Really hard biology question

Jack has just returned after a walk in the woods. He finds several sticky weed seeds stuck to his jersey with their prickly hooks.
Why do these seeds have prickly hooks?

This is actually a very easy question. Most plants rely on wind, water and animals to spread their fertilized seeds so they do not overcrowd each other. Having prickly hooks (such as in thistles) makes it easy for the seeds to stick to the coats of passing animals, or as in your example, to the clothing of a human, so that the seeds are spread far from the parent plant to allow room for growth and to spread the species in a wider area.

They have prickly hooks because the ancestral forms that didn't have prickly hooks didn't disperse as well and so didn't contribute as much to the next generation. Those with prickly hooks did disperse and survive to make a new generation of plants with prickly-hooked seeds. Over time, prickly-hooked plants displaced non-prickly-hooked plants until finally, today, seeds of all plants of that species have prickly hooks.

They have been made/evolved like That so that they can travel around on moving things ( such as Jack, or other animals) and then be dropped and planted. Its their way of growing and spreading the population. If they only stayed in one place, theyll get too overcrowded in one place. But if they have the ability to attach to something and move around, they will be spread so that they can survive better. Natural selection.

it Allows them to attach to animals, by the seeds moving away from the original source there is less compitition between seeds for nutrients,water and space. Chance of survival increases.

They have evolved so they are transported on other animals to bring them to a site where they are pollinated.

I hope this information was very helpful.

Its for animal mediated dispersal of seeds. Some plants use wind others animals.