Question

What features not present in seedless plants have contributed to the success of seed plants on land?

Short answer

In seedless plants the fusion of gametes occurs outside, whereas, in seed plants, fusion takes place inside the protective shell called the seed.

Seedless plants reproduce by forming spores that do not have any nutrient supply like seed plants. They also have less exposure to stress, and as they are covered in a shell, which also sustains the harsh and extreme environment and helps in dispersal.

Step-by-step solution

Fertilization

The process of fertilization involves the fusion of gametophytes to produce the zygote. There are different types of fertilization based on the spot of fusion: external and internal fertilization.

In external fertilization, the male and female gamete fusion occurs outside the female parent, and internal fertilization fusion occurs inside. After fertilization, the fused zygote undergoes the process of division like meiosis and mitosis for growth and development.

Seedless and seeded plants

In seedless plants, reproduction happens through spore formation leading to the formation of gametophytes. In contrast, seed plants contain a multicellular structure called seed, which bears plants with well-developed vascular tissues.

The seed plants have nutrient supply to the embryo and protect them from unfavorable conditions lacking in the spores. The pollen grains secrete a substance called sporopollenin to protect the fragile component from harsh exposures during dispersion.

Seed plants are successful

The protective tissue coat, the nutrient supply, and their ability to disperse make the seed plants more successful than the seedless plants and are sustainable on land.