PlantsPlants

ChaptersChapters

22-2522-25

What is a Plant?What is a Plant?

Eukaryotic Eukaryotic organismorganism

MulticellularMulticellular AutotrophicAutotrophic

ChloroplastChloroplast Plants have chloroplast Plants have chloroplast

that carry out that carry out PhotosynthesisPhotosynthesis

Photosynthesis (uses Photosynthesis (uses sunlight as energy sunlight as energy sourche): CO2 + H20 -> sourche): CO2 + H20 -> Glucose (C6H12O6) and Glucose (C6H12O6) and O2 O2

Chloroplast are green Chloroplast are green pigment that reflects pigment that reflects green lightgreen light

Has internal membrane Has internal membrane that increases surface that increases surface areaarea

What is the advantage to What is the advantage to Photosynthesis/Autotroph:Photosynthesis/Autotroph:

Can make own food donCan make own food don’’t t need to hunt of findneed to hunt of find

Plant cells have cell Plant cells have cell walls to add rigidity walls to add rigidity and protect the celland protect the cell

The cell walls are The cell walls are made of cellulose made of cellulose which we cannot which we cannot digestdigest

Cellulose is a Cellulose is a CarbohydrateCarbohydrate

Plant types

MossesMosses• They lack a They lack a

vascular system vascular system and true rootsand true roots

• Low growing plants Low growing plants that like to live near that like to live near a water supplya water supply

• These evolved fists- These evolved fists- why they are most why they are most primitiveprimitive

FernsFerns• Have roots and a Have roots and a

vascular systemvascular system• Do not have seedsDo not have seeds

RootsRoots The usually underground portion The usually underground portion

of a plant that lacks leavesof a plant that lacks leaves serves as supportserves as support draws minerals and water from draws minerals and water from

the surrounding soilthe surrounding soil sometimes stores foodsometimes stores food Root hairs- provide increase Root hairs- provide increase

surface areasurface area Roots are specialized for Mitosis Roots are specialized for Mitosis

why?why?

What is What is vascular tissuevascular tissue??

Tissue in the plant that transports Tissue in the plant that transports water and nutrientswater and nutrients• Xylem – transports water– transports water• Phloem – transports nutrientsPhloem – transports nutrients

• Transpiration – water flows through the – water flows through the plant from root to leafplant from root to leaf

Released onto leaf undersurface through Released onto leaf undersurface through stomata and evaporatesstomata and evaporates

How are roots and vascular tissue an How are roots and vascular tissue an adaptation: allow plant to live in adaptation: allow plant to live in more arid conditionsmore arid conditions

Grow to taller heights because can Grow to taller heights because can move water and nutrient by means move water and nutrient by means other then diffusionother then diffusion

GymnospermsGymnosperms

Cone bearersCone bearers• Seeds are exposedSeeds are exposed

• Called evergreens Called evergreens or conifersor conifers

• Remain green all Remain green all year- why is this an year- why is this an advantage?advantage?

Can perform Can perform photosynthesis all photosynthesis all yearyear

Seeds Seeds

A fertilized plant A fertilized plant ovule containing an ovule containing an embryo.embryo.

Why is this an Why is this an adaptation: sexual adaptation: sexual reproduction -> reproduction -> increased genetic increased genetic variationvariation

GerminationGermination•Process by which plants emerge from seeds and begin growth

•Can lay dormant for long periods and wait on proper conditions

•Temperature•Water

Why is this advantageous?•Best chance for survival

Pine NeedlesPine Needles The long, slender shape The long, slender shape

reduces leaf area, which, reduces leaf area, which, in turn, reduces the in turn, reduces the amount of water vapor amount of water vapor escaping the leaf. (one escaping the leaf. (one time less surface are is an time less surface are is an adaptation)adaptation)

Pine needles are shed year Pine needles are shed year round – just not all at one round – just not all at one time.time.

AngiospermsAngiosperms

Flowering plantsFlowering plants• Seeds protected by a layer of tissueSeeds protected by a layer of tissue• Flowers are the reproductive organsFlowers are the reproductive organs• Ovaries surround and protect seed Ovaries surround and protect seed

inside the flowerinside the flower• Many times the ovaries will develop into Many times the ovaries will develop into

fruitfruit

FlowersFlowers

known as a bloom or known as a bloom or blossom is the is the reproductive structure found structure found

in in flowering plants The biological function of a flower is The biological function of a flower is

to effect reproduction, usually by to effect reproduction, usually by providing a mechanism for the union providing a mechanism for the union of sperm with eggs.of sperm with eggs.• Increased by pollinatorsIncreased by pollinators

•Pollinators are attracted to flowers because of bright colors and they smell nice (same reason we like them)

•Spreads pollen (sperm) to other flowers increasing genetic variation

Plant Reproduction

Mostly sexual Mostly sexual reproductionreproduction• Some plants have a Some plants have a

way of carrying out way of carrying out asexual asexual reproductionreproduction

Pollen is the male gametes of Pollen is the male gametes of plantsplants• Can be compared to sperm cells in Can be compared to sperm cells in

animalsanimals Plants have ovules with eggs Plants have ovules with eggs

cells that can be fertilized by cells that can be fertilized by pollenpollen

The seed is an early embryo that The seed is an early embryo that can, in some cases remain can, in some cases remain dormant for long periods of timedormant for long periods of time

Covered seedsCovered seeds

The seed coat protects the seed The seed coat protects the seed The endosperm (food supply) The endosperm (food supply)

nourishes the embryo nourishes the embryo

Seed protectionSeed protection

Less likely to be eaten Less likely to be eaten

Protected from Protected from environmentenvironment

Nourishment for seedNourishment for seed

- better chance for - better chance for survivalsurvival

Seed dispersal

• Seeds have different shapes or protective Seeds have different shapes or protective coverings to aid in their dispersal coverings to aid in their dispersal

• Adaptation: move away from parent plant Adaptation: move away from parent plant or other seedlings – less competition or other seedlings – less competition

LeavesLeaves Wide broad leaves Wide broad leaves

provide additional provide additional surface area to absorb surface area to absorb sunlightsunlight• Increase photosynthesisIncrease photosynthesis

• However increase rate However increase rate of water loss which of water loss which could be bad- so how do could be bad- so how do plants over come thisplants over come this

Adaptation to avoid water lossAdaptation to avoid water loss

Cuticle: waxy covering on leaves Cuticle: waxy covering on leaves (lipids – hydrophobic) – keep water (lipids – hydrophobic) – keep water from entering or leavingfrom entering or leaving

Stomata: openings in the bottom of Stomata: openings in the bottom of the leaf that allow water to exit the leaf that allow water to exit • Has guard cells on both sides of stomata Has guard cells on both sides of stomata

to open and close to open and close

Specialized leaves for habitatSpecialized leaves for habitat Water lilies: thick cuticle to keep water Water lilies: thick cuticle to keep water

outout Cacti Needles: same as pine needles- Cacti Needles: same as pine needles-

reduce surface area (water loss) – also reduce surface area (water loss) – also provide protectionprovide protection

Broad leaves- for areas of limited Broad leaves- for areas of limited sunlight (rainforest floor)sunlight (rainforest floor)

Can Plants Move?Can Plants Move?

Plants cannot get up and walk like Plants cannot get up and walk like us, but they us, but they can move stems and can move stems and leaves toward certain stimulileaves toward certain stimuli

These movements are called These movements are called tropismstropisms

GravitropismGravitropism

Plant grows Plant grows upward against the upward against the pull of gravitypull of gravity• Allows seed to grow Allows seed to grow

up out of soilup out of soil• Adaptation: to get Adaptation: to get

sunlightsunlight

PhototropismPhototropism

Plant grows toward Plant grows toward light sourcelight source

To get sunlight for To get sunlight for photosynthesisphotosynthesis

ThigmotropismThigmotropism

A plantA plant’’s response s response to touch to touch • Can be used as Can be used as

protectionprotection• Can be used for Can be used for

stabilitystability• Venus fly trap uses Venus fly trap uses

to obtain to obtain food(nutrients)food(nutrients)

Plant HormonesPlant Hormones

Important for growth and maturationImportant for growth and maturation• Are chemical substances that control a Are chemical substances that control a

plantplant’’s patterns of growth and s patterns of growth and developmentdevelopment

• Example: AuxinExample: Auxin’’s role in phototropisms role in phototropism

Auxin stimulates the elongation of Auxin stimulates the elongation of cellscells

When light hits the tip of a plant, When light hits the tip of a plant, more auxin is produced in the more auxin is produced in the shaded areashaded area

The dark side of the stem elongates The dark side of the stem elongates causing the stem to bend toward the causing the stem to bend toward the light light

Uses of plantsUses of plants

Plants are a major Plants are a major food source for food source for heterotrophsheterotrophs• Where do plants get Where do plants get

their energy?their energy? They are autotrophic They are autotrophic

and photosyntheticand photosynthetic

Photosynthesis Photosynthesis produces Oxygenproduces Oxygen

Other usesOther uses

OilsOils MedicineMedicine LumberLumber AestheticsAesthetics Shelter for animalsShelter for animals Commercial productsCommercial products