Tag: photosystems

Questions Related to photosystems

In PS I, the reaction centre chlorophyll a has an absorption peak at

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. 650 nm

  2. 660 nm

  3. 680 nm

  4. 700 nm

Show answer
Correct Option: D
Explanation:
Photosystems are the protein complexes involved in photosynthesis. Each photosystem is characterized by the wavelength of light to which its reaction centre is most reactive. Photosystem I, reaction centre pigment chlorophyll a has absorption peak at 700nm. Thus photosystem I is also known as P$ _{700}$
So, the correct answer is '700 nm'

Consider the following.
a. Cytochrome $b6$
b. Cytochrome II f
c. Plastocynin
d. Plastoquinone
What is the correct sequence of these in the photo-induced electron carriers between PS$1$ to PS$2$ in photosynthesis?

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. $4, 1, 2, 3$

  2. $3, 4, 1, 2$

  3. $1, 2, 3, 4$

  4. $2, 3, 4, 1$

Show answer
Correct Option: A

In photosynthesis, during the operation of PS II, the cited $P680$ is rapidly photoxidised as it passes an electron _____________.

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. Carotene

  2. Ferridoxin

  3. Phaeophytin

  4. Phycoerythrin

Show answer
Correct Option: A

Which pigment system is inactivated in red drop?

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. PS-I and PS-II

  2. PS I

  3. PS II

  4. None

Show answer
Correct Option: C
Explanation:

  1. The fall in photosynthetic yield beyond the red region of the spectrum (680 runs) is called red drop.
  2. Reaction center of PS-2 is 680 while that of PA-1 is 700.
  3. So the psII system will be inactive.
So the correct option is PS II

PS II is physically located on which side of thylakoid membrane?

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. Inner side

  2. Outer sicde

  3. Within the lumen of thylakoid

  4. Position of PS II shifts from inner to outside

Show answer
Correct Option: A
Explanation:

Photosystem II or Pigment system II, a multiprotein complex involved in the non cyclic electron, proton translocation and photophosphorylation. It is located in the inner side of the thylakoid membrane.

So, the correct option is ‘Inner side’.

Choose the correct answer from the alternatives given.
Which of the following is a strong inhibitor of PS-II in photosynthesis

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. Dichlorophenyl dimethyl urea

  2. Ethylene

  3. Indole acetic acid

  4. Chloroform

Show answer
Correct Option: A
Explanation:

DCMU (Dichlorophenyl dimethyl urea) is a herbicide which most effectively inhibits PSII in photosynthesis by the stopping CO$ _2$ fixation, which is essential for photosynthesis.

Thus, the correct answer is 'Dichlorophenyl dimethyl urea.'

Which of the following is wrongly matched?

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. Sorghum - Kranz anatomy

  2. PEP carboxylase - Mesophyll cells

  3. Blackman - Law of limiting factors

  4. PS II - p700

Show answer
Correct Option: D
Explanation:

The core of PSII consists of a pseudo-symmetric heterodimer of two homologous proteins D1 and D2. The reaction center chlorophyll (or the primary electron donor) of photosystem II that is most reactive and best in absorbing light at wavelength of 680 nm. P680 is a group of pigments that are excitonically coupled or that act as if the pigments are a single molecule when they absorb a photon.

Thus, the correct answer is 'PS II - p700.'

PS II is located on ____________.
photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. Inner side of thylakoid membrane

  2. Outer side of thylakoid membrane

  3. Lumen of thylakoid membrane

  4. Stroma lamellae

Show answer
Correct Option: A
Explanation:

Photosystem I (Plastocyanin-ferredoxin oxidoreductase) is located in the membrane of stroma lamellae, while PSII  (water-plastoquinone oxidoreductase) is located in the grana region that is inner side of thylacoid membrane.

So, the correct answer is 'Inner side of thylakoid membrane'

During light reaction in photosynthesis, the following are formed. 
photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. ATP and sugar

  2. hydrogen,$ O _{2}$ and sugar

  3. ATP, hydrogen and $O _{2}$

  4. ATP, hydrogen and $O _{2}$ donor

Show answer
Correct Option: C
Explanation:

Light reactions occur inside thylakoids. It is dependent upon light. It involves photolysis of water (breaking of water into $H _{2}$ and $O _{2}$  and production of assimilation power (NADPH and ATP). Electron released during photolysis of water are  picked up by $P _{680}$ photocentre of photosystem II. From here electrons passes over series of carrier which include PQ, cytochrome b-f complex, and PC. While passing over cytochrome complex, the electron losses sufficient energy for creation of proton gradient and ATP from ADP and inorganic phosphate. From PC electron losses sufficient energy for creation of proton gradient and ATP from ADP and inorganic phosphate. From PC electron is picked by the trap center $P _{700} $of phtotsystem I, which pushes out electron after absorbing light energy. Electron passes over carriers Fes, ferredoxin and NADP reductase which gives electron to $NADP^+$ for combing with $H^+$ to produce NADPH.
$NADP^+ 2e^- + H^{+} \xrightarrow[NADP \,\, reductase]{} NADPH $ , So, the correct answer is 'ATP, hydrogen and O2'.

What of the following process happens in PS II?

photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

  1. ${ CO } _{ 2 }$ fixation

  2. ${ CO } _{ 2 }$ reduction

  3. Photolysis of H$ _2$O

  4. All of the above

Show answer
Correct Option: C
Explanation:

Photosystem II is the first protein complex in the light-dependent reactions of oxygenic photosynthesis and splitting of water is associated with it. Water is split into H+, [O] and electrons, creating O$ _{2}$ which is one of the net products of photosynthesis. The electrons needed to replace those removed from PS I are provided by PS II.

So, the correct option is 'Photolysis of H$ _{2}$O'.