Evolution of Land Plants

These flashcards cover key concepts of the evolution of land plants, their adaptations for surviving on land, and their ecological significance.

What were the first plants on land primarily derived from?

Aquatic green algae.

What is the significance of charophytes in the evolution of land plants?

Charophytes are the last common ancestor of land plants.

What are the two main categories of land plants?

Non-vascular plants and vascular plants.

What major evolutionary step occurred around 480 million years ago?

Charophytes evolved features allowing them to survive out of water.

What adaptations did early land plants develop to combat desiccation?

Plants evolved a cuticle to prevent water loss.

What is a stoma, and why is it important?

A stoma is a small opening that allows for gas exchange in plants.

What challenges did plants face moving from water to land?

Scarcity of water, solar radiation, and lack of structural support against gravity.

What is the role of xylem in vascular plants?

Xylem transports water and minerals from the roots to the rest of the plant.

What period marks the first appearance of seed plants?

The Devonian period.

Define angiosperms.

Angiosperms are flowering plants that evolved in the Cretaceous period.

What is the difference between gymnosperms and angiosperms?

Gymnosperms have naked seeds, while angiosperms have seeds enclosed within an ovary.

How did plants adapt to changing environments regarding water absorption?

Plants evolved roots to draw moisture from the soil.

What is turgor pressure?

Turgor pressure is the hydrostatic pressure that helps plants maintain rigidity and structure.

What evolutionary advantage did collenchyma and sclerenchyma provide to plants?

They provided supporting tissues for structural integrity against gravity.

Explain how auxins affect plant growth.

Auxins are hormones that regulate growth direction; they promote stem growth and slow root growth.

What role do sporopollenin play in plant reproduction?

Sporopollenin protects exposed zygotes and plant spores from desiccation.

What significant ecological impact did land plants have?

Land plants modulated global CO2 and O2 levels, contributing to an oxygen-rich atmosphere.