Biochemical tests for carbohydrates in root structure Y

Steps:

• Benedict's solution tests for reducing sugars, turning brick-red if present (+ result).
• Iodine solution tests for starch, turning blue-black if present (+ result).
• Root sections typically show Y as a non-storage tissue like xylem vessels, lacking sugars and starch.
• Thus, both tests yield negative results (-) for Y.

Why D is correct:

• D indicates both tests negative, matching Y's lack of reducing sugars and starch as per standard plant histology.

Why the others are wrong:

• A: Wrong; Y lacks sugars, so Benedict's should be negative.
• B: Wrong; Y lacks starch, so iodine should be negative.
• C: Wrong; Y lacks both, so iodine should be negative.

Final answer: D