Tag: importance of light for photosynthesis

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Multiple choice botany how plants grow experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases

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
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice botany how plants grow experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases

Match List-I with List-II and select the correct answer.

List-I List-II
a. Richnmond lang effect $1$. Reversal of red-drop
b. Emerson effect $2$. Inhabitation of glycolysis by oxygen
c. Pasteur effect $3$. Inhibition of photosynthesis by oxygen
d. Warburg effect $4$. Senscescence retardation in detached leaves
  1. A-$1$, B-$4$, C-$2$, D-$3$
  2. A-$4$, B-$1$, C-$3$, D-$2$
  3. A-$1$, B-$4$, C-$3$, D-$2$
  4. A-$4$, B-$1$, C-$2$, D-$3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Richmond-Lang effect refers to senescence retardation in leaves by cytokinins (4). Emerson effect is the enhancement of photosynthesis (reversal of red-drop) (1). Pasteur effect is the inhibition of glycolysis by oxygen (2). Warburg effect is the inhibition of photosynthesis by high oxygen concentration (3).

Multiple choice botany how plants grow experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases

The upper dormant seeds of cocklebur(Xanthium) germinate only under high oxygen levels. The oxygen is required for _______________.

  1. Degradation of inhibitors

  2. Synthesis of promoters

  3. Respiration

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

In many dormant seeds, oxygen is required for the aerobic respiration process that provides the energy and metabolic intermediates necessary to degrade growth inhibitors (like ABA) that maintain dormancy.

Multiple choice botany how plants grow experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases
Ingenhousz in an experiment showed that in bright sunlight, small bubbles were formed around the green parts of the plant, while in the dark, they did not. He identified these bubbles to be of ____________.
  1. $CO _{2}$
  2. $H _{2} O $
  3. $O _{2} $
  4. $H _{2} $
Reveal answer Fill a bubble to check yourself
C Correct answer
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. 

Multiple choice biology photosynthesis and respiration experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

Who observed that when chlorella cells are exposed to continuous light, the rate of  photosynthesis was less as compared to those exposed in intermittent light?

  1. Arnon

  2. Emerson

  3. Warburg

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

  • Warburg discovered that a decrease in photosynthesis by increasing the oxygen concentration. Oxygen is the competitive inhibitor of the carbon dioxide fixation by RuBisCo, which initiates photosynthesis. Furthermore, oxygen stimulates photorespiration which reduces photosynthetic output. These two mechanisms working together are responsible for the Warburg effect. So, this option is incorrect.
  • Arnon discovered the photosynthetic phosphorylation. So, this option is incorrect.
  • Samuel Ruben discovered that oxygen, which is released during photosynthesis came from a water molecule. So, this option is incorrect.
  • Emerson observed that when Chlorella cells are exposed to continuous light, the rate of photosynthesis was less as compared to those exposed to the intermittent light. 

So, the correct answer is option B.

Multiple choice botany how plants grow experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments various experiments on photosynthesis experiments on photosynthesis - gases

A beaker is filled with water and twigs of Hydrilla are inserted in the funnel so that the cut ends are in the tube of the funnel and the funnel is put in the water. Then a test tube full of water is inverted over the inverted funnel. Air bubbles from the plant collect at the tip of the tube. This experiment demonstrates that oxygen is evolved during photosynthesis. But, if boiled water is used instead of pond water in which Hydrilla grows, then?

  1. Air bubbles are not produced

  2. Air bubbles are produced in large numbers

  3. Only a few air bubbles are produced

  4. Only one air bubble is produced
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If boiled water is used in the test tube, there will be no air bubbles. This is hydrilla cannot survive the high temperature of boiled water. 

So, option A is the correct answer.

Multiple choice biology photosynthesis and respiration experiments on photosynthesis - light importance of light for photosynthesis photosynthesis necessities- experiments

A plant was kept in a dark room for a week. When its leaves are tested with iodine solution, it did not show the presence of starch. From this experiment we can conclude that _____ is required for photosynthesis.

  1. Sunlight

  2. Iodine

  3. Starch

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

Sunlight is essential for photosynthesis as the plant is kept in dark room for a week there is a lack of sunlight hence photosynthesis has not taken place.

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

Before setting up an experiment to show that seeds release $CO _{2}$ during respiration, the
seeds should be :

  1. dried completely.

  2. boiled to make them soft.

  3. soaked in vinegar.

  4. kept moist till they germinate.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To demonstrate respiration, seeds must be alive and metabolically active. Germinating seeds are actively respiring and consume oxygen while releasing carbon dioxide.

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

Four sets of three precautions to be taken while setting up the experiment to show that $CO _{2}$ is evolved during respiration are given below. Find the correct set of precautions.

  1. Airtight setup, delivery tube dips in water in beaker, germinating seeds in flask

  2. Thread holding KOH pellets, airtight flask, delivery tube just above the water level in the beaker

  3. Germinated seeds completely under the water in the flask, experimental setup not airtight, delivery tube above water level.

  4. Delivery tube touching the bottom of the beaker, KOH pellets kept along with germinating seeds at the bottom of the flask, seeds should not germinate.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The experiment requires an airtight setup to prevent atmospheric CO2 from interfering. KOH pellets are used to absorb the CO2 produced by the germinating seeds, creating a partial vacuum that draws water up the delivery tube.