plants adaptations notes

8/13/2019 Plants Adaptations Notes

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Overarching ThemeAdaptation (and Continuity as well!)

PLANTSHow have plants overcome the challenges of life on land?

Big IdeaPlants have changed over time and are now a diverse group of

organisms. Adaptations are evident that allow internal transport and conservation

of water in addition to life cycles that are not dependent on water.

Basics of Plant Structure

All vascular plants have true roots, stems, and leaves Adaptations plants need to be able to survive on land include;

1. Need to get sperm and egg together for reproduction2. Need to obtain water and nutrients3. Need to transport this water and nutrients throughout the body of the plant4. Need to prevent excess water loss to environment5. Need to support leaves so they can be exposed to as much sunlight as

possible for photosynthesis

Roots

there is much of a plant underground as there is above ground, the part belowground is the roots

they serve 2 main functions, anchor the plant in the ground and absorb water andminerals

in some plants they also serve as a store of food

roots are generally one of two basic plansfibrous or tap root The fibrous root plan has several main roots that branch out to form a tangled mass

of thin roots. Plants with this type of root system include grass, corn and most trees

The taproot plan consists of a long thick main root that has thin roots extendingfrom it. Examples of this include carrots, cacti and dandelions

On the epidermis, or outermost layer of a root, there are many thin, hair likeextensions called root hairs

These work to increase the surface area of the roots, thereby increasing the amountof water and nutrients the roots can absorb from the soil

The very tip of the root is covered by a structure called a root cap, this protects thetip of the root as it grows through the soil

Just behind this is region of meristematic tissue This tissue contains cells that can divide for as long as the life of the plant, this cell

division creates growth and helps the roots extend and explore further

We eat lots of rootsyams, beets, carrots


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Stems

stems contain vascular tissuethe xylem and the phloemthat transport water andnutrients throughout the plant

As well, vascular tissue provides structural support, allowing vascular plants to growtall and to support the plant as it grows up against gravity

Seeds

Is a plant structure that contains an embryo, nutrients for the embryo and a seedcoat (protective coating)

These enable the seed to survive harsh environmental conditions and then sproutwhen favourable conditions exist

Plants have developed several different ways to scatter their seeds (animals, wind,water)

Leaves

Vary greatly in size and shape Very important because they are the site of photosynthesis, the process in which

food is synthesized using light energy

Leaves typically have a network of veins that contain vascular tissue which isconnected to the vascular tissue in the stem

The leaf epidermis (outermost layer) is covered by a cuticle that protects the plantagainst water loss

This cuticle is pierced by tiny pores called stomata Stomata regulate gas and water exchange between the plant and the atmosphere Each little stomata is bounded by a pair of sausage shaped cells called guard cells In general, these cells are open at day and closed at night Plants keep stomata open just enough to allow photosynthesis to take place, but not

so much that they lose much water to the environment

Leaf Adaptations

Leaves of plants are so diverse in shape and form because each plant has evolvedleaves that are specially adapted to their environment

Plants that live in very windy areas such as coastlines often have small or featheryleaves that can withstand gales, large leaves would be torn to pieces


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How do these adaptations help plants survive in their habitats?

Non-Seed Producing Plants ContinuedMosses and Ferns

BRYOPHYTA (Mosses, Hornworts and Liverworts)Non-vascular Plants

Characteristics

- said to be halfway between aquatic plants and true land plants, so only exhibit a few special adaptations tohelp deal with life on land

- they still require water for reproduction (flagellated sperm has to swim to egg)- are small and low to the ground, this is because they do not have internal vascular system and rely on

simple cell-to-cell diffusion for water and nutrients, this is not very efficient and limits the growth of

bryophytes

- have root-like filaments called rhizoids that anchor plant to substrate- since they live in damp and shady areas, they do not have any adaptations to prevent water loss

Other leaves are modified intotendrils to help a plant climb or

twine itself around a tree orother structurethe tendrils ofa pea plant are actually leaves

Some leaves look more likespines or needles and act as

defence mechanisms preventinganimals from grazing on them

e.g. Cacti, holly, conifers

Rainforest plants, on the otherhand, often have wide large

leaves so that they can absorb asmuch light as possible in the dim

forest light

And finally we have leaves thatare modified to trap and digest

insects such as the Venusflytrap of the sundew plant

When an insect lands on theleaves of a Venus flytrap, their

movement triggers bristles thatcause the 2 halves of the leaf to

snap together trapping theinsect, then special digestiveglands secrete enzymes that

help the plant slowly digest theinsect


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Habitats

- live in moist environments, water must be plentiful to ensure survival- abundant in temperate rainforest biomeEcological Role

- bryophytes play an important role in ecological succession as they are among the first plants (=pioneerplants) to establish themselves on rocky faces or in soil where no other plants can grow

- usually lichen (mutualistic relationship between an alga and a fungus) cover the barren area first and startto break down the rock, then bryophyte spores land on lichen and their life cycle begins

- due to the bryophytes ability to retain water (sponge-like) other plant seeds fall on the lichen/bryophytebed and begin to grow as well

Uses of Bryophytes

- fertilizers (ground up sphagnummoss)- deposits of dead moss (peat) used as fuel in places such as Ireland and Newfoundland- wilderness first aid, sphagnummoss had antiseptic properties so can be used to dress wounds used in

gardening to retain water in flower beds/containers

- evolutionary linksDNA analysis has shown that liverworts lack DNA sequences of other plants, suggeststhat they are most primitive of land plants, first to move from water to land environments

Reproduction - Life Cycle of a Moss(refer to diagram)

- complex life cycle uses spores rather than seeds (like algae and ferns)

- the dominant stage that most of us recognize as a moss (green, leafy) is the gametophyte stage

- mosses are unique in that 2 generations or stages of the plant are contained on the same structure (draw

below)

1. the sporophyte grows out of the gametophyte on an elongated stalk that elevates the sporangiumabove the surface of the ground

2. the sporangium protects the spores until they are ready to be dispersed3. the life cycle of a new moss plant begins when haploid (n) spores are released from the sporangium4. spores are mainly dispersed by wind or water5. if the site where the spore lands is suitable, it germinates, if not suitable it can remain dormant for

years until right conditions exist6. after a few days of growth, the protonema begins to resemble the green, leafy gametophyte7. when the gametophyte matures, it produces the male and female sex organs on tips of leaves, male

structure=antheridium (produces sperm), female structure =archegonium (produces eggs)

8. fertilization occurs when the plant is wet (covered by dew or rainwater), the sperm swim to the eggand a zygote (2n) develops

9. this zygote grows into the mature sporophyte and the process begins again


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PTEROPHYTA (The Ferns and Horsetails)Seedless Vascular Plants


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Characteristics

Largest group of extant (living) seedless vascular plants Very diverse group of plants (water ferns, epiphytes, tree ferns and horsetails)

Have true vascular tissues, strong rootsandrhizomes=thick, fleshy creeping stem that grows either on

or just beneath the surface of the ground, helps with food storage.

Ferns have true leaves and true stems. A fern leaf is called a frond Vascular tissue consists of xylem(dead cells that create tubes to transport water and minerals up from

the roots) and phloem (living tissue that carries products of photosynthesis throughout the plant)

Also provides strength since thick cell walls contain cellulose, so plants with vascular tissue can growquite tall

Still require water for reproduction to occurHabitats

o Abundant in wet, or at least seasonally wet, habitats around the world.o Found living in the shadows of forest trees; can thrive with little lighto Grow best in the rain forests of the Pacific Northwesto Wet tropical areaso Tropical forests-grow as large as small trees in some places (e.g. New Zealand)

Uses of Ferns

Ferns are planted and cultivated by gardeners for their own ornamental value. Consumed by humans; Fern fronds, when young and cooked when they are fresh, are considered a

delicacy (fiddlehead greens)

Rice farmers in Asia grow a small, aquatic fern on their rice paddies because tiny pockets in the fernsfronds provide a home for specific blue - green algae. This alga produces natural fertilizers that enhance

the growth of the rice. All plants benefit, none are harmed, so=mutualistic relationship.

ReproductionLife Cycle of a Fern

- Ferns employ alternation of generations, but in ferns the diploid sporophyte is the dominant obviousstage.

1. In the sporophyte generation the fern grows long, green fronds. In many types of ferns, the developingfronds are curled at the top into a fiddlehead (yummy when slightly boiled!)

2. On the underside of the fern frond are tiny dots called sori. Each contains clusters of sporangia thatcontain spores.

3. the gametophyte stage begins when spores land in a suitable moist site and being to divide by mitosis intoa spongy, heart-shaped cushion of cells called a prothallus (barely visible to the naked eye). The gametophyte

is tiny and lives for only a short period of time.

4. The prothallus produces antheridia and archegonia, which produce male and female gametes. Ferns arenot fully-adapted to life on land as their sperm must swim through water (dew/raindrops) to get to the eggs.

The fertilized egg (zygote) grows into the sporophyte.5. The sporophyte is a well-developed land plant with true vascular tissues. The gametophyte lacks vasculartissues, is very tiny and delicate, and can grow only in moist areas.

Confirm your learningTranslation Activities


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Compare and Contrast Bryophytes and Pterophytes

BRYOPHYTES PTEROPHYTES

How are nutrients and

water transported in

the plant?

Explain adaptations

developed for life on land


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Seed Producing PlantsGymnosperms and Angiosperms

GYMNOSPERMS (Cycads, Gingkos, Gnetales and Conifers)Vascular Seed Plants

Characteristics- Most ancient of all seed plants, first appeared about 360 million years ago (m.y.a.), about the same time as

land animals.

- Throughout the age of dinosaurs (65-245 m.y.a.) gymnosperms were dominant form of plant life on Earth- Gymnos=naked, so called gymnosperms because have a naked seed (not protected by outer coating).- All have vascular tissue (transport water and nutrients efficiently and provides stability and strength),

more on this later.

- Develop roots that extend over a wide surface area, rather than penetrating deep down into the soil, thishelps hold the plant in locations where not much soil is present.

- Produce distinct male and female sex organs that are designed to transmit genetic material without water.Taxonomy and Habitats

- 4 phyla of gymnosperms have survived to present day1. Cycadstropical plants that look like palm trees- About 250 m.y.a. were a diverse and widespread group, now only 160 species remain; some close to

extinction.

2. Gingkoswere fairly common in the age of dinosaurs, but only 1 species exists today, Gingko biloba, aspecies that originated in Asia.

3. Gnetophytesshare characteristics with both gymnosperms and angiosperms- Are one of the only organisms on Earth that can survive the extremely hot and dry climate of the Namib

Desert in Africa.

4. Conifersmake up the largest group of gymnosperms and are extremely important to the economy of B.Cas they are a source of wood for building and paper making.

- Are about 550 species, most are large trees with needle or scale-like leaves.- Found throughout the world and include the worlds tallest trees (coast redwoods) and oldest trees (bristle

cone pines in Arizona and Nevada, thought to be 5000+ years old).

- Can survive in wide range of habitats because their narrow leaves are coated in thick cuticle (to preventwater loss) and their downward sloping branches allow snow to slide off so branches dont break under

heavy snow.

- Most common conifers in B.C. are from the Pine family (pines, spruces, firs, larches and cedars), the Yewfamily, the Cypress family and the Juniper family.

Confirm your learningGymnosperm Character Sketch

Economic and Ecological Importance

- Seeds of nearly all pines are edible and are high in protein.- 85% of all wood in buildings and furniture comes from conifers.- Conifers also used for fuels, paper, turpentine and medicines.- Trees help maintain balanced levels of CO2in our atmosphere, large forested areas often called carbon

sinks as they absorb high amounts of CO2gas.


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- Trees also prevent soil erosion, especially on steep slopes where tree roots keep soil in place; no trees leadto increase in landslides.

- Trees (both living and dead) provide important shelter for many animals including squirrels, many birds,bats

ReproductionLife Cycle of a Conifer(refer to diagram)

-As with ferns, the sporophyte generation is dominant.- All gymnosperms have a similar life cycle (we will look at a Pine tree).

1. The pine tree produces two different kinds of conesseed cones (female) and pollen cones (male).

2. The seed cones bear ovules that contain haploid spore cells. These develop into the female gametophyte

that makes the eggs (n).

3. The pollen cones have spores that divide by mitosis into pollen grains with sperm nuclei (n) inside.

4. Large amounts of pollen carried by the wind (=pollination) to the female cones.

5. The male pollen lands on the female cone and begins to grow a tube into the female cone until it reaches an

egg. Then the sperm is released through the pollen tube, unites with the egg and forms a zygote (2n).

6. The zygote divides by mitosis and grows into an embryo inside the seed in the female cone.

7. The seed falls to the ground and grows into the young sporophyte. The seed can remain dormant for years

and only breaks out of the seed coat and begins to grow when proper environmental cues are present

(rainfall, increase in sunlight).


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Confirm your learning - GAME!!!

Internal Structures(refer to cross-section diagram handout)

- Contain vascular tissue- Food made in leaves through photosynthesis is carried throughout plant by phloem tissue.- Water and nutrients are brought up from roots by xylem tissue.- On outside of tree is outer bark, protects tree from injury, keeps insects and diseases out and protects tree

tissues from freezing.

- New xylem and phloem (inner bark) are added to stems of conifers throughout life of tree, this isaccomplished by the vascular cambium, a thin layer of unspecialized cells between the xylem and phloem.

All new cells of stem grow from this layer.

- The division of cells from vascular cambium allows stem to grow wider.


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- Vascular cambium is a form of meristematic tissue=any plant tissue that contains cells capable of dividingfor the life of the plant, this type of tissue is also present at root tips and other parts of stem.

- Growth rings allow us to determine age of tree.- The cells produced by vascular cambium in spring and summer tend to be larger and have thinner cell

walls than those produced in late summer/early autumn, this is because there is much intense growth

during spring/early summer so cells grow more quickly.- By late summer/early autumn there is less sunlight, so cells do not divide as rapidly.- Winter is a period of dormancy (no growth) in Northern climates.- As a tree ages, some of the cells at the centre of the xylem fill with resins and gums, which prevent the

flow of water but help support the tree; this darker wood at the centre is called heartwood.

- The outer, lighter wood that has functioning xylem is called sapwood

ANGIOSPERMS (Flowering Plants)Vascular Seed Plants

Characteristics

- About 100 m.y.a., angiosperms became dominant form of plant life- Make up the largest group of plants in the world, with 250,000 known species.- Angio, comes from Greek word angion, meaning vessel so, angiosperms have covered seeds.- In angiosperms, the vessel or covering is the ripened ovary.- Widely distributed in wide variety of habitats due to successful adaptations- Contain vascular tissue that is arranged in bundles.- All produce flowers, but these vary greatly in size and shape.Flower Structures(refer to diagram of stylized flower)

- When flower is still a bud, it is enclosed in protective, leaf-like structures called sepals.- Sepals fold back and the flower opens to reveal the petals.


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- The colour and shape of petals attract insects and other animals that play a vital role in pollination.- Within the petals are the plants reproductive structures.- The thin stalks topped by small knobs are the male reproductive structures called stamensthese are

composed of a filament and an anther. The anther is where pollen grains are formed.

- The female structures are called pistils and are in the centre of the flower. Flowers have at least one pistil,but several have many.

- The sticky tip at the top of the pistil is the stigma; this is where pollen grains (from anther) land duringpollination.

- The stigma is connected to the ovary (hollow structure at base of flower) by a slender tube called a style.- The ovary contains one or more ovules.- Flowers that have both male and female parts are called perfect/complete flowers. Examples include lilies,

tulips and tomatoes.

- A flower that produces some flowers with male parts and some with female parts is called animperfect/incomplete flower. Examples include kiwi, blackberry, corn

Pollination and Fertilization

- A flower is pollinated when a pollen grain lands on the stigma- If pollen is from the same species of plant as the stigma it landed on, the pollen grain breaks open and

grows a pollen tube down through the style and into the ovary.

- The sperm from the pollen then travels down the pollen tube and fertilizes an egg cell inside an ovule.- The fertilized ovule is the seed.- Many flowers drop their petals after an egg has been fertilized. The remaining structures grow in size and

develop into a fruit. So, a fruit is really a ripened ovary that protects the seed/seeds. Apples and cherries

are fruits, as well as many other foods we normally call vegetables such as cucumbers, tomatoes and each

kernel on a cob of corn. All are fruits since they contain their seeds within a protective structure.

Confirm your LearningFlower Dissection

Monocots vs. Dicots

- Angiosperms are divided into two classes, Monocotyledons (Monocots) and Dicotyledons (Dicots).

- A cotyledon is a seed leaf that stores food for the germinating seedling. It falls off once the stem has grown

leaves that can provide plant with food through photosynthesis.


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- Monocots have their flower parts in 3s or multiples of 3sso the flower of a monocot may have 6 petals

and 9 stamens. They have leaves with parallel veins. Their stems dont have vascular cambium and they have

scattered vascular bundles. They also only have one cotyledon.

- Dicots have flower parts in multiples of 4s or 5s. Their leaves have net-like veins and their stems havevascular cambium and vascular bundles arranged in a ring.

- They have two cotyledons.

Confirm Your Learningwatch The Plants and The Bee: Plant Reproduction - CrashCourse Biology #38

http://www.youtube.com/watch?feature=player_detailpage&v=ExaQ8shhkw8

Connections to Biological ThemeUsing the theme of Adaptations as a guide, explain how Angiosperms havebecome the dominant plant form on Earth.

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Do you think that algae have stomata? Explain your answer.
http://www.youtube.com/watch?feature=player_detailpage&v=ExaQ8shhkwhttp://www.youtube.com/watch?feature=player_detailpage&v=ExaQ8shhkwhttp://www.youtube.com/watch?feature=player_detailpage&v=ExaQ8shhkw


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No. They are not vascular plants, so do not have true leaves or leaf cells such as mesophyll, xylem, phloem, etc.Their blades (photosynthetic surfaces) are extremely thin andfloat within the algaes water habitat and

exchange gases and water with the environment through simple diffusion. Since the plant lives in water, no

adaptations have developed to prevent water loss such as those required in terrestrial environments.

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