Plants movements

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Quiz Quiz 1. Gametophyte a. Fern b. Male angiosperms c. Female angiosperms 2. Protective covering of the sorus. 3. Nurse cells 4. Do flowers undergo secondary growth? Yes/No (3pts) 5. Structure that holds pollen among gymnosperms 6. Define double fertilization 7. Define pollination 8-10. Functions of flowers

description

Bio 103: Fundamentals in Plant Biology. This is a powerpoint presentation discussing about different types of plant movements.

Transcript of Plants movements

Page 1: Plants  movements

QuizQuiz1. Gametophyte a. Fern b. Male angiospermsc. Female angiosperms

2. Protective covering of the sorus.

3. Nurse cells

4. Do flowers undergo secondary growth? Yes/No (3pts)

5. Structure that holds pollen among gymnosperms

6. Define double fertilization

7. Define pollination

8-10. Functions of flowers

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Label the following

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Label the following

a b c d

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ESSAYESSAYCompare and contrast reproduction of angiosperms, gymnosperms and bryophytes.

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There are many types of tropisms :

• Phototropism

• Geotropism

•Thigmotropism

• Hydrotropism

• Chemotropism

• Thermotropism

TROPISMPlant growth in response to a

stimulus (“tropo” – ”turn”)

!!Tropisms allow plants to seek out the best conditions for survival

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TROPISM

POSITIVEPOSITIVE

If the plant moves TOWARD the stimulus

NEGATIVENEGATIVE

If the plant moves AWAY from the stimulus

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GEOTROPISM Geotropism is the growth of a plant in response to gravity.

Positive Geotropism

It is the growth of a plant towards the center of the earth-down with

gravity.Ex. roots growing down

Negative Geotropism It is the growth of a plant away

from the center of the earth-opposite from the pull of gravity

Ex. stems grow up

Positive Geotropism

Negative Geotropism

(“Geo” – Earth)

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IMPORTANCE OF GEOTROPISM

• Pulls roots down to anchor a plant

• Roots can get needed water and minerals if they stay in the soil

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PHOTOTROPISM

The growth response of a plant in response to light direction is called phototropism.

(“Photo” – light)

Ex. Stems growing toward the window to get to the light

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THIGMOTROPISMThigmotropism is the

growth of a plant in response to touch/contact.

NEXT

(“Thigmo” – “touch”)

Tendrils on a sweet pea

Photo by Christopher Meloche

Vines growing on a wall or fence

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HYDROTRHYDROTROPISMOPISMHydrotropism is the growth in

response to water. Ex. roots growing toward moisture

NEXT

(“hydro” – “water”)

THERMOTROPISMThermotropism is the tendency of plants or other

organisms to bend toward or away from heat.

Ex. curling of Rhododendron leaves in response to cold temperatures.

ChemotropismChemotropism is movement caused by chemical stimuli.

Ex. Growth of a pollen tube is always towards the ovules so that reproduction can occur

(“Therm” – “heat”)

(“Chemo” – chemical”)

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MOVEMENTS

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Nastic Movement

¤ Nastic Movements are plant movements that are in response to a stimulus (non-directional)

¤Examples:. Temperature, Humidity, & Light Irradiance

¤ The movement can be caused by turgor or changes in growth

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Plants That Have Nastic Movement

Prayer Plant (Flat) Prayer Plant (Vertical) Due to Daytime Due to Nighttime

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Nastic Movement

vs. Tropic

Movement

¤Nastic Movements differ from Tropic Movements in that the direction of Tropic Responses depend on the direction of the stimuli, whereas the direction of Nastic Movements are independent of the stimuli.

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NASTIC NASTIC RESPONSESRESPONSES

¤ The frequency of these responses increases as intensity of the stimulus increases.

¤ Example of Nastic Response: Opening and closing of flowers (Photonastic response)

¤ Nastic Responses are usually associated with plants:1. Photonasty: Response to light2. Nyctinasty: Movements at night or in the dark3. Chemonasty: response to chemicals or nutrients4. Hydronasty: response to water5. Thermonasty: Reponse to temperature6. Geonasty/Gravinasty: Response to gravity7. Thigmonasty/Seismonasty/Haptonasty: Response

to touch

¤ Notice that the Nastic Responses are named with the suffix “-nasty” and have prefixes that depend on the stimuli

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PHOTOPERIODIPHOTOPERIODICITYCITY

¤ Photoperiodicity is the physiological reaction of organisms to the length of day or night.

¤ Examples:

1.Shortday plants-Morning Glory, Tulip

2.Longday plants-Potato, Poppy

3.Day Neutral-Tomato, Dandelion, Corn

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-The term auxin is derived from the Greek word auxein which means to grow.

- Auxins were the first plant hormones discovered

Functions of Auxins:

-Stimulates cell elongation

-Stimulates cell division in the cambium

-Stimulates differentiation of phloem and xylem

-initiates response of bending in response to gravity and light

HORMONES

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Coleoptile or stem tip

Agar block prevents the movement of auxins in the stem

If auxins cannot move through the stem than the stems ability to respond to, say light ,is inhibited. This means that the plant will not be able to grow towards the light as it normally would. Place the tip back on the plant and all is well!!

EFFECTS OF AUXIN

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If the agar block is placed partially on the stem than the response would be as shown.

As the auxin (which is in the agar block) diffuses into that side of the coleoptile, it stimulates cell elongation and the coleoptile bends away from the block.

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Cytokinin Functions:

-Stimulates cell division

Ethylene :

-Ethylene, unlike the rest of the plant hormone compounds is a gaseous hormone

- stimulates the ripening of the fruit

Gibberellins:- Gibberellins affect:

The rate of cell divisionFloweringIncrease in size of leaves and fruitsSeed and bud dormancyInduction of growth at lower temperatures

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Abscisic acid :

-causes trees to lose their leaves in response to winter -buds to go dormant