Question

The process during double fertilization in which non motile male gametes are carried through hollow pollen tube is called

• A. chalazogamy
• B. porogamy
• C. mesogamy
• D. siphonogamy

Hint:

Fertilization types in plants are grouped by whether the male gametes swim on their own, which needs water, or are carried inside a tube toward the egg. Work out which broad category applies to non motile gametes before choosing among the entry point based terms in the options.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The process of fertilization in angiosperms involves the entry of the pollen tube into the ovule.
The pollen tube acts as a hollow carrier for the non-motile male gametes, protecting them as they travel towards the female gametophyte.

Step 2: Key Formula or Approach:
Identify the correct botanical term based on the etymology and biological definition of the pollen tube's function in carrying gametes.

Step 3: Detailed Explanation:
Porogamy is defined as the entry of the pollen tube directly through the micropyle.
Chalazogamy occurs when the pollen tube enters the ovule through the chalazal end.
Mesogamy is the entry of the pollen tube through the integuments or the funiculus.
Siphonogamy, however, is the specific botanical term used to describe the transport of non-motile male gametes through a hollow pollen tube.

Step 4: Final Answer:
The correct process is siphonogamy, which corresponds to option (D).

Answer 2

Concept:

• Fertilization mechanisms in plants are broadly classified by whether the male gametes are motile or non motile. Zoidogamy uses free swimming, motile male gametes that need external water, as seen in algae, bryophytes and pteridophytes. Siphonogamy uses non motile male gametes carried inside a pollen tube, as seen in gymnosperms and angiosperms.
• Porogamy, chalazogamy and mesogamy are not alternatives to siphonogamy. They are simply different routes by which the pollen tube, which is itself the siphonogamous mechanism, enters the ovule.

Step 1: Classify the fertilization type described in the question.
The question describes non motile male gametes carried through a hollow tube. This water independent transport mechanism is the defining feature of siphonogamy, as opposed to zoidogamy, where gametes must swim through a film of water to reach the egg.

Step 2: Examine what the other three options actually describe.
Porogamy is entry of the pollen tube through the micropyle. Chalazogamy is entry through the chalazal end. Mesogamy is entry through the integuments. Each of these terms already assumes a pollen tube is carrying the gametes, and only describes the point of entry into the ovule, not the transport mechanism itself.

Step 3: Identify the term that matches the transport mechanism rather than the entry point.
Since the question asks specifically about the mechanism of carrying non motile gametes through a hollow tube, and not about where that tube enters the ovule, the matching term is the one that names the transport process itself.

Final Answer: Siphonogamy