Plant Physiology Flashcards for NEET — 21 cards

First 8 of 21 Plant Physiology flashcards

Read the question, answer it in your head, then open the answer to check yourself.

1. Card 1 of 21

   Define Respiratory Quotient (RQ) and state the typical RQ values for Carbohydrates and Fats.

   Hint: Proteins have an RQ of roughly 0.9.

   Show answerHide answer

   Answer

   $RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$. RQ for Carbohydrates = 1.0. RQ for Fats = Less than 1 (approx. 0.7).

2. Card 2 of 21

   What are the primary roles of Chlorophyll $a$ and the accessory pigments (Chlorophyll $b$, Xanthophylls, Carotenoids)?

   Hint: Accessory pigments act like an antenna complex.

   Show answerHide answer

   Answer

   Chlorophyll $a$ is the chief pigment that acts as the reaction centre. Accessory pigments absorb broader wavelengths of light, transfer the energy to Chlorophyll $a$, and protect it from photo-oxidation.

3. Card 3 of 21

   What are the end products of the 'Light Reaction' (Photochemical phase) of photosynthesis?

   Hint: These are utilized in the dark reaction (biosynthetic phase) to fix carbon dioxide.

   Show answerHide answer

   Answer

   ATP, NADPH, and $O_2$.

4. Card 4 of 21

   According to the Chemiosmotic Hypothesis, what three events contribute to the proton gradient across the thylakoid membrane?

   Hint: Result: High proton concentration in the lumen, low in the stroma.

   Show answerHide answer

   Answer

   1. Splitting of water (releases protons into the lumen). 2. Movement of electrons through the photosystems (plastoquinone pumps protons from stroma to lumen). 3. NADP reductase reaction (removes protons from the stroma).

5. Card 5 of 21

   Name the three crucial stages of the Calvin Cycle ($C_3$ pathway). Which is the most crucial?

   Hint: Requires 3 ATP and 2 NADPH per $CO_2$ fixed.

   Show answerHide answer

   Answer

   1. Carboxylation (Fixation of $CO_2$ into a stable organic intermediate - the most crucial step). 2. Reduction (Formation of glucose). 3. Regeneration (Recovery of the $CO_2$ acceptor, RuBP).

6. Card 6 of 21

   What is the primary $CO_2$ acceptor and the first stable product in the $C_4$ pathway?

   Hint: This initial fixation occurs in the mesophyll cells, where RuBisCO is absent.

   Show answerHide answer

   Answer

   Primary acceptor: Phosphoenolpyruvate (PEP), a 3-carbon molecule. First stable product: Oxaloacetic acid (OAA), a 4-carbon acid.

7. Card 7 of 21

   What is 'Kranz anatomy' and in which type of plants is it found?

   Hint: Bundle sheath cells have thick, agranal chloroplasts and are impervious to gaseous exchange.

   Show answerHide answer

   Answer

   Kranz anatomy is a specialized leaf structure where bundle sheath cells form concentric layers (wreath-like) around vascular bundles. Found in $C_4$ plants (e.g., Maize, Sorghum).

8. Card 8 of 21

   State Blackman's Law of Limiting Factors.

   Hint: It is the factor which directly affects the process if its quantity is changed.

   Show answerHide answer

   Answer

   If a chemical process is affected by more than one factor, then its rate will be determined by the factor which is nearest to its minimal value (the limiting factor).