Vascular plants- Seedless Vascular Plants

Exam 1- set 3

What are the evolutionary shifts between bryophytes to polysporangiophytes?

The sporophyte became larger, branched, and more independent, eventually leading to vascular plants with specialized roots, shoots, and leaves.

What are bryophytes?

Nonvascular land plants, including mosses, liverworts, and hornworts.

What are polysporangiophytes?

Plants that produce multiple sporangia and have a branched, independent sporophyte.

What is the dominant generation in bryophytes?

Gametophyte (1n)

What is the dominant generation in polysporangiophytes?

Sporophyte (2n)

Do bryophytes have true vascular tissue?

NO

Do polysporangiophytes have vascular tissue?

YES

How does the gametophyte change from bryophytes to polysporangiophytes?

It becomes smaller and increasingly dependent on the sporophyte.

What is the shoot system of a plant?

The above-ground portion of a plant, including stems, leaves, and reproductive structures.

What is the root system of a plant

The underground system that anchors the plant and absorbs water and minerals

What was an important evolutionary advantage of roots

They allowed plants to anchor themselves and efficiently obtain water and minerals from soil.

What is the advantage of a shoot system?

It allows plants to grow upward toward light and expose leaves for photosynthesis.

What is a stele?

The central vascular cylinder of a plant stem/root containing vascular tissue

What is this vascular tissue type?

Protostele: The simplest stele, with a solid core of xylem surrounded by phloem. PROTO = primitive/simple → solid xylem

What is this vascular tissue type?

Siphonostele; A stele with a central pith surrounded by vascular tissue. SIPHON = hollow center/pith

What is this vascular tissue type?

Eustele; Vascular tissue arranged in separate vascular bundles around a central pith. EU = organized vascular bundles

What are the two evolution types of leaves?

Microphyll and Megaphyll

What is this leaf type?

Microphyll; A small leaf with one unbranched vein.

What is this leaf type?

Megaphyll; A leaf with multiple, branching veins.

What is the major difference between microphylls and megaphylls?

• Microphyll → one unbranched vein

• Megaphyll → multiple branching veins

What is a Oogamy?

A reproductive system where a large, nonmotile egg is fertilized by a small sperm.

What does it mean to exhibit an alternation of heteromorphic generations?

The life cycle alternates between two visibly different generations. 1n gametophyte ↔ 2n sporophyte

What generation is dominant, which one is reduced?

The sporophyte (2n) becomes dominant. The gametophyte becomes smaller and more reduced

What does it mean to be homospory?

A plant produces one type of spore.

One spore type → generally one type of gametophyte

What does it mean to be Heterospory?

A plant produces two different types of spores:

• Microspores → male gametophytes

• Megaspores → female gametophytes

Why is heterospory important evolutionarily?

It is associated with the evolution toward separate male and female gametophytes and eventually the highly reduced gametophytes seen in seed plants.

Evolutionary trend:

Bryophytes
↓
Gametophyte dominant (1n)
↓
Sporophyte becomes larger/independent
↓
Vascular tissue develops
↓
Roots + shoots
↓
Leaves evolve

• Microphylls

• Megaphylls
  ↓
  Sporophyte dominant (2n)
  ↓
  Gametophyte becomes reduced
  ↓
  Heterospory develops in some lineages
  ↓
  Seed plants