Structure of

Plants

Slide 1

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Chapter 23

A. Functions of Roots

1. Anchor & support plant in the ground

2. Absorb water & minerals

3. Hold soil in place

Slide 2

Fibrous RootsRoot Hairs

B. Root Types

2. Tap Roots –larger central root reaches deep water sources underground

Ex. Trees, Carrots, & Dandelions

1. Fibrous Roots: branching roots hold soil in place to prevent soil erosion

Ex. Grasses

Slide 3

Tap Root

1. Root Hairs: increase surface area for water & mineral absorption

2. Meristem: region where new cells are produced

3. Root Cap: protects tip of growing root

C. The Structure of a RootSlide 4

Root Hairs

MeristemRoot Cap

Xylem

Phloem

A. Functions of Stems

1.Support system for plant body

2.Transport system carries water & nutrients

3.Holds leaves & branches upright

Slide 5

Each light and dark tree ring equals one year of annual growth. Light rings for fast spring growth, dark for slow summer growth.

Smaller rings tell of past droughts that have occurred.

Looking at the picture to the left:

What years had the most rain?

What years experienced the worst drought?

A. Functions of LeavesSlide # 6

1. Main photosynthetic organ

2. Broad, flat surface increases surface area for light absorption

3. Have systems to prevent water loss• Stomata open in day but

close at night or when hot to conserve water

• waxy cuticle on surface

4. System of gas exchange

• Allow CO2 in and O2 out of

leaf Elephant Ear Plant

B. Leaf Structures

1.Cuticle: waxy layer; covers upper surface • Protects leaf against

water loss

2.Veins: transports water, nutrients and food• Made of xylem and

phloem

3.Mesophyll: contains cells that perform photosynthesis b/c they contain Chloroplasts.

2 GuardCells

Surround each Stoma

Mes

op

hyl

l

Slide # 7

(Opening)

Leaf Cross-Section

Veins

Cuticle

Stoma

Stoma- singular

Stomata-plural

More Plant Parts…

Guard Cells

4. Guard cells: • cells that open

and close the stoma

5. Stomata: openings in leaf’s surface; when open: • GAS EXCHANGE:

Allows CO2 in & O2

out of leaf • TRANSPIRATION:

Allows excess H2O

out of leaf

Slide # 8

Stoma

Slide # 9

Stoma Open Stoma Closed

Guard Cells

Stoma

Function of Stomata

Guard Cells

CO2

O2 H2O

What goes in?

What goes out?

•What process involves using CO2 and H2O releasing

O2 as a waste product?

•Photosynthesis

•What is the plant using this process to make?

•Carbohydrates-glucose

•If the plant needs water for photosynthesis, why is water coming out of the stoma?

Slide # 10

Stoma Open Stoma Closed

Guard Cells

Function of Guard Cells

Guard Cells•These stomata (leaf openings) naturally allow water to evaporate out.

•Why would the plant close stomata with guard cells?

•Prevent excess water loss through transpiration. (conserve water)

•So what is the point of having stomata?

•Allow gas exchange for photosynthesis

Slide # 11

A average size maple tree can transpire 200 liters of water per hour during the summer.

Transpiration is the #1 driving force for pulling water up

stems from roots.

C. Plants find a use for Transpiration

1. Transpiration: loss of excess water from plant leaves

2. Significance:

BA

a. Transpiration causes enough pressure to help pull water (& required nutrients) up stem from roots.

b. As part of the water cycle, trees transpire water back into the atmosphere.

c. Transpiration provides much of the daily rain in rainforest.

1.Pistil:female reproductive structure

a.Stigma: sticky tip; traps pollen

b.Style: slender tube; transports pollen from stigma to ovary

c.Ovary: contains ovules; ovary develops into fruit

d.Ovule: contains egg cell which develops into a seed when fertilized

FilamentAnther

StigmaStyle

Ovary

Pistil

PetalSepalOvule

Stamen

Slide # 12 Structure of a Flower

2.Stamen: male reproductive structure

a.Filament: thin stalk; supports anther

b.Anther: knob-like structure; produces pollen

c.Pollen: contains microscopic cells that become sperm cells

Structure of a FlowerSlide # 13

FilamentAnther

StigmaStyle

Ovary

Pistil

PetalSepalOvule

Stamen

3.Sepals: encloses & protects flower before it blooms

4.Petals: usually colorful & scented; attracts pollinators

 Structure of a FlowerSlide # 14

FilamentAnther

StigmaStyle

Ovary

Pistil

PetalSepalOvule

Stamen

Cross PollinationSlide # 15

• How does pollination happen?

• Pollen from an anther is caught by the stigma, travels through style to the ovules in the ovary.

• What is the result of pollination?

• A Fruit: An ovary containing seeds.

Plant

Responses

and

Adaptations

Slide # 16

Slide #17

Hormone-producing

cells

Target cells

Movement of hormone

Hormone Action on Plants

A. Plant cells can produce hormones: which are chemical messengers that travel throughout the plant causing other cells called target cells to respond.

B. In plants, hormones control:

1. Plant growth & development

2. Plant responses to environment

Cells in one blooming flower signals other

blooms using hormones to open.

C. Plant cells will send signals to one another to tell them:

1.When trees to drop their leaves.

2.When to start new growth.

3.When to cause fruit to ripen.

4.When to cause flowers to bloom.

5.When to cause seeds to sprout.

Slide # 18

Leaf Drop

Fruit Ripening

Sprouting Corn Seeds

Cactus Blooming

Tree Budding

D. Ethylene causes Fruit to Ripen

1.Fruit tissues release a small amount of ethlyene

2.Causes fruits to ripen.

3.As fruit become ripe, they produce more and more ethlyene, accelerating the ripening process.

Slide # 19

Ethylene released by apples and

tomatoes causes fruit to age quickly.

Plant Tropisms

1. Tropism: the way a plant grows in response to stimuli in the environment.

a.Phototropism: growth response to light

-Plants bend towards light

a.Geotrophism: growth response to gravity

-plant roots grow down with gravity, shoots (stems) grow up against gravity and out of the soil.

a.Thigmotropism: growth response to touch

-vines grow up around trees, venus flytrap closes when leaves are touched

Slide # 20

Slide # 21

Geotropism

What type of tropism is shown in these pictures?

Thigmotrophism

Thigmotrophism

Geotropism

Phototropism

Phototropism