Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
Last updated
1,790 questions · page 9 of 90
- A. Chitin
- B. Cellulose
- C. Lignin
- D. Proteins
Explanation: The cell walls of oomycetes are chiefly made of cellulose and other glucans, unlike true fungi, whose walls are mainly chitin.
Correct answer: Cellulose- A. Algae
- B. Amoeba
- C. Fungi
- D. Bacteria
Explanation: Fungi can grow in environments with high external osmotic pressure because their rigid cell walls and compatible-solute mechanisms help…
Correct answer: Fungi- A. Starch
- B. Glycogen
- C. Cellulose
- D. None of these
Explanation: Animals store excess glucose mainly as glycogen, a highly branched polysaccharide found especially in liver and skeletal muscles.
Correct answer: Glycogen- A. Starch
- B. Glycogen
- C. Cellulose
- D. Polysaccharide
Explanation: Iodine forms a blue to blue-black complex with the helical structure of amylose in starch.
Correct answer: Starch- A. Starch
- B. Glycogen
- C. Cellulose
- D. None of these
Explanation: Glycogen is called animal starch because it is the main storage polysaccharide in animals, especially in liver and muscles.
Correct answer: Glycogen- A. Phosphodiester bond
- B. Peptide bond
- C. Glycosidic Bond
- D. Ionic bond
Explanation: A glycosidic bond joins two monosaccharides through a condensation reaction, in which a water molecule is removed.
Correct answer: Glycosidic Bond- A. Starch
- B. Glycogen
- C. Amylose
- D. Amylopectin.
Explanation: Amylose, the mostly unbranched component of starch, can dissolve in hot water and forms a colloidal solution.
Correct answer: Amylose- A. Monosaccharide
- B. Oligosaccharide
- C. Polysaccharide
- D. None of these
Explanation: A monosaccharide is already a single sugar unit, so it cannot be hydrolysed into smaller carbohydrates.
Correct answer: Monosaccharide- A. 0.80%
- B. 0.08%
- C. 1.80%
- D. 8%
Explanation: Normal blood glucose is about 80 mg per 100 mL, which is 0.08 g per 100 mL, or approximately 0.08%.
Correct answer: 0.08%- A. Maltose
- B. Sucrose
- C. Fructose
- D. Glucose
Explanation: Starch, cellulose and glycogen are polysaccharides made from repeating glucose units, so complete hydrolysis releases glucose.
Correct answer: Glucose- A. Trioses
- B. Tetroses
- C. Pentose
- D. Hexose
Explanation: Ribose contains five carbon atoms, making it a pentose sugar. The common mistake is choosing hexose by confusing ribose with glucose or…
Correct answer: Pentose- A. Monosaccharides
- B. Oligosaccharides
- C. Polysaccharides
- D. None of these
Explanation: Polysaccharides are the most complex carbohydrates because they contain long chains of many monosaccharide units.
Correct answer: Polysaccharides- A. Lipid
- B. Carbohydrate
- C. Protein
- D. Carotein
Explanation: Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield these compounds on hydrolysis.
Correct answer: Carbohydrate- A. Monosaccharide
- B. Oligosaccharide
- C. Polysaccharide
- D. None of these
Explanation: Polysaccharides such as starch and cellulose are generally tasteless because their large molecules do not stimulate sweet taste receptors…
Correct answer: Polysaccharide- A. Soil Science
- B. Agronomy
- C. Metrology
- D. Ecology
Explanation: Agronomy is the applied science of crop production, including the management of soil, crops and their productivity.
Correct answer: Agronomy- A. Genetics
- B. Taxonomy
- C. Archeology
- D. Paleontology
Explanation: Taxonomy is the branch of biology concerned with identifying, naming and classifying organisms.
Correct answer: Taxonomy- A. 16 Bio-elements
- B. 12 Bio-elements
- C. 10 Bio-elements
- D. 6 Bio-elements
Explanation: About 99% of the human body's mass is contributed by six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.
Correct answer: 6 Bio-elements- A. Photosynthetic
- B. Chemosynthetic
- C. Completely parasitic
- D. Absorptive heterotrophs
Explanation: Fungi are absorptive heterotrophs: they secrete digestive enzymes onto food outside the body and absorb the soluble products.
Correct answer: Absorptive heterotrophs- A. fucoxanthin
- B. phycocyanin
- C. phycoerythrin
- D. bilirubin
Explanation: Red algae contain the red phycobilin pigment phycoerythrin, which absorbs green and blue light and helps them photosynthesise at greater…
Correct answer: phycoerythrin- A. carbon, oxygen, nitrogen, sulfur
- B. carbon, oxygen, hydrogen, nitrogen
- C. carbon, oxygen, sulfur, phosphorus
- D. carbon, sulfur, hydrogen, magnesium
Explanation: Carbon, hydrogen, oxygen and nitrogen are the four most abundant elements in living cells because they form carbohydrates, lipids…
Correct answer: carbon, oxygen, hydrogen, nitrogen