Key Adaptations of Seed Plants

When did seed plants first appear?

About 360 million years ago.

What allowed seed plants to dominate terrestrial ecosystems?

The evolution of the seed, which provides protection and nourishment for the embryo.

What is a seed?

An embryo and nutrients enclosed in a protective coat.

When did humans first domesticate seed plants?

Around 8,000 years ago, enabling permanent settlements.

What are the four key traits common to all seed plants?

1️⃣ Reduced gametophytes
2️⃣ Heterospory
3️⃣ Ovules
4️⃣ Pollen

What does “reduced gametophyte” mean?

The gametophyte is microscopic and dependent on the sporophyte for nutrition.

What advantage do reduced gametophytes provide?

They are protected from desiccation and UV radiation within the sporophyte tissues.

What is heterospory?

The production of two kinds of spores:

Megaspores → female gametophytes

Microspores → male gametophytes.

What is an ovule?

A structure that includes the megasporangium, megaspore, and protective integuments.

What is pollen?

A microspore that develops into a male gametophyte enclosed within a protective pollen wall.

What is pollination?

The transfer of pollen to the part of a seed plant containing the ovules.

How does pollen eliminate the need for water in fertilization?

The pollen tube carries sperm directly to the egg, so sperm no longer need to swim through water.

What does a seed develop from?

The entire ovule after fertilization.

What advantages do seeds have over spores?

Can remain dormant for years, Have a food supply, Can disperse long distances, Provide protection for the embryo

How do spores and seeds differ in complexity?

Spores are single-celled, Seeds are multicellular and have stored nutrients.