Lipid groups Wrong. Removal of phosphate group is called dephosphorylation reaction. Removal of a water molecule is called condensation reaction. Recall the formation of a peptide or a nucleotide. C. Correct! Yes. This is correct option according to the definition. No loss of electrons is oxidation. Loss of lipid molecules is often called lipolysis. Define the process Decarboxylation: Decarboxylation is a process of removal of a carboxyl group i.e., COO -, from a biomolecule. The correct answer is (C).

6 No. 6 of Look at the structure below and determine which of the following best describes it. (Butane) (A) Hydrophilic (B) Amphipathic (C) Free Radical (D) Hydrophobic (E) None of the above Organic molecules that have only carbon and hydrogen will be hydrophobic. Organic molecules that have only carbon and hydrogen will be hydrophobic. No free radical would be indicted by a lone electron adjacent to the structure. D. Correct! Organic molecules that have only carbon and hydrogen will be hydrophobic. Look closer there is a good answer to this question. Organic molecules that have only carbon and hydrogen will be hydrophobic. In this case the example is of a linear hydrocarbon. But a cyclic hydrocarbon would also be hydrophobic. It a good idea to take some time to look at the structures as well as their names and or chemical designation e.g. C 5 H 12. The correct answer is (D).

7 No. 7 of Which of the following is not one of the four types of biological compounds? (A) Carbohydrates (B) Nucleic Acids (C) Proteins (D) Lipids (E) All of the above This is one of the four basic types or categories of biological compounds. This is one of the four basic types or categories of biological compounds. This is one of the four basic types or categories of biological compounds. This is one of the four basic types or categories of biological compounds. E. Correct! Correct, all of the answers are one of the major biological compounds. By process of elimination this is then the correct answer. The four basic types of biological compounds are: Carbohydrates Nucleic Acids Proteins Lipids. The correct answer is (E).

8 No. 8 of Which of the following is not important in the classification of a carbohydrate? (A) Number of sugar units present. (B) Size of the carbon chain. (C) The degree of branching of the carbohydrate chains. (D) The stereochemistry of the carbohydrate. (E) The melting temperature of the carbohydrate. No, this is an important aspect in the classification of a carbohydrate. No, this is an important aspect in the classification of a carbohydrate. No, this is an important aspect in the classification of a carbohydrate. No, this is an important aspect in the classification of a carbohydrate. E. Correct! The melting temperature is not a parameter in classification of the carbohydrate. However the melting point is affected by all of the parameters listed in A-D. The classification of a carbohydrate is determined by a number of factors including: Number of sugar units present. Size of the carbon chain. The degree of branching of the carbohydrate chains. The stereochemistry of the carbohydrate. In addition to these listed it is also impacted by the types of side chains e.g. phosphate groups. Melting temperature will be effected by all of the factors listed so it is not a basis for categorization. The correct answer is (E).

9 No. 9 of Sugars are connected by what type of bond? (A) Peptide (B) Glycosidic (C) Amide (D) Sulfhydral (E) None of the above No, peptide bonds are typical of proteins. These occur between amino acids. B. Correct! Yes, this bond is typical of sugar linkages. No, this is typical of a bond between an amine and a carbohydrate. Sulfhydral bonds are thiol chemistry and do not typically involve sugar to sugar connections. These are more frequently seen in protein chemistry. Look closer there is a correct choice. This is an example of a glycosidic bond: A glycosidic bond is a type of functional group that joins a carbohydrate molecule to another molecule which may or may not be another carbohydrate. A glycosidic bond is made between the hemiacetal group of the saccharide and the hydroxyl group of another organic compound. The correct answer is (B).

10 No. 10 of Which of the following statements is the best with respect to protein structure? (A) Proteins are polymers consisting of amino acid monomers. (B) The amino acids have a backbone and side chain. (C) There are 20 different side chains in the 20 common amino acids. (D) All of the above (E) None of the above Although this is true, look more closely at the rest of the choices! Although this is true, look more closely at the rest of the choices! Although this is true, look more closely at the rest of the choices! D. Correct! All of these options are true! Look more closely at the rest of the choices! All of the statements A-C provided are true with respect to the structure of a protein. Proteins are polymers consisting of amino acid monomers. The amino acids have a backbone and side chain. There are 20 different side chains in the 20 common amino acids. The correct answer is (D).