Respiration in Plants

Solutions for Biology, Class 9, ICSE

Assertion Reason Type

6 questions

Question 2(i)

Assertion (A): Plants respire only during the daytime when stomata remain open.

Reason (R): Among all the parts of a plant, only the leaves respire because they contain stomata which help in the diffusion of respiratory gases.

  1. A is True and R is False.
  2. A is False and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

Both A and R are False.

Reason — Plants respire continuously, both day and night, to produce energy. All parts of a plant (leaves, stems, roots) respire, not just leaves. Stems respire via lenticels while roots respire via root hairs.

Question 2(ii)

Assertion (A): Respiration is an anabolic process which produces energy in the form of ADP.

Reason (R): Respiration is a destructive process which occurs in a single step and produces ADP.

  1. A is True and R is False.
  2. A is False and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

Both A and R are False.

Reason — Respiration is a catabolic process, not anabolic. It breaks down glucose to release energy in form of ATP. It is not a single-step process, it occurs in multiple steps to finally produce ATP.

Question 2(iii)

Assertion (A): End products of anaerobic respiration in plants are ethyl alcohol and carbon dioxide.

Reason (R): Incomplete breakdown of cellulose occurs in the anaerobic respiration of plants.

  1. A is True and R is False.
  2. A is False and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is True and R is False.

Reason — In anaerobic respiration in plants (e.g., yeast), the end products are ethyl alcohol and carbon dioxide. In anaerobic respiration incomplete breakdown of glucose takes place, not of cellulose.

Question 2(iv)

Assertion (A): In many respects, respiration and photosynthesis in plants are distinctly opposite processes.

Reason (R): In photosynthesis, food is oxidised; whereas in respiration, food is manufactured.

  1. A is True and R is False.
  2. A is False and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is True and R is False.

Reason — Photosynthesis and respiration are opposite processes.
In photosynthesis glucose is manufactured from carbon dioxide and water and energy, while in respiration glucose is broken down (oxidised) to obtain carbon dioxide water and energy.

Question 2(v)

Assertion (A): Kreb's cycle occurs in the cytoplasm of a cell and releases energy.

Reason (R): Glycolysis and kreb's cycle are the two steps of respiration. They both occur in the mitochondria and release energy.

  1. A is True and R is False.
  2. A is False and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

Both A and R are False.

Reason — The Krebs cycle occurs in the mitochondria, not in the cytoplasm. While glycolysis and the Krebs cycle are both part of aerobic respiration, but glycolysis occurs in the cytoplasm.

Question 2(vi)

Assertion (A): Lenticels are the openings found on the surface of roots.

Reason (R): Lenticels help in the diffusion of gases.

  1. A is True and R is False.
  2. A is False and R is True.
  3. Both A and R are True.
  4. Both A and R are False.
Assertion Reason Type

Answer:

A is False and R is True.

Reason — Lenticels are the openings found on the surface of stem. They help in gaseous exchange through diffusion.

Long Answer Type

7 questions

Question 1

Distinguish 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

Long Answer Type

Answer:

(a) Difference between Aerobic and anaerobic respiration:

Aerobic respirationAnaerobic respiration
Proceeds 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:

RespirationCombustion
Cellular processNon-cellular process
Occurs at body temperatureOccurs at high temperature (at ignition point)
Occurs in a series of chemical stepsOccurs in a single step
Carried out by enzymesCarried out by heat
Biochemical processPhysico-chemical process
Energy released as ATP and heatEnergy released as heat and light
Light energy is not producedLight energy is produced

(c) Difference between Stomata and lenticels:

StomataLenticel
Stomata 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:

PhotosynthesisRespiration
Occurs 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 animals
It leads to formation of ethanolIt leads to formation of lactic acid
Little heat is releasedMore heat is released

Question 2

How do the following structures help in respiration in plants?

(a) Lenticels

(b) Stomata

(c) Root hairs

Long Answer Type

Answer:

Given below are the ways in which the following structures help in plant respiration:

(a) Lenticel — These help the stem to participate in respiration.

(b) Stomata — These help the leaves to participate in respiration.

(c) Root hairs — These help the roots to participate in respiration.

Question 3

How are aerobic and anaerobic respirations different in plants?

Long Answer Type

Answer:

The differences between aerobic and anaerobic respiration in plants are as follows:

Aerobic Respiration in PlantsAnaerobic Respiration in Plants
Also called oxybiotic respirationAlso called anoxybiotic respiration
Proceeds in the presence of oxygenProceeds in the absence of oxygen
Occurs in mitochondriaOccurs in cytoplasm
Complete breakdown of glucoseIncomplete breakdown of glucose
End-products are Carbon dioxide and WaterEnd products are Ethyl Alcohol and Carbon dioxide
Large quantity of energy is liberated (38 ATP) from one mole of glucoseSmall quantity of energy is liberated (2 ATP) from one mole of glucose
Occurs normally throughout the lifeOccurs temporarily for short periods

Question 4

Explain why respiration is said to be the reverse of photosynthesis.

Long Answer Type

Answer:

Respiration is said to be the reverse of photosynthesis due to the following reasons :

  1. In respiration, the organic food is disintegrated into its inorganic compounds, namely –
    Carbon dioxide and Water. In photosynthesis, the organic food is manufactured from its inorganic components, namely - Carbon dioxide and Water.
  2. In respiration, Carbon dioxide is released whereas in Photosynthesis Carbon dioxide is consumed.
  3. Oxygen is consumed during respiration while Oxygen is evolved in photosynthesis
  4. Energy is liberated in Respiration while in Photosynthesis, energy is absorbed.

Question 5

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

Long Answer Type

Answer:

Oxidation of organic food particularly carbohydrates in living cells to release energy is called respiration.

Similarities between burning and respiration are —

  1. Oxygen is required by both.
  2. Energy is released by both.
  3. The outcome of both is water and carbon dioxide.

Differences between burning and respiration:

RespirationBurning
Cellular processNon-cellular process
Occurs at body temperatureOccurs at high temperature (at ignition point)
Occurs in a series of chemical stepsOccurs in a single step
Carried out by enzymesCarried out by heat
Biochemical processPhysico-chemical process
Energy released as ATP and heatEnergy released as heat and light
Light energy is not producedLight energy is produced

Question 6

Describe one experiment each you would perform to demonstrate the following phenomena: The germinating seeds

  1. Produce heat,
  2. Give out Carbon dioxide,
  3. Can respire even in total absence of air.
Long Answer Type

Answer:

  1. Aim — Experiment demonstrating the fact that germinating seeds produce heat.
Experiment demonstrating the fact that germinating seeds produce heat. Respiration in Plants, Concise Biology Solutions ICSE Class 9.

Procedure —

  1. Name two thermo flasks as 'A' and 'B', keep them aside
  2. Approximately 200 pea seeds or beans would be used in the experiment. Soak them in water for more than 24 hours.
  3. Split the seeds into two equal groups approximately
  4. One group of seeds are killed by boiling them and washing them with dilute formaline in order to restrict bacterial decay
  5. The live germinating seeds need to be placed in flask A and the boiled/killed seeds in flask B.
  6. Introduce a thermometer into each of the flasks and seal their mouths with cotton wool.
  7. Take note of the initial reading observed in the thermometer.

Inference —

  1. A few hours later, thermometer in the flask A shows a higher reading depicting that the seeds that germinate generate heat.

  2. Flask B shows no rise in the temperature.

  3. Aim — Experiment demonstrating the fact that germinating seeds produce Carbon dioxide.

Experiment demonstrating the fact that germinating seeds produce carbon dioxide. Respiration in Plants, Concise Biology Solutions ICSE Class 9.

Procedure —

  1. Name two thermo flasks as ‘A’ and ‘B’, keep them aside.
  2. At the base of both the flasks, place wet cotton wool.
  3. In flask A, take a few soaked seeds of pea, simultaneously take equal quantity of boiled seeds in flask B.
  4. To flask B, add some carbolic acid so as to inhibit bacterial growth on the dead seeds.
  5. Seal the flasks with a cork, leave them undisturbed for a couple of days.
  6. Observe the changes.

Inference —

  1. Post few days, germination of seeds in flask A is observed.

  2. Flask B shows no signs of seed germination.

  3. 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.

  4. Indication of carbon dioxide as expected in flask A is observed when lime water turns milky, thereby depicting that germinating seeds produce carbon dioxide.

  5. The gas in the flask B shows no effect upon coming in contact with limewater, indicating absence of carbon dioxide.

  6. Aim — Experiment demonstrating the fact that seed germination undergoes respiration even in complete absence of air

Experiment demonstrating the fact that seed germination undergoes respiration even in complete absence of air. Respiration in Plants, Concise Biology Solutions ICSE Class 9.

Procedure and Inference —

  1. Fill a test tube with mercury that is inverted into a beaker of mercury.
  2. Into this tube, push some soaked and peeled off pea seeds before inverting into the mercury beaker.
  3. You will observe that seeds will float up and are entirely girdled by mercury.
  4. A few days later, few changes are observed. Mercury level drops, presence of some gases are detected in the tube.
  5. Pour in some KOH into the tube.
  6. Gas in the tube is absorbed, mercury level rises again, depicting that the gas was carbon dioxide
  7. Consequently it is proved that the germinating seeds undergo respiration even in the total absence of air.

Question 7

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

Long Answer Type

Answer:

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

Draw a neat and labelled, diagram showing the experimental set up (initial and final stages) to demonstrate anaerobic respiration in germinating seeds. Respiration in Plants, Concise Biology Solutions ICSE Class 9.

Multiple Choice Type

12 questions

Question 1(i)

Glycolysis is a process

  1. in which glycogen is broken down into glucose
  2. which occurs in mitochondria
  3. in which glucose is broken down into pyruvate
  4. that occurs next to Krebs cycle.
Multiple Choice Type

Answer:

in which glucose is broken down into pyruvate

Reason — Glycolysis is the first phase of respiration in which glucose is broken down into pyruvate.

Question 1(ii)

In plants, a common function is performed by?

  1. Stomata and veins
  2. Stomata and lenticels
  3. Lenticels and sepals
  4. Lenticels and hydathodes
Multiple Choice Type

Answer:

Stomata and lenticels

Reason — Stomata are tiny pores present on surface of leaves and lenticels are present on stems. Both are responsible for gaseous exchange.

Question 1(iii)

Anaerobic respiration normally occurs in

  1. Grass
  2. Cactus
  3. Coconut
  4. Baker’s yeast
Multiple Choice Type

Answer:

Baker’s yeast

Reason — Anaerobic respiration normally occurs in fungi.

Question 1(iv)

On oxidation of 1 molecule of glucose, .............. ATP is produced through aerobic respiration.

  1. 2
  2. 20
  3. 18
  4. 38
Multiple Choice Type

Answer:

38

Reason — Oxidation of 1 molecule of glucose gives 38 ATP.

Question 1(v)

Respiration in plants occurs

  1. Only in stomata
  2. Only in leaves
  3. Only in lenticels
  4. In all the parts
Multiple Choice Type

Answer:

In all the parts

Reason — Leaves respire through stomata, stems respire through lenticel and roots respire through their general surface.

Question 1(vi)

Which of the following is produced during anaerobic respiration in plants?

  1. Soda lime
  2. Ethyl alcohol
  3. Lime water
  4. None of these
Multiple Choice Type

Answer:

Ethyl alcohol

Reason — Anaerobic respiration in plants leads to the formation of Ethyl alcohol.

Question 1(vii)

Glycolysis takes place in :

  1. Chloroplast
  2. Mitochondria
  3. Cytoplasm
  4. Ribosomes
Multiple Choice Type

Answer:

Cytoplasm

Reason — Glycolysis takes place in cytoplasm whereas Krebs cycle takes place in mitochondria.

Question 1(viii)

Lime water turns milky upon absorption of carbon dioxide gas due to the formation of:

  1. Calcium carbonate
  2. Sodium carbonate
  3. Calcium chloride
  4. Sodium chloride
Multiple Choice Type

Answer:

Calcium carbonate

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

Question 1(ix)

Which of the following is the main substrate for any kind of respiration ?

  1. Starch
  2. Oxygen
  3. Glucose
  4. Sucrose
Multiple Choice Type

Answer:

Glucose

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

Question 1(x)

Which of the following is a catabolic process ?

  1. Photosynthesis
  2. Respiration
  3. Both (a) and (b)
  4. None of these
Multiple Choice Type

Answer:

Respiration

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

Question 1(xi)

The two major phases during the breakdown of glucose in respiration are (P) ............... and (Q) ............... .

  1. P — Glycogenesis, Q — Kreb's cycle
  2. P — Aerobic respiration, Q — Anaerobic respiration
  3. P — Anoxybiotic respiration, Q — Oxybiotic respiration
  4. P — Glycolysis, Q — Kreb's cycle
Multiple Choice Type

Answer:

P — Glycolysis, Q — Kreb's cycle

Reason — 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 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?

  1. John and Kabir
  2. Kabir and Sukhvinder
  3. Sukhvinder and Aayush
  4. John and Aayush
Multiple Choice Type

Answer:

Sukhvinder and Aayush

Reason — 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 + Energy
  • In animals (like humans during vigorous exercise):
    Glucose → Lactic acid + Energy

As 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.

Progress Check 1

3 questions

Question 1

Write the important aspects about the overall chemical equation of respiration, pertaining to the following :

  1. Number of steps for glucose to break down into CO2 and H2O.
  2. Involvement of enzymes.
  3. Forms of energy liberated.
Progress Check 1

Answer:

  1. The breakdown of glucose to carbon dioxide and water does not occur in a single step, but in a series of chemical steps. These steps occur in two major phases — (i) glycolysis (glucose → pyruvate) occurring in cytoplasm and (ii) Krebs cycle (pyruvate → CO2 + 6H2O + ATP) occurring in mitochondria.
  2. Each breakdown step occurs due to a particular enzyme.
  3. The energy liberated in the breakdown of glucose molecule is not all in the form of heat, but a large part of it is converted into chemical energy in the form of ATP.

Question 2

List three ways in which respiration is different from burning.

Progress Check 1

Answer:

RespirationBurning
Cellular process.Non-cellular process.
Occurs in a series of chemical steps.Occurs in a single step.
No light energy is produced.Light energy is produced.

Question 3

Name the three inlets of oxygen for respiration in plants.

Progress Check 1

Answer:

The three inlets of oxygen for respiration in plants are:

  1. Stomata in leaves.
  2. Lenticels in stem.
  3. General surface of the roots.

Progress Check 2

3 questions

Question 1

Give the overall chemical equation for the two kinds of respiration in plants :

  1. Aerobic
  2. Anaerobic
Progress Check 2

Answer:

  1. Aerobic respiration
    C6H12O6 + 6O2 enzyme\xrightarrow{\text{enzyme}} 6CO2 + 6H2O + 38ATP

  2. Anaerobic respiration
    C6H12O6 ⟶ 2C2H5OH + 2CO2 + 2ATP

Question 2

Mention any one difference other than those reflected in the two chemical equations given above.

Progress Check 2

Answer:

Aerobic respiration is the primary and the most efficient way for plants to generate energy. On the other hand, Anaerobic respiration is a backup mechanism for plants when oxygen is limited and occurs temporarily for short periods.

Question 3

Certain organisms respire only anaerobically throughout their lives. Name any two such organisms.

Progress Check 2

Answer:

Bacteria and fungi.

Progress Check 3

4 questions

Question 1

In experiments on respiration, the seeds taken as control are boiled. Why?

Progress Check 3

Answer:

In experiments on respiration, the seeds taken as control are boiled to kill them. It is done in order to compare the live seeds that can respire to dead seeds that cannot respire.

Question 2

What is the use of the following, in the experiments on respiration?

  1. Soda lime
  2. Limewater
Progress Check 3

Answer:

  1. Soda lime is used to absorb any carbon dioxide released by the seeds.
  2. Limewater is used to test for the presence of carbon dioxide as carbon dioxide turns limewater milky.

Question 3

Suppose we conduct an experiment to demonstrate respiration in a green plant. What special precaution is required to be taken in it?

Progress Check 3

Answer:

It is necessary that this experiment is carried out in dark in order to stop the process of photosynthesis so that the carbon dioxide liberated in respiration is not used up for photosynthesis.

Question 4

In experiment no. 5, we are using mercury in the test tube and the beaker. Why can't we use water instead?

Progress Check 3

Answer:

We can't use water because it has some dissolved gases like oxygen and carbon dioxide.

Progress Check 4

2 questions

Question 1

Fill in the blanks:

In anaerobic respiration in plants, the end product is ............... and ............... instead of ............... in animals.

Progress Check 4

Answer:

In anaerobic respiration in plants, the end product is ethanol and carbon dioxide instead of lactic acid in animals.

Question 2

The table below is intended to give certain differences between photosynthesis and respiration, but a few points are given wrongly. Strike out the wrong ones and write the correct words instead.

PHOTOSYNTHESISRESPIRATION
Results in loss in weightResults in gain in weight
Sucrose is the productSucrose is broken down
Occurs in green cells onlyOccurs in all cells
Uses water and oxygenUses glucose and oxygen
Progress Check 4

Answer:

PHOTOSYNTHESISRESPIRATION
Results in gain in weightResults in loss in weight
Glucose is the productGlucose is broken down
Occurs in green cells onlyOccurs in all cells
Uses water and carbon dioxideUses glucose and oxygen

Short Answer Type

7 questions

Question 1

Define

(a) Respiration

(b) Combustion

(c) ATP

Short Answer Type

Answer:

(a) Respiration — Respiration is a catabolic process of releasing energy from glucose for carrying out life processes.

(b) Combustion — Combustion or burning is defined as a physio-chemical process in which energy is liberated in the form of heat and light.

(c) ATP — ATP is defined as energy currency of the cell as it acts as the immediate source of energy for different life processes.

Question 2

Name:

(a) Two raw materials of respiration.

(b) Two end products of aerobic respiration.

(c) Two microbes which normally respire anaerobically

Short Answer Type

Answer:

(a) Glucose and Oxygen

(b) Carbon dioxide and water

(c) Bacteria and Fungi

Question 3

Write the full form of ATP and ADP.

Short Answer Type

Answer:

Full form of ATP — Adenosine triphosphate

Full form of ADP — Adenosine diphosphate

Question 4

What happens to the energy liberated in respiration?

Short Answer Type

Answer:

The energy liberated in respiration is stored in the form of ATP inside the cells. Some part of it is lost as heat to the surroundings.

Question 5

How is the tilling of the soil useful for the crops growing in it?

Short Answer Type

Answer:

Tilling makes the soil porous and airy. The parts of the plant present below the ground receive adequate oxygen supply to respire. This way tilling facilitates faster crop growth.

Question 6

Why is it usually difficult to demonstrate respiration in green plants?

Short Answer Type

Answer:

During day time, both photosynthesis and respiration takes place in green plants. Evolution of carbon dioxide is an indicator to demonstrate respiration in living organisms. Carbon dioxide produced during respiration in plants gets utilized during photosynthesis and thus, there is no evolution of carbon dioxide. Consequently, it becomes difficult to demonstrate respiration in green plants as there in no evolution of carbon dioxide during day time.

Question 7

Can cell respiration occur in any organism at a temperature of about 65°C? Give reason.

Short Answer Type

Answer:

Cell respiration cannot occur in any organism at a temperature of about 65°C because the enzymes involved in respiration become inactivated at high temperatures.

Structured Application Skill Type

4 questions

Question 1

The following two chemical reactions are supposed to indicate a certain process occurring in the green plants under two different conditions:

(a) C6H12O6 + 6O2 → 6CO2 + ...... + 38ATP

(b) C6H12O6 → ...... + 2CO2 + 2ATP

  1. Fill in the blanks of each reaction
  2. Name the process represented by the two chemical equations
  3. What are the conditions under which the two reactions (a) and (b) are occurring?
Structured Application Skill Type

Answer:

  1. (a) 6H2O
    (b) 2C2H5OH
  2. (a) The process observed in this chemical reaction here is aerobic respiration
    (b) The process observed in this chemical reaction is anaerobic respiration
  3. The reaction occurring in (a) can take place only in the presence of oxygen as it is aerobic respiration. The reaction occurring in (b) can take place even in the absence of oxygen as it is anaerobic respiration.

Question 2

Given below is a set of six experimental set-ups (A-F), kept in this state for about 24 hours.

In how many flasks, the different plant parts have been kept under observation? What is the purpose of keeping a test-tube containing limewater in each flask? Respiration in Plants, Concise Biology Solutions ICSE Class 9.

(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?

Structured Application Skill Type

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 3

The following diagram refers to an apparatus which is used to demonstrate a physiological process:

What is the purpose of keeping potassium hydroxide solution in the test tubes X and Y? Why has the coloured water risen in tubing 1? Respiration in Plants, Concise Biology Solutions ICSE Class 9.

(a) What is the purpose of keeping potassium hydroxide solution in the test tubes X and Y?

(b) Why has the coloured water risen in tubing 1?

(c) What is the purpose of keeping boiled peas soaked in a disinfectant in test tube Y?

(d) Name the biological process which causes the above rise.

(e) Define the biological process shown in the experiment

Structured Application Skill Type

Answer:

(a) To check the presence of Carbon dioxide, potassium hydroxide is placed in the test tubes X and Y. Potassium hydroxide has a special property of absorbing Carbon dioxide if produced.

(b) In the test tube X, when the process of respiration takes place, the oxygen is consumed that is present in the test tube. Due to respiration, Carbon dioxide that is produced is absorbed by the KOH in the test tube. Due to consumption of Oxygen, a space is developed causing the colored water to rise in the tubing 1.

(c) It is because the seeds die once they are boiled and hence cannot undergo respiration. This is why respiration does not take place in test tube Y.

(d) The biological process that causes a rise is respiration.

(e) It is respiration. It is a catabolic process wherein energy is liberated from simple sugars to be able to carry out life processes.

Question 4

In 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:

Name the physiological process being studied. What is the function of soda lime in the bottle A and why is limewater placed in bottle B? Respiration in Plants, Concise Biology Solutions ICSE Class 9.

(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?

Structured Application Skill Type

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.

Very Short Answer Type

4 questions

Question 1

Fill in the blanks:

  1. ............... are the openings found on older stems.

  2. Glycolysis occurs in the ............... of the cells.

  3. ............... is a respiratory substance.

  4. Rate of ............... is more than the rate of ............... in the daytime in the case of green plants.

  5. ............... is a chemical substance which absorbs oxygen of the air.

  6. ............... is used to create vacuum to show anaerobic respiration.

Very Short Answer Type

Answer:

  1. Lenticels are the openings found on older stems.

  2. Glycolysis occurs in the cytoplasm of the cells.

  3. Glucose is a respiratory substance.

  4. Rate of Photosynthesis is more than the rate of Respiration in the daytime in the case of green plants.

  5. Pyrogallate of potash is a chemical substance which absorbs oxygen of the air.

  6. Caustic potash (KOH) is used to create vacuum to show anaerobic respiration.

Question 2

Name the following:

  1. Energy currency of cell.
  2. Oxidative breakdown of carbohydrates to release energy.
  3. An organism which respires throughout life anaerobically.
  4. A common phase in both aerobic and anaerobic respiration.
  5. A chemical which removes CO2 from the air.
Very Short Answer Type

Answer:

  1. ATP (Adenosine triphosphate)
  2. Respiration
  3. Fungus
  4. Glycolysis
  5. Soda lime

Question 3

Do the plants respire all day and all night or only at night?

Very Short Answer Type

Answer:

Respiration is an essential life process for all living organisms. Therefore, plants also respire all day and all night.

Question 4

Mention if the following statements are true or false. If false, rewrite them correctly.

  1. Aerobic respiration of one mole of glucose yields 138 ATP.
  2. Anaerobic respiration in plants yields lactic acid.
  3. Carbon dioxide readily dissolves in lime water.
  4. All leaves of a green plant normally respire anaerobically at night.
Very Short Answer Type

Answer:

  1. False
    Corrected Statement — Aerobic respiration of one mole of glucose yields 38 ATP.

  2. False
    Corrected Statement — Anaerobic respiration in plants yields ethanol.

  3. True

  4. False
    Corrected Statement — All leaves of a green plant normally respire aerobically at night.