All Exams Test series for 1 year @ ₹349 only
Question

Which one of the following living organisms gives litmus?

This question was previously asked in
CDS I 2022 English Previous Year Paper (10-April-2022)
The correct answer is

Lichen

Identifying the Living Organism that Provides Litmus

The question asks us to identify which of the given living organisms is the source of litmus. Litmus is a well-known indicator used to test whether a substance is acidic or alkaline.

Let's examine the options provided:

  • Protozoa: These are single-celled eukaryotic organisms. While diverse, they are not known to produce litmus.
  • Virus: Viruses are not typically considered living organisms as they require a host cell to reproduce. They do not produce litmus.
  • Lichen: A lichen is a symbiotic association between a fungus (usually an ascomycete) and a photosynthetic partner, which is typically an alga or cyanobacterium. Lichens are known to produce a variety of unique biochemical compounds, including pigments and secondary metabolites. Certain species of lichens, particularly those from the genus Roccella, are historically and commercially important sources of litmus.
  • Saccharomyces: This is a genus of yeast, which are a type of fungus. Saccharomyces cerevisiae is commonly known as baker's yeast or brewer's yeast. Yeasts are primarily used in fermentation processes and are not the source of litmus.

Based on this information, the living organism that gives litmus is lichen.

Litmus is extracted from certain species of lichens. It is a mixture of different dyes. In acidic solutions, litmus paper turns red, and in alkaline (basic) solutions, it turns blue. It is a classic example of a natural pH indicator.

Organism Association with Litmus
Protozoa Not a source of litmus.
Virus Not a living organism; not a source of litmus.
Lichen Primary natural source of litmus.
Saccharomyces (Yeast) Not a source of litmus.

Revision Table: Key Facts about Litmus Source

  • Litmus is a pH indicator.
  • It is extracted from specific species of lichens.
  • Lichens are a symbiotic relationship between a fungus and an alga/cyanobacterium.
  • Species from the genus Roccella are well-known sources.

Additional Information on Lichens and Indicators

Lichens are fascinating organisms that can grow in diverse environments, often colonizing surfaces like rocks, trees, and soil. Their ability to produce unique chemical compounds has led to various uses throughout history, including:

  • Dyes: Many lichens yield colorful dyes, used for dyeing textiles.
  • Traditional Medicine: Some lichens have been used in traditional remedies.
  • Air Quality Indicators: Lichens are highly sensitive to air pollution, particularly sulfur dioxide. Their presence or absence, and the species found, can be used to assess air quality. This makes them valuable bioindicators.
  • Litmus Production: As discussed, specific lichens are the source of the litmus indicator, which is crucial for basic chemistry experiments to determine acidity or alkalinity.

Understanding the source of common lab materials like litmus helps connect biology with chemistry and appreciate the diverse applications of living organisms.

Was this answer helpful?

Similar Questions

  1. An infection constantly maintained at a baseline level in a geographic area without external input is known as

  2. Which of the following limits the number of trophic levels in a food chain ?

  3. An antibiotic is not useful against a virus whereas a vaccine is. Which one of the following is the most appropriate reason for this ?

  4. A protein is synthesized in the endoplasmic reticulum bound ribosomes and it targets to the inner thylakoid space of chloroplast. How many double-layered membranes layers it has to pass to reach its destination?

  5. Consider the following statements associated with Malaria:

    1. Only the female Anopheles mosquitoes take human blood for reproduction

    2. Plasmodium can pass across the placenta from mother to foetus

    Which of the statements given above is/are correct?


Important Questions from Biology in Everyday life

  1. Which of the following occurs when an organism absorbs the chemicals at a faster rate then the metabolic capacity of their body?

  2. Which of the following is a primary producer in a food chain?

  3. Aphim, Morphin, Heroin, Methodine are the examples of:

  4. Due to which change in environment that Rekha's mother told Rekha not to sleep below the tree ?

  5. Which of the following plays an important role in balancing oxygen and carbon dioxide in the atmosphere?

Need Expert Advice?
Test Series
CDS img
Defence
UPSC CDS 2026 Mock Test Series
540 Tests 4 Tests Free
1624 Attempts
4.3(174)
English, Hindi
More Questions from CDS

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App