Biology

Photosynthesis in Plants

1,508 Questions

Photosynthesis is the biological process by which plants convert light energy into chemical energy. This page contains practice questions covering essential topics like chlorophyll, light reactions, and the pathways specific to plants. This material is crucial for medical entrance exams and academic assessments.

Chlorophyll and pigmentsLight reactionsCalvin cycleCAM plantsElectron transportPhotosynthesis factors

Photosynthesis in Plants Questions

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

UV or X-ray radiation is NOT suitable for photosynthesis is green plants because such a radiation.

  1. Is not visible

  2. Is not absorbed by chlorophyll

  3. Causes ionization of chlorophyll

  4. Leads to an increase in rotational and vibration energy of chlorophyll
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photosynthesis relies on the absorption of visible light by chlorophyll pigments. UV and X-ray radiations have much higher energy levels than visible light and are not effectively absorbed by chlorophyll to drive the photochemical reactions, often causing damage to biological molecules instead.

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

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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The balanced equation for photosynthesis is 6CO2 + 12H2O -> C6H12O6 + 6O2 + 6H2O. To produce one molecule of hexose (C6H12O6) from 6 molecules of CO2, 12 molecules of water are consumed, but 6 are released, resulting in a net requirement of 6 molecules of water.

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
B Correct answer
Explanation

Oxygen evolution in green plants is driven by Photosystem II, which performs the photolysis of water. Photosynthetic bacteria lack Photosystem II and possess only Photosystem I, utilizing other electron donors like hydrogen sulfide instead of water, and therefore do not release oxygen.

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 cell structure plant and animal cell cell structure and micro-organisms organisation of the organism

Planet cells that are photosynthetically  active are found in the ______ layer of leaf and are ____ cells.

  1. Epidermis ,Parenchymatous

  2. Mesophyll,Parenchymatous

  3. Mesophyll, Sclerenchymatous

  4. Aerenchyma,Collenchymatous
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photosynthetically active plant cells are primarily parenchymatous cells containing chloroplasts, collectively forming the chlorenchyma tissue found in the mesophyll layer of leaves. Epidermal cells generally lack chloroplasts, and sclerenchymatous cells are dead and provide structural support.

Multiple choice biology cell structure plant and animal cell cell structure and micro-organisms organisation of the organism

Which is incorrect for chloroplast

  1. Presence in algae and plants
  2. Release $O _2$

  3. Occurs only in cells with aerobic respiration

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chloroplasts are found in photosynthetic organisms and do not require aerobic respiration to function; they are the site of photosynthesis, which is independent of the cell's respiratory state.

Multiple choice biology cell structure plant and animal cell cell structure and micro-organisms organisation of the organism

Chloroplast contains maximum quantity of _________________.

  1. Pyruvic carboxylase

  2. Hexokinase

  3. RUDP caboxylase

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

Pyruvate carboxylase is a mitochodrial enzyme that catalyzes carboxylation of pyruvate into oxaloacetate. Hexokinase is an enzyme of glycolysis and is present in the cytoplasm. RUBP carboxylase catalyzes carboxylation of RuBP during photosynthetic carbon fixation. Chloroplasts is the site of photosynthesis and contain maximum quantity of RUBP carboxylase. The correct answer is C.

Multiple choice biology cell structure plant and animal cell cell structure and micro-organisms organisation of the organism

In a chloroplast, what is the ration of chl a : chl b and carotenes : xanthophylls respectively?

  1. 3 : 1 and 2 : 1

  2. 2 : 1 and 3 : 1

  3. 3 : 2 and 1 : 1

  4. 1 : 1 and 3 : 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • A chloroplast is the site of photosynthesis, it contains all the pigments required for the process of photosynthesis. Pigments are of two types: Chlorophylls and Carotenoids.
  • Chlorophylls are the green photosynthetic pigments, they are of mainly five types - chlorophyll a, b, c, d, and e. The amount of chlorophyll b is one-fourth of the total chlorophyll content while chlorophyll a is the universal or primary photosynthetic pigment and present in abundance.
  • Carotenes are hydrocarbons, they may be yellow, brown or reddish pigments.
  • Xanthophylls are oxygen-containing carotenes, yellowish brown in color.
So, the correct option is '3: 1 and 2: 1'.

Multiple choice biology cell structure and micro-organisms plant and animal cell cell structure organisation of the organism

Plant cell can do___________

  1. Breathing and respiration

  2. Respiration and photosynthesis

  3. Breathing and photosynthesis

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The plant cell can do respiration and photosynthesis. The plants get energy through the process of respiration in which glucose food breaks down in the presence of oxygen to form carbon dioxide and water with the release of energy. In plants, photosynthesis takes place in the cell organelle called chloroplast. A plant cell cannot breathe because in a plant body lungs are absent.
So the correct answer is 'Respiration and photosynthesis'.
Multiple choice zoology bio-geo chemical cycles in nature nutrient cycles- flow of substances carbon cycle biogeochemical cycles - gaseous

The biological process by which carbon is returned to its reservoir is

  1. photosynthesis

  2. denitrification

  3. carbon fixation

  4. cellular respiration
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A. Photosynthesis is the process in which plants prepare their own food using carbon dioxide and water which are converted into glucose in the presence of sunlight along with the release of oxygen.
B. Denitrification is a process of reduction of nitrate into molecular nitrogen by denitrifying bacteria.
C. Carbon fixation is the reduction and incorporation of inorganic carbon into organic compounds.
D. Cellular respiration is a metabolic reaction in which energy is released from the breakdown of complex substances. Oxygen is used in respiration and carbon dioxide is released. Hence, carbon is returned to its reservoir through cellular respiration.
So, the correct answer is 'cellular respiration'.
Multiple choice zoology bio-geo chemical cycles in nature nutrient cycles- flow of substances carbon cycle biogeochemical cycles - gaseous

Phtotochemical phase does not includes ________________.

  1. Fixation of ${CO} _{2}$
  2. Release of ${O} _{2}$

  3. Photolysis of water

  4. Formation of ATP and NADPH
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photochemical phase includes photolysis of water and production of assimilatory power (ATP and NADPH). It liberates O2  during photolysis of water. 

The photochemical phase do not include fixation of CO2.

Multiple choice biology classification of plants thallophyta cryptograms kingdom plantae

Which of the following is the principal pigment of Phaeophyceae?

  1. Phycocyanin

  2. Phycoerythrin

  3. Fucoxanthin

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

Fucoxanthin is a xanthophyll, with formula CHO. It is found as an accessory pigment in the chloroplasts of brown algae and most other heterokonts, giving them a brown or olive-green color. It is the principal pigment of Phaeophyceae.
Phycocyanin is a pigment-protein complex from the light-harvesting phycobiliprotein family, along with allophycocyanin and phycoerythrin. It is an accessory pigment to chlorophyll. All phycobiliproteins are water-soluble, so they cannot exist within the membrane-like carotenoids. 

Phycoerythrin (PE) is a red protein-pigment complex from the light-harvesting phycobiliprotein family, present in red algae.
Therefore, the correct answer is option C.