9 Most VSAQ’s of Photosynthesis in Higher Plants Chapter in Inter 2nd Year Botany (TS/AP)

2 Marks

VSAQ-1 : Name the processes which take place in the grana and stroma regions of chloroplasts.

Within the chloroplasts, two crucial processes occur in distinct regions. In the grana, the light reaction takes place, which is a pivotal part of the photosynthesis process. This is where light energy is captured and converted into chemical energy. On the other hand, in the stroma region, the dark reaction, also known as carbon fixation, occurs. This is where the Calvin cycle unfolds, utilizing the energy produced during the light reaction to convert carbon dioxide into glucose, a fundamental step in the overall process of photosynthesis.

VSAQ-2 : Where does the photolysis of H2O occur? What is its significance?

Photolysis of H2O occurs in the grana of chloroplasts during the light reaction of photosynthesis. Its significance lies in the release of oxygen as a by-product, which is crucial for sustaining life on Earth and contributes significantly to the production of atmospheric oxygen, essential for various organisms and the planet’s overall ecosystem.

VSAQ-3 : Distinguish between action spectrum and absorption spectrum.

  1. Action Spectrum:
    • Measures: Rate of photosynthesis at various light wavelengths.
    • Indicates: Efficiency of photosynthesis at each wavelength.
    • Purpose: Helps determine the most effective light wavelengths for driving photosynthesis.
  2. Absorption Spectrum:
    • Measures: Absorption of light by pigments (e.g., chlorophyll) at different wavelengths.
    • Indicates: Wavelengths absorbed most effectively by pigments, crucial for initiating photosynthesis.

VSAQ-4 : Define the law of limiting factors proposed by Blackman.

Blackman’s Law of Limiting Factors states that the rate of a biological process is primarily dictated by the factor that is most scarce or limiting, even if all other factors are abundantly available. In essence, this means that the process can only progress as swiftly as the limiting factor permits, irrespective of the abundance of other factors in the environment.

VSAQ-5 : What is the primary acceptor of CO2 in C3 plants? What is first stable compound formed in a Calvin cycle?

In C3 plants, the primary acceptor of CO2 is RuBP (Ribulose bisphosphate). The initial stable compound formed in the Calvin cycle is PGA (Phosphoglyceric acid).

VSAQ-6 : What is the primary acceptor of CO2 in C4 plants? What is the first compound formed as a result of primary carboxylation in the C4 pathway?

In C4 plants, the primary CO2 acceptor is PEP (Phosphoenolpyruvic acid). The first compound produced through primary carboxylation in the C4 pathway is OAA (Oxaloacetic acid).

VSAQ-7 : Which tissue transports photosynthatases? What experiment proves this?

Phloem is the tissue responsible for transporting photosynthetic products. This is proven by ringing or girdling experiments conducted on phloem, which demonstrate the role of phloem in the translocation of sugars and other organic materials within plants.

VSAQ-8 : How many molecules of ATP and NADPH are needed to fix a molecule of CO2 in C3 plants? Where does this process occur?

In C3 plants, fixing a molecule of CO2 necessitates the utilization of 3 molecules of ATP and 2 molecules of NADPH. This process takes place in the stroma of chloroplasts.

VSAQ-9 : What products drive calvin cycle? What products regenerate them?

  1. Products that Drive Calvin Cycle: The Calvin cycle is driven by ATP and NADPH.
  2. Regeneration: These ATP and NADPH molecules are regenerated during the light reaction phase of photosynthesis.