Tag: metabolism, cell respiration, and photosynthesis
Questions Related to metabolism, cell respiration, and photosynthesis
The function of light in photosynthesis is
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photolysis of water
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assimilation of carbon dioxide
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production of organic food
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activation of enzymes
Synthesis of an assimilatory power takes place in _____________ phase of photosynthesis.
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Light phase
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Dark phase
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Glycolysis
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All the above
Which statement are not true for photosynthesis?
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$CO _2$ reduction occur in dark reaction
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$H _2O$ oxidation occur in light reaction
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Light reaction is an enzymatic phase of photosynthesis
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Dark reaction may occur in dark if light reaction products are available there
The overall function of light-dependent reactions is to capture the energy from the light for the generation of ATP and NADPH molecules. The dark reactions of the C$ _{3}$ cycle utilize the energy from short-lived electronically excited carriers to convert CO$ _{2}$ & H$ _{2}$O into glucose catalyzed by the enzyme RuBisCo, and this constitutes carbon fixation and makes it the enzymatic phase.
Which one is not included in photochemical phase?
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Light absorption
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Photosphorylation
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${ H } _{ 2 }O$ splitting
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${ CO } _{ 2 }$ reduction
- The photochemical step is dependent upon light, therefore it is also called as Light or Hill reaction. It involves the following reactions:
- Photolysis of water: It is the phenomenon of breaking up of water into hydrogen and oxygen in the illuminated chloroplasts
- Production of assimilatory power: While passing over cytochrome complex, the electron loses sufficient energy for the creation of proton gradient and synthesis of ATP from ADP and inorganic phosphate. The process is called photophosphorylation
- So, the correct option is 'CO2 reduction'.
Chlorophylls absorb visible light of wavelengths
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400-500 nm only
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300-400 nm only
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600-800 nm only
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400-500 nm and 600-700 nm.
Chlorophyll present in the plants can absorb the the wavelength of both blue and red regions of VIBGYOR which ranges from 400-500 nm and 600-700 nm respectively. It reflects the green light range of 500-600 nm hence the leaves appear green.
Which one directly transfers electrons to $NADP^+$ during light reaction?
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PS I
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PS II
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Cytochromes
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Plastocyanin.
The light-dependent reactions start in photosystem II (PSII). When the pigment in the reaction centre of PS II i.e, P$ _{680}$ absorbs a photon, an electron in this molecule gets excited and transferred to a primary electron acceptor, Pheophytin and then go through molecules in a series of redox. The electron flow goes from PSII to cytochrome b6f complex than to PSI. In PSI, the electron is finally accepted by NADP. Thus photosystem I in light-dependent reaction directly transfers electrons to NADP.
Light energy is converted into chemical energy through the formation of
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$NADPH _2$
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$ATP$
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$ATP$ and $NADPH _2$
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None of the above.
In the light reactions of photosynthesis,
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PS I produces strong oxidant while PS II a strong reductant.
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PS I produces strong reductant $NADPH$ while PS II a strong oxidant.
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PS I emits electrons for PS II.
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PS I produces ATP which is not formed by PS II.
PS I: This system produces a strong reductant which reduces ${NADP}^+$ to $NADPH$.
Photosynthesis is considered as an oxidation reaction, because
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$CO _2$ is oxidised
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$H _2O$ is oxidised
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$O _2$ is released
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$(CH _2O)$ is oxidised.
A) Carbon dioxide is reduced, not oxidised.
B) Water is oxidised to form protons and release oxygen. ${ H } _{ 2 }O\longrightarrow { O } _{ 2 }+{ 2H }^{ + }$
D) ${ CH } _{ 2 }O$ does not undergo oxidation.
So the correct answer is '${ H } _{ 2 }O$ is oxidised'.
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approximates the action spectrum of photosynthesis
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shows that some colours of light are absorbed more than others
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explains why chlorophyll is a green pigment
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all of the above are correct
Green plants are green because they contain a pigment called chlorophyll as in the absorption spectra, chlorophyll absorbs light in the red (long wavelength) and the blue (short wavelength) regions of the visible light spectrum. The green light is not absorbed but reflected, making the plant appear green. An absorption spectrum shows all the light typically absorbed by a leaf. An action spectrum, meanwhile, shows all the light that is actually used for photosynthesis. The similarity of the action spectrum of photosynthesis and the absorption spectrum of chlorophyll tells us that chlorophyll is the most important pigments in the process. The spectra are not identical, though, because carotenoid, which absorbs strongly in the blue, play a role as well.