Transportation in Plants (Xylem, Phloem) MCQs

Q1. Consider the following statements about transport in plants: (I) Xylem carries water and minerals upward. (II) Phloem transports food (translocation). (III) Xylem is made of living sieve tubes. Which of the above statement(s) is/are correct?

• A.None of these
• B.Only I and II
• C.Only I
• D.Only III

Answer: B. Only I and II

The idea this question leans on: Correct: I, II. That fits the listed correct option directly - Correct. As for the rest: option A) 'None of these' doesn't hold - Re-check each statement individually; option C) 'Only I' doesn't hold - Re-check each statement individually. Hence the answer is B) Only I and II.

Q2. Transpiration is greatest when the air is:

• A.dark and damp
• B.humid and still
• C.dry, warm and windy
• D.cold and humid

Answer: C. dry, warm and windy

Which principle settles this? An ionic bond forms when a metal donates electrons to a non-metal: e.g. Na -> Na+ + e-, Cl + e- -> Cl-, and Na+ + Cl- -> NaCl; the resulting solid is held by strong electrostatic attraction => this fixes the property asked in the stem; hence the answer = dry, warm and windy. Does that line up with one of the options? Yes - Correct. And the rest? option A) 'dark and damp' misses the point - Dry, warm, windy air increases transpiration; option B) 'humid and still' doesn't hold - Humid still air lowers transpiration. Pick: C) dry, warm and windy.

Q3. Wilting of a plant on a hot day occurs when transpiration:

• A.is less than absorption
• B.exceeds water absorption by the roots
• C.stops completely
• D.equals absorption exactly

Answer: B. exceeds water absorption by the roots