The Plant Kingdom topic 9pages 83-87

• The Plant Kingdom: An Introduction - Learning Activity

• Amazing little food factories for themselves and most terrestrial food chains

• Retain stem cells ( meristems) for growth through out their life.

• Meristem cells are small and reproduce by mitosis and cytokinesis

Plant ClassificationBryophytes

• Mosses: have no true roots, only structures similar to root hairs called rhizoids.

More on bryophytes

• Mosses have simple leaves and stems.

Liverworts are bryophytes

• Liverworts consist of a flattened thallus.

Bryophytes

Maximum height is 0.5 ,meters

Reproductive structures: Spores are produced in a capsule. The capsule develops at the end of a stalk

Life Cycle of a Moss animation

• Spores produced in capsule, found on a stalk.

Filicinophytes

• Ferns have

• a rhizome with adventitious roots,

• Leaves

• short woody stems.

• The leaves are usually curled up in buds and are often pinnate ( divided up into pairs of leaflets).

Filicinophytes / Ferns

• Maximum height is 15 meters

• Spores are produced in sporangia, usually on the underside of leaves

• All have vascular roots, leaves & non-woody stems.

Pinnate leaves

• There is a main nerve, called midrib, from which the other nerves derive. Reproductive strategies:

• Cell Cycle & Cancer Animation

• Life cycle Flifecycle2

Coniferophytesconifers

• Conifers are shrubs or trees with roots, leaves and woody stems. The leaves are often narrow with a thick waxy cuticle

Produce cones for reproduction

conifers

• Maximum height is 100 meters

• Seeds are produced. The seeds develop from ovules on the surface of the scales of female cones. Male cones produce pollen

Angiospermophytesflowering plants

• Flowering plants are very variable but usually have roots, leaves and stems. The stems of flowering plants that develop into shrubs and trees are woody.

angiosperms

• Maximum height is 100 meters. Seed are produced. The seeds develop from ovules inside ovaries. The ovaries are part of flowers. Fruits develop from the ovaries, to disperse the seed.

Flowers. Pistil is female part and stamen is male

• Animations

• Animations

Photoperiodic control of flowering

• Short day plants

• Long day plants

• Studies have shown that it is not the length of time there is light but dark

• Go to study guide page 87

• Flower growers can manipulate light to produce flowering plants year round

Phytochrome and photoperiodism

Photoperiodism, Gravitropism, Photoperiodism, Gravitropism, and Thigmotropismand Thigmotropism

AP BiologyUnit 5

Photoperiodism

• How a plant responds (with respect to flowering) to the relative amount of light (“photoperiod”)

• In reality, plants are responding to the relative amount of night.

Slide 2 of 15

• Photoperiodism is a biological response to a change in relative length of daylight and darkness as it changes throughout the year.

• Hormones such as phytochrome, and others not yet identified, probably influence flowering and other growth processes.

Photoperiodism: Types of Plants

• 3 different types of plants:– “Short Day” flower when days

are short, nights are long (Ex. poinsettias, chrysanthemums)

– “Long Day” flower when days are long and nights are short (Ex. Spinach, Radish)

– “Day Neutral” flowering does not depend on length of day or night (Ex. tomato)

Images taken without permission from http://www.fernlea.com/xmas/pix/poinsettia.jpg, and http://www.illinoiswildflowers.info/weeds/plants/garden_radish.htm Slide 3 of 15

Question…

• Poinsettias are short day plants– how could nurseries make sure they bloom just before Christmas?– Control the amount of light and dark they

experience

Slide 4 of 15

Phytochromes

• Plants absorb light via blue-light photoreceptors and phytochromes (Pr

and Pfr).

• Pr and Pfr play a significant role in the

flowering and germinating responses

• Experiments into the control of flowering time

Slide 5 of 15

Phytochromes

• Germination and flowering occurs in response to red and far-red light– effects of both lights are

reversible

– Pr and Pfr are isomers

(alternate forms)– red light (660 nm) activates

Pr to become Pfr

– far-red light (730 nm) activates Pfr to become Pr

Slide 6 of 15

Flowering

• Pfr

– inhibits flowering in short day plants – promotes flowering in long day plants

• Sunlight consists of quite a bit of red light, not much far red light

• During the day, which form of phytochrome is in?– Pfr

Slide 7 of 15

Flowering

• At sunset, most of the phytochrome is in the Pfr form

• During the night, Pfr gets converted back into Pr or breaks down

• Whether a plant flowers or not depends on the amount of Pfr left (which relates to the amount of night)

Slide 8 of 15

Plant HormonesPlant Hormones

Phototropism/gravitropism

• http://bcs.whfreeman.com/thelifewire/content/chp38/3801s.swf

Auxins

• Tutorial 38.2 Went's Experiment

• Plant Hormones

ExperimentsPredict what will happen in each of these experiments.

Normal young shoot

Tip removed

from shoot

Tip covered with a foil

cap

Tip removed and replaced with an

agar block containing auxin

Tip removed and replaced on one side

with a small agar block containing auxin

Can you explain the use of hormones in each diagram.

Click to reveal the answer.

Fresh fruits are shipped around the world.

Plant hormones are used to slow the ripening of

the fruit, so they are just ripe as they reach the

supermarket.

Applications of plant hormones

When a gardener takes cuttings from a plant, the base of each

cutting is first dipped into a rooting compound to stimulate

the growth of roots.

Many rooting compounds contain auxin.

Can you explain the use of hormones in each diagram.

Click to reveal the answer.

Applications of plant hormones

Plants adapt to where they grow

• Xerophytes - plants that are adapted to grow in very dry habitats.

• Spines instead of leaves, to reduce transpiration

• Thick stems containing water storage tissue

• Very thick waxy cuticle covering stem, reducing water loss

• Vertical stems to absorb sunlight early and late in the day but not at midday when the light is most intense

• Very wide spreading network of shallow roots to absorb water after rains

• CAM physiology, which involves opening stomata during the cool nights instead of during intense day heat

Thick leaves and cuticle

Hydrophyteswater plants

• Air space in the leaf to provide buoyancy

• Stomata in the upper epidermis of leaf is in contact with the air

• Waxy cuticle on the upper surface but not on bottom surface

• Small amounts of xylem in stems and leaves

Leaves

• Tissues of leaves and their function

• Xylem – brings water to replace losses due to transpiration

• Phloem – transports products of photosynthesis out of leaf. (source to sink)

• Both xylem and phloem are called the vascular system of plants. The vein is centrally located to be close to all cells.

phloem

Transport in phloem

• Phloem is located inside leaves. Used to transport sugars, amino acids, and other organic compounds from photosynthesis.

• Structures called sieve tubes do the transporting.

• This is an active process requiring ATP

• High concentration in sieve tubes of solute cause water to move in by osmosis

Translocation in phloem

• Phloem tissue found throughout plants.

• Links sources and sinks.

• Sources = photosynthetic tissue

• Sink = roots, fruits, seeds, and leaves

• Sometimes sources turn into sinks and vice versa depending on plant needs.

• This creates a high enough pressure for movement where ever the plant needs these products.

• The transport of any biochemical (includes sprayed on chemicals) in phloem is called translocation.

• Sucrose Transport animation• Sugar Transport in Plants• Tutorial 36.1 The Pressure Flow Model

Food storage in plants

The excess products of photosynthesis may be stored in storage area called tubers.

Transpiration

• Flow of water from the roots, through the stems to the leaves of plants (transpiration)

• Starts with evaporation of water from the cell walls of spongy mesophyll.

• Water is replaced with water from the xylem

Xylem and transport of water

• Google Image Result for http://www.phschool.com/science/biology_place/labbench/lab9/images/xylem.gif

• Animations

Structure of xylem

Transpiration

• LabBench transpiration

Factors which affect transpiration

• 1. Light – causes stomata to open increasing the rate of transpiration . Close in darkness, no need to absorb carbon dioxide, water conservation

• 2. Humidity – water vapor in air. Because of evaporation of water from moist cells walls the humidity is usually 100% in the leaf. The lower the humidity outside the leaf the faster the rate of diffusion of water- higher rate of transpiration.

• 3 Wind

• High wind increases transpiration.

• In still air or light winds rate decreased due to higher humidity in plant.

• 4. temperature

• High temperatures evaporation rates rise. Increases rater of diffusion between the air spaces inside the leaf and air outside.

• Increases in temperature allow the air to hold more water vapor and so reduce the relative humidity or air outside the leaf. The concentration gradient therefore increases and water is lost more rapidly.

Food storage in plants

The excess products of photosynthesis may be stored in storage area called tubers.

Monocot and Dicot

True dicots vs monocots ( animation)

• Plants: Plant Organs – Stems

• Primary meristems are located at the tips of stems and roots – called apical meristems.

Function of stem

• Connects roots, leaves, and flowers

• Transport materials between them using xylem and phloem

• Support the aerial parts (especially xylem in woody plants)

• Pith and cortex provide cell turgor

Terrestrial plant stems/support

• Turgid cells

• Cellulose cell walls

• Xylem tissue which has cell walls impregnated with lignin ( woody)

• Plants: Plant Organs - Stems

Monocot / dicot stems

• Stem organization

Monocot stems

• In most monocots, the vascular bundles arc scattered throughout thc ground tissue.

Dicot stem

• The stems of most dicots have vascular bundles arranged as a ring that divides the ground tissue into the outer cortex and inner pith.

Roots dicots

• In most dicots (and in most seed plants) the root develops from the lower end of the embryo, from a region known as the radicle. The radicle gives rise to an apical meristem which continues to produce root tissue for much of the plant's life.

Monocot root

• By contrast, the radicle aborts in monocots, and new roots arise adventitiously from nodes in the stem. These roots may be called prop roots when they are clustered near the bottom of the stem.

Roots

• Roots absorb mineral ions and water from the soil

• Anchor the plant and are sometimes used for food storage

• Plants: Transport and Nutrition - Water Movement

Mineral uptake by roots

• Plants absorb potassium, nitrate and other mineral ions

• Concentration is lower than inside roots

• = active transport

• Root hairs provide surface area for ion uptake

Water uptake by roots

• High solute concentration in roots therefore water moves in to root from soil.

• Two paths :

• Symplastic movement from cell to cell through the cytoplasm

• Movement by capillary action through cortex cell walls called apoplastic

Nutrients Plants: Transport and Nutrition – Nutrients

(animation)

Flowers

• Monocots have their flower parts in threes or multiples of three;

• Dicots have their flower parts in fours (or multiples) or fives (or multiples).

Reproduction in flowering plants

• Egg and pollen formation and fertilization animation

• Life cycle of cherry (Prunus)

• The transfer of pollen from the anther to the female stigma is termed pollination. This is accomplished by a variety of methods. Flower color is thought to indicate the nature of pollinator: red petals are thought to attract birds, yellow for bees, and white for moths. Wind pollinated flowers have reduced petals, such as oaks and grasses.

Double Fertilization

• The process of pollination being accomplished, the pollen tube grows through the stigma and style toward the ovules in the ovary ( you need to know double fertilization for AP only)

• Life cycle of a lily ( animation )

• Tutorial 39.1 Double Fertilization

• Observe : FLOWERS AND FRUITS - BIOLOGY 2402 IMAGE DATABASE

Pollen tube

• Monocot seeds will not separate into two Halves. Instead, the food is stored around the embryo.

• have one seed leaf which is generally long and thin

• Rice wheat corn

Dicots

• has two halves. • called cotyledons. • food stored in the fleshy

seed leaves to nourish the new plant until its roots and true leaves are ready. first two seed leaves look quite different from the adult leaves, which will develop later.

Seeds

Seeds in a Pod,

germination

• Requirements: proper • temperature. • water • Water-allow vigorous metabolism to begin. • leach away germination inhibitor • common among desert annuals. (ABA). • oxygen • a preceding period of dormancy (often).

Metabolic events of seed germination

• Water re hydration -metabolically active.

• Growth hormone gibberellins is produced in the cotyledons

• stimulates the production of amylase which converts the stored starch into maltose

• Maltose is converted into glucose needed for cellular respiration

• Leaves appear above ground and photosynthesis begins.

• Teachers' Domain: From Seed to Flower

Germination in Dicots

• The primary root emerges through the seed coats while the seed is still buried in the soil.

• The hypocotyl emerges from the seed coats pushes up through the soil.

• bent in a hairpin shape — the hypocotyl arch • as it grows up. The two cotyledons protect the

epicotyl structures — the plumule — from mechanical damage.

• Once the hypocotyl arch emerges from the soil, it straightens out. This response is triggered by light.

• The cotyledons spread apart exposing the

• epicotyl, consisting of

• two primary leaves and the

• apical meristem

• Plant development ( animation)

Germination in Monocots

• the primary root pierces the seed

• grows down;

• primary leaf grows up.

• protected by the coleoptile — a hollow, cylindrical structure.

• Once the seedling above surface, the coleoptile stops growing and the primary leaf pierces it.

Go back to 3 slides and watch monocot plant development

Growth and development in plants

• Root organization

• http://www.wadsworthmedia.com/biology/0495119814_starr/big_picture/ch25_bp.swf

Review of topic

• General & Human Biology