Tag: experiments on photosynthesis - gases

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Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

In the experiment to show that $CO _{2}$, is given out during respiration the chemical filled in the small test tube is :

  1. alcohol

  2. KOH

  3. lime water

  4. iodine solution
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

KOH (potassium hydroxide) is used in the experiment because it effectively absorbs carbon dioxide gas, which allows the student to observe the change in pressure.

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

Moll's half experiment is performed to show that

  1. Light is needed for photosynthesis.

  2. Chlorophyll is needed for photosynthesis.

  3. Oxygen is evolved during photosynthesis.
  4. CO$ _{2}$ is needed for photosynthesis.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CO$ _{2}$ is needed for photosynthesis is shown by Moll's half leaf experiment. In this experiment, only that part of the leaf will show blue color which was present outside the bottle because they are able to take carbon dioxide from the stomata of the leaf.

So, the correct answer is option D.

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

In Moll's half leaf experiment, only that part of leaf will show blue colour which was ........... the bottle.

  1. Inside

  2. Outside

  3. Whole leaf shows blue coloration

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In Moll's half-leaf experiment, the part of the leaf inside the bottle is deprived of CO2, preventing photosynthesis. The part outside has access to CO2, allowing photosynthesis to occur and starch to be produced, which turns blue with iodine.

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

Path of carbon in photosynthesis was found by using 

  1. Centrifugation

  2. Radio isotopes

  3. Fractionation

  4. Chromatography
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calvin cycle is used for the fixation of carbon dioxide to produce glucose. Radioactive isotopes of carbon (C-14) and phosphorus (P-32) was used to trace the path for the carbon assimilation. A photosynthesizing plant does not strongly discriminate between the most abundant natural carbon isotope C-12 and C-14. During photosynthesis in the presence of 14$CO _2$, the compounds formed become labeled with the radioisotope.

So, the correct answer is option B.

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

Given below are assertions and reasons. Point out if both are true with reason being correct explanation (A), both true but reason is not correct explanation (B), assertion true but reason is wrong (C), both are wrong (D).
Assertion. Under conditions of high intensity and limited $CO _2$ supply, photorespiration has a useful role in protecting the plants from photo-oxidative damage.
Reason. If enough $CO _2$ is not available to utilise light energy for carboxylation to proceed, the excess energy may not cause damage to plants

  1. A

  2. B

  3. C

  4. D
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The assertion is true because photorespiration dissipates excess light energy when CO2 is limiting, preventing photo-oxidative damage. The reason is false because if CO2 is not available for carboxylation, the excess energy is precisely what causes damage, which photorespiration helps mitigate.

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases
Moll's half - leaf experiment proves that _________ is essential for photosynthesis to take place. 

  1. chlorophyll
  2. $CO _{2} $

  3. light
  4. $H _{2} O $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In Moll's half leaf experiment a destarched plant is used.Half part of one of the leaves from the plant is inserted into a corked bottle containing either KOH solution or KOH palletes. The plant is then placed in sunlight for a few hours. The leaf is then tested for starch with iodine solution. Part of the leaf that was inserted in the bottle does not turn blue or test positive for starch. This is because $CO _2$ present in the bottle was aborbed by KOH and the bottle was corked to prevent any entry of air.Proving that $CO _2$ is essential for photosynthesis.

So, the correct answer is $CO _2$


Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

Choose the correct answer from the alternatives given.
Molls experiment demonstrates the necessity of which of the following in photosynthesis

  1. water

  2. oxygen

  3. carbon dioxide

  4. chlorophyll
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Molls experiment evidently shows that plants do not form starch when carbon dioxide is not at their disposal, all the carbon dioxide contained in the bottle having been absorbed by the caustic potash solution.

Thus, the correct answer is 'Carbon dioxide.'

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases
Photochemical phase does not include 

  1. light absorption
  2. water splitting and $ O _{2}$ release

  3. ATP and NADPH formation
  4. $CO _{2}$ fixation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The complete process of photosynthesis is studied under two phases - photochemical phase and biosynthetic phase. Photochemical phase involves absorption of light energy, photolysis of water with the release of $O _{2}$ and production of assimilatory power (i.e. ATP + NADPH).$CO _{2} $ fixation occurs during biosynthetic phase of photosynthesis. 

Multiple choice biology nutrition and respiration importance of light for photosynthesis various experiments on photosynthesis experiments on photosynthesis - gases

In the experiment " To show that $CO _{2}$ is given out during respiration" the water level in the bent tube rise after sometime because

  1. germinating seeds consume all the $O _{2}$ and $CO _{2}$ in the flask.
  2. the germinating seeds consume $O _{2}$ and give out $CO _{2}$ which is absorbed by a chemical filled in the small test tube.
  3. $CO _{2}$ is given out by the germinating seeds.

  4. seeds need water for germination and grow.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Germinating seeds respire, consuming O2 and releasing CO2. The KOH solution in the small test tube absorbs the CO2, creating a partial vacuum in the flask, which causes the water level in the bent tube to rise.