Photosynthesis in Higher Plants (VSAQs)
Botany-2 | 4. Photosynthesis In Higher Plants – VSAQs:
Welcome to “VSAQs” in “Chapter 4: Photosynthesis In Higher Plants”. This page covers the most important VSAQs from previous exams. Use these concise answers to strengthen your understanding and get ready to do well in your final exams.
VSAQ-1: Name the Processes Which Take Place in the Grana and Stroma Regions of Chloroplasts
Inside chloroplasts, the grana and stroma are two key areas where important processes of photosynthesis happen. The grana are stacks of thylakoid membranes, and here, the light reaction of photosynthesis takes place. This is the part where light energy from the sun is captured and converted into chemical energy. Think of it as solar panels on a house that convert sunlight into usable energy.
In contrast, the stroma is the fluid-filled space surrounding the grana. It’s in this area that the dark reaction, also known as the Calvin cycle or carbon fixation, occurs. This process uses the chemical energy produced in the light reaction to convert carbon dioxide from the air into glucose, a type of sugar that plants use as food. Imagine the stroma as a kitchen where the ingredients (energy) are used to cook a meal (glucose).
VSAQ-2: Where Does the Photolysis of H₂O Occur? What Is Its Significance?
Photolysis of water happens in the grana of chloroplasts, specifically during the light reaction of photosynthesis. In this process, water molecules (H₂O) are split to release oxygen as a by-product. This release of oxygen is incredibly important as it provides the oxygen we breathe and supports life on Earth. It’s like a tree exhaling oxygen, which is essential for our survival and that of other organisms.
VSAQ-3: Distinguish Between Action Spectrum and Absorption Spectrum
The action spectrum and absorption spectrum are both crucial for understanding how plants capture light energy, but they focus on different aspects.
The action spectrum measures the rate of photosynthesis at various light wavelengths. It shows which wavelengths of light are most effective for driving photosynthesis. Imagine a gardener who tests different types of light to see which one helps plants grow best.
On the other hand, the absorption spectrum measures how well different pigments (like chlorophyll) absorb light at different wavelengths. It tells us which light wavelengths are absorbed most effectively by the pigments. This is similar to knowing which colors of light are best at making a particular type of solar panel work efficiently.
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?
- Products that Drive Calvin Cycle: The Calvin cycle is driven by ATP and NADPH.
- Regeneration: These ATP and NADPH molecules are regenerated during the light reaction phase of photosynthesis.