UNIT VPLANTS: Anatomy,

Growth and Function

Kingdom Plantae• Multicellular, non-motile, cell wall with cellulose, mostly autotrophic • Plant life cycles• Plant Structures relate to plant needs

– Sunlight, water and minerals, gas exchange, – Reproduce without water to transmit male

gamete (in Angiosperms)– Vascular tissue, roots, stems, leaves, seeds, flowers

Vascular and Non-vascular plants (13.1)• Plants consist of 3 main parts:

– Roots: anchor plant to soil, helps obtain water

– Leaves: surface area for photosynthesis

– Stems: rigidity and support for leaves• In order to supply each of these parts

with water, energy and nutrients, plants contain vascular tissue made up of cells that conduct solutions throughout the plant, linking the tips of the roots to the highest leaves– Transports water, dissolved minerals

and sugars to all parts of the plant• Non-vascular plants: mosses, liverworts,

and hornworts no or poorly developed roots, leaves and stems

Reproductive Strategies• Algae: release unprotected

gametes into water• Pollen (male gametes)

carried to female plants by wind, insects or other animals

• Zygote develops inside a seed

• Seed = embryo, stored food and a tough waterproof coat

Major Groups of Plants

• Three traditional groupings:– Bryophytes—nonvascular plants– Pteridophytes — vascular, seedless plants– Seed plants

• Gymnosperms• Angiosperms

Ginkgo bilobaGinkgos are often very long-lived.

Some specimens are thought to be more than 3,500

years old.

Classification of Plants (13.2)

Evolutionary tree for major plant groups

Non-vascular Plants• Do not posses vascular system• Require moist environment for reproduction

and the transfer of water and food by osmosis and diffusion

• They have no roots or poorly developed roots (rhizoids), stems and leaves

• 3 divisions: mosses (bryophytes, hornworts (Anthocerophytes), and Liverworts (Hepatophytes)

• Grow in mats of low tangled vegetation that can hold water

• Life cycle is dominated by gametophyte phase

• Gametophytes are the green plants commonly found in moist shady areas

• Moisture is required for the sperm to swim to the egg during fertilization

• After fertilization the zygote remains on the female plant to develop into a sporophyte

Life Cycle of a Moss

Sexual Reproduction in Plants• Seeds are the product of sexual reproduction in most

plants. • SEED = EMBRYO + FOOD + PROTECTIVE COATING • A seed can remain dormant and therefore will live

through rough times while adult plants may die off. This ensures the survival of the species.

• Flowering Plants are more successful than conifers because they produce a protective coating around their seeds which increases the chance of the embryo surviving in rough times.

• Seed-bearing plants can be classified into two groups:– angiosperms and – gymnosperms.

Gymnosperms (14.1)• Have seeds without a seed coat• They are attached to the scales

of cones• They thrive in environments with

long cold winters and low amount of nutrients in the soil

• They provide fibres for making paper and wood for building materials

• Pollination in gymnosperms: the pollen from the male cones are carried by the wind to the female cones to make seeds in a process similar to angiosperms

• The seeds are protected by a structure like a maple key and fall to the ground to germinate and grow into new trees.

Tutorial 30.1 Life Cycle of a Conifer

Angiosperms – flowering plants• Their number is far greater than gymnosperm species• They are also more diverse• They are important as a source of food for many organisms,

including humans• Flowers are the angiosperm’s reproductive organs which

mature into seed containing fruit• E.g.: trees, grasses, vegetables, wildflowers and herbs• They two angiosperm classes are monocots (have one

cotyledon) and dicots (two cotyledons)

• Pollination in angiosperms: pollen is spread from the anther to the stigma of another plant (cross-pollination) or the same plant (self-pollination) by bees, insects, wind, etc.

• a pollen tube grows down the style into the ovary • a sperm travels down the tube to fertilize one egg resulting in the

development of a seed Pollination in angiosperms: pollen is spread from the anther to the stigma of another plant (cross-pollination) or the same plant (self-pollination) by bees, insects, wind, etc.

• a pollen tube grows down the style into the ovary • a sperm travels down the tube to fertilize one egg resulting in the

development of a seed Life Cycle of an Angiosperm

Monocots• About 10% of all

monocots are woody (tough and rigid) stems

• E.g. palm and bamboos, other are dates, coconuts, bananas, palm oil and sugar (found in warm climates)

• Most monocots are non-woody or herbaceous (soft/fleshy stems) orchids, lilies, tulips, onions and grasses (wheat, corn and rice)

Dicots• Most Canada’s native tree species are dicots

• Most native wildflowers are also dicots

• E.g.: lettuce, tomatoes, radishes and sunflower sprouts

• The staples foods of many cultures are dicots e.g.: yam, potatoes, cabbage (rich in starch), bean (rich in protein)

The Differences Between Monocot and Dicot Plants

MONOCOTS•One cotyledon (1 Seed Leaf) •Leaves of 3 petals •Parallel Veins •Scattered Vascular Bundles

• DICOTS•One cotyledon (2 Seed Leaves) •Leaves of 4 or 5 petals •Network Veins •Vascular Bundles in RINGS

True dicots vs monocots

Structure of a Seed• Epicotyl: cells at the tip of the

embryo that form the leaves and upper stem of the plant

• Hypocotyl: middle part of the embryo that becomes the lower part of the stem

• Radicle: cells on the other end of the embryo that develop into the roots system of the young plant

• Cotyledon: a source of energy and nutrients for the embryo

• Seed coat: protects the seed and also controls germination by restricting water and oxygen to the embryo

Life cycle of a lily

Tutorial 39.1 Double Fertilization

Plant TissueThere are Four Main types of plant Tissue:1. Protective: epidermis and cuticle • prevents disease and foreign invaders

2. Fundamental: cortex and parenchyma • provides support

3. Meristemic: the area of the plant where growth occurs (due to hormones)

a. Apical – found in tips of roots and leaves

makes roots, leaves and flowersb. Lateral

– found in the sides of stems– makes xylem and phloem (vascular cambium)– makes bark (cork cambium)

4. Conductive: xylem and phloem • carries water, nutrients and minerals • arranged in bundles

• The tissues of a plant are organized into three tissue systems: the dermal tissue system, the ground tissue system, and the vascular tissue system.

Morphology of a tomato plant

Body plan for a tomato plant

Tissue Systemand Its Functions

Component Tissues Location of Tissue Systems

Dermal Tissue System• protection• prevention of water loss

EpidermisPeriderm (in older stems and roots)

Ground Tissue System• photosynthesis• food storage• regeneration • support• protection

Parenchyma tissueCollenchyma tissueSclerenchyma tissue

Vascular Tissue System• transport of water and minerals• transport of food

Xylem tissuePhloem tissue

14.2 Vascular Systems• Plants with Vascular Tissue are

so successful because... – vascular Tissue is well

adapted to carry water – vascular Tissue is very strong

and provides support • The vascular bundles in a stem arc

continuous, tube-like strands connecting the vascular tissue of the root to the vascular tissue in the leaves.• The transportation of water and dissolved minerals is carried out by specialized tissue called xylem in the vascular bundles.• The transportation of dissolved food is carried out by specialized tissue called phloem in the vascular bundles.

monocot

dicot

Xylem• Xylem is the principal water conducting

tissue of vascular plants. • It consists of tracheids and vessel

elements/membersVessel Elements– Larger in diameter than tracheids– They are dead at maturity and

contain no cytoplasm– They are arranged end to end just

like barrels piled on top of each otherTracheids

– Long thick wall cells with tapering ends

– They are dead at maturity and are hollow

– They ends of the tracheids overlap, allowing water to pass from one cell to the next

Transpiration Cohesion Theory1. Water enters the roots by

osmosis. This causes root pressure which pushes the water into the xylem.

2. Water molecules climb the sides of the xylem vessels by clinging to the narrow vessel walls (molecular adhesion)

3. Each water molecule clings to the next one forming a continuous column from the roots to the leaves (molecular cohesion)

4. Transpiration causes water to move through the leaf by osmosis, pulling water out of the xylem cells.

The Cohesion Tension Theory

http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/animations/0031.swf

PhloemThe phloem is made up of a companion

cell, sieve-tube elements and sieve plates.• These cells remain alive, unlike the xylem cells.• Although sieve-tube elements lack a nucleus at maturity, because they have a cytoplasm and all of the other organelles it is still able to function.• The cytoplasm of the sieve-tube cell is connected by pores to a nucleated companion cell next to it. It appears that the companion cell directs the activity of the sieve-tube cell.• The sieve-tube elements are arranged end-to-end with sieveplates separating them. Because of the large pores in the sieve plates, the cytoplasm of extends from one sieve-tube cell to the next

Animation - Phloem Loading

The Bulk Flow Theory

Sources and SinksSource: the places where

sugars are made. Since photosynthesis occurs in the leaves, this will be the place where sugars are loaded into the phloem

Sink: The plant parts that require carbohydrates. These are the places where the sugars are unloaded from the phloem

The conducting tissue of the phloem connects the sources with the sinks.

1. Active transport moves solute into phloem

2. Sieve tube solution is now concentrated, therefore water moves in from neighbouring cells

3. Hydrostatic pressure is created and the solution inside the sieve tube cells moves from source to sink by bulk flow

4. Active transport moves solute out into sink cells

5. Solution in sieve cells is now less concentrated and water moves out

Tutorial 36.1 The Pressure Flow Model

Sugar Transport in Plants

  Xylem Phloem

Substance It Carries

Water & Minerals Glucose

Direction It Carries It

Upwards (from soil to leaves)

Downwards (from leaves to stem)

Method Of Carrying It

1. Root Pressure:no where for the water to go but up Capillary Action: water is polar and "sticks" to the sides of the xylem tube, climbing up

Cohesion-Tension : water evaporates off the leaves so more water moves there to replace it

1. Mass-Flow Theory high concentration of glucose in leaves and low water, therefore water moves in by osmosis and "washes" the glucose down the stem

Structure - hollow, dead cells -living cells

Vascular tissues

14.3: Structure and Function Leaf Cross Section

The Leaf• Epidermis: protects the inside tissue of a leaf from injury

and from drying out• Cuticle: waxy substance secreted by the epidermal cells• Palisade layer: long narrow parenchyma cells where

photosynthesis takes place• Spongy layer: smaller more loosely packed parenchyma

cells where photosynthesis takes place• Stomata: allow movement of gases and water vapour

into and out of the leaf• Guard cell: these cells change shape and by doing so,

open and close the stomata. These cells also contain chloroplasts unlike other epidermal cells

• Vascular bundle (xylem and phloem): transport water and food

Leaf structure

Gas Exchange in LeavesThe guard cells are the only cell in the epidermis that

contain chloroplasts. They must therefore perform photosynthesis. It is the occurrence of photosynthesis that causes a stoma to open in the morning and close at night.

An Open Stoma• In daylight, the guard cells produce glucose via

photosynthesis• The presence of sugar inside the guard cells causes

water to enter by osmosis from neighbouring epidermal cells

• The increase in turgor pressure causes the guard cells to swell opening the stoma between them

• The open stoma allow O2 and CO2 to leave and enter the leaf

Gas Exchange in Leaves

A Closed Stoma• When the sun sets,

photosynthesis stops and the guard cells stop producing glucose.

• Water no longer enters the cells by osmosis and the turgor pressure decreases

• The stoma then closehttp://trc.ucdavis.edu/biosci10v/bis10v/week8/stomata.mov

The Root• All roots are responsible for:

– anchoring the plant to the ground – extracting water and minerals from the soil – Some plant roots also store food energy (as starch).

• There are three main types

of roots: – tap root – fibrous root – adventitious

Root Structures

15.2: Importance of Plants to Humans• Food source – Wheat, grains, fruits,

vegetables

• Medicine – Aspirin, cancer treatments, stimulants

• Industry – Agriculture, wood products, cotton

Sugercane

How Plants Help the AtmosphereRemoval of Carbon• Carbon can be stored in

organic tissue carbon storage

• Trees and vegetation can store excess carbon in their tissues for as long as they are alive.

• Carbon sink: an area where there is a lot of carbon stored in organic tissue

Production of Oxygen• Give up oxygen during the

process of photosynthesis

16.2: The Process of SuccessionPrimary Succession: sequence of change in a

community that starts with bare rock and ends with a stable ecosystem

Secondary succession: sequence of change in a community that begins with a previously existing but disturbed community Tutorial 55.1 Primary Succession on a

Glacial Moraine

Primary Succession Secondary Succession

Climax Community• Final stage of succession rocks broken

down and converted to fresh soil

• Canada’s Biomes: temperate forest, boreal, tundra…