Tag: photosystems

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Questions Related to photosystems

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Hill reaction completes in the

  1. Light.

  2. Dark.

  3. Both A and B.

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

Hill reaction occurs in light or can be called as light reaction. Hill first of all demonstrated that isolated chloroplasts can release oxygen in presence of suitable inorganic electron acceptors. The Hill reaction is the light-driven transfer of electrons from water to Hill reagents (non-physiological oxidants) against a chemical potential gradient. 

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Which element is essential for photolysis of water?

  1. Nitrogen

  2. Chlorine

  3. Carbon

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

Photolysis of water refers to the light dependent split of water, which occurs during the light phase of photosynthesis in the chloroplast. The minerals essential for the process of photolysis are calcium, chlorine and manganese.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Which of the following element is essential for photolysis of water?

  1. Fe

  2. Mg

  3. Mn

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

Photolysis of water occurs during non cyclic electron flow. During non cyclic electron flow, the ultimate source of electrons is water. The water molecule is split in a process, called as photolysis. The electrons are ultimately used in reduction of oxidised NADP to form reduced $NADPH _2$. The oxygen is released as a byproduct of photosynthesis. The mineral ions essential for photolysis are manganese, chlorine and calcium.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Oxygen released during photosynthesis comes from

  1. Water

  2. Carbon dioxide

  3. Chloroplast

  4. Chlorophyll
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Photolysis takes place in the light dependent reaction of the photosynthesis. The reaction can be represented as:
H$ _2$O + 2 photons --> 2 e$^-$ + 2H$^+$ + O. 
Here, the electrons released are accepted by the photosystem to fulfill the electron gap. The last electron acceptor is the oxygen and thus, the oxygen is liberated from the water molecule. The experiments conducted by Samuel Ruben and Martin Kamen by using radioactive isotopes helped to prove that the oxygen liberated during photosynthesis came from photolysis the water.
Thus, the correct answer is option A.
Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

In photosynthesis, there is an (a)

  1. Reduction of $H _{2}O$.
  2. Oxidation of $H _{2}O$.
  3. Oxidation of $CO _{2}$.
  4. Oxidation of $NO _{2}$.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The process of photosynthesis occurs in two stages light reaction and dark reaction. The light reaction involves oxidation of water (photolysis i.e., light dependent splitting of water), which releases oxygen as a by product. The photolysis of water also releases electrons, which are used to drive electron flow in the thylakoid membrane ultimately this electron flow results in the synthesis of ATP and $NADPH _2$. These products ATP and $NADPH _2$ are used up subsequently in the process of dark reaction.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Manganese, calcium and chloride ions present in PS-II play an important role in.

  1. Absorption of light
  2. $CO _2$ assimilation

  3. Photolysis of water

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

As we know that the PS-II or photosystem II constantly supplies electrons during the light reaction.

This is possible because of the splitting of that is associated with PS-II. The water splits into H⁺, (O) and electrons. The ions Manganese, Calcium and chloride that are present plays an important role in this.

2H₂O---------------> 4H⁺ + O₂ + 4e⁻

So, the correct option is 'Photolysis of water.'

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Manganese and chlorine is required in plants for

  1. Nucleic acid synthesis

  2. Plant cell wall formation

  3. Photolysis of water during photosynthesis

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

The process of water dissociation during photosynthesis is called as photo-oxidation of water. It requires the presence of Mn++, Ca+ and Cl- , a water oxidising enzyme and an unknown substance Z.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

Water has high specific heat due to

  1. Its dipole nature

  2. Smaller angle between hydrogen atoms and oxygen atom

  3. Hydrogen bonds amongst molecules

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

Water has high specific heat due to hydrogen bonds amongst molecules. Due to high specific heat, water minimizes changes in temperature. Hydrogen bonds are broken when it absorbs heat. Similarly, hydrogen bonds are formed when water releases energy in the form of temperature. This decreases the temperature of water.

Thus, the correct answer is option C.

Multiple choice botany photosynthesis modern concept of photosynthesis photosystems photosynthesis in higher plants

The source of $O _{2}$ liberated in photosynthesis in green plants is

  1. Photosynthetic enzyme

  2. Carbohydrate present in leaf

  3. Water

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

When the chlorophyll molecule is excited by light, the energy level of an electron in its structure is boosted to a higher energy level and this excited chlorophyll moves rapidly the reaction center of the photosystem I where it transfers its extra energy to an electron which is then expelled from the reaction center and is accepted by the first member of a chain of electron carriers and ultimately reaches NADP$^+$, reducing it to NADPH. The reaction center has lost an electron and this electron hole is filled by stripping electrons from water which leaves hydrogen ion (H$^+$) and molecular oxygen (O$ _2$). The pathway of electrons from water to NADP$^+$ has Z shape called as Z scheme. 

Therefore, the correct answer is option C.