Gymnosperms are a group of seed-producing plants that includes conifers, cycads, and ginkgo. They are characterized by their naked seeds, which are not enclosed within a fruit. Gymnosperm reproduction involves the production and transfer of pollen grains to the female gametophyte, where fertilization takes place.

The false statement regarding gymnosperms is option D, which states that every megaspore that is created after meiosis undergoes mitosis to form a female gametophyte. This statement is incorrect because gymnosperms undergo a different process called heterospory, where two types of spores are produced, the megaspores and the microspores.

Explanation:

1. Pollen grains produce a tube-like structure when they reach the female gametophyte, which carries sperm to the egg:
- When pollen grains are released from the male cones of a gymnosperm plant, they are carried by wind or insects to the female cones or ovules.
- Once a pollen grain reaches the female gametophyte, it produces a tube-like structure called a pollen tube.
- The pollen tube grows and extends down through the tissues of the female gametophyte, eventually reaching the egg cell.
- This tube-like structure serves as a conduit for the sperm cells to reach the egg for fertilization.

2. Gymnosperm fertilization is also known as siphonogamy:
- Siphonogamy is the process of fertilization in gymnosperms where the male gametes (sperm cells) are transported through a pollen tube to reach the egg cell.
- This process is different from angiosperms, where fertilization is achieved through double fertilization, involving the fusion of one sperm cell with the egg cell and another sperm cell with the central cell to form the endosperm.

3. Unlike angiosperm ovules, gymnosperm ovules are not protected:
- Gymnosperm ovules are not enclosed within a protective structure, such as a fruit or ovary, as seen in angiosperms.
- Instead, gymnosperm ovules are usually exposed on the surface of cone scales or within female cones.
- The lack of protection in gymnosperm ovules is one of the characteristic features that differentiate them from angiosperms.

4. Every megaspore that is created after meiosis undergoes mitosis to form a female gametophyte:
- This statement is false. In gymnosperms, after meiosis, the megasporangium produces several megaspores.
- Only one of these megaspores survives and undergoes mitosis to form a multicellular structure called the female gametophyte.
- The female gametophyte contains the egg cell(s) and other cells necessary for reproduction.
- This process is different from angiosperms, where a single megaspore mother cell undergoes meiosis to produce four megaspores, of which only one survives and develops into the female gametophyte.

In summary, the false statement regarding gymnosperms is option D, where it is stated that every megaspore that is created after meiosis undergoes mitosis to form a female gametophyte. In reality, only one megaspore survives and develops into the female gametophyte in gymnosperms.