Tag: various experiments on photosynthesis

Questions Related to various experiments on photosynthesis

Which of the following scientists concluded by his experiments that green plant play a role in  purifying the noxious air only in the presence of sunlight?
  1. Priestley

  2. Ingenhousz

  3. Sachs

  4. Engelmann


Correct Option: B
Explanation:

Jan Ingenhousz (1730-1799), in his experiment with an aquatic plant, showed that in bright sunlight, small bubbles were formed around the green parts while in the dark, no such bubbles formed. He found out these bubbles to be of oxygen. He thus, confirmed that purification of air or formation of dephlogiston is carried out by green plants only in presence of sunlight. 

The process in which liquid water changes into gas is called

  1. Precipitation

  2. Condensation

  3. Evaporation

  4. Transpiration


Correct Option: C
Explanation:

Sun derives the water cycle, heats up water in ocean and seas, and then water vapours evaporate to air. As the vapours move upward the cool temperature there causes it to condense into clouds and they fall as precipitate like rain, hailstone etc.

It is advantageous to use a water plant to demonstrate photosynthesis other than a land plant because

  1. It photosynthesize rapidly

  2. It respires slowly

  3. It does not transpire

  4. O$ _2$ bubbles from cut water plant can be collected over H$ _2 $O


Correct Option: C

The chemical compound used in the experiment to show that oxygen is evolved during photosynthesis is

  1. KOH.

  2. NaOH.

  3. KHCO$ _{3}$.

  4. All of the above.


Correct Option: C

In 1772, Joseph Priestley demonstrated that

  1. Plants foul the air

  2. Animals purify the air during day time

  3. Plants and animals restore air for each other

  4. Plants get killed in the air produced by animals


Correct Option: C
Explanation:
Joseph Priestley discovered oxygen which is used by the plant and animals. He demonstrated that plants liberate oxygen as a product during photosynthesis and that oxygen is utilised by the animals during respiration. Further, plant consumes the carbon dioxide, exhaled by the animals, to carry out photosynthesis. Thus plants and animals restore air for each other.
So the correct answer is 'Plants and animals restore air for each other'.

Hydrilla leaf is used in an experiment to test that

  1. Chlorophyll is necessary for photosynthesis.

  2. Light is necessary for photosynthesis.

  3. CO$ _{2}$ is necessary for photosynthesis.

  4. Oxygen is evolved during photosynthesis.


Correct Option: D
Explanation:

To test that oxygen is evolved during photosynthesis few fresh Hydrilla plants in a glass beaker filled with water. A pinch of KHCO$ _{3}$ is added to it. It is kept in sunlight. After some time some bubbles (oxygen) escapes from the plant. This proves that oxygen is produced during the photosynthesis. It is evolved during the light reaction of the photosynthesis.

So, the correct answer is option D.

How many molecules of water are needed by a green plant to produce one molecule of hexose reduce $6$ molecules of $CO _{2}$?

  1. $6$

  2. $12$

  3. $24$

  4. Only one


Correct Option: A

Oxygen evolution takes place during photosynthesis in green plants but not in bacterial photosynthesis, because _________________.

  1. Bacteria are prokaryotic and green plants are eukaryotic

  2. Only photo system I is present in bacterial photosynthesis

  3. Bacterial cell wall composition is different from green plant cell wall

  4. Rate of $O _2$ consumption in bacteria is higher than that in green plants


Correct Option: A