Respiration in Plants
Class 11 · Biology
5 ideas in Class 11 Biology, explained in plain words, with games and quizzes to practise.
Breathing and Glycolysis
Part of: Breathing and Anaerobic Paths
Leaves breathe through pores, bark through lenticels, each part self-serving since cells hug air. Stepwise oxidation banks ATP currency instead of wasting heat. Cytoplasmic EMP chains spend two ATP, bank four and two NADH, halving glucose to pyruvate.
Why it matters. Self-service explains missing lungs. Net-two math governs all downstream fates.
Formulas
- Glycolysis: glucose gives 2 pyruvate + net 2 ATP + 2 NADH
- C6H12O6 + 6O2 gives 6CO2 + 6H2O + energy
Key words
- Cellular respiration
- : Stepwise oxidation of food that banks energy as ATP instead of wasting it as heat.
- Glycolysis
- : Splitting one glucose into two pyruvate molecules in the cytoplasm.
- Lenticel
- : A pore in woody bark through which stems exchange gases.
- ATP
- : The energy currency the cell spends to drive work.
Try it in two minutes
- Find pores and lenticels.
- Order ten glycolytic steps.
- Subtract spent from banked ATP.
Try at home. Compare sprouting seeds with dry ones.
Fermentation
Part of: Breathing and Anaerobic Paths
Pyruvate forks to lactate, ethanol plus CO2, or mitochondria. Yeast decarboxylates then reduces; muscles reduce directly; both recycle NAD+ while banking two ATP and under seven percent energy, risking acid or ethanol buildup that caps brews near thirteen percent.
Why it matters. NAD+ recycling sustains glycolysis without oxygen. Low yields explain why aerobes dominate.
Formulas
- Yeast: pyruvate gives CO2 + ethanol; muscle: pyruvate gives lactate
Key words
- Fermentation
- : Partial breakdown of pyruvate without oxygen that recycles NAD+ for glycolysis.
- Lactic fermentation
- : Pyruvate reduced directly to lactate, as in worked muscles.
- Ethanol fermentation
- : Pyruvate decarboxylated then reduced to ethanol, as in yeast.
- NAD+ recycling
- : Reoxidising NADH so glycolysis can keep running without oxygen.
Try it in two minutes
- Name three pyruvate fates.
- Recycle NAD+ on paper.
- Cap brews at thirteen.
Try at home. Watch dough rise from yeast gas.
Krebs Cycle
Part of: Aerobic Respiration
Pyruvate decarboxylates to acetyl CoA banking two NADH; citrate synthase marries acetyl with OAA; twin decarboxylations spin through GTP and carriers, doubling per glucose while OAA restocks each turn.
Why it matters. Turn counting predicts carrier totals. OAA restocking explains continuity.
Formulas
- Per acetyl CoA turn: 3 NADH + 1 FADH2 + 1 ATP + 2 CO2
Key words
- Pyruvate oxidation
- : Removing CO2 from pyruvate to form acetyl CoA before the cycle.
- Acetyl CoA
- : The two-carbon fuel that joins oxaloacetate to enter the cycle.
- Citrate synthase
- : The enzyme that joins acetyl CoA with oxaloacetate to start the turn.
- Oxaloacetate
- : The four-carbon acceptor that is restocked every turn of the cycle.
- GTP
- : An energy carrier banked once per cycle turn, equivalent to ATP.
Try it in two minutes
- Enter acetyl into citrate.
- Count carriers per turn.
- Double for glucose.
Try at home. Chart Krebs inputs and outputs.
ETS and ATP Balance
Part of: Aerobic Respiration
Inner-membrane complexes pass carrier electrons to terminal oxygen while proton flows through F0-F1 mint ATP at four protons each; NADH triples and FADH2 doubles yields, totalling thirty-eight under ideal assumptions that living traffic routinely breaks.
Why it matters. Donor identity sets payouts. Assumption lists explain theory-reality gaps.
Formulas
- 1 NADH gives 3 ATP; 1 FADH2 gives 2 ATP
- Aerobic tally per glucose: up to 38 ATP
Key words
- Electron transport chain
- : Membrane carriers passing electrons down to oxygen to release energy.
- Terminal oxidation
- : Final handover of electrons and hydrogen to oxygen, forming water.
- Oxidative phosphorylation
- : Minting ATP as protons flow back through the F0-F1 particle.
- Proton gradient
- : The stored difference in H+ concentration that powers ATP synthesis.
Try it in two minutes
- Order complexes one to five.
- Multiply carriers by yields.
- List four assumptions.
Try at home. Tally the 38 ATP on paper.
Amphibolic Pathway and RQ
Part of: Fuels and Quotients
Glucose leads but fats join as acetyl, glycerol as PGAL and proteins after deamination; shared roads serve building as well as burning, hence amphibolic. CO2-over-O2 reads one for carbs, near 0.7 for tripalmitin and 0.9 for proteins.
Why it matters. Entry points map any diet. Quotients reveal the fuel mix.
Formulas
- RQ = volume of CO2 given out / volume of O2 taken in
- RQ is 1 for carbohydrates and about 0.7 for fats
- RQ of proteins is about 0.9
Key words
- Amphibolic pathway
- : A shared road used for both building up and breaking down molecules.
- Deamination
- : Removing the amino group so a protein fragment can enter respiration.
- Respiratory quotient
- : CO2 released divided by O2 taken in, revealing the fuel being burnt.
- Tripalmitin
- : A fat used as the standard example with RQ near 0.7.
Try it in two minutes
- Place three fuels at entries.
- Withdraw one for building.
- Divide CO2 by O2.
Try at home. Rank foods by expected RQ.
What your child will practise
- Amphibolic Pathway and RQ: Desert Quick Fire (Quick Fire)
- Breathing and Glycolysis: Space Puzzle (Clue Puzzle)
- ETS and ATP Balance: Desert Quest (Flip and Match)
- Fermentation: Jungle Quick Fire (Quick Fire)
- Krebs Cycle: Candy Puzzle (Clue Puzzle)
- Quiz: Amphibolic Pathway and RQ (8 questions)
- Quiz: Breathing and Glycolysis (8 questions)
- Quiz: ETS and ATP Balance (8 questions)
- Quiz: Fermentation (8 questions)