BIOLOGY 11: UNIT 4: Kingdom Plantae: Green Algae, Mosses, Ferns, Gymnosperms,AngiospermsChapters 9, 10, 11

UNIT 4 OBJECTIVES:GREEN ALGAE, MOSSES, FERNS:1. Examine green algae, mosses, and ferns and describe characteristics

that unify each.

2. Demonstrate the correct use of the dissection microscope.

3. Explain the benefits of alternation of generations.

4. Use examples of unicellular, colonial, and multicellular green algae to illustrate their diversity.

5. Describe the ecological roles of green algae, mosses, and ferns.

6. Describe the role of mosses as pioneer plants.

7. Compare and contrast how ferns and mosses have adapted to a land environment.

GYMNOSPERMS:1. Describe the characteristics that unify gymnosperms.

2. Explain how gymnosperms are adapted for survival in a land environment with respect to the following: alternation of generations, needles, seeds, pollen, and vascular tissue.

3. Explain the role of meristems in primary and secondary stem growth.

4. Evaluate the economic and ecological importance of gymnosperms.

ANGIOSPERMS:

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1. Examine angiosperms and describe characteristics that unify them.

2. Compare and contrast the ways in which angiosperms and gymnosperms have adapted to a land environment.

3. Use specimens to differentiate between moncots and dicots

UNIT 4: PLANTAE: Chapters 9, 10, 11

Introduction and plant diversity:Plants have been classified in many ways because there are 300,000 to 500,000 species. These classifications are based on evolutionary relationships & adaptations.

This textbook classifies plants into 3 groups:1) Aquatic plants2) Non vascular plants3) Vascular plants

Characteristics of all Plants:, p. 2451. Eukaryotic.2. Cell walls with cellulose.3. Alternation of generations in life cycles.4. Produce carbohydrates by photosynthesis5. Lack mobility.

Evolutionary Adaptations by Plants:, As the environment changed, over time plants adapted structures & systems for:

1) Transport of H 2O - root, stems & leaves

2) Method of reproduction that did not depend on H 2O for dispersal of gametes.

Life Cycles of Plants Involve 2 Stages: 1) Gametophyte Stage - stage of life cycle that produces haploid gametes (N).

2) Sporophyte Stage - stage of life cycle that produces diploid spores (2n). This stage arises from the union of 2 haploid gametophytes. In simple plants like mosses, the sporophyte depends on the gametophyte for water & nutrients. This role is reversed in complex plants like ferns & seed plants.

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AQUATIC PLANTS: ALGAE:

Characteristics of aquatic plants:, p. 2461. Mostly multicellular, some are unicellular, filamentous or colonial2. Simple plants3. No conductive tissue - no true roots, stems or leaves4. Live surrounded by water

Water:1) Prevents cells from drying out.2) Structural support to the plant.3) Provides nutrients.4) Accommodates the dispersal of spores & meeting of sex cells

Aquatic Plants Belong to One of 3 Divisions:

1. Green Algae : Chlorophyta: (Volvox & Spirogyra) These are single-celled or multicellular algae containing pigments chlorophyll a, b & carotene & store starch. Cell walls contain cellulose.Habitat: fresh water, moist soils, & coastal tropical seas. Sexual reproduction: involves alternation of generations. Asexual reproduction: by fragmentation or by spores

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2. Brown Algae: Phaeophyta: (Fucus=Rockweed)Multicellular algae contain pigments chlorophyll a, c & fucoxanthin & store laminarin & oils. Cell walls contain cellulose. Habitat: colder seawater.Sexual reproduction: involves alternation of generations. Asexual reproduction: by fragmentation or by spores.

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3. Red Algae: Rhodophyta: (Dulse, Irish Moss, Plumaria) Multicellular algae contain pigments chlorophyll a, d and Carotenes & Phycobilins. Cell walls contain cellulose & store starch. Habitat: mainly warmer seawater & some fresh water. Sexual reproduction: involves alternation of generations. Asexual reproduction: by vegetative reproduction.

Ecological Role of Aquatic Plants:Algae play an important role in the global environment. Phytoplankton are primary food producers and are a source of biological energy for nearly all food webs in aquatic habitats, they supply about 67% of the global supply of oxygen. Human wastes and pollutants reduce algae populations. Algae is used to make agar a gel used in labs to grow bacteria on petri plates. Carrageen is used to make ice cream & pie fillers.

Reproduction in Algae:, p. 248Higher algae have complex life cycles incorporating features found in higher plants and animals.

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Sexual Reproduction: This involves the fusion of 2 haploid cells gametes producing a zygote.

1. Conjugation: union of isogametes, that are identical gametes of different strains (-) & (+), such as in the Spirogyra.

2. Fertilization: union of heterogametes, that are different gametes (larger = egg) & (smaller = sperm), such as in the Fucus.

Zygote formation: occurs after sexual reproduction. The zygote may germinate or form a zygospore: a thick-walled resistant spore, it can survive unfavourable environmental conditions and then germinates, undergoes meiosis, & grows into mature cells.

Asexual or Vegetative Reproduction:There is neither cell fusion nor a change in chromosome number. There are 3 methods of asexual reproduction.

1. Fragmentation : thallus or body part breaks off

2. Formation of spores : motile zoospores & non-motile spores

3. Mitotic Division : in single-celled plants.

<Homework - Review Questions, p. 251 (8 - 15)>

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Importance of Terrestrial Plants:, P. 256Colonization of land by terrestrial plants occurred more than 400 million years ago and is one of the major events in the evolution of life.

The transition from aquatic life to life on land took millions of years. Plants transformed land & created environmental changes. Increasing adaptation of herbivores & their predators followed.

Problems for Plants that Lived on Land:1) Air provides little support to plants.2) Obtaining water & nutrients.3) Transporting & water, minerals & products of photosynthesis.4) Preventing excessive water loss by evaporation.5) Gas exchange between plants & air.6) Reproduction & protection of the embryo.7) Withstanding extreme fluctuations in environmental conditions.

Adaptations of land plants: involve the roots, stems, leaves, and reproduction:

1. Roots : anchor plants in ground & absorb water & nutrients from the soil. Mycorrhizae associated with roots enhance nutrient absorption, and have been responsible for the evolution of land plants.

2. Stems : stem fibers became stronger, being able to support stems & leaves in the air = vascular system. The vascular system was an efficient transport system for food, water & minerals.

The vascular system consists of 2 tissues: xylem and phloem1) Xylem: carries water & minerals, consists of dead cells that form tubes.2) Phloem: transports food, which was made in the leaves throughout the plant.

3. Leaves : primary organs for photosynthesis, allowing plants to make food more efficiently.

Leaves consist of 2 adaptations: cuticle and stomata1) Cuticle: secreted by epidermal cells & forms a waxy covering over the stem & leaves.

It helps to retain water & prevent drying out in the air.2) Stomata: microscopic pores (singular "stoma") found in leaves & permit exchange of

gases.

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4. Reproduction : methods of reproduction that are less dependent on water for gamete dispersal.

Land Plants Belong to One of 2 Divisions:

1) Nonvascular Plants: Bryophyta: (Mosses)

MOSSES: are the most familiar and the largest group of Bryophytes. Habitat: Swampy &moist regions. They are low-growing clumps of cushiony, or green velvety carpets. They have many adaptations to survive conditions on land.

Gametophyte Stage: dominant stage is a low-growing leafy plant with simple leaves, stems & roots. Stems &Leaves: have simple elongated cells to carry water, minerals & products of photosynthesis. Each leaf is at the top of the stalk and absorbs water & minerals, and performs photosynthesis.Roots: called rhizoids anchor the plant.

Sporophyte Stage: diploid plant that has an elongated stalk that elevates the spore-bearing capsule called the sporangium and provides more efficient arrangement for scattering spores. Sporangium: is the capsule where spores are produced by meiosis.

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Ecological Role of Mosses: Mosses are pioneer plants, and establish themselves on exposed rock or soil surfaces where there are no plants. They enrich the soil as they die and build organic content that leads to soil formation. Mosses form peat (heating fuel), they possess antiseptic properties (low pH), and they clean up oil spills.Reproduction: Life Cycle of a Moss: Mosses have a life cycle that involves spores rather than seeds. Both sporophyte and gametophyte stages exist on the same plant. Mosses undergo alternation of generations (from haploid to diploid ….and diploid to haploid).

Sexual Reproduction of Moss Plants:, P. 2591) Haploid spores (n) are produced by meiosis in the sporangium capsule (2n) and are

released into wind or water.2) Protonema (n) forms after a spore germinates & undergoes mitosis, and resembles

a filamentous green algae.3) The protonema (n) forms a small gametophyte plant consisting of root-like rhizoids,

shoots & green leaflets.4) Mature gametophyte plant develops sex organs at its tip.

Antheridium = male sex organ, produces sperm cells (n).Archegonium = female sex organ, produces eggs (n).

5) Fertilization occurs when plant is wet so sperm can swim to the egg (n + n) and a zygote (2n) develops.

6) Zygote (2n) develops into a sporophyte plant (2n) consisting of a stalk & sporangium.

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Asexual Reproduction of Mosses:1) fragmentation - parts breaking off the plant2) gemmae - small, disk-like bodies made by gametophytesCLASSIFICATION OF LAND PLANTS:

2) Vascular Plants: Tracheophyta : (Ferns, Gymnosperms & Angiosperms)All vascular plants except ferns are free of total dependence of water for reproduction. Vascular tissue provides continuous internal conduction between roots, stems & leaves and structural support.

Characteristics of Vascular Plants:, P. 2611) Multicellular 2) True Terrestrial Plants: Ferns, Conifers (gymnosperms) & Flowers (angiosperms)3) Vascular System To Transport Nutrients 4) Dominant Sporophyte Generation5) Gametophyte Stage Is Small & Dependent

Seedless Plants: Pterophyta: (Ferns)

FERNS: are the most familiar simple vascular plants. They are the most successful seedless plants. Habitat: they grow on bare, exposed rock in open bogs & marshes. Some ferns grow on trees = epiphytes. Most prefer shady, moist habitats & they show the greatest diversity in rainforests.Sporophyte stage: is the dominant stage & it produces spores. Spores are produced in clusters; called sori (singular "sorus") located on the lower surface of the frond. Underground Stems: rhizomes

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Roots: adventitious because they grow from rhizomesStems & roots: possess a primitive vascular system with tracheidsLeaves: called fronds consist of leaflets.

Gametophyte stage: starts as a prothallus and then exists as a heart-shaped plant.

Ecological Role of Ferns: p. 263Important as pioneer species, ferns establish themselves where no plants live & there is very little soil (burned-over forests, barren areas, pastures, volcanic lava, land exposed by retreat of glaciers). They improve living conditions for other species by creating soil & preventing erosion until other plants take over. Ferns grown for food, "fiddleheads", are young ferns are considered a delicacy, also used as decorations.

Reproduction: Life Cycle of a Fern: The Life Cycle is primitive with separate sporophyte & gametophyte stages. Ferns undergo alternation of generations (from haploid to diploid ….and diploid to haploid).

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Asexual Reproduction of Ferns:1) fragmentation - parts breaking off the plant2) gametophyte - sometimes live independently with no sporophyte generation

Sexual Reproduction of Fern Plants:, 1) Haploid spores (n) are produced by meiosis in the sporangium (2n) sori and are released into the wind.2) A prothallus forms after a spore germinates & undergoes mitosis. The prothallus is a small, thin, green, heart-shaped gametophyte.3) The prothallus (n) forms a small gametophyte heart-shaped plant consisting of root-like rhizoids.4) Mature gametophyte plant develops sex organs on the same plant (hermaphrodite).

Antheridium = male sex organ, produces sperm cells (n).Archegonium = female sex organ, produces eggs (n).

5) Fertilization occurs when plant is wet so sperm can swim to the egg (n + n) and a zygote (2n) develops.6) Zygote (2n) develops into a sporophyte plant (2n) consisting of fiddleheads, fronds, rhizomes and adventitious roots.

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<Homework - Review Questions, p.263 (1-9)>Seed Plants: Conifers (Gymnosperms) & Flowering Plants (Angiosperms):Seed plants are mostly free-living, some are parasitic.Habitat: widely distributed, most prefer dry land, few prefer wetlands. Size: varies from 1 mm to more than 100 m tall and are very complex.

Adaptations of Seed Plants: P.2641) Reproductive adaptations: separate male & female gametophytes.

2) Produce seeds: each seed contains an embryo (2n) or partially developed plant.

3) Improved vascular system: helps move minerals, water, products of photosynthesis

Two Types of Seed Plants:1) Gymnosperms (Conifers): unprotected, naked seeds in cones.2) Angiosperms (Flowering Plants): seeds are protected inside the fruit.

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1) Gymnosperms: Conifers: (Pines, spruces, junipers, firs, etc)

GYMNOSPERMS: are cone-bearing plants are widely distributed.Habitat: they can live in harsh conditions (hot, dry & cold)

Leaves: are needlelike called needles. A hard, waxy cuticle covers the needles and helps retain moisture.

Roots: extend over a wide surface area rather than penetrate deep into the soil, holds the tree firm, even with little soil.

Seeds : are formed in cones and are not protected by the ovary wall. Gymnosperm means "naked seed." Mature seeds are released from the cone and carried by the wind.

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Ecological & Economic Role of Gymnosperms:Balance level of gases (they remove co2). Felling large regions of forests for lumber is upsetting balance. They provide food & shelter for animals. They control flooding by absorbing water through their roots, & prevent erosion. The softwood lumber industry is one of the biggest exports in Canada, with most of the wood going to the USA. Pine, fir, spruce and cedar are all examples of conifers used around the world for building homes, furniture, or almost anything else made with wood. They provide 80% of wood for construction, furniture, & pulp & paper. They provide chemicals, such as: turpentine, varnishes, disinfectants, fuels & medicines (epinephrine & taxol). Some are harvested to the point of being endangered (California redwood & Newfoundland red pine).Life Cycle of Conifers: Alternation of Generations in Gymnosperms:The life cycle is complex with a dominant sporophyte (2n) stage & a reduced gametophyte. Pine trees produce two types of cones - male cones & female cones.

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Sexual Reproduction of Gymnosperms (Conifers):, p. 2661) Pollen grains (n) with wings, produced by meiosis in the male cone, are released into

the wind.2) Pollen grains (n) land on the female cone, pollen is trapped in the sap & the pollen

tube grows toward the ovule.3) Sperm is released from the pollen tube & unites with the egg to form a zygote (2n)4) A year later, the zygote develops into an embryo (2n). The seed contains: an

embryo, a female gametophyte, & seed coat. Seeds are shed from the cone.5) The seed develops into a seedling, which forms a mature sporophyte (2n), a tree.6) The mature tree (sporophyte 2n) forms male cones (2n) at the bottom and

female cones (2n) at the top.

Other Gymnosperms: Cycads and ginkgoes are among the oldest, rarest, & most unique. Cycads resemble palms, and are believed to have been the main nourishment for herbiverous dinosaurs. Ginkgo is called a "living fossil", because it is the only species of its division that has survived to present day. The trees have small flat leaves, and produce seeds that look like fruit.2) Angiosperms: Flowering Plants: (Herbs, shrubs, trees, flowering plants)

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ANGIOSPERMS: There are >250,000 species known & new ones are discovered daily; these are the most diverse group of plants. Their success is due to the evolution of insects. Insects could not survive without flowers = COEVOLUTION.

Habitat: they live in every type of climate.

Leaves: vary in shape, size, and thickness. A waxy cuticle covers the leaves and helps retain moisture.

Roots: penetrate deep into the soil and hold the tree firm, like a tap root.

Seeds : are formed in fruits and are protected by the ovary wall which forms the fruit.

Flowers: vary in colour, shape, size, and odor.

The development of the flower, and therefore fruit, are key factors to the success of angiosperms. These specialized structures create a symbiotic relationship with certain animals to aid in fertilization and well as dispersion of the species. A flower attracts insects or birds by scent and colour, and offers it sugary nectar for food. In exchange, the animal is sprinkled with pollen to carry to the next flower for fertilization. After fertilization, the flower will develop into a fruit, which may be harvested and eaten by animals and may be carried for miles to be dropped with a bit of extra fertilizer.

COMMON FLOWER STRUCTURES:

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Stamen = Male Part of the Flower and Consists of:1) Filament: thin stalk2) Anther: structure where meiosis occurs and pollen grains are formed

Pistil = Carpel: Female Part of the Flower & Consists of:1) Stigma: sticky part where pollen grains land and grow.2) Style: slender stalk that leads from the stigma to the ovary.3) Ovary: contains the ovule which is attached to the wall by a short stalk that was formed by carpels. The ovule is where meiosis occurs and produces the embryo sac that holds the egg cell (n) and endosperm cell (n+n).

Sepals: small, green leaf-like structures that surround the carpel and stamen.

Petals: colourful part of flowers that attract pollinators. At the base of the petals is nectar.

Seed: fertilized ovule contains an embryonic plant & stored food.

Fruit: remaining structures of the ovary. Numerous seeds are found in fruits.

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Fruit develop from flowers. The fleshy part of the fruit develops from the ovary wall and ovary of the flower. The function of this flesh varies in different plants, it nourishes, protects, and aids in transport of the seeds. The fruit can take on a specialized shape to be transported by wind (maple) or water (coconut), or can develop into a fruit that offers an animal nutrition in exchange for transport. Many foods are fruits, such as apples, bananas, oranges or melons, nuts, peas and beans, tomatoes, squash, cucumber, and zucchini.

Ecological & Economic Role of Angiosperms:Angiosperms play a major role for many animals by providing food, shelter, and protection. For Humans, as with gymnosperms, angiosperms are important for lumber. However, they generally have a different usage and are known as the hardwoods. Due to their durability and strength, they are used for more expensive furniture and flooring. Birch, maple, and oak are each examples of hardwoods that are commonly used for these purposes.

When we think of angiosperms, we think of flowers and fruit, many parts of the plant are consumed. For example, with sugar beets the root is used to make sugar, and with sugar cane the stalk of the plant is used. We eat the roots of carrots, leaves of lettuce, and stalk and flowers of broccoli. However, one group of fruits has an extremely large effect on world nutrition. These are the grains. Wheat, corn and rice are consumed worldwide as a base of consumption, providing starch to the diet.

Other uses of angiosperms are seen in drinks such as tea, coffee, cola or cocoa. Or in clothing that is made of cotton. Rubber was derived from the rubber tree. One of the largest plant markets, is the drug market. Opium, tobacco, cocaine and marijuana are all examples of drugs that are derived from plants

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Life Cycle of Flowering Plants: Alternation of Generations in Angiosperms:Life cycle is complex with a dominant sporophyte (2n) stage & reduced gametophyte.

Sexual Reproduction of Angiosperms (Flowers)1) Pollen grains (n), produced by meiosis in the anther (2n), are dispersed by wind,

water, insects etc.2) Pollination: pollen (n) lands on the sticky stigma (2n) and forms a pollen tube (n) that

grows down the style (2n) toward the ovule (n) in the ovary (2n).3) The embryo sac (8 nuclei) is produced by meiosis, 3 nuclear divisions and

cytoplasmic divisions in the ovule, and is ready for the pollen tube.4) The pollen tube reaches the ovule containing the embryo sac and releases 2 sperm.5) Double fertilization occurs after 2 sperm are released & they unite with the egg cell

(n) & endosperm mother cell (n + n). A zygote (2n) & the triploid endosperm cell (3n) are produced after fertilization. The zygote & triploid endosperm cell develop into an embryo. The seed contains the embryo, endosperm, and the seed coat. Still surrounding the seeds at this point is the fruit that has developed from the ovary wall.

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Seed Dispersal: Two Advantages of Seed Dispersal: 1. Eliminates Competition2. Increase Probability of Survival*dispersal ensures plants do not drop under the parent plant

There are 4 Methods of Seed Dispersal: 1) Wind : small lightweight seeds can be carried great distances by winds (orchid,

poppies), fluffy parachute-like structures attached to seeds (dandelions, milkweed), and wing-like structures attached to seeds (maple, sycamore, elm & ash).

2) Water : plants can use water to carry the seeds in streams and can move great distances (water lilies, coconuts). These plants have air trapped in seed tissues & fruit tissues so they can float (some for a year and still germinate).

3) Animals : excreting seeds ingested far from location of eating fruits, carrying seeds with burrs, hooks, spines & stickers, allowing seeds to be carried from one place to another on clothes, fur, feathers, and on the muddy feet of birds, ants & squirrels. Squirrels bury acorns & other seeds while getting ready for hibernation.

4) Explosive "Mechanical Propulsion" : plants have capsule fruits or pods that explode when mature and propel the seed at some distance away from the parent.

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Pollination: Various agents carry pollen to the stigma. Pollen grains are small grains containing the male gametophyte and do not require water to fertilize to the egg. The pollen grain is transported to the female gametophyte; the pollen tube grows toward the ovule and releases the sperm.

THERE ARE SEVERAL METHODS OF DISPERSAL

1) Wind Dispersal : involves inconspicuous flowers (grasses, corn, wheat, trees, poplars, walnuts, alders, birches, oaks, ragweed & sage). Flowers lack odor & nectar. They are small and unattractive to insects. Pollen is lightweight, dry and easily blown.

2) Insect Pollination : involves sweet smelling & brightly coloured flowers pollen is carried on the bodies of insects and rubs off onto stigmas of other flowers that the insect visits. Bees land on plants to gather nectar, moths, butterflies & humming birds gather nectar while hovering. Moths will pollinate flowers at night.

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The Seed:The seed consists of the embryo, endosperm, and seed coat.

Embryo development (2n): this begins while the ripened ovary or fruit is attached to the plant. The growing embryo slowly forms root and shoot structures. In the monocot a single seed leaf (cotyledon) develops and in the dicot two seed leaves (cotyledons) form.

Endosperm (3n): this is nutrient-rich food for the development of the new plant until sufficient root hairs and chlorophyll for photosynthesis can sustain the plant.

Seed coat: called the testa protects the seed, and the seed may be dormant for many years.

Germination: when conditions are optimal, the seed absorbs water & the seed coat softens. The embryo begins to grow rapidly and the root and shoot break open the seed coat. The root grows downward and the shoot grows upward and opens to expose the cotyledons. The endosperm supports growth of the new plant.

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ANGIOSPERM DIVERSITY: Flowering plants are grouped into 2 classes:

1) Monocotyledons (monocots) 2) Dicotyledons (dicots).

Cotyledon: seed leaf that stores food for the young sporophyte and becomes the first leaf to appear as the seed germinates. Angiosperms are further classified into two groups, the monocots and the dicots. This is based on their seed type and growth pattern. The food portion of the seed is called the cotyledon, and as the name suggests, a monocot has one cotyledon, and a dicot has two. Other differences are exemplified in the table below.

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Examples of Monocots: grasses, lilies, tulips, irises, crocuses, onions, orchids, crop plants, wheat, corn, coconuts barley and rye.

Examples of Dicots: larger group of plants, maples, oaks, and cacti most forest trees and a majority of flowering plants such as roses, fireweed, apples, cherries, and peaches.

<Homework - Review Questions, p. 274 (10-19)>

LAB: GERMINATION OF MONOCOT & DICOT SEEDS, P.275MERISTEMS: Plant cells only divide in specific regions called meristems. 1) Apical meristems : are found in the root and shoot tips2) Lateral meristems : increase plant's diameter

Primary Growth: In seed plants, root & shoot tissues begin to form in the embryo, within the seed. As the seed germinates, cells at the root & shoot tip divide and elongate. Lengthwise growth is called: primary growth. In young plants, evidence of primary growth is seen when the green shoots emerge. Mature plants show primary growth in the lengthening of their roots & stems. Due to the presence of meristems at the roots and shoots, called apical meristems, primary growth occurs.

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Secondary Growth: Many dicots and a few monocots exhibit secondary growth. Secondary growth originates in tissues other than the root and shoot tips, but it results in increases to the diameters of stems and roots. Due to the presence of meristems in the trunk of the tree, called lateral meristems, secondary growth occurs.

<Homework - Review Questions, p.289 (1-5)>

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