Lecture 17: Evolution of Plants

BIO EXAM 3

What are Charophytes?

It represents a transition towards terrestrial plants

What is true about land plants?

Land plants evolved from green algae, specifically charophyceans or chlorophytes

Where did charophycean ancestors (green algae) live?

they lived on the waters’ ledge where they had more access to lots of UV and a lot of CO₂ with nutrient rich soil and fewer herbivores and pathogens

What are sporopollenin?

it is a layer of a durable polymer that prevents exposed zygotes from drying out found in charophyceans and their ancestors

What did sporopollenin allows charophyeans do?

This adaptions allowed them to take advantage of an open “niche” in habitats and move onto land

What was a visible change of earth when plants moved onto land?

the earths surface changed

What did the earths changing surface mean?

It represented am explosion in available habitats and niches for other evolutionary divergences

What changed about plants dependence?

this evolution moved towards less dependence on free water and a seed stage that is more packaged in a protective coat

What are some common feature between Charophyceans and Land plants

Multicellular, eukaryotic, photosynthetic, autotrophic, cell walls of cellulose, many biochemical details

What are four key traits that appear in nearly all land plants but are absent in charoyceans?

Alternation of generations (with multicellular dependent embryos), walled spores produced in sporangia, multicellular gametangia, apical meristems

How do alternation of generations work?

two different free-living stages per generation

What is a Diploid Sporophyte?

it produces haploid spores which grow into the gametophyte

What is a Hapolid Gametophyte

it produces N gamete, sperm ad egg, which fuse and form Diploid zygote

What are sporangia?

when the sporophyte produces walled spores (haploid) in organs

What is contained within spore walls?

sporopollenin which makes them resistant to harsh environments

What are gametangia?

organs where gametes are produced

What are archegonia?

female gametangia produce eggs and are the site of fertilization

What are antheridia?

male gametangia are the site of sperm production and release

Where does sperm travel from and to?

sperm travels from Antheridia to the archegonia, and it must have water to travel

What are apical meristems?

Where plants sustain continual growth and cells from apical meristems differentiate into various tissues

What are non-vascular plants?

has an absence of vascular tissues ‘pipes”. bryophytes like mosses, liverworts, and hornworts

What are vascular plants?

has vascular tissues, pipes and has two important sub groups seedless and seed plants

What are seedless plants?

it can be divided into clades, lycophytes and monilophytes (pterophytes)

What are lycophytes?

seedless plants that are club mosses and other relatives

What are Monilophytes (pterophytes)?

seedless plants that are ferns and their relatives

What is a seed plant?

a seed is an embryo and nutrients surrounded by a protective coat

What are seed plants?

gymnosperms and angiosperms

What are gymnosperms?

The naked seed plants including conifers