Early Plants - PowerPoint Presentation

Slide1

Early Plants

The earliest plants were similar to today’s mosses. They grew close to damp ground and depended on water to complete their life cycles (to carry the gametes).Slide2

Kingdom Plantae

(page 550)Characteristics:

- eukaryotic

-

multicellular

(most)

- have cell walls made of a complex carbohydrate called cellulose

- sessile (anchored by roots)Slide3

- Autotrophic - Contain chlorophyll in chloroplasts within their cells. (The green pigment necessary for photosynthesis) Some plants though, are also parasitic or saprobes.

-Reproduce both sexually (production of sex gametes) and asexually (fragmentation, budding, spores)Slide4

Life cycle (page

552) - Undergo a life cycle called “

alternation of generations

”.

This means the plant alternates between a gametophyte (produces gametes/haploid cells) and a sporophyte (produces spores/diploid cells).

One generation is usually dominant.

Slide5
Slide6

Land plants

Land plants are first divided

into

non-vascular

and

vascular

plants.

Vascular plants have a system of “vessels” that carry food and water around. Non-vascular plants do not. Slide7

Special cells, called

tracheids which transport water were developed. Tracheids

are hollow cells with thick cell walls that resist osmotic pressure. They join together and die, leaving a long hollow tube like a straw. Slide8

Tracheids

allowed for the development of vessels and vascular plants.Slide9

Xylum

is the

transport system

in plants that carries water.

Phloem

transports the solutions of nutrients and carbohydrates produced by photosynthesis. Slide10

Xylem and PhloemSlide11
Slide12

Phylum

Bryophyta (Bryophytes) (mosses and their relatives)

Non-vascular plants

No “tissues”

Depend

on water for reproduction

(HOW?)

Draw up water by osmosis only

Have to be short, growing only a few centimeters above ground

(WHY?)Slide13

Phylum Bryophyta

continued

The sperm must swim to reach

neighbouring

eggs

Must live in, near water or heavy dew for at least some of the year. (near streams, forest floor) Slide14

Phylum Bryophyta

continued

Can tolerate low temperatures and fairly harsh climatesSlide15

”leaves” are only one cell thick

has rhizoids rather than true rootsSlide16

In the life cycles of plants, there are two “generations

” (phases) ; gametophyte

or

sporophyte.

Gametophyte is the dominant

generation (Moss spends most of its life cycle in this generation). Slide17

Life Cycle of a Bryophyte, including peat moss (page 558)

Moss spore lands in a moist place

Germinates and grows into

protonema

.

As the

protonema

grows, it forms rhizoids that grow into the ground and shoots that grow into the air. Slide18

Bryophyte Life CycleSlide19

The shoots are the gametophyte stage of the moss’s life cycle and this is what we see and think of as “moss”Slide20

http://www.youtube.com/watch?v=jcWYAnmm-QESlide21

Know this!

Antheridium (antheridia – plural)

Archegonium

(archegonia - plural)

.

Homework:

Questions 1, 3, 4, and 5 on page 559.Slide22

Vascular Plants

(all plants except those in the Phylum Bryophyta

)

Ferns, herbs, trees, flowers, vegetables.

The vascular system allows these plants to transport nutrients and water throughout the plant, even against gravity.

Sporophyte

generation is dominant (diploid)

Gametophyte generation is short (haploid)

Slide23

Seedless vascular plants (club mosses, horsetails and ferns)

Have:

Roots

: underground organs that absorb water and minerals. Water-conducting tissues are in the center of the root

Leaves

: photosynthetic organs that contain one or more bundles of vascular systems gathered into

veins

made of xylem and phloem. Slide24

Stems:

supporting structures that connect roots and leaves, carrying water and nutrients between themSlide25

Phylum Pterophyta

(ferns)

Most numerous phylum of seedless vascular plants (over 11 000 species).

Ferns have:

Vascular tissue

Strong roots

Underground systems called

rhizomes

Large leaves called

frondsSlide26

Pterophyta

Like wet habitats

Like shady areas

In tropical areas can grow as large as small treesSlide27

Life cycle of the fern



Ferns and other vascular plants have a life cycle in which the diploid

sporophyte

is the dominant stage.

Fern

sporophytes

develop haploid spores on the underside of their fronds in tiny containers called

sporangia

.(also see page 562).Slide28

Sporangia are grouped together in tiny clusters called

sori (singular, sorum

). Slide29

When the spores germinate, they develop into haploid gametophytes.

The gametophyte first grows a set of root-like rhizoids.

It then flattens into a thin, heart-shaped green structure that is the mature gametophyte.Slide30

The gametophyte contains both egg (in the

archaegonia) and sperm (in the antheridia).

Once the egg is fertilized by the sperm, it grows into a

sporophyte

.

See the diagram on page 562 in your text for the life cycle of the fern.Slide31

Answer these questions from page 559

1. How is water essential in the life cycle of a bryophyte?3. What is the relationship between the

gametophye

and the

sporophyte

in mosses?

4. What is an

archegonium

? An

antheridium

? How are these structures important in the life cycle of a moss?

5. What characteristic of bryophytes is responsible for their small size?