chapter 8 part 2

What are the 4 major groups of land plants that are related and show the major evolutionary steps?

1. Bryophytes (moss plant)

2. Pteridophytes (fern plant)

3. Gymnosperms (naked seed)

4. Angiosperms (vessel seed)

When did plants without seeds first appear?

460 million years ago

What were the first land plants called?

Bryophytes (means “moss

How many species of Bryophytes are there?

Over 24,000 species

What are the 3 phyla of Bryophytes?

• Mosses – rhizoids are multicellular

• Liverworts (wort means plant) – rhizoids are unicellular

• Hornworts – rhizoids are also unicellular

What type of generation do Bryophytes have?

Bryophytes have a dominant haploid gametophyte generation.

Where are Bryophytes found?

Found in every moist environment, but do not need to be completely submerged like algae

Where can Bryophyte spores grow?

Found in every moist environment, but do not need to be completely submerged like algae

Do Bryophytes need soil like seeds?

Doesn’t need soil like seeds, but must have water to carry the sperm to the egg in the gametophyte stage

What happens after fertilization in the Bryophyte life cycle?

Turning it into millions of diploid spores

What do all plant life cycles display?

Heteromorphy, or a quality in which they have two genetically and morphologically distinct generations that alternate

What are the two plant generations?

A haploid gametophyte and a diploid sporophyte

What is haploid (n)?

Single set of chromosomes, like our sperm and egg

What is diploid (2n)?

2 full sets of chromosomes, like our somatic cells

How are plant gametophytes different from animals?

Plants utilize organically distinct haploid gametophytes, which would almost be as though our sperm and eggs formed totally separate biological organisms unto themselves

What is the tiny green growth you see in moss?

The gametophyte (n) phase

What does each haploid moss plant produce?

One producing sperm and one producing eggs

What is the dominant phase in Bryophytes?

Gametophyte is the dominant phase – which is unique to the bryophytes

What is the relationship between the sporophyte and gametophyte in mosses?

he sporophyte is dependent on the gametophyte. Both are visible with the naked eye

Do mosses have true roots or leaves?

They do not have true roots or leaves (because they lack vascular tissue)

What do mosses use instead of roots?

Rhizoids that anchor them to the ground

How do mosses absorb water and nutrients?

They absorb water and nutrients from the soil via diffusion

What is the ploidy of female (archegonia) and male (antheridia) gametophytes?

Female (archegonia) and male (antheridia) gametophytes are haploid

Where are sperm cells made in moss?

At the tip of the male, sperm cells are made

Where are egg cells made in moss?

Inside the female, eggs cells are made

What role does rain play in moss reproduction?

When it rains, a layer of moisture on the ground allows the sperm to swim to the egg

What is fertilization in mosses?

Fertilization results in the diploid zygote (2n) inside the haploid archegonium

What does fertilization begin in the moss life cycle?

This begins the sporophyte stage

What does the zygote grow into?

The zygote grows into an embryo, then grows a stalk (seta) that moves upward

What is found at the top of the stalk (seta)?

At the top is a capsule (called sporangium)

What process occurs in the sporangium?

Through meiosis (cutting the chromosome number in half), haploid spores are created

What happens to haploid spores after they are created?

The haploid spores are released into the air

What do haploid spores grow into?

Some will form male gametophytes and others will form female gametophytes

How do new gametophytes grow?

They grow through mitosis

What happens to the moss life cycle after gametophytes form?

The cycle repeats again

What structures are labeled in the moss life cycle diagram related to spores?

Capsule, sporangium, meiosis, spores, spore dispersal, peristome

What structures are labeled in the moss life cycle diagram related to fertilization and growth?

Archegonium, antheridia, sperm, egg, fertilization, zygote (2n), embryo, seta, young sporophyte, mature sporophytes

What are PTERIDOPHYTES?

Vascular seedless (use spores like mosses)

How many species of Pteridophytes are there and where do they live?

Over 13,000 species and live in moist environments (needed for fertilization)

What is the size range of Pteridophytes?

Size: 1 inch to 36 feet tall

How are Pteridophytes different from Bryophytes?

Unlike Bryophytes, they have true leaves, stems, and roots

What is the most simple form of Pteridophytes?

Most simple form – FERNS

What are fern leaves called?

The leaves are called FRONDS

What are young fronds called?

Young fronds are called FIDDLEHEADS

What is the mature hermaphroditic gametophyte called and what is its shape?

The mature hermaphroditic gametophyte is ‘heart-shaped’ and is called the prothallus

Is the prothallus dependent or independent?

It is free-living!

What is the size of the prothallus?

It measures 8 mm x 8 mm

Where are reproductive spore sacs found on ferns?

On the underside of the fronds

What are reproductive spore sacs called and what do they contain?

Reproductive spore sacs called SORI (plural) which contain thousands of microscopic spores

What does each sorus (singular) contain?

Each sorus (singular) contains many sporangia

How are spores made in ferns?

This is where spores are made through meiosis

What happens to haploid spores after they are released?

These haploid (n) spores are released into the air and land on wet soil and germinate to form the gametophyte haploid stage

What structures does the mature gametophyte form?

The mature hermaphroditic gametophyte forms antheridium (sperm) and archegonium (egg)

Why do ferns need water to reproduce?

They need WATER to reproduce

What happens during fertilization in ferns?

Sperm swim through water to the egg = fertilization to form zygote (2n)

What does the zygote grow into?

A new sporophyte forms that grows on top and out of the gametophyte

What happens to the gametophyte as the fern grows larger?

As the fern grows larger, the gametophyte withers away and dies

What is the dominant generation in ferns?

This sporophyte (dominant) is the plant we recognize as a fern

What is the difference between MOSS and FERN?

• MOSS dominant generation = Gametophyte (n) and non-vascular

• FERN dominant generation = Sporophyte (2n) and vascular

What do both mosses and ferns depend on for reproduction?

BOTH depend on water for reproduction

What do mosses and ferns have in common regarding seeds?

BOTH are seedless (spores only for reproduction)

How do Pteridophytes help the environment and humans?

• Help prevent erosion

• Ornamental plants for yards and homes

• Helped form coal deposits 380 million years ago in the Carboniferous Period

What groups are included in Pteridophytes?

Includes: ferns, whisk ferns and horsetails

What are spores?

Spores are microscopic, require a moist environment, transported by air, unicellular, no food reserve, millions are produced to ensure survival.

What is the ploidy of spores?

HAPLOID

What are seeds?

Seeds are macroscopic, transported by animals, nutrient food reserve, multicellular, baby embryo with roots, leaves and stems. Does not require moisture.

What is the ploidy of seeds?

DIPLOID

What kind of embryo is found in seeds?

Multicellular sporophyte embryo in a protective cover!

Is there a free-living gametophyte stage in seed plants?

No free-living gametophyte stage.

What is a seed?

A seed is the embryo of a new plant and as such is a living thing, but in a dormant state.

What does a seed require to end dormancy?

Being buried in soil and a combination of temperature, light and water to trigger off the renewal process.

Do vegetables and fruits die the moment they are harvested?

Vegetables and fruits don’t die the moment they are harvested.

What happens to plant cells after harvest?

Even after they’ve been harvested and cut from one another, their cells remain active and alive.

What can scraps of fruits and vegetables do?

There are also many fruits and vegetables that you can grow using the scraps that you usually cut off and discard.

What is an example of regrowing food from scraps?

If you give the base/root of a celery stalk some water and sunlight, you can regrow a whole new stalk of celery from it.

When did seed plants appear?

360–400 million years ago (most recent plants – much diversity)

What are examples of seed plants?.

E.g. Grasses – Pine Trees – Palm Trees – Oak Trees – Maple Trees – Shrubs – Deciduous Trees – Flowering Plants – etc.

What do seed plants use for reproduction?

Use SEEDS (pollen and ovule) not spores for reproduction (does not need water to reproduce)

What are the reproductive structures of seed plants?

Reproductive structure: cones (gym) and flowers (angio).

What is a seed?

Seed: young plant in a protective covering.

What are the three parts of a seed?

Three parts: embryo, stored food and seed coat.

What is germination?

Germination: when the embryo grows and pushes out of the seed coat.

What does Gymnosperm mean?

Gymnosperm (700–900 species) means “naked seed”

Why are gymnosperms called naked seed plants?

They lack ovaries (no flowers or fruit) and the (eggs) ovules develop exposed on the surface of the cone scales.

When were gymnosperms most common?

Gymnosperms were the most common plants during the Mesozoic era (the age of dinosaurs

What type of leaves do most gymnosperms have?

Most are evergreen (maintain needles all year).

What are the most common gymnosperms?

Most common are the cone bearers (separate male and female cones).

What are gymnosperms often referred to as?

This group is often referred to as softwoods.

What are the four major gymnosperm phyla?

4 Major phyla: conifers, ginkos, cycads, gnetophytes.

Where does the adult sporophyte grow in gymnosperms?

Adult sporophyte grows in the forest.

What reproductive structures are produced in gymnosperms?

Ovule and pollen cones are produced.

What do pollen cones create?

Pollen cones create microsporocytes (2n) that through meiosis create pollen grains (n) which are carried by the wind.

What do female cones contain?

Female cones contain an ovule (two in each scale) called the megasporocyte or mother cell (2n).

What happens inside the ovule?

Inside that ovule, the megasporocyte undergoes meiosis producing 4 haploid (n) cells. Only ONE will become the surviving megaspore (n).

What happens to the megaspore?

The spore grows by mitosis to become the female gametophyte.

What is inside the female gametophyte?

Inside this female gametophyte, there is an egg and the endosperm (nutritive tissue that sustains life once fertilization has occurred).

What is pollination in gymnosperms?

Pollination: pollen lands on a female cone.

What happens after pollen lands on the female cone?

The pollen germinates sperm that enters the micropyle (an opening in the female cone near the ovule).

How does sperm reach the egg in gymnosperms?

The sperm finds its way through the scales of the cone to fertilize the egg using a pollen tube = zygote (2n).

What does the zygote grow into?

It grows into an embryo – then into a protected seed.