Question

Assertion (A): Filiform apparatus is important for pollen tube guidance.
Reason (R): Synergids secrete chemotropic substances that attract the pollen tube.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Filiform apparatus is a characteristic feature of synergids and helps in attracting and guiding the pollen tube.

Answer 1

The Correct Option is A

The mature embryo sac in most angiosperms is typically 7-celled and 8-nucleate. At the micropylar end of the embryo sac lies the egg apparatus, which consists of:
• One egg cell
• Two synergids The synergids are highly specialized cells that play a major role in guiding the pollen tube toward the egg apparatus. Each synergid possesses a special finger-like wall thickening called the filiform apparatus. These wall ingrowths increase the surface area of the synergids and help in absorption and transfer of nutrients. The filiform apparatus also plays an extremely important role in directing the pollen tube toward the egg cell. Synergids secrete certain chemotropic substances that attract the pollen tube chemically. Due to this chemical attraction, the pollen tube grows toward the micropylar end and usually enters one of the synergids. Thus:
• The Assertion is true because filiform apparatus assists in pollen tube guidance.
• The Reason is also true because synergids produce chemotropic signals.
• The Reason correctly explains the Assertion since chemotropic guidance is associated with the synergids containing filiform apparatus. Option analysis:
• Option (A): Correct
• Option (B): Incorrect because the reason directly explains the assertion
• Option (C): Incorrect because both statements are true
• Option (D): Incorrect because Assertion is also true Hence, the correct answer is: \[ \boxed{\text{(A)}} \]