CBSE Questions for Class 11 Medical Biology Photosynthesis In Higher Plants Quiz 15 - MCQExams.com

Photosynthetic algae carry out fixation of carbon dioxide into glucose wherein the first step includes carboxylation of RuBP into unstable 6C compounds which are immediately broken down into 2 molecules of 3C compounds called as phosphoglyceraldehyde (PGA). The follow-up reactions of Calvin cycle leads to the formation of one glucose molecule by three successive cycles. After five seconds, the radioactive carbon will be present in PGA only as the formation of glucose takes 3 successive Calvin cycles. Acetyl CoA is produced during cellular respiration of glucose, photosynthetic carbon is not incorporated into ATP and ADP. So, the correct answer is B.  

$$\textbf{Correct Option B}$$

$$\textbf{Solution}$$

$$\bullet$$ The plants in which there is a novel leaf anatomy along with modified gene expression are known to possess a distinctive Kranz leaf anatomy.

• Photosystem II has P$$_{680}$$ reaction centre wherein oxygen atoms of two water molecules bind to a cluster of manganese atoms. 
• These Mn atoms are associated with an enzyme that splits water, removes electrons one at a time. 
• After the removal of four electrons from the two water molecules, O$$_2$$ is released. Sunlight-driven splitting of water is called as photolysis. 
• Noncyclic photophosphorylation includes the flow of electron from PSII through quinone, cytochrome b6-f complex and plastocyanin to NADPH via PSI. 
• NADP reductase enzyme is located on the stromal side of PSI and catalyzes the reduction of NADP into NADPH. 
• Splitting of water and flow of electron through cytochrome b6-f complex add protons to thylakoid lumen. 
• These protons are transported which drives the synthesis of ATP. 

In an electron transport process, the excited electron from PS II  is accepted by primary acceptor quinone, which sends them to an electron transport system consisting of plastoquinone, cytochrome complex and plastocyanin. The excited electron absorbed by PS I reaction centre, then transfer to the ferredoxin (Fe), then the reduced Ferredoxin donates the electron to NADP$$^+$$. H$$_2$$O undergoes photo-oxidation or photolysis to provide the electrons to the PS II and to release the oxygen.

Hence, the correct answer is 'H$$_2$$O'.

In electron transport process the excited electron from P$$_6$$$$_8$$$$_0$$ is accepted by primary acceptor quinone, which sends them to an electron transport system consisting of plastoquinone, cytochrome complex and plastocyanin.

The excited electron absorbed by P$$_7$$$$_0$$$$_0$$ reaction centre, then transfer to the ferredoxin (Fe), then the reduced Ferredoxin donates the electron to NADP$$^+$$.

The NADP$$^+$$ takes electron from ferredoxin, protons from the medium and get reduced to NADPH in presence of enzyme ferredoxin- NADP- reductase.

Hence, the correct answer is 'NADP$$^+$$'.

C$$_4$$ plants can absorb CO$$_2$$ even in a much low CO$$_2$$ concentration while the C$$_3$$ plants fail to avail it. C$$_4$$ cycle is much more efficient photosynthetically.

Primary Carboxylation of phosphoenolpyruvate (PEP) to form oxaloacetic acid (a 4- carbon compound) in presence of enzyme phosphoenolpyruvate carboxylase (PEP carboxylase).

Photorespiration: It is inhibition of photosynthesis by high O$$_2$$ level. It was termed as Warburg effect. However, the inhibition was observed mostly in C$$_3$$ plants. The C$$_4$$ plants were hardly affected by varying O$$_2$$ concentrations.’

Hence, the correct answer is 'A'.

In the electron transport process, the excited electron from PS II  is accepted by primary acceptor quinone, which sends them to an electron transport system consisting of plastoquinone, cytochrome complex and plastocyanin.

The excited electron absorbed by PS I reaction centre, then transfer to the ferredoxin(Fe), then the reduced Ferredoxin donates the electron to NADP$$^+$$.

So, a- excited PS II, b- Quinone, c- plastoquinine, d- plastocyanin.

Hence, the correct answer is 'd'.

$$\textbf{Correct Option A}$$

$$\textbf{Solution}$$

$$\bullet$$ $$\textbf{Option A}$$  During the process of photosynthesis, the process of phosphorylation of ADP to form ATP in the presence of Sunlight is known as photophosphorylation. This option is correct.

$$\bullet$$ $$\textbf{Option B}$$  Kranz anatomy is a specific structure of leaves that are found in C4 plants. In this type of anatomy issues like mesophyll cell are collected to form a ring around the veins of the leaf. Some examples of C4 plants are Maize, papyrus. This is the correct option.

$$\bullet$$ $$\textbf{Option C}$$ During the Calvin cycle the NADPH is required for the conversion of free PGA molecules into molecules of 3 carbon sugar. There is no reduction of an NADP to NADPH in Calvin cycle. This option is incorrect.

$$\bullet$$ $$\textbf{Option D}$$ The magnesium ions are present in the porphrin head of chlorophyll. This option is wrong.

So, the correct options are a and b.

So, the correct option is A.