Plant Physiology

Julius Von Sachs is known for first demonstrating hydroponics, the method of growing plants without soil, using only water-based nutrient solutions. Thus, the correct answer is (Julius Von Sachs).

Let’s evaluate each statement:
- (a) True: When protons (H ) are pumped out of guard cells, it leads to an increase in pH inside the cell due to loss of acidity.
- (b) False: Efflux of K and Cl increases the water potential (i.e., becomes less negative), causing water to exit guard cells, resulting in stomatal closure.
- (c) True: In darkness, guard cells lose K and Cl , leading to water loss and stomatal closure.
- (d) True: ABA (abscisic acid) triggers the efflux of K , contributing to stomatal closure under stress conditions like drought.
Hence, the correct statements are a, c, and d.

In dorsiventral (dicotyledonous) leaves, the vascular bundles are arranged such that the xylem is oriented towards the upper side, i.e., the adaxial (upper) epidermis, and the phloem is directed towards the lower side, i.e., the abaxial (lower) epidermis.
This orientation supports optimal transport of water to photosynthetic cells on the upper side of the leaf while transporting the synthesized food from the lower phloem side.
Hence, in a dorsiventral leaf, xylem lies towards the adaxial (upper) epidermis.

In C\textsubscript{4} (Hatch-Slack) pathway: \begin{itemize} \item OAA (Oxaloacetic acid) is formed in mesophyll cells. Hence, statement III is correct. \item PEP is the primary CO\textsubscript{2} acceptor and is present in mesophyll cells, not bundle sheath. Hence, IV is also correct. \item Statement I is incorrect because mesophyll cells in C\textsubscript{4} plants do have RuBisCO but it functions predominantly in bundle sheath cells. \item Statement II is incorrect because PEP carboxylase is found in mesophyll cells, not in bundle sheath. \end{itemize}

Step 1: Evaluate the Assertion (A).
The plant vacuole stores ions, nutrients, and waste, typically having a higher solute concentration than the cytoplasm. This helps maintain turgor pressure and store materials, while the cytoplasm has a lower concentration due to its metabolic role.
Conclusion: Assertion (A) is true.
Step 2: Evaluate the Reason (R).
The tonoplast, i.e., the vacuolar membrane, contains proton pumps (e.g., H\textsuperscript{+}-ATPases) that generate a proton gradient. This gradient drives the active transport of ions and other materials into the vacuole against their concentration gradient. This process is well-documented in plant cells. Conclusion: Reason (R) is true.
Step 3: Determine if R explains A.
The higher concentration in the vacuole (A) is due to the tonoplast’s active transport of ions and materials against the concentration gradient (R). This mechanism directly explains the concentration difference.
Conclusion: R explains A.
Step 4: Check the options.
Option (1) matches: (A) and (R) are true, and (R) explains (A).
Step 5: Verify option (4) as requested.
Option (4) is: (A) is false, but (R) is true:
% Option (A) is true (vacuole concentration is higher), not false.
% Option (R) is true (tonoplast facilitates active transport).
Option (4) is incorrect since (A) is not false.
Final Answer: (1) (A) and (R) are true, (R) is correct explanation for (A).

Plasmolysis is the process in which cells lose water in a hypertonic solution, leading to shrinkage of the protoplast.

Explanation: In the translocation mechanism, sugar is loaded into the phloem at the source (usually the leaf), causing water to enter by osmosis due to increased solute concentration. This generates pressure that drives the flow toward sink tissues. Hence, the correct flow is from the leaf, where sugar enters sieve tubes, followed by water movement through osmosis.

A. Nucleic acids structure — IV. Phosphorous: Phosphorus is a key element in nucleotides and thus in the structure of nucleic acids.
B. Synthesis of nucleic acid — I. Magnesium: Magnesium ions are essential cofactors for enzymes involved in nucleic acid synthesis.
C. Stabilize protein structure — II. Sulphur: Sulphur helps in forming disulfide bridges, which stabilize protein structure.
D. Catalase — III. Iron: Iron is a component of catalase, which is an iron-containing enzyme.

Step 1: Analyze each item in List-I and match with List-II and List-III.
I. Stroma of the chloroplast
The stroma contains chloroplast DNA (circular, double stranded) and protein synthesis machinery. The “80 S ribosomes” may be a typo (chloroplasts have 70 S ribosomes), but we match based on the options.
Match: I Circular, double stranded DNA, 80 S ribosomes.
II. Chromoplasts
Chromoplasts store carotenoid pigments (yellow/orange colors). Carotenoids are lipid-soluble, not water-soluble, but we match based on the given options.
Match: II Carotenoid pigments, Water soluble.
III. Chloroplast
Chloroplasts have grana thylakoids (site of light reactions) and stroma lamellae (connecting grana).
Match: III Grana thylakoids, Stroma lamellae.
IV. Microbodies
Microbodies include glyoxysomes (e.g., in seeds for fat-to-sugar conversion) and peroxisomes (e.g., in photorespiration).
Match: IV Glyoxysomes, Peroxisomes.
Step 2: Compile the matches.
I: Circular, double stranded DNA, 80 S ribosomes.
II: Carotenoid pigments, Water soluble.
III: Grana thylakoids, Stroma lamellae.
IV: Glyoxysomes, Peroxisomes.
Step 3: Check the options.
Option (3) III, IV matches:
III: Grana thylakoids, Stroma lamellae (chloroplast).
IV: Glyoxysomes, Peroxisomes (microbodies).
Step 4: Verify option (4) as requested.
Option (4) is IV, I:
IV (Glyoxysomes, Peroxisomes): Correct.
I (Circular DNA, 80 S ribosomes): Stroma has circular DNA, but 80 S ribosomes are incorrect (chloroplasts have 70 S).
Option (4) is less accurate due to the ribosome mismatch.
Final Answer: (3) III, IV.

Explanation: Adhesion refers to the attraction between water molecules and polar surfaces, such as the walls of xylem vessels (tracheary elements). This helps in upward movement of water along with cohesion forces among water molecules.

Step 1: Analyze Assertion (A)
In grasses, bulliform cells are specialized epidermal cells that help in leaf rolling during water stress to reduce transpiration. Hence, Assertion is correct. Step 2: Analyze Reason (R)
Bulliform cells are indeed large, empty, and colourless cells which enables them to collapse easily, causing leaf rolling. Hence, Reason is also correct. Step 3: Examine the explanation relationship
The Reason correctly explains the Assertion, as the structural nature of bulliform cells directly contributes to their water-saving function.