Tag: modern concept of photosynthesis

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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.

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

Which of the following pigment is soluble in water?

  1. Chlorophyll

  2. Carotene

  3. Anthocyanin

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

Anthocyanins are water-soluble vacuolar pigments, that may appear red, purple, or blue depending on the pH. Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits.

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

Photolysis of water involves

  1. Excitement of water

  2. Evolution of oxygen

  3. Breakdown of water by light
  4. Splitting of water into its ions, $H^+$ and $OH$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Photolysis, as the name suggests, is the breakdown of water in the presence of sunlight to form H⁺ and  O₂ and electron. This takes place during the light phase of photosynthesis in the PS-II. This creates the oxygen which is the net product of photolysis.

So, the correct option is 'Breakdown of water by light'

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

Source of protons within the chloroplasts is

  1. Water

  2. Excited chlorophyll

  3. Carbon dioxide

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

Chemiosmotic hypothesis explains how ATP is synthesized in the chloroplast. ATP synthesis is linked to the development of a proton gradient across the membrane of the thylakoid of chloroplast and proton accumulation is towards the inside of the membrane i.e., in the lumen. Source of protons within the chloroplasts is water. The splitting of water molecule takes place on the inner side of the membrane and so the protons (hydrogen ions) are produced, they accumulate within the lumen of the thylakoids. Thus, the correct answer is option A.

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

Which of the following helped in confirming that oxygen evolved in photosynthesis comes from water?

  1. $H _2 \,\,\, ^{18}O$
  2. $^{14}CO _2$
  3. $^{15}NO _3$
  4. $^{3}H _2O$.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the process of photosynthesis, water acts as a stable oxygen donor. To prove the theory radioisotopic technique was used. 

Instead of the normal oxygen, the radioisotope was taken. It was seen that after the oxidation of water, the oxygen formed was ¹⁸O₂.
So, the correct option is '¹⁸O'

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

The evidence that during photosynthesis oxygen comes from water

  1. Photosynthetic bacteria employ $H _2S$ and $CO _2$ to form carbohydrates, water and sulphur.

  2. Isolated illuminated chloroplasts release oxygen if provided with potassium ferrocyanide.
  3. Isotopic $^{18}O$ provided as $H _2\,\, ^{18}O$ appears as $^{18}O _2$ liberated in photosynthesis.

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

A)In 1930, C.B.Van Niel proved that the sulphur bacteria use H$ _2$S and CO$ _2$ to synthesize carbohydrates.

B)When an isolated chloroplast is placed in potassium ferrocyanide it reacts with copper to make a complex and water is split to release oxygen.
C)In 1942 Ruben and Kamen using Chlorella algae prove that oxygen in photosynthesis come out during slitting of water by using an isotope of oxygen in water i.e.,$H _2^ {18}O$.
So, the correct option is 'All the above.'