Intro to Plants and The Vascular System 5.2

KINGDOM PLANTAE Plants evolved about 500 million years ago from simple green algae that lived in the ocean. All plants are autotrophic and some, like the famous Venus fly-trap, can also be heterotrophic. All plants are eukaryotic and multicellular.

PLANT CELLS Like animal cells, plant cells contain a nucleus and organelles, but they have two distinguishing features: –Cell wall (made of cellulose, a complex carbohydrate, provides rigid structural support; difficult to digest) –Chloroplast (organelle that conducts photosynthesis) Animal cells have lysosomes that release the cellular equivalent of digestive enzymes. Why don’t plants need these?

PLEASE... CONSIDER THE FOLLOWING: How can plants stand up straight without a skeleton?

PLANT DIVERSITY Currently over species of plants, including: –Mosses –Ferns –Conifers –Flowering plants Most plants live on land and can withstand a wide variety of climates. Cacti live in arid, dry areas whereas mosses need to be in moist environments to survive.

CLASSIFYING PLANTS Plants are classified based on the presence or absence of vascular tissue Vascular tissue can be compared to arteries and veins: a network of specialized cells that allows plants to transport water, minerals and sugar throughout the plant What would you expect a non- vascular plant, without vessels to transport nutrients and water, to look like?

Plants Non-vascular (ex. moss) Cannot transport foot or water between plant parts Transport of fluid is through simple absorption or osmosis Must live in moist environments; need water for reproduction Vascular (ex. tree, sunflower) Contain a vascular system allowing for transportation of nutrients / water throughout the plant

WHAT MIGHT VASCULAR PLANTS LOOK LIKE?

FUNCTION OF STEMS 1.Support system for plant body 2.Transport system carries water & nutrients (through vascular tissue!) 3.Holds leaves & branches upright Looking at the picture below: What years had the most rain? What years experienced the worst drought?

FUNCTION OF LEAVES 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 CO 2 in and O 2 out of leaf Elephant Ear Plant

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 vascular tissue 3.Mesophyll: Spongy and Palisade -contains cells that perform photosynthesis b/c they contain chloroplasts. 2 Guard Cells Surround each Stoma M e s o p h y l l (Opening) Leaf Cross-Section Stoma Veins Cuticle

LEAF STRUCTURES 4.Guard cells: Cells that open and close the stoma Conserve water by preventing excess water transpiration 5.Stomata: openings in leaf’s surface; when open: GAS EXCHANGE: Allows CO 2 in & O 2 out of leaf TRANSPIRATION: Allows excess H 2 O out of leaf Guard Cells Stoma

FUNCTION OF ROOTS 1.Anchor & support plant in the ground 2.Absorb water & minerals 3.Hold soil in place Fibrous Roots Root Hairs

STRUCTURE OF ROOTS 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 Root Hairs Meristem Root Cap Where do you think all new growth starts?

Types of Roots A: Fibrous root B: Taproot C: Modified root

QUIZ TIME! BEFORE WE CONTINUE… VASCULAR OR NON-VASCULAR?

VASCULAR PLANTS Gymnosperms “Naked seeds” are not enclosed in an ovule (like a pine cone). Plants are usually evergreens. Ex. pines, cedars, spruces and firs. Angiosperms Mature seed is surrounded by the ovule (think of an apple). Angiosperms are trees/plants that shed leaves every autumn. Ex. Oaks, maples and dogwoods are examples of deciduous trees. Contain a vascular system allowing for transportation of nutrients / water throughout the plant

QUIZ TIME! BEFORE WE CONTINUE… GYMNOSPERM OR ANGIOSPERM ?

KEY WORDS: PLANT BIOLOGY Cell wall Chloroplast Vascular tissue Non-vascular tissue Stomata Cuticle Veins Mesophyll Chlorplast Guard cell Stomata Transpiration Root hair Meristem Root cap Gymnosperm Angiosperm

Learning Check Pg 557, Q 19-24

Vascular Systems

Like humans, plants have a vascular system for moving water and nutrients around. Unlike humans though, they do not have a pumping mechanism.

Monocot and Dicot Vascular Tissue Arrangement Remember the arrangement of vascular tissue in dicots and monocots.

Xylem Water transport Consists of two main cell types: tracheids and vessels elements, both are non-living, hollow cells. Start as living cells, grow to fill the space required and then die and become hollow, easily allowing water to move through. Gymnosperms only have tracheids as part of their Xylem.

Phloem Sugar movement Made up of living cells, which use oxygen while moving sugar around, therefore use energy. Made up of sieve tube elements connected by sieve plates. Companion cells lie adjacent to sieve tubes and help provide energy.

Pg 549, Q 7-12