Tag: metabolism, cell respiration, and photosynthesis

Quizzes (10) Questions (154)

Questions Related to metabolism, cell respiration, and photosynthesis

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

Which "photosynthetic bacteria" possess both PS I and PS II

  1. Purple sulphur bacteria.

  2. Cyanobacteria.

  3. Purple nonsulphur bacteria.

  4. Green sulphur bacteria.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photosynthetic bacteria posses only one type of photosystem and are mostly anaerobic and contains two type of pigment bacteriochlorophylls and bacterioviridin while cyanobacteria or blue-green algae posses two photosystems  PS I and PS II.

So the correct option is 'Cyanobacteria'.

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

PS I has

  1. More chlorophylls and more accessory pigments

  2. More chlorophylls and less accessory pigments

  3. Less chlorophylls and more accessory pigments

  4. Less chlorophylls and less accessory photosynthetic pigments
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photosystem I is one of the two membrane-bound photosystems of plants, algae and cyanobacteria that facilitate light-determined electron transport from water to NADPH. It utilizes absorbed light for electron transport from plastocyanin on the lumenal side to ferredoxin on the stromal side of the thylakoid membrane. In plants, this special integral membrane complex consists of more than 15 protein subunits, approximately 175 chlorophyll molecules, 2 phylloquinones and 3 Fe$ _4$S$ _4$ clusters. Whereas Photosystem II (of cyanobacteria and green plants) is as many as 35 chlorophyll a, 12 beta-carotene, two pheophytins, two plastoquinone, two heme, one bicarbonate, 20 lipid molecules and other ionic clusters. Thus Photosystem I contains more chlorophylls and accessory pigments.

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

DCMU inhibits

  1. PS II

  2. PS I

  3. Destroys chloroplast

  4. Inhibits oxidative phosphorylation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DCMU or Dichlorophenyl dimethyl urea inhibits PS II in photosynthetic plants by blocking electron transfer from plastoquinone to cytochrome. DCMU binds to and blocks the site of plastoquinone, thus hinders the path and growth of plants. It is used as herbicide and algicide. It is also used in studying photosynthetic activity.

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

Photosynthesis II is concerned with

  1. Photolysis of water

  2. Flowering
  3. Reduction of CO$ _2$

  4. Release of energy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Being a light reaction, non-cyclic photophosphorylation occurs in the thylakoid membrane. First, a water molecule is broken down into 2H+ + 1/2 O2 + 2e− by a process called photolysis (or light-splitting). The two electrons from the water molecule are kept in photosystem II, while the 2H+and 1/2O2 are left out for further use. Then a photon is absorbed by chlorophyll pigments surrounding the reaction core center of the photosystem. The light excites the electrons of each pigment, causing a chain reaction that eventually transfers energy to the core of photosystem II, exciting the two electrons that are transferred to the primary electron acceptor, pheophytin. The deficit of electrons is replenished by taking electrons from another molecule of water. 


So, the correct option is 'Option A'.

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

PS I is inactive at

  1. 550 nm

  2. 680 nm

  3. 690 nm

  4. 780 nm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A) PS I can funtion at wavelengths of 700 nm or less. So, it will be active at 550 nm. But its maximum activity is at 700 nm.
B) It will be active at 680 nm.
C) It will be active at 690 nm.

D) PS I cannot function at wavelengths greater than 700 nm.
So the correct answer is '780 nm'.

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

A photosystem Contains

  1. pigments, a reaction centre, and an electron acceptor
  2. ADP1 P1 and hydrogen ions $(H^+)$

  3. protons, photons and pigments

  4. both (b) and (C)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Photosystems refer to PSI and PSII. Photosystem II contains chlorophyll a, as well as up to 50% chlorophyll b. It probably evolved later as a supplement to Photo I. It is needed to capture enough energy to do the biosynthetic reactions of the dark reaction. Its reaction centre is a molecule called P680 which absorbs light maximally at 680 nm. Similarly, PSI or P700 absorbs light at 700nm. A reaction centre comprises several (>10 or >11) protein subunits, that provide a scaffold for a series of cofactors. The cofactors can be pigments (like chlorophyll, pheophytin, carotenoids), quinones, or iron-sulfur clusters and electron acceptors for transduction in the electron transport chain. 

So, the correct option is, 'pigments, a reaction centre, and an electron acceptor'.

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

The active component of photosystem-I composed of

  1. chlorophyll-a with absorption peak at 680 nm

  2. chlorophyll-a with absorption peak at 700 nm

  3. chlorophyll-b with absorption peak at 680 nm

  4. chlorophyll-a chlorophyll-b with absorption peak at 700 nm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The reaction center of photosystem-I is composed of two chlorophyll molecules and is therefore referred to as a dimer. The dimer is composed of one chlorophyll a molecule and one chlorophyll a' molecule with absorption peak at 700 nm.
Thus, the correct answer is 'chlorophyll a with absorption peak at 700 nm.'
Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

The product of the light reaction of photosynthesis which is not common between cyclic and non-cyclic photophosphorylation and is not utilised in the Calvin cycle is 

  1. O$ _2$

  2. ATP
  3. $NADPH _2$
  4. O$ _2$ and ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In cyclic phosphorylation, oxygen is not evolved as the by-product where as, oxygen is evolved as a by-product during non-cyclic phosphorylation. Calvin cycle is the second stage of photosynthesis in which carbon atoms from carbon dioxide are combined, using the energy in ATP and NADPH, to make glucose.

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

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

How many quanta of lights are required to evolve one oxygen molecule in photosythesis?

  1. Three

  2. Eight

  3. Four

  4. Two
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
 The quantum of light required in photosynthesis is 8 photons for one molecule of oxygen to be evolved. In this, 4 photons are required by photosystem II and 4 by photosystem I. The equation for the same is, 
2 x 2H$ _2$O --> 4H$^+$ + O$ _2$ + 4 electrons. 
Thus, the correct answer is 'Eight.'
Multiple choice botany metabolism, cell respiration, and photosynthesis light dependent or hill reaction phases of photosynthesis emerson's experiments & hill's reaction

During the light phase of photosynthesis .......... is oxidized and .......... is reduced.

  1. $CO _2$ and Water
  2. Water and $CO _2$
  3. Water and $NADP$
  4. $NADPH _2$ and $CO _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The light reaction takes place in thylakoid discs. There, water is oxidized and oxygen is released. The hydrogen is accepted by $NADP$ and hence get reduced to $NADPH _2$. 

So the correct answer is 'water and $NADP$' respectively.