Question

Which of the following statements is true regarding open vascular bundles?

• A. They are present in dicot stem
• B. Secondary growth is absent
• C. They are found in monocot root
• D. Xylem and phloem are not separated by cambium

Hint:

Open vascular bundle = Cambium present = Secondary growth possible = Typical feature of dicot stems.

Answer 1

The Correct Option is A

Concept: A vascular bundle consists of xylem and phloem tissues. Depending on the presence or absence of cambium between these tissues, vascular bundles are classified as open or closed.

Step 1: Definition of Open Vascular Bundle
When cambium is present between xylem and phloem, the vascular bundle is called an open vascular bundle. Such bundles possess the ability to undergo secondary growth.

Step 2: Occurrence in Plants
Open vascular bundles are characteristic of dicot stems. The cambium remains active and produces secondary xylem and secondary phloem.

Step 3: Examine Option (B)
Secondary growth is not absent; rather, it is possible because cambium is present. Therefore, Option (B) is incorrect.

Step 4: Examine Option (C)
Monocot roots do not possess typical open vascular bundles responsible for extensive secondary growth. Hence, this statement is incorrect.

Step 5: Examine Option (D)
In open vascular bundles, xylem and phloem are separated by cambium. Therefore, this statement is incorrect. Conclusion: Open vascular bundles are characteristic of dicot stems. \[ \boxed{\text{(A) They are present in dicot stem}} \]