Biomolecules Class 11 Notes - Chapter 9

The topic of biomolecules in class 11 biology mainly explains the different types of biomolecules and their importance in living organisms. This topic is not only important for the class 11 exam but also for competitive exams.

To help the students to understand this topic properly, here, the biomolecule notes for class 11 are provided. Students can check these notes and learn this chapter in a more effective way. Along with the notes, some important questions related to biomolecules are also provided.

These notes given here are easily understandable and engaging. The students are suggested to go through these notes thoroughly to understand biomolecules and its fundamentals completely. Students can also check BYJU’S video lessons to learn various topics in a more effective way.

What are Biomolecules?

All the carbon-based compounds that are found in or produced by organisms and are essential to a biological process are called biomolecules. Examples of biomolecules include proteins, lipids, carbohydrates and nucleic acids. Even molecules such as metabolites (primary and secondary) are considered as biomolecules.


Most enzymes discovered to date are proteins. There are even nucleic acids that exhibit characteristics of enzymes are called ribozymes. Enzymes are similar to proteins, wherein, it possesses a primary structure as well as secondary and tertiary structures.

In the simplest of sense, enzymes work on a “lock and key” basis (based on the model first postulated by the Emil Fischer.) The model takes the analogy that the lock is the enzyme and the substrate functions as the key.  A substrate is a molecule acted on by an enzyme, hence, only the correctly sized substrate will fit in the keyhole (an analogy for the active site) of the lock (or the enzyme in this case).


Macromolecules are very large molecules, usually consisting of thousands of atoms or more. Proteins and lipids are macromolecules that are found in living organisms. Synthetic macromolecules include plastics and carbon nanotubes.

According mammalian systems, there are three major types of macromolecules:

  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic Acids.

Read more: Macromolecules

Biomolecules Class 11 Notes – Questions

  1. Define macromolecules with an example.
  2. Diagrammatically represent a glycosidic bond.
  3. What are secondary metabolites?
  4. What are proteins?
  5. Expand RuBisCO.
  6. What are Polysaccharides? State two examples.
  7. What is a nucleotide?
  8. Define Metabolism.
  9. What is ATP? State its function.
  10. Explain anabolic pathways
  11. State the factors influencing enzyme activity.
  12. What is a competitive inhibitor?
  13. Briefly describe the classification of enzymes.
  14. List the important characteristics of enzymes.
Also Access 
NCERT Solutions for Class 11 Biology Chapter 9
NCERT Exemplar for Class 11 Biology Chapter 9

To learn more about Biomolecules Class 11, explore important questions, and discover new topics, register at BYJU’S.

Further Reading

Frequently asked Questions on CBSE Class 11 Biology Notes Chapter 9: Biomolecules


What are Biomolecules?

Biomolecules are chemical compounds found in living organisms. For ex., nitrogen, sulphur, phosphorus, carbon, hydrogrn, etc.


What are some of the main uses of biomolecules?

Biomolecules have multiples roles to play in a human body: 1. Carbohyrates: Helps in sugar breakdown and glucose creation 2. Lipids: energy supply to cells 3. Proteins: Act as building blocks of life


What is the abbreviation of DNA?

DNA stands for ‘Deoxyribonucleicacid’.


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