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Unit 15 PLANT NOTES 2015 Ch. 20-22

Chapter 20: Plant Diversity

20.1 Origins of Plant LifePlant life began in the water and became adapted to land.

Green Algae (Domain Eukarya, Kingdom Protista) and Plants (Domain Eukarya, Kingdom Plantae) share many characteristics:

photosynthetic eukaryotes contain chlorophyll—green pigment that captures energy from sunlight during

photosynthesis use starch as a storage product have cell walls with cellulose (all plants and most green algae) are multicellular reproduction involving sperm and egg

Green algae are not currently classified with plants since algae do not have roots, stems or leaves, and most species are aquatic.

Plants have 4 major adaptations that allow them to live on land.1. Retaining moisture (prevent desiccation)

cuticle —clear waxy, waterproof layer that helps hold in moisture stomata —holes in the cuticle surrounded by special cells allowing

the stomata to close to prevent water loss or to open to exchange gases with the air (bring in CO2 and release O2 and water vapor).

2. Transporting resources vascular system —a collection of specialized tissues that bring

water and mineral nutrients up from the roots and transport sugars to where they are used or stored

vascular system allows the plants to grow taller nonvascular plants must remain small because water moves by

osmosis3. Growing upright

tall plants compete better for light lignin—hardens the cell wall of some tissues to provide support,

such as in wood4. Reproducing on land

pollen grain —contains a cell that will form sperm; structure of the pollen allows it to be carried by wind or animals and not require water

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seed —storage device for a plant embryo; the seed coat protects the embryo from drying out

20.2 Classification of Plants

The Plant Cell: Review• Are plants autotrophic or heterotrophic?

– autotrophic (plants are producers and they make their own food via photosynthesis; have chloroplasts)

• Are plants prokaryotic or eukaryotic?– eukaryotic (eukaryotes have a nucleus just like we do and YOU are

EUkaryotic)• Are plants multicellular or unicellular?

– multicellular• Plant cell walls are made of….

– cellulose

The Plant Cell: Label

Not in animal cells:

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Nonvascular Plants (3 phyla) Vascular Plants (6 phyla) do not have a system for

transporting water and other nutrients within their body

– nonvascular plants are small and lack vascular tissue (xylem and phloem); therefore cannot develop stems, roots, and leaves

– include mosses (bryophytes), liverworts, and hornworts

contain structures with vascular tissue (roots, stems and leaves)

vascular plants (also known as tracheophytes) are composed of:

– tissue (roots, stems, leaves)

– each plant part – tissue, root, stem, leaf - has a specific role in keeping the plant alive through photosynthesis

– include club mosses, ferns, gymnosperms, & angiosperms

Plants are divided into two major groups:Nonvascular Plant - moss Sphagnum moss is commonly used by humans. It does not decay when it dies and thick deposits of this are known as peat. Peat has many uses:

can be burned as fuel absorb water, so often used to make soil more productive antibacterial properties (which prevents decay) serves as carbon reservoirs in the carbon cycle

Question: If nonvascular plants don’t have roots or stems, why do we find most of them near water?

Vascular Plants - contain vascular tissue (xylem & phloem—discussed later) There are two types of

vascular plants: - seedless plants - seeded plants

Plants with seeds can be grouped into two additional categories:

- gymnosperms and angiosperms

– Advantages of conducting tissue

o transportation of water and sugar within a planto development of true roots, stems, and leaveso grow taller (gaining more sunlight) and deeper (gaining more water)o store sugars for future useo don’t rely on osmosis and diffusion

Seedless Vascular Plants:– spore – haploid asexual reproductive cell that divides by

mitosis into a multicellular haploid organism– spores have thickened walls that prevent the cells from

drying out– diagram shows spores growing in clusters called sori on

the back of the fern– Examples: ferns, club mosses, horsetails, and whisk ferns

Answer:They don’t have the structures to transport water so in order to get water they have to be near it to “absorb” it directly; it moves cell to cell by osmosis

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staminate cone- from a pine tree (male)

Seeded Vascular Plants:seed- adaptation to terrestrial life composed of a plant embryo, stored food and a protective coat• advantages of seeds

• seeds allow reproduction without free-standing water• seeds protect and nourish a plant’s embryo.• seeds disperse the offspring and delay the growth of the embryo until

conditions are favorable.

Types of seeded vascular plants:• Gymnosperms

• seed plants whose seeds are not enclosed in fruit• the cone is the reproductive structure;

contains pollen in males and ovules (eggs) in females• Examples: conifers (pine, fir, cedar cypress),

cycads, ginkgoes, and gnetophytes

• Angiosperms• seed plants that have seeds enclosed in some type of fruit• the flower contains the reproductive structures• Examples: monocots and dicots.

Angiosperm are categorized by seed type:• Monocots:

– one cotyledon—food source for baby plant before it has true leaves for photosynthesis

– veins in leaf parallel– vascular bundles in complex arrangement

(scattered)– fibrous root system – floral parts in multiples of three– Ex) grasses, corn, wheat, tulips, lilies

• Dicots: – two cotyledons – leaf veins netlike– vascular bundles arranged in ring – taproot usually present – floral parts in four or five– Ex) most deciduous trees, roses, daisies, peanuts

Angiosperm are also categorized by stem type and lifespan:

– stem type: woody or herbaceous

– lifespan: o annual (life cycle in one

year), ex. petunias and pansies

ovulate cone- from a pine tree (female)

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o biennial (life cycle in two years)ex. carrots

o perennial (lives more than 2 years) ex. trees and shrubsChapter 21: Plant Structure & Function

21.1 Plant Cells & Tissues organ -group of tissues working together to perform a common function tissue -group of cells working together for a common purpose Plants have three main organs—leaves, stems, and roots. These three organs are made up of three tissue systems—dermal, ground, and

vascular. These three tissue types are made up of three basic cell types—parenchyma,

collenchyma, and sclerenchyma.

3 basic plant cell types:– parenchyma – found throughout the plant and store starch, oils, and water;

also house chloroplasts in the leaves; makes up most of fruits, stems, and roots

– collenchyma – found in younger tissues of leaves and roots; provide support while the plant grows.

– sclerenchyma — strongest of these cell types that have a second cell wall hardened by lignin; provide support; cells are dead at maturity and make up wood, nut shells, seed coats

3 tissue systems in plants:– dermal tissue system – covers the plant; epidermal

(outer) layer of cells of plants.– ground tissue system – specialized for

photosynthesis in leaves and for storage and support in stems and roots.

– vascular tissue system – internal system of tubes and vessels that transports water, mineral nutrients, and organic compounds to all parts of the plant.

2 types of vascular tissue: xylem and phloem

1. xylem – transports water and minerals UP from the roots to the shoots (memory trick—remember “wxyz”…water carried by the xylem (xy sounds like a z))

2. phloem – transports sugar (food) from where it’s made (leaves) or stored (cells in leaves or roots) to where it’s needed

(remember phloem (ph sounds like an f) transports food).

21.2 & 21.3 The Vascular System and Stems & Roots

Stems5

Function: support, storage, and transport

Support:– stems can be woody or herbaceous– stems support leaves, flowers, and fruits

Storage:– stems can store food and water (ex. cacti, potatoes, ginger)

Transport:xylem – transports water and minerals up from the roots to the shoots

forces responsible for the movement of fluids through xylem are transpiration, cohesion, adhesion, and absorption.

See Figure 2.2 p. 622 and watch Animated Biology--Movement Through A Plant:What process is the main force for the movement of fluids through xylem? transpiration

phloem – transports sugar (food) from where it’s made (leaves) or stored (cells in leaves or roots) to where it’s needed

The transport of sugar down the plant requires energy. Plants pump sugar from a source into the phloem. The change in the concentration causes water to follow sugars into the phloem, increasing the pressure and pushing the sugars through the phloem into a sink.

http://tinyurl.com/msun9zk

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blade

petiole

RootsFunction- support the plant, absorb water and nutrients, transport water and nutrients to the stem, and store nutrients

Roots are either fibrous or form a taproot.

Main parts of the root:– vascular cylinder (or stele) is in

the center; contains the xylem and phloem

– root hairs—tiny projections of epidermal cells on the roots that increase the surface area which increases absorption of water; microscopic

– root cap—protects the growing tip– meristem—where the new cells are produced (aka zone of

cell division)

Remember that nitrogen fixation happens near the roots where bacteria live.

(Nitrogen fixation is when nitrogen in the atmosphere is converted by bacteria into nitrogen compounds like ammonia, nitrates and nitrites.)

Nitrogen is important for making nucleic acids, proteins, and chlorophyll.

21.4 LeavesLeaves absorb light and carry out photosynthesis.

LeavesFunction - site of sunlight absorption and photosynthesis

– flat structure increases surface areaLeaf Characteristics:• composed of blade and petiole• simple or compound (based on the how many leaves/leaflets are

coming off of the main branch)• venation- types of veins – parallel or net-like (palmate or pinnate)

• palmate- veins meet/touch at the base of the leaf• pinnate- veins attach to one large vein that is throughout leaf• parallel- veins run parallel to one another down the

length of the leaf (like a blade of grass)

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guard cells

stomata

Leaf Tissues (layers of the leaf): • cuticle – clear, waxy layer that protects leaf from drying out (desiccation);

secreted by the epidermis• epidermis – outer layers of leaf, made of dermal tissue• mesophyll – layer of ground tissue in the leaf in between the epidermal

layers, surrounds the vascular tissues (xylem and phloem) and is divided into two layers:• palisade layer – rectangular cells below the upper epidermis that

capture the majority of sunlight; where the majority of photosynthesis occurs; ground tissue

• spongy layer – loosely packed cells with air spaces that connect to the stomata; where some photosynthesis occurs; ground tissue

• stoma(ta) – site of transpiration and gas exchange; holes in the upper and lower surfaces of leaves; surrounded by guard cells

• guard cells - control water loss by closing a plant’s stomata when water is scarce

Cross-section of a Leaf

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Ch. 22: Plant Growth, Reproduction, and ResponsePlants reproduce either sexually or asexually and hormones help regulate their growth, development, and response to their environment.

22.1 Plant Life Cycles Plant life cycles alternate between producing spores and gametes; this is known as alternation of generations.• gamete- a haploid (unpaired

chromosome) reproductive cell that unites with another haploid reproductive cell to form a diploid zygote (fused cell)

• gametophyte- haploid structure that makes gametes; microscopic in most plants

• sporophyte- diploid structure that makes spores; most plants

Spore vs. Seed Spores: Seeds:• nonvascular plants-

– water needed for fertilization

– reproduces with spores• vascular seedless plants

– water needed for fertilization

– reproduces with spores

• vascular seeded plants– gymnosperms- cones– angiosperms

• make pollen and ovules (ovaries)

• once fertilized, the ovules produce fruit

• fruit houses/protects seeds

Alternation of Generations

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22.2 Reproduction in Flowering Plants (Angiosperms)Reproduction of flowering plants takes place within flowers.

Flowers have four layers—sepals, petals, stamens, and pistils. • sepals- modified leaves that are the outermost structures that protect the

developing flower; often green but can be brightly colored.

• petals- modified leaves that are the innermost structures that are colorful to attract pollinators

• stamen- male reproductive structure– anthers produce pollen

• pollen grains contain sperm

– filaments holds anthers up to make accessible to wind or pollinators

• pistil- female reproductive structure; made of one or more carpels that have three parts:– stigma- top of the style, sticky so pollen sticks – style- tube that leads from the stigma to the ovary– ovary- where ovules (eggs) develop

• Ovaries with ovules become fruits with seeds after the ovule (egg) is fertilized by sperm from the pollen; See Figure 2.3 page 647.

pollination – when a pollen grain reaches the stigma of the same plant speciesfertilization – the process of the sperm combining with the egg to form the diploid zygote and the food for the growing plant embryo that is within the seed (read p. 646 if you would like to learn about the more complex details of double fertilization in plants)

Parts of a seed – seeds contain an embryo (baby plant), which is a new sporophyte, and a

supply of stored nutrients for the embryo– cotyledons of a seed help transfer nutrients to the embryo– seed coat covers and protects a seed

Fruit or Veggie? • fruit - ripened ovary; contains seeds• botanically, tomatoes, peppers, squash, olives, and cucumbers are FRUITS, not

vegetables• vegetables – edible parts of plants not involved in reproduction (leaves, stems,

roots)o roots – carrots, turnips, radisheso stems – celery, bok choi, rhubarb, garlic, broccoli, onions, potatoes o leaves – lettuce, cabbage, parsley

other plant parts we eat: o seeds – pinto beans, peas, sunflower seeds, corn, pepper corns, rice, pecans, coconut

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o flowers – anise flowers (licorice), basil22.3 Seed Dispersal and Germination Seeds are spread (dispersed) by many vectors, including:

Wind - some seeds are shaped to be carried by the wind easily Animals -

o some seeds stick to animals that brush past ito when insects drink nectar, they get coated in pollen

which will, in turn, be passed on to the next flower the insect gathers nectar from

o animals eat seeds or fruit with seeds; seeds are dispersed when solid waste is excreted by the animal

Water - can easily carry seeds miles away from parent plantSeeds begin to grow when environmental conditions are favorable:

dormancy – state of inactivity during which an embryo is not growing but is alive; Ex. A 2000 year old seed from an extinct date palm was discovered; scientists put it in favorable conditions and the seed began to sprout.

germination – the process of the embryo breaking out of the seed coat and growing (sprouting) into a seedling when the conditions are favorable; usually triggered by water

22.4 Asexual ReproductionPlants can produce genetic clones of themselves through asexual reproduction.Plants can reproduce asexually with stems, leaves, or roots:

regeneration - process in which plants grow a new individual from a fragment of a stem, leaf, or root; ex. prickly pear cactus

vegetative propagation – a process in which stems, leaves, or roots attached to the parent plant produce new individuals; ex. irises, strawberries, potatoes, bulb plants

o humans often produce plants with desirable traits using vegetative propagation techniques

22.5 Plant Hormones and ResponsesPlant hormones regulate plant functions.

hormone – a chemical messenger produced in one part of an organism that stimulates or suppresses the activity of cells in another part. Ex. gibberellins, ethylene, cytokinins, auxins(if you would like to know more about the various plant hormones, read pages 656-657)

tropism--plant response to the an environmental stimulus such as direction of light, gravity, and touch

o result of hormone action ex) hormones trigger cell division on one side of a stem making the stem curve

o can be positive (toward the stimulus) or negative (away from the stimulus)Plants can respond to light, touch, gravity, and seasonal changes.

phototropism – the growth of a plant toward a light source thigmotropism – turning or bending of a plant in response to contact with an object;

response to touch; Ex: vines growing up latticework or the side of a house gravitropism- growth of plants in response to gravity; plant stems grow upward,

against gravity (negative), and roots grow toward the gravitational pull (positive) rapid responses – response that does not involve growth, but is an adaptation that

helps protect plants from predators; ex. mimosa plant quickly folds its leaves together after being touched; Venus flytrap closing its leaves on an insect.

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photoperiodism – the response of an organism to changes in the length of the day; ex. shorter days and longer nights trigger the leaves of deciduous trees to change color; poinsettia plants flower when the days are short

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13Kingdom Plantae

ALL AUTOTROPHICMULTICELLULAREUKARYOTIC CELLSHAVE CELL WALLS & CHLOROPLASTS

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