Biology · Chemistry

Biomolecules and Enzymes

1,432 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice

The presence of arginase confirms that :

  1. urea cycle is operating

  2. urea cycle may be operating

  3. arginine is being converted into ornithine

  4. arginine is being converted into citrulline
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During urea cycle, the cytosolic enzyme arginase cleaves arginase to yield urea and ornithine. Ornithine is transported into the mitochondrion to initiate another round of the urea cycle.

Multiple choice

Which of the following amino acids constitutes a component of urea cycle?

  1. Tryptophan

  2. Phenylalanine

  3. Arginine

  4. Leusine
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Arginine is directly involved in the urea cycle as an intermediate; it's hydrolyzed by arginase to produce urea and regenerate ornithine. Tryptophan and phenylalanine are aromatic amino acids unrelated to nitrogen excretion. Leusine is also not part of the urea cycle.

Multiple choice

In sickle cell anaemia, the change in amino acid is

  1. 6th amino acid is valine instead of serine in beta chain

  2. 6th amino acid is valine instead of glutamic acid in beta chain

  3. 6th amino acid is valine instead of glutamic acid in alpha chain

  4. 5th amino acid is valine instead of glutamic acid in alpha chain
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

6 th amino acid is valine instead of glutamic acid in beta chain which causes this mutation.

Multiple choice

The active site of an enzyme

  1. looks like a lump projecting from the surface of an enzyme

  2. forms no chemical bonds with substrates

  3. determines the specificity of an enzyme by its structure

  4. never changes shape
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The active site of an enzyme determines specificity of an enzyme by its structure.

Multiple choice

The simplest amino acid is

  1. alanine

  2. glycine

  3. lysine

  4. tyrosine
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glycine is the simplest amino acid. Its chemical formula is NH2CH2COOH.

Multiple choice

Co- enzymes differ from enzymes as

  1. co-enzymes are polymers of amino acids

  2. co-enzymes are small like vitamins

  3. co-enzymes are specific for one reaction

  4. co-enzymes always carries high-energy phosphate
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Co-enzymes differ from enzymes as co-enzymes are small like vitamins.

Multiple choice

A stain called Feulgen is specific for

  1. protein

  2. lipid

  3. carbohydrate

  4. DNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Feulgen stain is specific for DNA. It is a staining technique developed by Robert Feulgen and is used in histology to identify DNA or chromosomes.

Multiple choice

Alginate is

  1. algae derived protein

  2. red algae derived pigment

  3. kelp derived toxin

  4. kelp derived carbohydrate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alginate is a carbohydrate found in the cell walls of kelp or brown algae and is of great use as jelling and thickening agent in ice-creams and also in pharmaceutical industry.