Litmus is got naturally from?

Appeared in: HPSSC Staff Nurse - 2021

Explanation

Litmus is a water-soluble mixture of different dyes extracted from various species of lichens.
Lichens are composite organisms, representing a symbiotic relationship between a fungus (mycobiont) and an alga or cyanobacterium (photobiont).
It is one of the oldest known pH indicators, commonly used in chemistry to test materials for acidity and alkalinity.

Option A: While algae are a component of the lichen symbiotic structure, they are not the direct source of litmus dye. Commercially, algae are harvested for other products.
Option B: Fungi are also a component of lichens, but on their own, they do not produce litmus. Fungi are more famously known for producing other substances.
Option D: Protozoans are single-celled microscopic organisms and are not involved in the production of any large-scale commercial dyes like litmus.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Natural source of the pH indicator litmus as background academic context rather than a clinical decision trigger.
The principle of pH indication, as demonstrated by litmus, is fundamental to many clinical nursing assessments.
A critical application is the verification of nasogastric (NG) tube placement. A nurse aspirates stomach contents and tests the pH. A pH of 5.5 or less confirms acidic gastric placement, which is crucial for preventing aspiration pneumonia from misplaced feedings.
What if? If the pH of the NG tube aspirate is greater than 6, it may indicate the tube is in the respiratory tract or the intestine. The nurse must withhold feedings or medications and notify the physician for further assessment, which often includes a confirmatory X-ray.

How to Approach the Question

This is a factual recall question from basic sciences (Biology/Chemistry).
First, identify the key term in the question: 'Litmus'.
Access your knowledge about common natural products and their biological sources.
Systematically evaluate each option: Algae (known for agar), Fungi (known for penicillin), Lichens (a known source of dyes), and Protozoans (microscopic organisms).
Select the option that correctly matches the product (litmus) with its scientifically established source (lichens).

Concept Tested & Keywords

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Practise the full HPSSC Staff Nurse - 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.