Class Notes (839,195)
Canada (511,223)
Biology (116)
BIOL 1020 (18)
Lecture

Bio1020, Diversity of Life: February 28.docx

5 Pages
52 Views

Department
Biology
Course Code
BIOL 1020
Professor
Robert Laird

This preview shows pages 1 and half of page 2. Sign up to view the full 5 pages of the document.
Description
February 28, 2014 – Biology Origin of vascular plants • Bryophytes were prevalent for first 100 million years of plant evolution • Vascular plants originated in the Silurian and underwent great diversification during the Devonina and Carboniferous periods (dominant types of plants) • Vascular plants now dominant non-vascular plants • Greater bio mass today • Paraphyletic group • Early vascular plants o 425 millions years ago o Tiny o Independent, branching sporophytes o Living vascular plants have…  Life cycles with dominant sporophytes  Vascular tissues called xylem and phloem  Well-developed roots and leaved • Early vascular plants lacked roots  Dichotomous branching (symmetrical): even branching (earlier)  Overtop branching (asymmetrical): upright, taller quickly (modern) • Evolutionary innovation: vascular tissue o Vascular tissue allowed these plants to grow tall (competition for sunlight), limits the evolution of plant height? (falling over, shallow soil) increased in volume to height diameter : height. o Unlike bryophytes, in which lacks of specialized conductive tissues severely limits size • Seedless vascular plants o The first vascular plants were seedless o Recall that a seed consists of an embryo and its food supply surrounded by protective coat o Main groups: both originate from a seedless vascular plant  Lycophytes • Club mosses (not true mosses) • Spike mosses (not true mosses) • Quillworts  Pterophytes • Ferns • Horsetails • Whisk ferns o Flagellated sperm, and are usually restricted to moist environments (not as seriously as the bryophytes) Life cycles of seedless vascular plants • Sporophyte is dominant, gametophyte (small, live flat on the ground or below the soil) • Figure 29.13 o Spore -> young gametophyte -> bisexual gametophyte (has both antheridium and archegonium) (egg and sperm do not mature at the same time to reduce inbreeding) -> zygote grows by mitosis -> sporophyte is a diploid -> growth of the sporangium (inside there is meiosis which creates spores Transport in vascular tissue • Xylem: water, minerals, through dead cells (tracheids) • Water-conducting cells are strengthened by lignin and proved structural support • Phloem consists of living cells and distributes sugars, amino acids, and other organic products • This evolution allowed the first forests to occur (carboniferous forest) Evolution of roots and leaves • Roots o Organs that anchor vascular plants o Enable vascular plants to absorb water and nutrients from the soil o Roots may have evolved from subterranean stems (not agreed if they only have one origin or multiple) • Leaves o Organs that increa
More Less
Unlock Document

Only pages 1 and half of page 2 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit