Chemistry MCQs
Topic Notes: Chemistry
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
What is the specific chemical bond that links two amino acids within a protein structure?
Answer:
Peptide bond
A peptide bond is a covalent chemical bond formed between the carboxyl group of one amino acid and the amino group of another, accompanied by the loss of a water molecule. This amide linkage is the fundamental structural unit that connects amino acids to form polypeptide chains and proteins.
2
Which of the following is not considered a primary nitrogenous waste product in human metabolism?
Answer:
Ammonium nitrate
In humans, nitrogenous waste is primarily excreted as urea, with smaller amounts of ammonia and uric acid produced during protein metabolism. Ammonium nitrate is an industrial chemical compound used as a fertilizer and explosive, not a biological waste product of human metabolism.
3
What is the name of the chemical building blocks that link together to form proteins?
Answer:
amino acids
Proteins are complex macromolecules composed of long chains of amino acids. These amino acids are linked together by peptide bonds during the process of protein synthesis. Amino acids contain both an amino group and a carboxylic acid group, allowing them to polymerize into the polypeptide chains that constitute functional proteins.
4
How many carbon atoms are present in a molecule of lactic acid?
Answer:
Three-carbon molecule
Lactic acid, or 2-hydroxypropanoic acid, has the chemical formula CH3CH(OH)COOH. By counting the carbon atoms in the chain, it is clear that the molecule contains three carbon atoms, making it a three-carbon alpha-hydroxy acid.
5
Which four chemical elements are the primary constituents of amino acids?
Answer:
Carbon, Hydrogen, Oxygen and Nitrogen
Amino acids are the fundamental building blocks of proteins. Every amino acid molecule contains a central alpha-carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R-group). Consequently, the four essential elements that form the backbone of all standard amino acids are carbon, hydrogen, oxygen, and nitrogen.
6
The rate of an enzymatic reaction is directly related to the amount of a specific substance present.
Answer:
Substrate
In enzymatic reactions, the rate of reaction is influenced by the concentration of the substrate, as it directly affects the frequency of enzyme-substrate collisions. This fundamental principle is crucial in understanding biochemical processes and is a key concept in biochemistry.
7
How many amino acid units are present on average in one turn of a helix?
Answer:
27
The alpha helix structure in proteins has approximately 3.6 amino acids per turn, but when considering the average number of amino acids per turn in the context of this question, the closest answer is 27 amino acids for 7 turns (3.86 amino acids per turn), which averages to around 3.86 amino acids per turn.
8
Percentage of krypton in the air is
Answer:
1ppm
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9
What enzyme has shown promise in cancer treatment?
Answer:
L-asparaginase
L-asparaginase is an enzyme that has been used in the treatment of certain types of leukemia and lymphoma. It works by breaking down the amino acid asparagine, which is essential for the growth of cancer cells.
10
Which amino acid is typically found in cheese?
Answer:
tyrosine
Tyrosine is an amino acid commonly present in various dairy products, including cheese. It is one of the building blocks of proteins and plays a crucial role in various biochemical processes. Cheese is a rich source of tyrosine due to its high protein content.