Question

Identify the CORRECT pair from the following.

• A. Englemann -- Plants produce oxygen in the presence of sunlight
• B. Pelletier and Caven Tou -- Obtained an extract of the green coloured substance from leaves
• C. Jan Ingenhousz -- The gas released by plants supports the existence of living organisms
• D. Joseph Priestley -- Point of maximum rate of photosynthesis

Hint:

Key photosynthesis history: Priestley (oxygen from plants, 1771) $\to$ Ingenhousz (light required, 1779) $\to$ Pelletier & Caventou (isolated chlorophyll, 1817) $\to$ Engelmann (red & blue light most effective, 1882). Remember: ``Pelletier and Caventou = Chlorophyll'' --- they named it from the Greek words for green leaf.

Answer 1

The Correct Option is B

Concept:
The history of photosynthesis research involves many scientists, each contributing key discoveries. This question tests knowledge of the correct attribution of discoveries to the scientists who made them.

Step 1: Verify each scientist-discovery pair.

(A) Englemann -- Plants produce oxygen in the presence of sunlight: INCORRECT
Theodor Wilhelm Engelmann (1843--1909) conducted the famous

prism experiment with Spirogyra algae in 1882. He split white light into a spectrum using a prism and shone it on a filament of green algae, then observed which parts attracted oxygen-seeking bacteria. He demonstrated that

the rate of photosynthesis was highest in red and blue light. He did NOT discover that plants produce oxygen in sunlight --- this was already known from earlier work by Priestley and Ingenhousz. So option (A) misattributes the discovery.

(B) Pelletier and Caventou -- Obtained an extract of the green coloured substance from leaves: CORRECT
Pierre Joseph Pelletier and Joseph Bienaimé Caventou were French chemists who in

1817 isolated the green pigment from leaves and named it

chlorophyll (from Greek chloros = green, phyllon = leaf). This is exactly what option (B) states --- they obtained an extract of the green-coloured substance from leaves. This is the CORRECT pair.

(C) Jan Ingenhousz -- The gas released by plants supports the existence of living organisms: INCORRECT
Jan Ingenhousz (1730--1799) demonstrated in 1779 that

plants only release oxygen (and perform photosynthesis) in the presence of light. In darkness, he showed that plants produce carbon dioxide. His core discovery was the

role of light in photosynthesis. The statement in option (C) --- ``the gas released by plants supports living organisms'' --- more accurately describes

Joseph Priestley's discovery (1771), not Ingenhousz's specific contribution.

(D) Joseph Priestley -- Point of maximum rate of photosynthesis: INCORRECT
Joseph Priestley (1733--1804) discovered in 1771 that a

candle placed with a plant in a sealed container could burn again after a period, discovering that plants produce oxygen (the gas that supports combustion and living organisms). The ``point of maximum rate of photosynthesis'' is associated with

Engelmann's spectrum experiment, not Priestley.

Step 2: Summary of key photosynthesis scientists.
tabular|l|l|

Scientist &

Key Discovery
Joseph Priestley (1771) & Plants release oxygen (support combustion & life)
Jan Ingenhousz (1779) & Light is necessary for oxygen production by plants
Pelletier & Caventou (1817) & Isolated and named chlorophyll
Engelmann (1882) & Red & blue light most effective for photosynthesis
tabular