Engelmann's bacteria
"Engelmann's bacteria" is a free, interactive Class 11 Biology simulation for NEET, built on the NCERT section "Pigments involved in photosynthesis" in Photosynthesis in Higher Plants. Shine a prism spectrum on a Cladophora filament and watch aerobic bacteria crowd where O2 is released; overlay the action spectrum on chlorophyll a and b absorption. NEET has asked about this idea 3 times in 10 years of papers.
From the lesson Pigments involved in photosynthesis in Photosynthesis in Higher Plants. Change the values and watch what happens.
What it shows
NCERT §11.2–11.4
Shine a prism spectrum on a Cladophora filament and watch aerobic bacteria crowd where O2 is released; overlay the action spectrum on chlorophyll a and b absorption.
Controls
3 to try
- Sliderwavelength band 400–700 nm
- Toggleshow absorption curves chl a / chl b / carotenoids
- Toggleremove accessory pigments
Try this
Find the two wavelength bands where most bacteria gather, and show which bands lose bacteria when accessory pigments are removed.
Common mistake
Green light drives most photosynthesis.
In NEET
10 years of papers
Asked 3 times in 10 years of NEET.
See the past questions: Photosynthesis in Higher Plants (chapter)
The idea behind it
NCERT §11.4
- Separating leaf pigments by paper chromatography reveals four of them: chlorophyll a (bright or blue-green), chlorophyll b (yellow-green), carotenoids (yellow to yellow-orange) and xanthophylls (yellow).
- Chlorophyll a is the chief pigment of photosynthesis.
- An absorption spectrum shows chlorophyll a absorbs most strongly in the blue and red regions of light.
- The action spectrum (rate of photosynthesis versus wavelength) peaks in the blue and red regions too, and roughly matches the absorption spectrum of chlorophyll a, confirming most photosynthesis occurs in blue and red light.
- Some photosynthesis also occurs at other visible wavelengths because accessory pigments (chlorophyll b, xanthophylls, carotenoids) absorb them and pass the energy to chlorophyll a.
- Accessory pigments widen the range of usable wavelengths and also protect chlorophyll a from photo-oxidation.
Questions
4 answers
- What does the "Engelmann's bacteria" simulation show?
- Shine a prism spectrum on a Cladophora filament and watch aerobic bacteria crowd where O2 is released; overlay the action spectrum on chlorophyll a and b absorption.
- What mistake does the "Engelmann's bacteria" simulation fix?
- A common mistake it clears up: green light drives most photosynthesis.
- Has NEET asked about this idea?
- Yes. NEET has asked about this idea 3 times in 10 years of papers.
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Pigments involved in photosynthesis" in Photosynthesis in Higher Plants (Class 11 Biology).
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