Ch 21 The Diversity of Plants

Plant adaptations to life on land include a(n)___________________________, which reduces evaporation of water, and ____________________, which open to allow gas exchange but close when ___________________ is scarce. In addition, the bodies of vascular plants gain increased support from ___________________ impregnated with the polymer____________________; these structures also help __________________ and _______________________ to move within the plant body

cuticles, stomata (pores), water; conducting cells, lignin, water, minerals

seed plants

differ from nonvascular plants and seedless vascular plants by their production of pollen and seeds. -in seed plants gametophytes (which produce the sex cells) are tiny. the female gametophyte is a small group of haploid cells that produces the egg. -the male gametophyte is the pollen grain.

Sporophytes

diploid cells in the plant body that undergo meiosis to produce haploid reproductive cells called spores, the haploid spores develop into multicellular, haploid bodies called gametophytes -gametophyte ultimately produce male and female haploid gametes (sperm and egg) by mitosis. gametes, like spores, are reproductive cells but, unlike spores, and individual gamete cannot develop into a new individual -two gametes of opposite sex fuse to form a diploid zygote which then develops into a diploid embryo.

angiosperms

flowering plants

2 types of seed plants

gymnosperms and angiosperms

the seed plants fall into two major categories: the nonflowering _______________________ and the flowering _______________________. Flowers were favored by natural selection because they ____________________________. Fruits were favored by natural selection because they______________

gymnosperms, angiosperms, attract pollinators; enable dispersal of seeds.d

gymnosperms

lack flowers. evolved earlier than flowering plants. Only 4 groups of gymnosperms survived today: 1. ginkos 2. cycads 3. gnetophytes 4. conifers

3 types of nonvascular plants

liverworts, hornworts, and moss

archegonium

reproductive structure in nonvascular plants where eggs develop.

antheridium

reproductive structure of nonvascular plants where sperm are formed

seedless vascular plants must reproduce when conditions are wet because their sperm must _______________

swim to the egg

Photosynthetic

- green color comes from the pigment chlorophyll which plays a crucial role in photosynethes--> the process by which plants use energy from the sunlight to convert water and CO2 to sugar.

nonvascular plants

- retain some characteristics of their algal ancestors. -gametes are dispersed by water, and they lack true roots, leaves, and stems. They do possess rootlike anchoring structures called rhizoids that bring water and nutrients to the plant but lack well developed structures for conducting water and nutrients. As a result, body size is limited. -size is also limited due to the absence of lignin in their bodies. without lignin, nonvascular plants cannot grow upward very far. -most nonvascular plants are less than 1 inch tall.

How plant bodies evolved to resist gravity and dying

- roots or root-like structures anchor the plan and absorb water and nutrients from the soil - waxy cuticle that covers the surfaces of leaves and stems and limits the evaporation of water -pores called stomata, in the leaves and stems that open to allow gas exchange but close when water is scarce. -lignin--a stiffening substance, a rigid polymer that impregnates the conducting cells and supports the plant body against the force of gravity.

how are conifers adapted to cold, dry conditions? 3 reasons

-1. most conifers retain green leaves throughout the year, enabling these plants to continue photosynthesizing and growing slowly during times when most other plants become dormant. for this reason conifers are often called evergreens 2. conifer leaves are thin needles covered with a thick, waterproof surface that minimizes evaporation. 3. conifers produce "antifreeze" in their sap that enables them to continue transporting nutrients below freezing temperatures. this substance gives rise to their fragrant piney scent.

2 types of enclosed reproductive structures in nonvascular plants that keep gametes from drying out

1. archegonia(singular archegonium)-where eggs develop -antheridia (singular antheridium)- where sperm are formed.

angiosperm life cycle

1. female gametophytes develop from ovules within the ovary, male gametophytes are formed inside a structure called an anther. 2. pollen is released from the anthers and carried away on the wind or by animals 3. if a pollen grain lands on a stigma (a sticky pollen catching structure), a pollen tube begins to grow from the pollen grain 4. the tube bores down to the female gametophyte. fertilization occurs when the pollen tube reached the egg cell 5. the resulting zygotes developed into an embryo enclosed in a seed ready for dispersal.

The number of species of flowering plants is greater than the number of species in the rest of the plant kingdom. what features are responsible for the enormous success of angiosperms?

1. flowers--attract pollinators that carry their pollen from flower to flower 2. fruit--attract animals that eat the fruit and disperse seed or the seeds of fruits can cling to fur or form wings that carry the seed through the air ( like in maples) 3. broad leaves--collect more sunlight for photosynthesis.

3 groups of nonvascular plants

1. liverworts 2. hornworts 3. mosses.

3 characteristic traits of plants

1. photosynthesis 2. multicellular embryos 3. alternation of generations.

Wewitchia

A type of gnetophyte (1 of 4 gymnosperm plants) -Welwitschia can survive in extremely dry desserts. it has a root that can extend 100 feet down into the soil. grows only two leaves that never shed. the oldest welweitchia are more than 2,000 years old

Cycads

- 1 of 4 gymnosperm (nonflowering seed plant) plant. -also abundant during jurrasic period. have large finely divided leaves and bear a superficial resemblance to palms or larger ferns -tissues contain toxins, is now endangered

List the structural adaptations necessary for the invasion of dry land by plants. -Which of these adaptations are possessed by nonvascular plants? -By ferns?

-roots that anchor the plant and absorb water and nutrients from the soil -a waxy cuticle that covers the surface of leaves and stems which limits water evaporation -pores called stomata (stoma singular) in the leaves and stems that open to allow gas exchange but close when water is scarce. -none, they don't live on dry land. nonvascular plants lack true roots, leaves, and stems. they must rely on poor diffusion with poor conducting tissues to allow water and nutrients to pass through. They also lack lignin which stunt their growth. -ferns are seedless vascular plants. contain lignin which allow them to grow taller -

Ginkos trees

1 of 4 gymnosperm (non flowering seed plants) -widely seen in the Jurassic period are more resistant to pollution which is why cities plants them

conifers

1 of 4 gymnosperms (non flowering seed plant) -still heavily abundant today. 500 species of pines, firs, spruce, hemlocks, and cypresses must abundant where climate is dry and cold.

What is meant by alternation of generations? What two generations re involved?

All plants undergo a life cycle that takes them through both haploid (n) and diploid generations. -The multi cellular diploid (n) plant structure is called the sporophyte, which produces spores through meiotic (asexual) division. -The multi cellular haploid plant structure is called the gametophyte, which is formed from the spore and give rise to the haploid gametes. -The fluctuation between these diploid and haploid stages that occurs in plants is called the alternation of generations

vascular vs nonvascular plants

Nonvascular (bryophytes)--> require a most environment to reproduce and thus straddle the boundary between aquatic and terrestrial ife -vascular plants (tracheophyts)--> plants that are able to colonize drier habitats.

sporophyte vs gametophyte

The sporophyte are diploid cells, undergo sexual reproduction meiosis ot produce haploid cells called spores. spores are reproductive cells that can develop gametophytes -these spores develop into multicellular haploid bodies called gametophytes. through mitosis, gametiphyte produces egg and sperm haploid gametes. gamets, unlike spores, can't develop into a new indivdiual -must fuse with opposite sexes to form a diploid zygote

multicellular embryos

a plant embryo is multicellular and is attached to and dependent on its parent. -as it grows and develops, the embryo receives nutrients from t he tissues of the parent plant.

Lignin*

a stiffening substance, a rigid polymer that impregnates the conducting cells and supports the plant body against the force of gravity.

seeds

analogous to the eggs of birds and reptiles, seeds consist of an embryonic sporophyte plants, a supply of food for the embryo, and a protective outer coat. -the seed coat maintains the embryo in a state of dormancy until conditions are suitable for growth.

what is another word for flowering plants

angiosperms

Gnetophytes

one of 4 gymnosperms (non flowering seed plant) -70 species of shrubs, vines, and small trees. -some leaves act as appetite suppressant or energy booster in humans, however bc they can cause death or heart problems, the US banned such substances as a weight loss aid -Welwitschia can survive in extremely dry desserts. it has a root that can extend 100 feet down into the soil. grows only two leaves that never shed. the oldest welweitchia are more than 2,000 years old

alternation of generations *

plant reproduction is characterized by this. -separate diploid and halpoid generations alternate with one another( diploid organisms have paired chromosomes ; a haploid organism had unpaired chromosomes). - in the diploid generation, the body consists of diploid cells and is known as the sporophyte. -

two adaptations that allow seed plants to reproduce more efficiently on dry land are ______________ and ______________

pollen and seeds

gametophytes

the haploid spores develop into multicellular, haploid bodies called gametophytes -gametophyte ultimately produce male and female haploid gametes (sperm and egg) by mitosis. gametes, like spores, are reproductive cells but, unlike spores, and individual gamete cannot develop into a new individual -two gametes of opposite sex fuse to form a diploid zygote which then developed into a diploid embryo

Pollen

the male gametophyte. the pollen grains are dispersed by wind or by bees. in this way, sperm move through the air to fertilize egg cells.

Fruits

the second adaption (besides flowers) that has contributed to the success of angiosperms. - many fruits entice animals to disperse seeds. -not all fruits depend on edibility, some fruits (called burs) cling unto animal fur, and other fruits (like from maples) form wings that carry the seed through the air.

Flowers

the structures in which both male and female gametes are formed. evolutionary theory that the relationship between ancient gymnosperms and their animal pollinators was so beneficial that natural selection favored the evolution of showey flowers that advertised the presence of pollen to insects and other animals.

flowering plants

their enormous success is due in part to three major adaptations: flowers, fruits, and broad leaves.

reproductive structures of non vascular plants

they are enclosed, which prevents the gametes from drying out. -two types of reproductive structures 1. archegonia: in which eggs develop 2. antheridia: where sperm are formed. - in all nonvasculr plants, the sperm must swim to the egg

vascular vs non vascular plants

vascular plants are distinguished by specialized groups of tube-shaped conducting cells. These cells are impregnated with stiffening substance lignin and serve both supportive and conducting functions. they allow vascular plants to grow taller both bc of the extra support provided by lignin and bc the conducting cells allow water and nutrients absorbed by the roots to move to the upper portions of the plant. -in vascular plants, the diploid sporophyte is the larger, more conspicuous generation; in nonvascular plants, the haploid gemetophyte is more evident.