PLANT BIOLOGY: INTRO

Unit 5 – Plant Anatomy, Growth & Function

PLANTS IN OUR SOCIETY• In small groups, brainstorm uses for plants

in OUR society.

USES FOR PLANTS IN OUR SOCIETY

• Fuel (ethanol from corn)• Medicine (aloe vera, med. marijuana)• Tools (wood, toxins in wood to kill fish, weapons)• Food• Construction• Alcohol (potato vodka; grapes wine)• To breathe! • Shade• Fragrances• Composting• Narcotics• Clothing (ex. Hemp, cotton)• Dyes, tattoos, henna• Paper• Soaps• Flour, mint, herbs, tea, spices• Make-up, cosmetics, beauty and skin care, jewellery

Important Crops in Canada (thousands of tonnes)

• Wheat 28, 611

• Canola 12, 642

• Barley 11, 781

• Grain corn 10, 592

Food Security

http://www.youtube.com/watch?v=PiYDG11zIUs

Monoculture

• One type of plant is grown in place of the natural ecosystem

• What are some pros and cons of this approach?

Learning Check

• Pg 539, Q 1-6

Medicinal Uses

• 25% of prescription medicines contain plant extracts

• Rosy periwinkle (vincristine andvinblastine) – childhood leukemia and Hodgkin’s. Survival rates have gone from 20% to 90% with these 2 compounds

• Goldenseal – colds and sore gums

• Ginseng – immune system function

Biofuels

• Most biofuels come from corn (ethanol). What are some pros and cons of this method?

• Research is being done to get fuel from cellulose and oil from algae

• http://www.youtube.com/watch?v=VI4Qm2AMiEY • http://www.youtube.com/watch?v=n9_-ZguuhBw

• Read Quirks and Quarks on page 542

Erosion Control• The paradox of farming: farmers need good soil to farm,

yet farming destroys good soil.

• 2.5 million acres each year are lost to urbanization and soil erosion.

• About 1/3 of the country's topsoil has been lost due to urbanization and soil erosion.

Medicinal Plants Assignment

• Pg 573

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 350 000 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?

WHAT MIGHT VASCULAR PLANTS LOOK LIKE?

FUNCTION OF STEMS1.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 CO2 in and O2 out of leaf

Elephant Ear Plant

LEAF STRUCTURES1. 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: contains cells that perform photosynthesis b/c they contain chloroplasts.

2 GuardCells

Surround each Stoma

Meso

ph

yll

(Opening)

Leaf Cross-Section

Stoma

Veins

Cuticle

LEAF STRUCTURES4. 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 CO2 in & O2 out of leaf

• TRANSPIRATION: Allows excess H2O out of leaf

Guard Cells Stoma

FUNCTION OF ROOTS1. Anchor & support plant

in the ground2. Absorb water &

minerals3. Hold soil in place

Fibrous RootsRoot 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

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

http://dendro.cnre.vt.edu/forsite/idtype.htm

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