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CBSE Class 11 · Biology

Respiration in Plants

Official NCERT chapter from Biology (book code kebo1). ExamMaster notes are original teaching at CBSE Class 11 depth.

This lesson follows the official chapter “Respiration in Plants” in Biology. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 11
  • Medium level
  • 8 concepts

1Do Plants Breathe?

Do plants breathe? Yes in the school sense: they take O2 and release CO2 when they respire, as taught — even while green leaves also photosynthesise in light. Breathe here is the gas-exchange of respiration, not a lung. Night-versus-day looks if the lesson split them.

“Plants only give O2, never take it” is the leftover this heading refuses.

Figure. A plant exchanges gases at leaf, stem, and root. There is no lung — the job is still uptake of O2 and release of CO2.

How it works

  1. Name O2 in and CO2 out for respirationPlants do breathe.
  2. Keep photosynthesis as a different light-jobTwo jobs.
  3. Refuse lungs as the plant-testA gas-job.

2Glycolysis

Glycolysis: glucose-split in the cytoplasm as taught, to pyruvate, a little ATP. Glycolysis is the shared first path, aerobic or not. One 10-step dump is the wrong size — keep the start, the end, the place.

A mitochondrion as the glycolysis-room is a miss.

Figure. Glycolysis is a cytosol path: one six-carbon sugar becomes two three-carbon pyruvates. The net cash is two ATP and two NADH, not a mitochondrion step.

How it works

  1. Name cytoplasm + glucose → pyruvateGlycolysis.
  2. Keep a little ATP as the school gainThe yield-hint.
  3. Refuse a nucleus as the siteCytoplasm.

3Fermentation

Fermentation (school): pyruvate to ethanol + CO2 or to lactate as taught, without the full O2-path. Fermentation is the no-oxygen leftover path, not “all plant respiration”. Yeast as the ethanol case if named.

A running leaf in air labelled fermentation-only is a miss.

Figure. Without oxygen, pyruvate has two school endings: ethanol plus CO2, or lactate. Neither path is the Krebs cycle.

How it works

  1. Name no-full-O2 and the taught productFermentation.
  2. Keep yeast or the plant-case as framedThe example.
  3. Refuse it as the only plant pathA leftover path.

4Aerobic Respiration

Aerobic respiration: pyruvate into mitochondria as taught; Krebs (TCA) and the electron chain; much more ATP. Aerobic is the O2-using full path. CO2 and H2O as the leftovers if named.

Glycolysis alone labelled “aerobic” is a half-name.

Figure. Aerobic work is compartmented: Krebs in the matrix, electron transport on the inner membrane. Oxygen is the last acceptor, written as water.

How it works

  1. Name mitochondria + O2 + much ATPAerobic.
  2. Keep Krebs and the chain as the inner map if taughtThe extras.
  3. Refuse cytoplasm as the whole aerobicMitochondria.

5The Respiratory Balance Sheet

The respiratory balance sheet (school): a taught ATP-count per glucose (about 38 or 36 as the lesson chose — copy that number). The sheet is a count, not a second path. Do not invent a new total.

A 100-ATP guess is a mute sheet.

Figure. The school balance sheet for one glucose is 2 + 2 + 34 = 38 ATP on the complete-oxidation count. Bar length is that stage’s ATP, not a drawing of a mitochondrion.

How it works

  1. Copy the lesson’s ATP-per-glucoseThe sheet.
  2. Keep glycolysis + aerobic as the addends if shownThe parts.
  3. Refuse a new invented totalHonest count.

6Amphibolic Pathway

Amphibolic pathway: respiration’s bits also feed build-paths as taught — a dual-use. Amphibolic is both-break-and-build, not a third gas. One amino-acid-from-a-Krebs-bit mention is enough.

A slogan “respiration only destroys” hides amphibolic.

Figure. Acetyl-CoA is a hub. Fuel can be broken toward Krebs, or the same intermediates can be drawn off to build fats and other bits. That two-way job is amphibolic.

How it works

  1. Name break-and-build from the same bitsAmphibolic.
  2. Keep one taught branchThe case.
  3. Refuse a third lung-wordA dual-use.

7Respiratory Quotient

Respiratory quotient: CO2 released / O2 used as taught. RQ near 1 for carbohydrate, different for fat if named. RQ is a ratio, not a speed. One substrate-hint is enough.

RQ as “how tired the plant is” is a miss.

Figure. Respiratory quotient is volumes of CO2 released over O2 used. Carbohydrate sits at 1, fat below 1, organic acid above 1. The bar is that ratio, not a flask.

How it works

  1. Form CO2 / O2 as taughtRQ.
  2. Read ~1 as carb if the lesson said soThe hint.
  3. Keep it a ratio, not a moodHonest.

8A miss: treating plants as if they only photosynthesise

A miss: treating plants as if they only photosynthesise. Green leaves still respire; the two jobs can run in the same cell as taught. Night still has respiration.

A daytime-only O2-poster as the whole plant-gas story is the miss.

Figure. A plant does not only photosynthesise. In the light both jobs run; in the dark respiration still runs. Treating the leaf as a sugar factory only is the miss.

How it works

  1. Keep photosynthesis and respiration as two jobsThe split.
  2. Name O2-use when they respireThe breathe-word.
  3. Refuse only-photosynthesise as the plantThe miss named.
Glycolysis happens in the
  1. Cytoplasm — glucose toward pyruvate
  2. Chloroplast thylakoid only
  3. Nucleus

The shared first path.

Notes

  • Mapped to the official NCERT chapter “Respiration in Plants”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Formulas

  • RQ = CO2 released / O2 used
  • copy the lesson’s ATP-per-glucose

Recap

Hold these pegs from the official chapter “Respiration in Plants”. The wording is ExamMaster’s teaching, not a textbook recap.

Do Plants Breathe?
Do plants breathe? Yes in the school sense: they take O2 and release CO2 when they respire, as taught — even while green leaves also photosynthesise in light.
Glycolysis
Glycolysis: glucose-split in the cytoplasm as taught, to pyruvate, a little ATP.
Fermentation
Fermentation (school): pyruvate to ethanol + CO2 or to lactate as taught, without the full O2-path.
Aerobic Respiration
Aerobic respiration: pyruvate into mitochondria as taught; Krebs (TCA) and the electron chain; much more ATP.
The Respiratory Balance Sheet
The respiratory balance sheet (school): a taught ATP-count per glucose (about 38 or 36 as the lesson chose — copy that number).
Amphibolic Pathway
Amphibolic pathway: respiration’s bits also feed build-paths as taught — a dual-use.

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