Plant Evolution Flashcards
What evidence supports plant evolution from green algae?
- Presence of homologous chloroplasts with chlorophyll A&B, thylakoid membranes, and similar plant chloroplast DNA to that of green algae. 2. Biochemical similarities in the cellulose cell wall and food storage in starch form. 3. Similar genes and rRNA
What challenges did plants face to adapt to land?
Plants had to overcome dessication both for reproductive purposes and for ensuring enough water was available within the plant for use. Plants also had to overcome the lack of buoyancy and find a new system of support for body structure in air.
How did plants adapt to lack of abundant water for use and support?
Plants developed the cuticle, stomata, and flavonoids. The cuticle protects the plant from water loss, and stomata control the passage of water vapor and other gases through the leaves. The vascular system and roots allows the transport of water and other nutrients throughout the plants, and also provides support. Plants also receive support from lignified cell walls. To solve the problem of reproduction outside of water, plants developed sporic reproduction.
What is the difference between a sporophyte and a gametophyte in the plant sporic life cycle?
The sporophyte (2n) is the structure that produces the spores via meiosis. The gametophyte (n) produces the gametes via mitosis.
What is the difference between vascular and nonvascular plants?
Vascular plants have a dedicated vascular system. Nonvascular plants do not and are limited by size because water and nutrient transport needs to be efficient.
For bryophytes, which phase is dominant in the life cycle?
Gametophyte
For ferns and mosses, which phase is dominant in the life cycle?
Sporophyte
Why are bryophytes not fully adapted to life on land?
They are avascular and require a small amount of water to reproduce.
How did ferns advance over the bryophytes?
They have a vascular system with lignified cell walls that allows vertical growth, they have a cuticle to protect form water loss, they have a small independent gametophyte, and the sporophyte stage dominates the life cycle.
How are seeds adapted to a terrestrial environment?
Seeds replace spores as the dispersal agent for plant reproduction. Seeds protect the embryo and provide it with food. The protection around the seed allows for broader dispersal by animals, wind, water, etc.
How have flowers and fruits led to evolutionary success for angiosperms?
Flowers and fruits attract animals that can help disperse the seeds of angiosperms to new habitats. The fruit also provides the seed additional protection and nutrition.
