Tag: phases of photosynthesis

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Questions Related to phases of photosynthesis

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Light reaction or photochemical phase includes
I. light absorption
II. water splitting
III. oxygen release
IV. ATP and NADPH formation
Choose the correct option.

  1. I, II and IV

  2. I, II and III

  3. I, III and IV

  4. I, II, III and IV
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Light reaction or photochemical phase is called as photophosphorylation or Hill's reaction. It includes non-cyclic phosphorylation and cyclic phosphorylation. During this reaction, the light is absorbed by the chlorophyll and water splits into H$ _2$ and 1/2O$ _2$. Oxygen is released as the byproduct of the reaction along with formation of carbohydrate. Along with oxygen, ATP and NADPH are also formed.

Thus, the correct answer is 'I, II, III and IV.'

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Which of the following events does not occur during the light reaction of photosynthesis?

(1) Photolysis of H$ _2$O
(2) Reduction of NADPH to NADP+
(3) Evolution of molecular oxygen
(4)Synthesis of assimilatory powers
(5)Conversion of CO$ _2$ to carbohydrates

  1. 1 and 2 only

  2. 2 and 5 only

  3. 2 ,3 and 5 only

  4. 1, 3 and 4 only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The events occurring in the light reaction of the photosynthesis are:

  1. Absorption of sunlight by the chlorophyll and release of the electron to the carriers.
  2. Photolysis of water to provide the electron to the chlorophyll.
  3. The release of molecular oxygen due to the photolysis of water.
  4. Assimilatory powers are synthesized in the form of ATP and NADPH
  5. Reduction of NADP$^{+}$ occurs to form NADPH
The oxidation of NADPH and conversion of CO$ _{2}$ occurs during the dark reaction.

Hence, the correct answer is '2 and 5'.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Which of the following is not correct regarding light compensation point?

  1. This condition occurs usually in evening and morning

  2. Net production is equal to respiration consumption

  3. Gross production is more than Net production

  4. There is no gaseous exchange with environment by plant
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The (light) compensation point is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration.
  •  When the rate of photosynthesis equals the rate of respiration or photorespiration, the compensation point occurs.
  • The compensation point is reached during early mornings and late evenings.
  • Hence This condition occurs usually in evening and morning is not correct regarding light compensation point.
  • So, the correct answer is 'Option A'.
Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

The site of light reaction is

  1. Granum

  2. Stroma

  3. Unit membrane

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

The light-dependent reactions take place on the thylakoid membranes. The inside of the thylakoid membrane is called the lumen, and outside the thylakoid membrane is the stroma, where the light-independent reactions take place. Thylakoids are arranged in stacks called grana.
The chloroplast matrix is called the stroma and contains enzymes that catalyze the light-independent reactions of photosynthesis. But stroma is not the site for light reactions. 
Stromal lamellae connect two or more grana to each other. In this way, the lamellae act as a skeleton of the chloroplast, maintaining efficient distances between the grana, thereby maximizing the overall efficiency of the chloroplast. 
Each chloroplast is enclosed by (surrounded) a chloroplast envelope or unit membrane consisting of three layers. Overall the chloroplast envelope is semi-permeable. It is permeable to glucose molecules and certain ions including Fe$^{2+}$and Mg$^{2+}$, and oxygen and carbon dioxide.

So, the correct answer is option A.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

In photosynthesis, the energy is transferred in 

  1. One energy step

  2. Small energy steps

  3. Large energy steps

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In photosynthesis, energy is transferred in small energy steps. Photosynthesis is the primary energy source for most of the biosphere. Even though photosynthetic light harvesting complexes display great variety in their design and function, many of them are membrane proteins that comprise of pigment antenna arrays, which absorb light and transfer the resulting electronic excitation to a reaction center, which in turn converts this excitation energy to a charge gradient across the membrane and help to synthesise ATP. This energy is utilized in dark phase for synthesizing glucose.

So, the correct answer is option B.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Translocation of sugar in angiosperms occur in the form of 

  1. Glucose

  2. Starch

  3. Lactose

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

Translocation is the process of movement of nutrients from leaves to other parts of plant. During the process of photosynthesis, carbohydrates (sugars) specifically sucrose is synthesized in the cytosol of cell and then translocated to other demanding parts of plant. Sucrose is complex, less reactive and energy efficient sugar so, angiosperms and other plants translocate sugar in the form of sucrose.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

Light reaction of photosynthesis results in products like

  1. Starch and O$ _2$.
  2. ADP, NADPH + H$^+$ and electrons.
  3. ATP, NADPH + H$^+$ and O$ _2$.
  4. Glucose and O$ _2$.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The light reaction takes place in the grana of the chloroplast. This is also known as the cyclic and non-cyclic form of photophosphorylation in which the ATP and NADPH + H$^+$ are produced. In the non-cyclic photophosphorylation, there is splitting of the water molecules which results in the production of oxygen molecule. 

Thus, the correct answer is option C. 

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

ATP formation during photosynthesis is known as

  1. Phosphorylation.

  2. Photophosphorylation.

  3. Oxidative phosphorylation.

  4. Substrate level phosphorylation.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photophosphorylation refers to the use of light energy from photosynthesis to ultimately provide the energy to convert ADP to ATP, thus replenishing the universal energy currency in living things. Light generally provides energy to form the bonds. It is an endothermic reaction.

So, the correct answer is option B.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

What percentage of usable radiant energy entering a reaction site of photosynthesis is converted to potential energy _________.

  1. 10%

  2. 20%

  3. 35%

  4. 42%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In photosynthesis, only a small fraction of the total incident solar energy is converted into chemical energy. Scientific literature typically cites values in the range of 1% to 5% for overall efficiency, but specific textbook contexts sometimes use 35% as a theoretical maximum for specific wavelengths or specific reaction steps.

Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

In light phase of photosynthesis there is formation of

  1. $ATP$
  2. $NADPH _2$
  3. Both $ATP$ and $NADPH _2$

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

In light-dependent reactions, the energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of electron carrier molecules like ATP and NADPH.

Light energy is harnessed in Photosystems I and II, both of which are present in the thylakoid membranes of chloroplasts.
Just as the name implies, light-dependent reactions require sunlight. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy, in the form of the electron carrier molecule NADPH (nicotinamide adenine dinucleotide phosphate) and the energy currency molecule ATP (adenosine triphosphate). The light-dependent reactions take place in the thylakoid membranes in the granum (stack of thylakoids), within the chloroplast.