Question 1

Question 1Distinguish between the following pairs:(a) Aerobic and anaerobic respiration(b) Respiration and combustion(c) Stomata and lenticels(d) Photosynthesis and respiration(e) Anaerobic respiration in plants and animals

Accepted Answer

(a) Difference between Aerobic and anaerobic respiration:Aerobic respirationAnaerobic respirationProceeds in the presence of oxygen.Proceeds without using oxygen.Complete breakdown of glucose.Incomplete breakdown of glucose.End products are carbon dioxide and water.End-products are ethyl alcohol and carbon dioxide.Energy liberated in large quantity (38 ATP) from one mole of glucose.Energy liberated in small quantity (2 ATP) from one mole of glucose.Occurs normally throughout life.Occurs temporarily for short periods.(b) Difference between Respiration and combustion:RespirationCombustionCellular processNon-cellular processOccurs at body temperatureOccurs at high temperature (at ignition point)Occurs in a series of chemical stepsOccurs in a single stepCarried out by enzymesCarried out by heatBiochemical processPhysico-chemical processEnergy released as ATP and heatEnergy released as heat and lightLight energy is not producedLight energy is produced(c) Difference between Stomata and lenticels:StomataLenticelStomata are present in leaves and green stems.Lenticels are present in mature stems, roots and fruits.Stomata are active only during day time.Lenticels are active both during day and night.Stomata have guard cells and they can be opened and closed.Lenticels do not have guard cells, they are always open.(d) Difference between Photosynthesis and respiration:PhotosynthesisRespirationOccurs only in the presence of chlorophyll.Occurs in all living cells.Occurs only in presence of light.Occurs at all times.Uses carbon dioxide and water.Uses oxygen and glucose.Oxygen is released as an end product.End product is carbon dioxide.Light energy is converted into chemical energy.Chemical energy is converted into useful energy (ATP) and heat.Results in gain in weight.Results in loss in weight.Anabolic process.Catabolic process.(e) Difference between Anaerobic respiration in plants and animals:Anaerobic respiration in plantsAnaerobic respiration in animalsIt leads to formation of ethanolIt leads to formation of lactic acidLittle heat is releasedMore heat is released

Question 2

Question 3How are aerobic and anaerobic respirations different in plants?

Accepted Answer

The differences between aerobic and anaerobic respiration in plants are as follows:Aerobic Respiration in PlantsAnaerobic Respiration in PlantsAlso called oxybiotic respirationAlso called anoxybiotic respirationProceeds in the presence of oxygenProceeds in the absence of oxygenOccurs in mitochondriaOccurs in cytoplasmComplete breakdown of glucoseIncomplete breakdown of glucoseEnd-products are Carbon dioxide and WaterEnd products are Ethyl Alcohol and Carbon dioxideLarge quantity of energy is liberated (38 ATP) from one mole of glucoseSmall quantity of energy is liberated (2 ATP) from one mole of glucoseOccurs normally throughout the lifeOccurs temporarily for short periods

Question 3

Question 5What is respiration? How are respiration and burning similar and how are they different?

Accepted Answer

Oxidation of organic food particularly carbohydrates in living cells to release energy is called respiration.Similarities between burning and respiration are —Oxygen is required by both.Energy is released by both.The outcome of both is water and carbon dioxide.Differences between burning and respiration:RespirationBurningCellular processNon-cellular processOccurs at body temperatureOccurs at high temperature (at ignition point)Occurs in a series of chemical stepsOccurs in a single stepCarried out by enzymesCarried out by heatBiochemical processPhysico-chemical processEnergy released as ATP and heatEnergy released as heat and lightLight energy is not producedLight energy is produced

Question 4

Question 6Describe one experiment each you would perform to demonstrate the following phenomena: The germinating seedsProduce heat,Give out Carbon dioxide,Can respire even in total absence of air.

Accepted Answer

Aim — Experiment demonstrating the fact that germinating seeds produce heat.Procedure —Name two thermo flasks as 'A' and 'B', keep them asideApproximately 200 pea seeds or beans would be used in the experiment. Soak them in water for more than 24 hours.Split the seeds into two equal groups approximatelyOne group of seeds are killed by boiling them and washing them with dilute formaline in order to restrict bacterial decayThe live germinating seeds need to be placed in flask A and the boiled/killed seeds in flask B.Introduce a thermometer into each of the flasks and seal their mouths with cotton wool.Take note of the initial reading observed in the thermometer.Inference —A few hours later, thermometer in the flask A shows a higher reading depicting that the seeds that germinate generate heat.Flask B shows no rise in the temperature.Aim — Experiment demonstrating the fact that germinating seeds produce Carbon dioxide.Procedure —Name two thermo flasks as ‘A’ and ‘B’, keep them aside.At the base of both the flasks, place wet cotton wool.In flask A, take a few soaked seeds of pea, simultaneously take equal quantity of boiled seeds in flask B.To flask B, add some carbolic acid so as to inhibit bacterial growth on the dead seeds.Seal the flasks with a cork, leave them undisturbed for a couple of days.Observe the changes.Inference —Post few days, germination of seeds in flask A is observed.Flask B shows no signs of seed germination.Cork is removed to test the gases in each of the flasks. The flask is toppled over a test tube which carries limewater. The test tube is then shaken up.Indication of carbon dioxide as expected in flask A is observed when lime water turns milky, thereby depicting that germinating seeds produce carbon dioxide.The gas in the flask B shows no effect upon coming in contact with limewater, indicating absence of carbon dioxide.Aim — Experiment demonstrating the fact that seed germination undergoes respiration even in complete absence of airProcedure and Inference —Fill a test tube with mercury that is inverted into a beaker of mercury.Into this tube, push some soaked and peeled off pea seeds before inverting into the mercury beaker.You will observe that seeds will float up and are entirely girdled by mercury.A few days later, few changes are observed. Mercury level drops, presence of some gases are detected in the tube.Pour in some KOH into the tube.Gas in the tube is absorbed, mercury level rises again, depicting that the gas was carbon dioxideConsequently it is proved that the germinating seeds undergo respiration even in the total absence of air.

Question 5

Question 7Draw a neat and labelled, diagram showing the experimental set up (initial and final stages) to demonstrate anaerobic respiration in germinating seeds.

Accepted Answer

Below diagram shows the experimental set up (initial and final stages) to demonstrate anaerobic respiration in germinating seeds:

Question 6

Question 1(viii)Lime water turns milky upon absorption of carbon dioxide gas due to the formation of:Calcium carbonateSodium carbonateCalcium chlorideSodium chloride

Accepted Answer

Calcium carbonateReason — Calcium carbonate is formed when carbon dioxide reacts with lime water.

Question 7

Question 1(ix)Which of the following is the main substrate for any kind of respiration ?StarchOxygenGlucoseSucrose

Accepted Answer

GlucoseReason — Glucose is the simplest sugar. Any sugar first breaks to form glucose, which further breaks down to release energy.

Question 8

Question 1(x)Which of the following is a catabolic process ?PhotosynthesisRespirationBoth (a) and (b)None of these

Accepted Answer

RespirationReason — Photosynthesis (anabolic process) leads to formation of glucose while respiration(catabolic process) leads to break down of the glucose molecules.

Question 9

Question 1(xi)The two major phases during the breakdown of glucose in respiration are (P) ............... and (Q) ............... .P — Glycogenesis, Q — Kreb's cycleP — Aerobic respiration, Q — Anaerobic respirationP — Anoxybiotic respiration, Q — Oxybiotic respirationP — Glycolysis, Q — Kreb's cycle

Accepted Answer

P — Glycolysis, Q — Kreb's cycleReason — In glycolysis glucose is broken down to form pyruvate and in Kreb's cycle it is completely oxidised to form CO2, ATP, and NADH.

Question 10

Question 1(xii)A biology teacher asked her students to give the end products of anaerobic respiration in plants/animals.John said: Carbon dioxide and water.Kabir said: Glucose and water vapour.Sukhvinder said: Carbolic acid and lactic acid.Aayush said: Lactic acid.Who were correct?John and KabirKabir and SukhvinderSukhvinder and AayushJohn and Aayush

Accepted Answer

Sukhvinder and AayushReason — Anaerobic respiration is the breakdown of glucose in the absence of oxygen. The end products vary depending on the organism:In plants and yeast:Glucose → Ethanol + Carbon dioxide + EnergyIn animals (like humans during vigorous exercise):Glucose → Lactic acid + EnergyAs Aayush said Lactic acid so his answer is correct. Sukhvinder said Carbolic acid and lactic acid. Carbolic acid is wrong, but lactic acid is correct for animals. So, Sukhvinder's answer is partially correct.

Question 11

Question 2Given below is a set of six experimental set-ups (A-F), kept in this state for about 24 hours.(a) In how many flasks, the different plant parts have been kept under observation?(b) What is the purpose of keeping a test-tube containing limewater in each flask?(c) In which tube/tubes the limewater will turn milky?(d) What is the purpose of the set-up F?(e) What conclusion can you draw from this experiment?

Accepted Answer

(a) The different plant parts for observation have been placed in five flasks right from A-E flasks as observed in the diagram.(b) It is the property of limewater to absorb Carbon dioxide. Hence it is placed in the flask, so as to absorb Carbon dioxide and turn milky in the presence of any Carbon dioxide.(c) Limewater turns milky in the presence of Carbon dioxide. All five flasks from A to E have plant parts hence respiration takes place in all five parts causing the limewater to turn milky. In flask F, respiration does not take place as there is no plant part, hence no change is observed(d) In the experiment, the setup F depicts the experiment control, wherein all conditions are maintained in the same way except for the plant part that is absent in flask F.(e) The experiment clearly shows that Carbon dioxide is produced during the process of respiration.

Question 12

Question 4In order to study and prove a particular physiological process in plants, the following experiment was set up. Study the same and then answer the questions that follow:(a) Name the physiological process being studied.(b) What is the function of soda lime in the bottle 'A' and why is limewater placed in bottle 'B'?(c) What change would you expect to observe in bottle 'D'?(d) Represent the physiological process named in (a) above in the form of a chemical equation.(e) In order to obtain accurate results, the bottle ‘C’ should be covered with a piece of black cloth. Why?(f) If bottle 'C' was fitted with a 3-holed rubber stopper and a thermometer were introduced in such a way that its bulb reaches close to the germinating seeds, what would you observe? Why?

Accepted Answer

(a) The experiment demonstrates that carbon dioxide is produced during the process of respiration in germinating seeds.(b) Soda lime is placed in bottle ‘A’ as it indicates the passage/presence of Carbon dioxide in bottle A. Another property of soda lime is that is absorbs Carbon dioxide that is present in the air. The clear limewater in bottle B indicates that the air that enters the flask C is free from Carbon dioxide.(c) The bottle D holding limewater should indicate that carbon dioxide is produced as a result of respiration occurring in bottle ‘C’ possessing the germinating seeds. As carbon dioxide is produced in the bottle C, limewater turns milky that enters the bottle 'D'.(d) The chemical reaction is as written below:C6H12O6 + 6O2 → 6CO2 + 6H2O + 38ATP (energy)(e) The bottle 'C' is covered with a black cloth in order to restrict any chance of photosynthesis so as to make sure the process of respiration only is carried out and observed.(f) A thermometer is inserted in bottle C to observe the changes in temperature. Respiration causes the temperature to rise, if there is no respiration, the temperature will not rise.

Respiration in Plants

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Multiple Choice Type

Structured Application Skill Type