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Find out a qualitative test for proteins, fats and oils, amino acids a...

Find out a qualitative test for proteins | Class 11 Biology Chapter Biomolecules, Biomolecules NCERT Solutions

Welcome to the NCERT Solutions for Class 11 Biology - Chapter Biomolecules. This page offers a step-by-step solution to the specific question from Exercise 1, Question 13: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 13: Find out a qualitative test for proteins, fats and oils, amino acids and test any fruit juice, saliva, sweat and urine for them.

Answer:

(a) Test for protein

Biuret’s test – If Biuret’s reagent is added to protein, then the colour of the reagent changes from light blue to purple.

(b) Test for fats and oils

Grease or solubility test

(c) Test for amino acid

Ninhydrin test – If Ninhydrin reagent is added to the solution, then the colourless solution changes to pink, blue, or purple, depending on the amino acid.

Item		Name of the test	Procedure	Result	Inference
1.	Fruit juice	Biuret’s test	Fruit juice + Biuret’s reagent	Colour changes from light blue to purple	Protein is present.
		Grease test	To a brown paper, add a few drops of fruit juice.	No translucent spot	Fats and oils are absent or are in negligible amounts.
		Ninhydrin test	Fruit juice + Ninhydrin reagent + boil for 5 minutes	Colourless solution changes to pink, blue, or purple colour	Amino acids are present.
2.	Saliva	Biuret’s test	Saliva + Biuret’s reagent	Colour changes from light blue to purple	Proteins are present.
		Grease test	On a brown paper, add a drop of saliva.	No translucent spot	Fats/oils are absent.
		Ninhydrin test	Saliva + Ninhydrin reagent + boil for 5 minutes	Colourless solution changes to pink, blue, or purple colour	Amino acids are present.
3.	Sweat	Biuret’s test	Sweat + Biuret’s reagent	No colour change	Proteins are absent.
		Solubility test	Sweat + Water	Oily appearance	Fats/oil may be present.
		Ninhydrin test	Sweat + Ninhydrin reagent + boil for 5 minutes	No colour change, solution remains colourless	Amino acids are absent.
4.	Urine	Biuret’s test	Few drops of urine + Biuret’s reagent	Colour changes from light blue to purple	Proteins are present.
		Solubility test	Few drops of urine + Water	Little bit of oily appearance	Fats may or may not be present.
		Ninhydrin test	Few drops of urine + Ninhydrin reagent + boil for 5 minutes	Colourless solution changes to pink, blue, or purple colour depending on the type of amino acid	Amino acids are present.

Other Questions of Chapter Biomolecules

Q: Can you attempt building models of biomolecules using commercially available atomic models (Ball and Stick models).

Write the name of any one aminoacid, sugar, nucleotide and fatty acid.

Q: Explain the composition of triglyceride.

Q: Find out and make a list of proteins used as therapeutic agents. Find other applications of proteins (e.g., cosmetics, etc.)

Reaction given below is catalysed by oxidoreductase between two substrates A and A’, complete the reaction.
A reduced + A’ oxidised

Q: Find out how much cellulose is made by all the plants in the biosphere and compare it with how much of paper is manufactured by man and hence what is the consumption of plant material by man annually. What a loss of vegetation!

Q: Proteins have primary structure. If you are given a method to know which amino acid is at either of the two termini (ends) of a protein, can you connect this information to purity or homogeneity of a protein?

Q: Illustrate a glycosidic, peptide and a phospho-diester bond.

Q: Describe the important properties of enzymes.

Q: Draw the structure of the amino acid, alanine.

Popular questions of class 11 Biology

Q: Describe briefly the four major groups of Protozoa.

Q: Why are living organisms classified?

Q: State two economically important uses of: (a) Heterotrophic bacteria (b) Archaebacteria

Q: What is the difference between direct and indirect development?

Define a taxon. Give some examples of taxa at different hierarchical levels.

What are the steps involved in formation of a root nodule?

Q: Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.

Q: How is a key helpful in the identification and classification of an organism?

Q: What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.

Q: Define and understand the following terms:
(i) Phylum
(ii) Class
(iii) Family
(iv) Order
(v) Genus

Recently Viewed Questions of Class 11 Biology

Name the pathological condition when uncontrolled cell division occurs.

Aquatic animals generally are ammonotelic in nature where as terrestual forms are not. Comment.

Name the cells/tissues in human body which
a. exhibit ameboid movement
b. exhibit ciliary movement

Q: How is the study of plant anatomy useful to us?

How do you distinguish between a skeletal muscle and a cardiac muscle?

Q: Explain the term thecodont and diphyodont.

Why earthworm is called the friend of farmer?

Q: Draw the labelled diagram of the following:
(i) Gram seed
(ii) V.S. of maize seed

Which of the following is correct:
(a) Cells of all living organisms have a nucleus.
(b) Both animal and plant cells have a well defined cell wall.
(c) In prokaryotes, there are no membrane bound organelles.
(d) Cells are formed de novo from abiotic materials.

Mitosis results in producing two cells which are similar to each other. What would be the consequence if each of the following irregularities
occur during mitosis?
a. Nuclear membrane fails to disintegrate
b. Duplication of DNA does not occur
c. Centromeres do not divide
d. Cytokinesis does not occur.

Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

Read the question carefully and focus on the core concept being asked.
Reference examples and data from the chapter when answering questions about Biomolecules.
Review previous year question papers to get an idea of how such questions may be framed in exams.
Practice answering questions within the time limit to improve your speed and accuracy.
Discuss your answers with your teachers or peers to get feedback and improve your understanding.

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