Exam 2 Flashcards

Question

Bryophytes Phylum Hepatophyta Liverworts Liverworts are so named because the lobes of their thalli superficially resemble the lobes of the human liver; wort is derived from the Old English word wyrt, meaning, “plant.”

Answer 1

dominant gametophyte generation, but the gametophytes of some liverworts are quite different from those of mosses. o Their body form is often a flattened, lobed structure called a thallus (pl., thalli) that is not differentiated into leaves, stems, or roots. o The common liverwort, Marchantia polymorpha, is thalloid (FIGS. 27-9a & b). o On the underside of the liverwort thallus are hairlike rhizoids that anchor the plant to the soil. o Other known as leafy liverworts, superficially resemble mosses, w/ leaflike blades, “stems,” & rhizoids rather than a lobed thallus (FIG. 27-9c). o As in the mosses, leafy liverwort “leaves” consist of a single layer of undifferentiated cells. o small, generally inconspicuous plants that are largely restricted to damp environments. o Lack stomata, although some liverworts have surface pores thought to be analogous to stomata. Liverworts reproduce both sexually & asexually (see Figs. 27-9a & 27-9b). Their sexual reproduction involves production of archegonia & antheridia on the haploid gametophyte.

Answer 2

large, located toward outside of ovule typically develops into a suspensor, an embryonic tissue that anchors the developing embryo & aids in nutrient uptake from the endosperm.

Answer 3

a ground tissue at the center of the herbaceous eudicot stem that consists of large, thin-walled parenchyma cells that function primarily in storage. Because of the arrangement of the vascular tissues in bundles, there is no distinct separation of cortex and pith between the vascular bundles.

Answer 4

Leaves are arranged on a stem in one of three possible ways. Plants such as beeches and walnuts have an alternate leaf arrangement, with one leaf at each node. In an opposite leaf arrangement, as occurs in maples and ashes, two leaves grow at each node. In a whorled leaf arrangement, as in catalpa trees, three or more leaves grow at each node.

Answer 5

A type of life cycle characteristic ofplants and a few algae and fungi in which they spend part of their life in a multicellular (n) gametophyte stage and part in a multicellular (2n) sporophyte stage.

Answer 6

Primary growth is an increase in the length of a plant and occurs at apical meristems located at the tips of roots and shoots and also within the buds of stems. all plants

Answer 7

The haploid portion of the life cycle is called the gametophyte generation because it gives rise to haploid gametes by mitosis

Answer 8

land plants descended fromthis group of green algae

Answer 9

usually composed of a broad, flattened blade and a petiole. typically have netted venation. In a cross section of a eudicot blade often shows veins in both cross-sectional and lengthwise views. guard cells are shaped like kidney beans.

Answer 10

A type of life cycle characteristic ofplants and a few algae and fungi in which they spend part of their life in a multicellular n gametophyte stage and part in a multicellular 2n sporophyte stage.

Answer 11

thalloid plants (gametophytes) live is disturbed habitats single large chloroplast in ecah cell resembles certain algals cells more that plant cells (Anthoceros natans), archegonia & antheridia are embedded in the gametophyte thallus rather than on archegoniophores & antheridiophores. o After fertilization & development, the needlelike sporophyte projects out of the gametophyte thallus, forming a spike or “horn”—hence the name hornwort. o A single gametophyte often produces multiple sporophytes (FIG. 27-10). o Meiosis occurs, forming spores w/ in each sporangium (pl., sporangia), or spore case. o The sporangium splits open from the top to release the spores; each spore can give rise to a new gametophyte thallus. o A unique feature of hornworts is that the sporophytes, unlike those of mosses & liverworts, continue to grow from their bases for the remainder of the gametophyte’s life, a characteristic known as indeterminate growth. Some botanists think that indeterminate growth may indicate that hornworts evolved from plants w/ larger, more complex sporophytes.

Answer 12

In flowering plants, the thin stalk of a stamen; the filament bears an anther at its tip.

Answer 13

Type of leaf found in horsetails, ferns, gymnosperms, and angiosperms; contains multiple vascular strands (i.e., complex venation). Compare with microphyll.

Answer 14

A process in the flowering plant life cycle inwhich there are two fertilizations; one fertilization results in formation of a zygote, whereas the second results in formation of endosperm.

Answer 15

the outermost covering over woody stems and roots, consists of all plant tissues located outside the vascular cambium. two regions, a living inner bark composed of second- ary phloem and a mostly dead outer bark composed of periderm.

Answer 16

Leaves may also be modified for storage of water or food. For example, a bulb is a short, underground stem to which large, fleshy leaves are attached. Onions and tulips form bulbs. Many plants adapted to arid conditions, such as jade plant, medicinal aloe, and string-of-beads, have succulent leaves for water storag. These leaves are usually green and function in photosynthesis.

Answer 17

Collenchyma tissue, a simple plant tissue composed of collenchyma cells, is an extremely flexible structural tissue that provides much of the support in soft, nonwoody plant organs. individual cells, including collenchyma cells, support it. Collenchyma cells, which are usually elongated, are alive at maturity. Their primary cell walls are unevenly thickened and are especially thick in the corners. Collenchyma is not found uniformly throughout the plant and often occurs as long strands near stem surfaces and along leaf veins. The “strings” in a celery stalk, for example, consist of collenchyma tissue. collenchyma cells have primary cell walls, but their walls are chemically distinct because the thickened areas of collenchyma walls contain large quantities of pectin in addition to cellulose and hemicelluloses.

Answer 18

A diagnostic test involving thousands of DNA molecules placed on a glass slide or chip.

Answer 19

A phylum of spore-producing, nonvascular, thallose or leafy plants with a life cycle similar to that of mosses.

Answer 20

Aplantthatshedsleavesoveralongperiod,sosome leavesarealwayspresent.Comparewithdeciduous.

Answer 21

Small pores located in the epidermis of plants that provide for gas exchange for photosynthesis; each stoma is flanked by two guard cells, which are responsible for its opening and closing.

Answer 22

The female reproductive organ of a flower; consists of either a single carpel (simple)or two or more fused carpels (compound). See carpel. Each pisti; generally has 3 sections: a stigma, a style, and an ovary.

Answer 23

``` The wearing away or removal of soil from the land; although soil erosion occurs naturally from precipitation and runoff, human activities (such as clearing the land) accelerate it. ```

Answer 24

1) A noncell, waxy covering over the epidermis of the aerial parts of plants that reduces water loss. (2) The outer covering of some animals, such as roundworms.

Answer 25

The n spore in heterosporous plants that gives rise to a male gametophyte. Compare with megaspore.

Answer 26

tiny hairlike absorptive structures

Answer 27

The deposition of material leached from the upper layers of soil into the lower layers.

Answer 28

red water-soluble pigments called anthocyanins may accumulate in the vacuoles of epidermal leaf cells in some species; anthocyanins may protect leaves against damage by ultraviolet radiation. The various combinations of carotenoids and anthocyanins are responsible for the brilliant colors found in autumn landscapes in temperate climates.

Answer 29

The normal (usually seasonal) fall of leaves or other plant parts, such as fruits or flowers.

Answer 30

At first, each pollen grain consists of two cells surrounded by a tough outer wall. One cell, the generative cell, divides mitotically to form two nonflagellate male gametes, known as sperm cells. The other cell, the tube cell, produces a pollen tube, through which the sperm cells travel to reach the ovule.

Answer 31

The underground portion of a plant that anchors it in the soil and absorbs water and dissolved minerals.

Answer 32

In plants, a type of sclerenchyma cell; fibers are long, tapered cells with thick walls. often occur in patches or clusters

Answer 33

a relatively thin layer of Earth’s crust that has been modified by the natural actions of weather, wind, water, and organisms.

Answer 34

Mechanisms of communication between cells. Cells signal one another with secreted signaling molecules, or a signaling molecule on one cell combines with a receptor on another cell. See signal transduction.

Answer 35

(1) A young organism before it emerges fromthe egg, seed, or body of its mother. (2) Developing human until the end of the second month, after which it is referred to as a fetus. (3) In plants, the young sporophyte produced following fertilization and subsequent development of the zygote.

Answer 36

Two kinds of meristematic growth may occur in plants. Primary growth is an increase in stem and root length. All plants have primary growth, which produces the entire plant body in herbaceous plants and the young, soft shoots and roots in woody trees and shrubs.

Answer 37

appearance of a ring in cross section is due to differences in cell size and cell wall thickness between secondary xylem formed at the end of the preceding year’s growth and that formed at the beginning of the following year’s growth. In the spring, when water is plentiful, wood formed by vascular cambium has large-diameter conducting cells (tracheids and vessel elements) and few fibers and is appropriately called springwood or early wood. As summer progresses and water becomes less plentiful, the wood formed, known as summerwood or late wood, has narrower conducting cells and many fibers. It is this difference in cell size between the summerwood of one year and the springwood of the following year that gives the appearance of rings.

Answer 38

The n spore in heterosporous plants that gives rise to a female gametophyte. Compare with microspore.

Answer 39

A flowering plant (herbaceous/woody) that lives for many years.In temperate climates, the aerial (aboveground) stems of herbaceous perennials such as iris, rhubarb, onion, and asparagus die back each winter. Their underground parts (roots and underground stems) become dormant during the winter and send out new growth each spring. in certain tropical climates with pronounced wet and dry seasons, the aerial parts of herbaceous perennials die back, and the underground parts become dormant during the unfavorable dry season. Other tropical plants, such as orchids, are herbaceous perennials that grow year-round.

Answer 40

a simple, dry fruit that develops from a single carpel and splits open along one suture to release its seeds.

Answer 41

An area of dividing tissue, locatedat the tip of a shoot or root, that gives rise to primary tissues; apical meristems cause an increase in the length of the plant body.Compare with lateral meristems.

Answer 42

see angiosperms

Answer 43

any response of a plant to the relative lengths of daylight and darkness. Initiation of flowering at the shoot apical meristem is one of several physiological activities that are photoperiodic in many plants. Plants are classified into four main groups— short-day, long-day, intermediate-day, and day-neutral—on the basis of how photoperiodism affects their transition from vegetative growth to flowering.

Answer 44

In plants,the multicellular female gametangium (sex organ) that contains an egg. Compare with antheridium.

Answer 45

``` A process in which a cell converts and amplifies an extracellular signal into an intracellular signal that affects some function in the cell. ```

Answer 46

The deposition of material leached from the upper layers of soil into the lower layers.

Answer 47

Initially green & photosynthetic, the sporophyte becomes golden brown at maturity. It consists of three main parts: * A foot, which anchors the sporophyte to the gametophyte & absorbs minerals & nutrients from it * A seta, or stalk * A capsule, which contains sporogenous cells (spore mother cells). The capsule of some species is covered by a caplike structure, the calyptra, which is derived from the archegonium

Answer 48

Growth in response to the direction of gravity Most stem tips exhibit negative gravitropism by growing away from Earth’s center, whereas most root tips exhibit positive gravitropism. The root cap is the site of gravity perception in roots; when the root cap is removed, the root continues to grow, but it loses any ability to perceive gravity. Special cells in the root cap possess starch-containing amyloplasts that collect toward the bottom of the cells in response to gravity, and these amyloplasts may initiate at least some of the gravitropic response. If the root is put in a different position, as when a potted plant is laid on its side, the amyloplasts tumble to a new position, always settling in the direction of gravity. The gravitropic response (bending) occurs shortly thereafter and involves the hormone auxin.

Answer 49

The structure (i.e.,megasporangium) in the plant ovary that develops into the seed following fertilization.

Answer 50

An area of dividing tissue, located at the tip of a shoot or root, that gives rise to primary tissues; apical meristems cause an increase in the length of the plant body.Compare with lateral meristems.

Answer 51

Special multicellular or unicellular structure of plants, protists, and fungi in which gametes are formed.

Answer 52

Having male and female reproductive structures on separate plants; compare with monoecious.

Answer 53

As hyphae grow, they form a tangled mass or tissuelike network

Answer 54

A segment of a plant stem between the points where leaves are attached.

Answer 55

In botany,a type of branching in which one part always divides into two more or less equal parts.

Answer 56

A phylum of spore-producing, nonvascular, thallose plants with a life cycle similar to that of mosses.

Answer 57

growth in response to a mechanical stimulus, such as contact with a solid object. The twining or curling growth of tendrils or stems, which helps attach a climbing plant such as a vine to some type of support, is an example of thigmotropism.

Answer 58

The free-living, n gametophyte in ferns and other seedless vascular plants.

Answer 59

Cytoplasmic channels connecting adjacent plant cells and allowing for the movement of molecules and ions between cells.

Answer 60

blue light activates proton pumps → proton pump moves H⁺ out of guard cells → K⁺ and Cl^- diffuse into guard cells through voltage--activated ion channels → water diffuses by osmosis into guard cells → guard cells change shape and stoma opens To summarize, different mechanisms appear to regulate the opening and closing of stomata. The uptake of potassium and chloride ions is mainly associated with stomatal opening, and the declining concentration of sucrose is mainly associated with stomatal closing.

Answer 61

fall off at maturity

Answer 62

Flowers are reproductive shoots usually composed of four parts— sepals, petals, stamens, and carpels—arranged in whorls (circles) on the end of a flower stalk, or peduncle (FIG. 28-10). The pedun- cle may terminate in a single flower or a cluster of flowers known as an inflorescence. The tip of the flower stalk that bears the flower parts is known as the receptacle. All four floral parts are important in the reproductive pro- cess, but only the stamens (the “male” organs) and carpels (the ## Footnote “female” organs) produce gametes.

Answer 63

In flowering plants, the base of the carpel that contains ovules; ovaries develop into fruits after fertilization. Each young ovule contains a female G. phyte that form 1 f.male gamete (egg), 2 polar nuclei, & several other haploid cells. After fertilization ovule develops into a seed and the ovary into a fruit.

Answer 64

In seed plants, the transfer of pollen from the male to the female part of the plant.

Answer 65

Hydrostatic pressure that develops within a walled cell and presses outward against the plasma membrane.

Answer 66

The seed leaf of a plant embryo, which may contain food stored for germination. monocots 1 eudicot 2

Answer 67

One of the clades of flowering plants; magnoliids are core angiosperms that were traditionally classified as “dicots,” but molecular evidence indicates they are neither eudicots or monocots.

Answer 68

The 2n, spore-producingstage in the life cycle of a plant. Compare with gametophyte generation.

Answer 69

Even though roots live in the soil, they still require oxygen for aerobic respiration. Flooded soils are depleted of oxygen, so these aerial “breathing” roots, known as pneumatophores, may assist in getting oxygen to the submerged roots. help anchor the plant, have a well-developed system of internal air spaces that is continuous with the submerged parts of the root, presumably allowing gas exchange.

Answer 70

The condition of having more than twosets of chromosomes per-nucleus. Compare with diploid and haploid.

Answer 71

One of a pair of scalelike or leaflike structures found at the base of certain leaves.

Answer 72

a simple, fleshy or fibrous fruit that contains a hard stone (pit) surrounding a single seed. Ex include peaches, plums, olives, and almonds. The almond shell is actually the stone, which remains after the rest of the fruit has been removed.

Answer 73

(1) The thin, expanded part of a leaf. (2) The flat, leaflike structure of certain multicellular algae.

Answer 74

small, live in dense colonies/beds tiny hairlike absorptive structrures called rhizoids some have sugar/water conducting cells may have both or seperate sex plants Fertilization occurs when one of the sperm cells fuses w/ the egg w/ in the archegonium. Sperm cells, which have flagella, are transported from antheridium to archegonium by flowing water, such as splashing rain droplets. Alternatively, arthropods such as insects & mites may touch the sperm-laden fluid & inadvertently carry it for considerable distances. Once in a film of water on the female moss, a sperm cell swims into the archegonium, which secretes chemicals to attract & guide the sperm cells, & fuses w/ the egg. diploid zygote, formed by fertilization, grows by mitosis into a multicellular embryo that develops into a mature moss sporophyte. This sporophyte grows out of the top of the female gametophyte & remains attached & nutritionally dependent on the gametophyte throughout its existence. the sporogenous cells undergo meiosis to form haploid spores (see Fig. 27-7). * When spores are mature, the capsule opens & releases the spores, which are then transported by wind or rain. * If a moss spore lands in a suitable spot, it germinates & grows into a filament of cells called a protonema. * The protonema, which superficially resembles a filamentous green alga, forms buds, each of which grows into a green gametophyte, & the life cycle continues.

Answer 75

Cells that conduct dissolved sugar in the phloem of flowering plants. Joined end to end to form long sieve tubes. The cells’ end walls, called sieve plates, have a series of holes through which cytoplasm extends from one sieve tube element into the next. Sieve tube elements are living at maturity, but many of their organelles, including the nucleus, vacuole, mitochondria, and ribosomes, disintegrate or shrink as they mature. among the few eukaryotic cells that can function without nuclei. (bout a yr, notable)

Answer 76

Epidermal cells of aerial parts secrete a waxy cuticle over the surface of their exterior walls; this waxy layer greatly restricts water loss from plant surfaces. slows diffusion of CO₂

Answer 77

A phylum of spore-producing nonvascular plants with an alternation of generations in which the dominant n gametophyte alternates with a 2n sporophyte that remains attached to the gametophyte.

Answer 78

the gradual deterioration, and often death, of trees been observed in many European and North American forests in recent decades. may be partly the result of soil changes, such as leaching of essential cations, caused by acid precipitation.

Answer 79

The transfer of pollen grains from anther to stigma

Answer 80

Leaves may be simple (having a single blade) or compound (having a blade divided into two or more leaflets). Sometimes it is difficult to tell whether a plant has formed one compound leaf or a small stem bearing several simple leaves. One easy way to determine if a plant has simple or compound leaves is to look for axillary buds, so-called because each develops in a leaf axil (the angle between the stem and petiole). Axillary buds form at the base of a leaf, whether it is simple or compound. However, axillary buds never develop at the base of leaflets. Also, the leaflets of a compound leaf lie in a single plane (you can lay a compound leaf flat on a table), whereas simple leaves usually are not arranged in one plane on a stem.

Answer 81

an embryonic shoot

Answer 82

Secondary growth is an increase in the girth (thickness) of a plant. For the most part, only gymnosperms and woody eudicots have secondary growth. (Woody eudicots include trees and shrubs such as oak, sycamore, ash, cherry, apple, beech, and maple.)

Answer 83

ground tissue system All tissues in the plant body other than the dermal tissue system and vascular tissue system; consists of 3 tissues parenchyma, collenchyma, and sclerenchyma. Plant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis, and support.

Answer 84

Any of a group of seed plants in which the seeds are not enclosed in an ovary; gymnosperms frequently bear their seeds in cones. Includes four phyla: conifers, cycads, ginkgoes, and gnetophytes.

Answer 85

antheridium (pl., antheridia) In plants, the multicellular male gametangium (sex organ) that produces sperm cells. Compare with archegonium.

Answer 86

aboveground shoots that develop from adventitious buds on roots. Each sucker grows additional roots and becomes an independent plant when the parent plant dies. Examples of plants that form suckers include black locust, pear, apple, cherry, blackberry, and aspen.

Answer 87

A root system common to monocots consisting of a mat of thin roots spreading out below the soil surface. taproot= better for deep water fib root = better for absorbing water around plant

Answer 88

The part of a leaf that attaches to a stem.

Answer 89

The outer protective covering of a seed.

Answer 90

Pollen sacs within the anther contain numerous diploid cells called microsporocytes, each of which undergoes meiosis to produce 4 haploid cells called microspores. Each microspore divides mitotically to produce an immature male gametophyte, also called a pollen grain, that consists of two cells, the tube cell and the generative cell. The pollen grain becomes mature when its generative cell divides to form 2 nonmotile sperm cells.

Answer 91

preprophase band In plant cells, a dense array of microtubules just inside of the plasma membrane that appears just prior to mitosis and determines the plane in which the cell will divide. (encircle nucleus like a belt)

Answer 92

The areas of parenchyma between the vascular bundles are often referred to as pith rays.

Answer 93

flower when the night length is equal to or greater than some critical period two kinds of short-day plants: qualitative and quantitative. In qualitative short-day plants, flowering occurs only in short days; in quantitative short-day plants, flowering is accelerated by short days.

Answer 94

The biological process that captures light energy and transforms it into the chemical energy of organic molecules (e.g., carbohydrates), which are manufactured from carbon dioxide and water.

Answer 95

Of plant organs, such as roots or buds, that arise in an unusual position on a plant. The main roots of a fibrous root system do not arise from pre-existing roots but from the stem; such roots are called adventitious roots

Answer 96

In many plants, the mesophyll is divided into two sublayers. Toward the upper epidermis, the columnar cells are stacked closely together in a layer called palisade mesophyll. specialized for light capture and is the main site of photosynthesis in the leaf.

Answer 97

Some leaves associated with flower clusters (inflorescences) are modified as bracts. In flowering dogwood, the inconspicuous flowers are clustered in the center of each inflorescence, and what appears to be four white or pink petals are actually bracts. Similarly, the red “petals” of poinsettia are not petals at all but bracts

Answer 98

Type of leaf found in club mosses; contains one vascular strand (vein ) (i.e., simple venation). Compare with megaphyll.

Answer 99

roots of many tropical rainforest trees are shallow and concentrated near the surface in a mat only a few centimeters (an inch or so) thick. The root mat catches and absorbs almost all minerals released from leaves by decomposition. Swollen bases or braces called buttress roots hold the trees upright and aid in the extensive distribution of the shallow roots

Answer 100

Involves a clearly defined alternation of generations. o The ferns grown as houseplants (EX: Boston fern, maiden-hair fern, & staghorn fern) represent the larger, more conspicuous sporophyte generation. The fern sporophyte consists of a horizontal underground stem, or rhizome, that bears leaves, called fronds, & true roots. o As each young frond first emerges from the ground, it is tightly coiled & resembles the top of a violin, hence the name fiddlehead (FIG. 27-15b). o As fiddleheads grow, they unroll & expand to form fronds. Fern fronds are usually compound (the blade is divided into leaflets), w/ the leaflets forming beautifully complex leaves. o Fronds, roots, & rhizomes all contain vascular tissues. Spore production usually occurs in certain areas on the fronds, which develop sporangia. o Many species bear the sporangia in clusters, called sori (sing., sorus) (FIGS. 27-15c & d). o Within sporangia, sporogenous cells (spore mother cells) undergo meiosis to form haploid spores. o The sporangia burst open & discharge spores that may germinate & grow by mitosis into gametophytes. The mature fern gametophyte, which bears no resemblance to the sporophyte, is a tiny (less than half the size of one of your fingernails), green, often heart-shaped structure that grows flat against the ground. o Called a prothallus (pl., prothalli), the fern gametophyte lacks vascular tissues & has tiny, hairlike absorptive rhizoids to anchor it (FIG. 27-15e). o The prothallus usually produces both archegonia & antheridia on its underside. o Each archegonium contains a single egg, whereas numerous sperm cells are produced in each antheridium. Ferns use water as a transport medium. o The flagellate sperm cells swim, usually from a nearby prothallus, to the neck of an archegonium through a thin film of water on the ground underneath the prothallus. o After one of the sperm cells fertilizes the egg, a diploid zygote grows by mitosis into a multicellular embryo (an immature sporophyte). o At this stage, the sporophyte embryo is attached to & dependent on the gametophyte; but as the embryo matures, the prothallus withers & dies, & the sporophyte becomes free-living. The fern life cycle alternates between the dominant, diploid sporophyte w/ its rhizome, roots, & fronds, & the haploid gametophyte (prothallus) (FIG. 27-16). o The sporophyte generation is dominant not only because it is larger than the gametophyte but also because it persists for an extended period (most fern sporophytes are perennials), whereas the gametophyte dies soon after reproducing.

Answer 101

A method that allows researchers to study the ion channels of a tiny patch of membrane by tightly sealing a micropipette to the patch and measuring the flow of ions through the channels.

Answer 102

As a result of double fertilization and subsequent growth and de- velopment, each seed contains a young plant embryo and nutritive tissue (the endosperm), both of which are surrounded by a protec- tive seed coat. In monocots the endosperm persists and is the main source of food in the mature seed. In most eudicots the endosperm nourishes the developing embryo, which subsequently stores food in its cotyledons. As a seed develops from an ovule following fertilization, the ovary wall surrounding it enlarges dramatically and develops into a fruit. In some instances, other tissues associated with the ovary also enlarge to form the fruit (see discussion of fruits in Chapter 37). Fruits serve two purposes: to protect the developing seeds from desiccation as they grow and mature and to aid in the dispersal of seeds. For example, dandelion fruits have feathery plumes that are lifted and carried by air currents. Animals often assist in dispersing seeds found in edible fruits. Once a seed lands in a suit- able place, it may germinate and develop into a mature sporophyte that produces flowers, and the life cycle continues as described.

Answer 103

A nonprotein substance needed by an enzyme for normal activity; some cofactors are inorganic (usually metal ions); others are organic (coenzymes).

Answer 104

ability of roots and stems to grow throughout a plant’s life is known as indeterminate growth

Answer 105

One or more layers of nonvascular cells surround the larger veins and make up the bundle sheath. composed of parenchyma or sclerenchyma cells. Frequently, has support columns, called bundle sheath extensions,

Answer 106

Permanently attached to one location,e.g.,coral animals.

Answer 107

a modified underground bud in which fleshy storage leaves are attached to a short stem. A bulb is globose (round) and covered by paperlike bulb scales, which are modified leaves. It frequently forms axillary buds that develop into small daughter bulbs (bulblets). These new bulbs are initially attached to the parent bulb, but when the parent bulb dies and rots away, each daughter bulb can become established as a separate plant. Lilies, tulips, onions, and daffodils are some plants that form bulbs.

Answer 108

The net movement of water (the principal solvent in biological systems) by diffusion through a selectively permeable membrane from a region of higher concentration of water (a hypotonic solution) to a region of lower concentration of water (a hypertonic solution).

Answer 109

adventitious roots that develop from branches or a vertical stem and grow downward into the soil to help support the plant in an upright position. Prop roots are more common in monocots than in eudicots. Corn and sorghum, both monocots, are herbaceous plants that produce prop roots.

Answer 110

The photosynthetic ground tissue of the leaf, called the mesophyll is sandwiched between the upper epidermis and the lower epiderimis. Mesophyll cells, which are parenchyma cells packed with chloroplasts, are loosely arranged, with many air spaces between them that facilitate gas exchange. These intercellular air spaces account for as much as 70% of the leaf ’s volume.

Answer 111

A structure that has the potential to form a lateral shoot, or branch. The bud appears in the angle formed between a leaf and a stem.

Answer 112

simple, dry fruits that have a stony wall and do not split open at maturity. usually large, single seeded, and often derived from a compound ovary. Examples of nuts include chestnuts, acorns, and hazelnuts. Many so called “nuts” do not fit the botanical definition. Peanuts and Brazil nuts, for example, are seeds, not nuts.

Answer 113

an organic compound that acts as a chemical signal eliciting a variety of responses to growth & development.

Answer 114

a directional growth response that is elicited by an environmental stimulus. positive or negative, depending on whether the plant grows toward the stimulus (a positive tropism) or away from it (a negative tropism).

Answer 115

a charge and concentration differnece forms on the two sides of the guard cell plasma membrane.

Answer 116

a molecule that absorbs the light

Answer 117

Having male and female reproductive parts in separate flowers or cones on the same plant; compare with dioecious.

Answer 118

Nonvascular plants including mosses,liverworts, and hornworts.

Answer 119

The 3n nutritive tissue that is formed at some point in the development of all angiosperm seeds.

Answer 120

Some rhizomes produce greatly thickened ends called tubers, which are fleshy underground stems enlarged for food storage. When the attachment between a tuber and its parent plant breaks, often as a result of the death of the parent plant, the tuber grows into a separate plant. Potatoes and elephant’s ear (Caladium) are examples of plants that produce tubers. The “eyes” of a potato are axillary buds, evidence that the tuber is an underground stem rather than a storage root such as a sweet potato or carrot.

Answer 121

Embryonic tissue at the tip of a shoot (stem) , made up of developing leaves and a compact series of nodes and internodes.

Answer 122

Because it has an inner core of vascular tissue, the primary eudicot root lacks pith, a ground tissue found in the centers of many stems and roots.

Answer 123

The area at the base of the petiole where the leaf will break away from the stem. Also known as abscission zone. protective layer of cork cells develops on the stem side of the abscission zone.

Answer 124

A reproductive cell that gives rise to individual offspring in plants, fungi, and certain algae and protozoa.

Answer 125

Hyphae that contain two genetically distinct, sexually compatible nuclei within each cell

Answer 126

The appearance of water droplets on leaves, forced out through leaf pores by root pressure.

Answer 127

Certain nitrogen-fixing bacteria, collectively called rhizobia, form associations with the roots of leguminous plants—clover, peas, and soybeans, for EX. Nodules (swellings) that house millions of the rhizobia develop on the roots. Bacteria receive photosynthetic products from plants while helping plants meet their nitrogen requirements by producing ammonia (NH3) from atmospheric nitrogen. initial signal molecules produced by rhizobial bacteria are called nodulation factors, or nod factors. These nod factors help root-hair cells in the roots of leguminous plants recognize the presence of the bacteria; recognition is the first step in the infection by rhizobia and the development of root nodules. The nod factor apparently attaches to a plant receptor on the root-hair plasma membrane. This attachment triggers a calcium-dependent signal transduction cascade within root cells that alters gene expression and metabolism, resulting in nodule formation. The plant hormone cytokinin is involved in root nodule formation.

Answer 128

Rhizoids are on gametophytes Rhizomes are on sporophytes

Answer 129

the area of the stem where one or more leaves are attached.

Answer 130

Hyphae that contain only one nucleus per cell

Answer 131

family of yellow pigments light-activated kinases, enzymes that transfer phosphate groups.

Answer 132

In flowering plants, one of two n cells in the embryo sac that fuse with a sperm during double fertilization to form the 3n endosperm.

Answer 133

Buds are dormant embryonic shoots that eventually develop into branches.

Answer 134

The genus Gnetum contains tropical vines, shrubs, and trees with broad leaves. Species in the genus Ephedra include many shrubs and vines that grow in deserts and other dry temper- ate and tropical regions. Some Ephedra species resemble horsetails in that they have jointed green stems with tiny leaves. Commonly called joint fir, Ephedra has been used medicinally for centuries. An Asiatic Ephedra is the source of ephedrine, which stimulates the heart and raises blood pressure. At one time, ephedrine was commonly sold over the counter in weightcontrol medications and herbal energy boosters; several deaths were reported from chronic use or overdose of products containing ephedrine, so its use has been restricted.

Answer 135

When two gametes fuse, the diploid portion of the life cycle, called the sporophyte generation, begins. The sporophyte generation produces haploid spores by the process of meiosis; These spores represent the first stage in the gametophyte generation. Haploid gametophytes produce male gametangia, known as antheridia (sing., antheridium), in which sperm cells form, and/or female gametangia, known as archegonia (sing., archegonium), each bearing a single egg Sperm cells reach the female gametangium in a variety of ways, & one sperm cell fertilizes the egg to form a zygote, or fertilized egg. The diploid zygote is the first stage in the sporophyte generation. The zygote divides by mitosis & develops into a multicellular embryo, the young sporophyte plant. o Embryo development takes place w/ in the archegonium; thus, the embryo is protected as it develops. o The embryo grows into a mature sporophyte plant.

Answer 136

The veins, or vascular bundles, of a leaf extend through the mesophyll. Branching is extensive, and no mesophyll cell is more than two or three cells away from a vein. Therefore, the slow process of diffusion does not limit the movement of needed resources between mesophyll cells and veins. Each vein contains two types of vascular tissue: xylem and phloem.

Answer 137

partly decayed organic portion of the soil is referred to as humus. is not a single chemical compound but a mix of many organic compounds, binds mineral ions and holds water. On average persists in agricultural soil for about 20 years. Certain components may persist in the soil for 100s of years. Although its somewhat resistant to decay, a succession of microorganisms gradually reduces it to carbon dioxide, water, and minerals.

Answer 138

During winter, the plant’s metabolism, including its photosynthetic machinery, slows down or halts temporarily. related to a plant’s water requirements, which become critical during the physiological drought of winter. As the ground chills, absorption of water by the roots is inhibited. When the ground freezes, no absorption occurs. If the broad leaves were to stay on the plant during the winter, the plant would continue to lose water by transpiration but would be unable to replace it with water absorbed from the soil.

Answer 139

Cells that conduct dissolved sugar in thephloem of flowering plants.

Answer 140

A type of water-conducting and supporting cell in the xylem of vascular plants.

Answer 141

In sexual reproduction, the hyphae of two genetically compatible mating types come together, and their cytoplasm fuses

Answer 142

Inmosses,a filament of n cells that grows from a spore and develops into leafy moss gametophytes.

Answer 143

a tissue that can be anywhere from several to many cell layers thick, forms under the epidermis to provide a new protective covering as the epidermis is destroyed. As a woody plant continues to increase in girth, its epidermis is sloughed off, exposing the periderm. forms the outer bark of older stems and roots. It is a complex tissue composed mainly of cork cells and cork parenchyma cells. Cork cells are dead at maturity, and their walls are heavily coated with a waterproof substance called suberin, which helps reduce water loss. Cork parenchyma cells function primarily in storage.

Answer 144

A member of an ancient gymnosperm group that consists of a single living representative (Ginkgo biloba), a hardy, deciduous tree with broad, fan-shaped leaves and naked, fleshy seeds (on female trees).

Answer 145

Undifferentiated tissue formed on an explant (excised tissue or organ) in plant tissue culture.

Answer 146

Production of one type of n spore that gives rise to a bisexual gametophyte. Compare with heterospory.

Answer 147

The neck connecting the stigma to the ovary of a carpel.

Answer 148

The tissue that forms the outer covering over a plant; the epidermis or periderm.

Answer 149

An extension, or outgrowth, of a root epidermal cell. Root hairs increase the absorptive capacity of roots.

Answer 150

A flower that lacks one or more of the four parts: sepals, petals, stamens, and/or carpels. Compare with complete flower.

Answer 151

all initiated and orchestrated by changing levels of plant hormones, particularly ethylene. Briefly, the process is this: As autumn approaches, sugars, amino acids, and many essential minerals (such as nitrogen, phosphorus, and possibly potassium) remobilized and transported from the leaves to other plant parts; these minerals will be reused during the following spring.

Answer 152

In certain plants, a conelike structure that bears spore-producing sporangia.

Answer 153

Fungi communicate chemically by secreting signaling molecules called pheromones.

Answer 154

the mineral ions are pumped against their concentration gradient—that is, from an area of low concentration of that mineral in the soil solution to an area of high concentration in the plant’s cells.

Answer 155

Secondary growth is an increase in the girth (thickness) of a plant as a result of the activity of lateral meristems located within stems and roots. The new tissues formed by the lateral meristems are called secondary tissues to distinguish them from primary tissues produced by apical meristems. some do both (usually woody) A woody plant increases in length by primary growth at the tips of its stems and roots, whereas its older stems and roots farther back from the tips increase in girth by secondary growth. In other words, at the same time that primary growth is increasing the length of the stem, secondary growth is adding wood and bark, thereby causing the stem to thicken.

Answer 156

One of the parts of the flower attached inside the whorl of sepals; petals are usually colored, broad flat and thin but vary in shape/color, used to attract specific pollinators.

Answer 157

stack of vessel elements, called a vessel, resembles a miniature water pipe.

Answer 158

In plants,a sclerenchyma cell that is variable in shape but typically not long and tapered. C

Answer 159

The study of both visible and micro- scopic details of tree rings, has been used extensively in several fields.

Answer 160

The male [reproductive organs] part of a flower; consists of a filament and anther.Just inside & above the petals.

Answer 161

hardwood is the wood of flowering plants and softwood is the wood of conifers (cone-bearing gymnosperms). The wood of pine and other conifers typically lacks fibers (with their thick secondary cell walls) and vessel elements; the conducting cells in gymnosperms are tracheids. These cell differences generally make conifer wood softer than the wood of flowering plants, although there is a substantial variation from one species to another. The balsa tree, for example, is a flowering plant whose extremely light, soft wood is used to fashion airplane models.

Answer 162

leaves lack a petiole; they are narrow, and the base of the leaf often wraps around the stem to form a sheath. Parallel venation is characteristic of monocot leaves. In a cross section of a monocot leaf, in contrast, the parallel venation pattern produces evenly spaced veins, all of which appear in cross section. guard cells of many monocots are shaped like kidney beans. Other monocot leaves (those of grasses, reeds, and sedges) have guard cells shaped like dumbbells.

Answer 163

a fleshy fruit that has soft tissues throughout and contains few to many seeds; a blueberry is a berry, as are grapes, cranberries, bananas, and tomatoes. Many so-called “berries” do not fit the botanical definition. Strawberries, raspberries, and mulberries, for ex, are not berries.

Answer 164

Some plants form detachable plantlets (small plants) in notches along their leaf margins.

Answer 165

a lateral meristem responsible for secondary growth

Answer 166

quick movements These include the closing of the carnivorous Venus Flytrap leaf when it captures prey or the folding of the mimosa leaf when it is disturbed.

Answer 167

may have noticed that some trees have wood with two different colors. The functional secondary xylem—the part that conducts water and dissolved minerals—is the sapwood, a thin layer of younger, lighter-colored wood that is closest to the bark. Heartwood, the older wood in the center of the tree, is typically a brownish red. A microscopic examination of heartwood reveals that its vessels and tracheids are plugged with pigments, tannins, gums, resins, and other materials. Therefore, heartwood no longer functions in conduction but instead functions as a storage site for waste products. Because it is denser than sapwood, heartwood provides structural support for trees. Some evidence suggests that heartwood is also more resistant to decay.

Answer 168

occurs that seals off the infected area, causing it to die. These necrotic lesions, or dead areas, prevent or slow the spread of the initial infection

Answer 169

permits the transfer of materials (C compounds produced by photosynthesis) from roots to the fungus. At same time, essential minerals, such as Ph, move from the fungus to the roots of the host plant. The threadlike body of the fungal partner extends into the soil, extracting minerals well beyond the reach of the plant’s roots. In some, the fungal mycelium encircles the root like a sheath; in others, the fungus penetrates cell walls of the root cortex and forms branching arbuscules. The mycorrhizal relationship is mutually beneficial because when mycorrhizae are not present neither the fungus nor the plant grows as well. The hyphal network of mycorrhizae appears to interconnect the roots of different plant species in the community so that carbon compounds may flow from one plant to another through their mutual fungal partner.

Answer 170

The traditional name for flowering plants, a very large (more than 300,000 species), diverse phylum of plants that form flowers for sexual reproduction and produce seeds enclosed in fruits; include monocots and eudicots.

Answer 171

The stalk of a flower or inflorescence.

Answer 172

(splitting) Reaction in which a covalent bond between two subunits is broken through the addition of the equivalent of a water mol- ecule; a hydrogen atom is added to one subunit and a hydroxyl group to the other.

Answer 173

Each stoma is flanked by two specialized epidermal guard cells, which are responsible for opening and closing the stoma. Guard cells are usually the only epidermal cells with chloroplasts.

Answer 174

composed primarily of loosely packed parenchyma cells, composes the bulk of a herbaceous eudicot root., usually lack supporting collenchyma cells, probably because the soil supports the root, although roots as they age may develop some sclerenchyma. Primary function of the root cortex is storage. microscopic examination of the parenchyma cells that form the cortex often reveals numerous amyloplasts which store starch. large intercellular (between-cell) spaces, a common feature of the root cortex, provide a pathway for water uptake and allow for aeration of the root. The oxygen that root cells need for aerobic respiration diffuses from air spaces in the soil into the intercellular spaces of the cortex and from there into the cells of the root.

Answer 175

An environmental resource that because it is scarce or unfavorable tends to restrict the ecological niche of an organism. The three elements that are most often limiting resources for plants are nitrogen, phosphorus, and potassium.

Answer 176

Swellings on the roots of plants, such as legumes, in which symbiotic nitrogen-fixing bacteria (Rhizobium) live.

Answer 177

Pine tree = mature sporophyte → heterosporous= micro/megaspores (separate cones). Male [pollen] cones(near bottom part time) smaller(consist of sporophylls leaflike scales that bear sporangia on the underside.) female larger(various) (length)(upper,yr round, bear seeds after reproduction). At base of each sporophyll are 2 microsporangia, which contain numerous microsporocytes, aka microspore mother cells. → undergoes meiosis to form 4 haploid microspores. → develop into extremely reduced male gametophytes. Each immature male gametophyte, aka pollen grain, consists of 4 cells, 2 of which—a generative cell and a tube cell—are involved in reproduction. The other 2 cells soon degenerate. Two large air sacs on each pollen grain provide buoyancy for wind dissemination. Male cones shed pollen grains in great numbers, and wind currents carry some to the immature female cones. ## Footnote female cones (aka seed cones) may be modified branch systems. Each cone scale bears 2 ovules, or megasporangia, on its upper surface. Within each megasporangium, meiosis of a megasporocyte, or megaspore mother cell, produces 4 haploid megaspores. One of these divides mitotically, developing into the female gametophyte, which produces an egg within each of several archegonia. The other three megaspores are nonfunctional & soon degenerate. When the ovule is ready to receive pollen, it produces a sticky droplet at the opening where the pollen grains land. Pollination, the transfer of pollen to the female cones, occurs in the spring for a week or 10 days, after which the pollen cones wither and drop off the tree. One of the many pollen grains that adhere to the sticky female cone grows a pollen tube, an outgrowth that digests its way through the megasporangium to the egg within the archegonium. The germinated pollen grain with its pollen tube is the mature male gametophyte. Ultimately, two nonmotile (nonflagellate) sperm cells form within the germinated pollen grain. When it reaches the female gametophyte, the pollen tube discharges the two sperm cells near the egg. One of these sperm cells fuses with the egg, in the process of fertilization, to form a zygote, or fertilized egg, which subse- quently grows into a young pine embryo in the seed. The other sperm cell degenerates. The developing embryo consists of an embryonic root and an embryonic shoot with several cotyledons (embryonic leaves). Haploid female gametophyte tissue surrounds the embryo and becomes the nutritive tissue in the mature pine seed. A tough, protec- tive seed coat derived from the integuments encloses the embryo and nutritive tissue. The seed coat forms a thin, papery wing at one end that enables dispersal by air currents. Some seeds remain within the female cones for several years before being shed.

Answer 178

A continuum consisting of the interconnected, porous plant cell walls, along which water moves freely. Compare with symplast.

Answer 179

A flowering plant (herbaceous) that requires two years to complete its life cycle. Ssn 1 produce extra carbohydrates, which they store and use in the 2nd year. When flowers typically form/reproduce.

Answer 180

A flower that has all four parts: sepals, petals, stamens, and carpels. Compare with incomplete flower.

Answer 181

A leaf that is modified for protection, such as a cactus spine.

Answer 182

A type of water-conducting cell in the xylem of vascular plants. highly specialized for conduction. As they develop, cells undergo apoptosis, or programmed cell death. As a result, mature vessel elements are dead and therefore hollow; only their cell walls remain. flowering plants possess extremely efficient vessel elements. The cell diameters are usually greater than those of tracheids. Hollow, but unlike tracheids, the end walls have holes, known as perforations, or are absent. Stacked one on top of the other, and water is conducted readily from one vessel element into the next. Have pits in their side walls that permit the lateral transport (sideways movement) of water from one vessel to another.

Answer 183

Chlorophyll breaks down, allowing the carotenoids (orange carotenes and yellow xanthophylls), some of the accessory pigments in the chloroplasts of leaf cells, to become evident. Accessory pigments are always present in the chloroplasts but are masked by the green of the chlorophyll. The various combinations of carotenoids and anthocyanins are responsible for the brilliant colors found in autumn landscapes in temperate climates.

Answer 184

A substance found in many plant cell walls that confers rigidity and strength, particularly in woody tissues.

Answer 185

One of two classes (large ones) of flowering plants; monocot seeds contain a single cotyledon, or embryonic seed leaf, endosperm (nutritive tissue) usually present in mature seed. include palms, grasses, orchids, irises, onions, & lillies mostly herbaceous w/ long narrow leaves that have parallel veins. parts usually occur in 3's. Compare with eudicot.

Answer 186

A strand of vascular tissue that is part of the network of conducting tissue in a leaf.

Answer 187

a simple, dry fruit that develops from a single carpel and splits open along two sutures.

Answer 188

Stolons, or runners, are horizontal, aboveground stems that grow along the surface and have long internodes. Buds develop along the stolon, and each bud gives rise to a new shoot that roots in the ground. When the stolon dies, the daughter plants live separately. The strawberry plant produces stolons.

Answer 189

A flower that has both stamens and carpels. Compare with imperfect flower.

Answer 190

The diffusion of CO2 is facilitated by stomata (sing., stoma). minute pores in the epidermis that are surrounded by two cells called guard cells. Many gases, including CO2, oxygen, and water vapor, pass through the stomata by diffusion. generally open during the day when photosynthesis is occurring, and the water loss that also takes place when stomata are open provides some evaporative cooling. At night, usually close. In drought conditions, the need to conserve water overrides the need to cool the leaves and exchange gases. Thus, during a drought, the stomata close in the daytime.

Answer 191

directional growth of a plant caused by light. Most growing shoot tips exhibit positive phototropism by bending (growing) toward light, something you may have observed if you place houseplants near a sunny window. This growth response increases the likelihood that stems and leaves receive adequate light for photosynthesis. The bending response of phototropism is triggered by blue light with wavelengths less than 500 nm. ( blue light also induces stomata to open.)

Answer 192

Flowering plants are vascular plants that reproduce sexually by forming flowers and, following a unique double fertilization process, seeds within fruits. The fruit protects the developing seeds and often aids in their dispersal (see Chapter 37). Flowering plants have efficient water-conducting cells called vessel elements in their xylem and efficient sugar-conducting cells called sieve tube elements in their phloem (see Chapter 33).

Answer 193

A leaflike structure that bears spores.

Answer 194

One of a family of transport proteins located in the plasma membrane that facilitate the rapid movement of water molecules into or out of cells.

Answer 195

an organism reduces its metabolic state to a minimum level to survive unfavorable conditions. Atemporary period of arrested growth in plants or plant parts such as spores, seeds, bulbs, and buds.

Answer 196

Evidence indicates that several clades of basal (early-diverging) angiosperms evolved before the divergence of core angiosperms. The 170 species of basal angiosperms represent groups thought to be ancestral to all other flowering plants. The oldest surviving clade of basal angiosperms is represented by a single extant species, Amborella trichopoda. A shrub native to New Caledonia, an island in the South Pacific, Amborella may be the nearest living relative to the ancestor of all flowering plants. The water lilies & related families compose the second clade of basal angiosperms. This clade, which contains about 70 species of aquatic or wetland herbs, may be the second- oldest surviving lineage. Star anise & relatives—the third clade of basal angiosperms—consist of about 100 species of vines, trees, & shrubs found mostly in warmer climates. Star anise is important economically because it is a source of spice used by confectioners & anise oil. Star anise is also used to make Tamiflu, one of the treatments for influenza. ## Footnote The core angiosperms comprise magnoliids, monocots, & eudicots. Most angiosperm species belong to a clade of core angiosperms, which is divided into three subclades: magnoliids, monocots, & eudicots. Magnoliids include species in the magnolia, laurel, & black pepper families, as well as several related families. Although magnoliids were traditionally classified with the eudicots as “dicots,” molecular evidence such as DNA sequence comparisons indicates that the magnoliids are neither eudicots nor monocots. Native to tropical or warm temperate regions, magnoliids include sev- eral economically important plants, such as avocado, black pepper, nutmeg, and bay laurel.

Answer 197

toward the inside of the ovule, develops into the plant embryo Initially, the apical cell divides to form a small cluster of cells, called a proembryo. As cell division continues, a sphere of cells, often called a globular embryo, develops. Cells begin to develop into specialized tissues during this stage. When the eudicot embryo starts to develop its two cotyledons (seed leaves), it has two lobes and resembles a heart; this is often called the heart stage. During the torpedo stage, the embryo continues to grow as the cot- yledons elongate. As the embryo enlarges, it often curves back on itself and crushes the suspensor.

Answer 198

a series of molecular events in which the activities of certain genes are altered in ways that cause a cell to progressively commit to a particular differentiation pathway.

Answer 199

The process by which dissolved materials are washed away or carried with water down through the various layers of the soil.

Answer 200

Process of association of a substance with the partial positive and/or negative charges of water molecules.

Answer 201

Although irrigation improves the agricultural productivity of arid and semiarid lands, it sometimes causes salt to accumulate in the soil, a process called salinization.

Answer 202

A localized area of mitotic cell division in the plant body. do not differentiate. Instead, they retain the ability to divide by mitosis, a trait that many differentiated cells lose. The persistence of mitotically active meristems means that plants, unlike most animals, can grow throughout their entire lifespan. Meristematic cells, which are cube shaped, remain small because they are continually dividing. (In meristems, as daughter cells begin to enlarge, one or both will divide again.)

Answer 203

The n spore in heterosporous plants that gives rise to a female gametophyte. Compare with microspore.

Answer 204

in most fungi, hyphae are divided by cross walls, called septa (sing., septum), into individual cells containing one or more nuclei

Answer 205

A lateral meristem that produces cork cells and cork parenchyma; cork cambium and the tissues it produces make up the outer bark of a woody plant. Compare with vascular cambium.

Answer 206

The collective term for all sepals of a flower.

Answer 207

middle lamella The layer composed of pectin polysaccharides that serves to cement together the primary cell walls of adjacent plant cells.

Answer 208

Colorless plastids; include amyloplasts, which are used for starch storage in cells of roots and tubers.

Answer 209

a receptor converts an extracellular signal into an intracellular signal that causes 1 or more cellular responses.

Answer 210

hefemalegametophytegenerationinfloweringplants.

Answer 211

The mature sporophyte has special cells called sporogenous cells (spore-producing cells, also called spore mother cells) that divide by meiosis to form haploid spores. Fertilization of egg by sperm cell → zygote → embryo →mature sporophyte plant→ sporogenous cells → meiosis → spores

Answer 212

The outer cell layers that surround the megasporangium of an ovule; develop into the seed coat.

Answer 213

The third gnetophyte genus, Welwitschia, contains a single species found in deserts of southwestern Africa. Most of Welwitschia’s body—a long taproot—grows underground. Its short, wide stem forms a shallow disc, up to 0.9 m (3 ft) in diameter, from which two ribbonlike leaves extend. These two leaves continue to grow from the stem throughout the plant’s life, but their ends are usually broken and torn by the wind, giving the ap- pearance of numerous leaves. Each leaf grows to about 2 m (6.5 ft) in length. When Welwitschia reproduces, cones form around the edge of its disclike stem.

Answer 214

The seed leaf of a plant embryo, which may contain food stored for germination.

Answer 215

vascular bundles

Answer 216

A substance, e.g., cyclic AMP or calcium ions, that relays a message from a hormone bound to a cell-surface receptor; leads to some change in the cell.

Answer 217

flower when the night length is equal to or less than some critical period. In qualitative long-day plants, flowering occurs only in long days; in quantitative long-day plants, long days accelerate flowering.

Answer 218

a horizontal underground stem that may or may not be fleshy. Fleshiness indicates that the rhizome is used for storing food materials, such as starch. Although resemble roots, they are really stems, as indicated by the presence of scalelike leaves, buds, nodes, and internodes. (Roots have none of these features.) Rhizomes frequently branch in different directions. Over time, the old portion of the rhizome dies, and the two branches eventually separate to become distinct plants. Irises, bamboos, ginger, and many grasses are examples of plants that reproduce asexually by forming rhizomes.

Answer 219

consists of one main root that formed from the seedling’s enlarging radicle, or embryonic root

Answer 220

Conducts water and dissolved minerals from the roots to the stems/leaves & provides structural support. In flowerng plants, is a complex tissue composed of 4 cell types: tracheids, vessel elements, parenchyma cells, & fibers. 2 of the 4 cell types ;the tracheids and vessel elements, conduct water & dissolved minerals. also contains fibers that provide support, & parenchyma cells, known as xylem parenchyma, that perform storage functions.

Answer 221

A phylum of seedless vascular plants with a life cycle similar to that of ferns.

Answer 222

An extinct group of seed bearing woody plants with fernlike leaves; seed ferns probably descended from progymnospermsand gave rise to cycads and possibly ginkgoes.

Answer 223

The vascular tissue that conducts dissolved sugar and other organic compounds in plants.

Answer 224

The portion of the carpel where pollen grains land during pollination (and before fertilization).

Answer 225

A type of water-conducting and supporting cell in the xylem of vascular plants. highly specialized for conduction. As they develop, both cells undergo apoptosis, or programmed cell death. As a result, mature tracheids are dead and therefore hollow; only their cell walls remain. Tracheids, the chief water-conducting cells in gymnosperms (such as pine) and seedless vascular plants (such as ferns), are long, tapering cells located in patches or clumps. Water is conducted upward, from roots to shoots, passing from one tracheid into another through wide pits.

Answer 226

One of a phylum of seedless vascular plants that reproduce by spores produced in sporangia; ferns undergo an alternation of generations between the dominant sporophyte and the gametophyte (prothallus).

Answer 227

Bud scales cover the terminal bud and protect its delicate apical meristem during dormancy. When the bud resumes growth, the bud scales covering the terminal bud fall off, leaving bud scale scars on the stem where they were attached. Because temperate-zone woody plants form terminal buds at the end of each year’s growing season, the number of sets of bud scale scars on a twig indicates its age. A leaf scar shows where each leaf was attached on the stem; the pattern of leaf scars can be used to determine leaf arrangement on a stem—alternate, opposite, or whorled. The vascular (conducting) tissue that extends from the stem out into the leaf forms bundle scars within a leaf scar. Axillary buds may be found above the leaf scars. Also, the bark of a woody twig has lenticels, which look like tiny specks on the bark of a twig.

Answer 228

The vascular tissue that conducts dissolved sugar and other organic compounds in plants.

Answer 229

A fibrous root system has several to many roots of similar size developing from the end of the stem, with lateral roots branching off these roots. Form in plants that have a short-lived embryonic root. The roots originate first from the base of the embryonic root and later from stem tissue

Answer 230

A type of asexual reproduction in which the offspring are maternal clones. advantage of apomixis over other methods of asexual reproduction is that the seeds and fruits produced by apomixis can be dispersed by methods associated with sexual reproduction.

Answer 231

Each young ovule within an ovary contains a diploid cell, the megasporocyte, which undergoes meiosis to produce 4 haploid megaspores. 3 of these usually disintegrate, and the 4th, the functional megaspore, divides mitotically to produce a multicellular female gametophyte, also called an embryo sac. The female gametophyte, which is embedded in the ovule, typically contains 7 cells with 8 haploid nuclei. 6 of these cells, including the egg cell (the female gamete), contain a single nucleus each; a large central cell has 2 nuclei, called polar nuclei. The egg and both polar nuclei participate directly in fertilization.

Answer 232

Conducts food materials (carbohydrates formed in photosynthesis) throughout the plant and provides structural support. In flowering plants, is a complex tissue composed of four cell types: sieve tube elements, companion cells, fibers, and phloem parenchyma cells. Fibers, which are usually extensive in the phloem of herbaceous plants, provide additional structural support for the plant body.

Answer 233

The absorption of water by a seed prior to germination.

Answer 234

environment. Play an important role in forming soil. o Mosses die, forming a thin layer of organic matter in which grasses & other plants can grow. o Because they grow tightly packed in dense colonies, mosses hold soil in place & help prevent erosion. At the same time, they retain moisture that they & other organisms need. o Waxwings & other birds use moss, as nesting material. Commercially, the most important mosses are the peat mosses in the genus Sphagnum. One of the distinctive features of Sphagnum “leaves” is the presence of many large, empty cells that absorb & hold water. o This feature makes peat moss a useful packing material for shipping live plants/ it’s a good soil conditioner. o Added to sandy soils, for ex: peat moss helps absorb & retain moisture. o Acidic & anaerobic conditions of a peat bog retard the growth of bacterial & fungal decomposers. o As a result, dead peat mosses accumulate as thick deposits—some several meters in depth—under the growing mat of living peat mosses. o Over time, the organic material compresses to form peat. In some countries, EX: Ireland & Scotland, people cut out blocks of peat that has accumulated for hundreds of years in peat bogs, dry them, & burn them for fuel. o Occasionally, the remains of well-preserved humans have been uncovered during the excavations of old peat bogs in Ireland & other parts of Europe. o The name moss is often misused to refer to plants that are not truly mosses. EX: reindeer “moss” is lichen that is a dominant form of vegetation in the arctic tundra, Spanish “moss” is a flowering plant, & club “moss” is a relative of ferns.

Answer 235

voltage-activated ion channels Ion channels in the plasma membrane of neurons that are regulated by changes in voltage. Also called voltage-gated channels.

Answer 236

The fusion of two n gametes; results in the formation of a 2n zygote. Compare with double fertilization.

Answer 237

Any of a phylum of gymnosperms that live mainly in tropical and semitropical regions and have stout stems (to 20 m in height) and fernlike leaves.

Answer 238

An area of dividing tissue, located at the tip of a shoot or root, that gives rise to primary tissues; apical meristems cause an increase in the length of the plant body. Primary growth occurs as a result of the activity of apical meristems, areas located at the tips of roots and shoots, including within the buds of stems. Leaf primordia (developing leaves) and bud primordia (developing buds) arise from the shoot apical meristem. The tiny leaf primordia cover and protect the shoot apical meristem. As the cells formed by the shoot apical meristem elongate, the shoot apical meristem is pushed upward. Subsequent cell divisions produce additional stem tissue and cause new leaf and bud primordia to appear. Farther from the stem tip, the immature cells differentiate into the three tissue systems of the mature plant body.

Answer 239

A protective sheath that encloses the young stem in certain monocots.

Answer 240

The main, or central,vein of a leaf.

Answer 241

Each young ovule w/in an ovary contains a megasporocyte (megaspore mother cell) that undergoes meiosis to produce 4 haploid megaspores. 3 of these usually disintegrate, & 1 divides mitotically & develops into a mature female gametophyte, aka embryo sac. Embryo sacs in the for the most part contain 7 cells with 8 haploid nuclei. 6 of these cells, including the egg cell, contain a single nucleus each, & a central cell has 2 nuclei, called polar nuclei. The egg & the central cell w/ 2 polar nuclei are directly involved in fertilization; the other 5 cells in the embryo sac have no direct role in fertilization process & disintegrate. As the synergids (the two cells _flanking_ the egg) disintegrate, they release chemicals that may affect the direction of pollen tube growth. ## Footnote Each pollen sac, or microsporangium, of the anther contains numerous microsporocytes (microspore mother cells), each of which undergoes meiosis to form 4 haploid microspores. Every microspore develops into an immature male gametophyte, aka pollen grain →. Pollen, small; each consists of 2 cells, the tube & generative cell. → Anthers split open & begin to shed pollen. A variety of agents—including wind, water, insects, and other animal pollinators—transfer pollen grains to the stigma. If compatible w/ stigma, the pollen grain germinates, & a pollen tube grows down the style & into the ovary. The germinated pollen grain w/ its pollen tube is the mature male g. phyte. Next, the generative cell divides to form 2 nonflagellate sperm cells → move down pollen tube & are discharged into the embryo sac. Both sperm cells are involved in fertilization. 1 sperm cell fuses w/ the egg, forming a zygote that grows by mitosis & develops into a multicellular embryo in the seed. The 2nd sperm cell fuses w/ the 2 haploid polar nuclei of the central cell to form a triploid (3n) cell that divides by mitosis & develops into endosperm, a nutrient tissue rich in lipids, proteins, & carbohydrates that nourishes the growing embryo. This fertilization process, which involves 2 separate nuclear fusions, is called double fertilization & is, with two exceptions, unique to flowering plants. (Double fertilization has been reported in the gymnosperms Ephedra nevadensis and Gnetum gnemon. This process differs from double fertilization in flowering plants in that an additional zygote, rather than endosperm, is produced. The 2nd zygote later disintegrates.)

Answer 242

a tissue is a group of cells that forms a structural and func- tional unit. Simple tissues are composed of only one kind of cell, whereas complex tissues have two or more kinds of cells.

Answer 243

Growing plants in an aerated solution of dissolved inorganic minerals, i.e., without soil.

Answer 244

After double fertilization takes place within the ovule, the ovule develops into a seed, and the ovary surrounding it develops into a fruit.

Answer 245

The female reproductive unit of a flower; carpels bear ovules. Compare with pistil, located in the center or top of most.

Answer 246

Leaf blades may possess parallel venation, in which the primary veins—strands of vascular tissue—run approximately parallel to one another (generally characteristic of monocots), or netted venation, in which veins are branched in such a way that they resemble a net (generally characteristic of eudicots. Netted veins can be pinnately netted, with major veins branching off in succession along the entire length of the midvein (main or central vein of a leaf ), or palmately netted, with several major veins radiating out from one point.

Answer 247

As a stem thickens from secondary growth, the epidermis, including stomata that exchange gases for the herbaceous stem, dies. Stomata are replaced by lenticels, which permit gas exchange through the periderm.

Answer 248

A continuum consisting of the cytoplasm of many plant cells, connected from one cell to the next by plasmodesmata. Compare with apoplast.

Answer 249

epidermis also contains special outgrowths, or hairs, called trichomes,Vary in sizes and shapes and have a variety of functions. Plants that tolerate salty environments have specialized trichomes on their leaves to remove excess salt that accumulates in the plant. The presence of trichomes on the aerial parts of desert plants may increase the reflection of light off the plants, thereby cooling the internal tissues and decreasing water loss. Other trichomes have a protective function. For example, the trichomes on stinging nettle leaves and stems contain irritating substances that may discourage herbivorous animals from eating the plant.

Answer 250

All plants produce spores by meiosis, in contrast w/ algae & fungi, which may produce spores by meiosis or mitosis. The spores represent the first stage in the gametophyte generation. Each spore divides by mitosis to produce a multicellular gametophyte, & the cycle continues

Answer 251

The 3n nutritive tissue that is formed at some point in the development of all angiosperm seeds.

Answer 252

A cluster of flowers on a common floral stalk.

Answer 253

located in the outer bark, is composed of a thin cylinder or irregular arrangement of meristematic cells. Cells of the cork cambium divide and form cork cells toward the outside and one or more underlying layers of cork parenchyma cells that function in storage. Collectively, cork cells, cork cambium, and cork parenchyma make up the periderm.

Answer 254

The immature male gametophyte of seed plants (gymnosperms and angiosperms) that produces sperm capable of fertilization.

Answer 255

track sun Growth or orientation of a sessile organism, especially a plant, toward or away from the light of the sun.

Answer 256

Root hairs are simple, unbranched trichomes that increase the surface area of the root epidermis (which comes into contact w/ the soil) for more effective water and mineral absorption.

Answer 257

many leaves and flowers have determinate growth; that is, they stop growing after reaching a certain size.

Answer 258

A viscous organic material that certain plants produce and secrete into specialized ducts; may play a role in deterring disease organisms or plant-eating insects.

Answer 259

Some fungi, called coenocytic fungi, lack septa. In these species, nuclear division is not followed by cytoplasmic division.

Answer 260

The sex organs, or gametangia (sing., gametangium), of most plants are multicellular, whereas the gametangia of algae are unicellular

Answer 261

plant tissues in addition to ovary tissue make up the fruit. For ex, the edible portion of a strawberry is the red, fleshy receptacle. Apples and pears are also accessory fruits; the outer part of each of these fruits is an enlarged floral tube, consisting of receptacle tissue along with portions of the calyx, that surrounds the ovar.

Answer 262

the short [ortion of the embryonic shoot connectiong the radicle to 1 or 2 cotyledons

Answer 263

A flowering plant (herbaceous) that completes its entire life cycle in a single year or growing season.

Answer 264

The reciproca ladaptation of two or more species that occurs as a result of their close interactions over a long period.

Answer 265

second main type of fruit. An aggregate fruit is formed from a single flower that contains several to many separate (free) carpels. After fertilization, each ovary from each individual carpel enlarges. As they enlarge, the ovaries may fuse to form a single fruit. Raspberries, blackberries, and magnolia fruits are examples of aggregate fruits.

Answer 266

The end of a flower stalk where the flower parts (sepals, petals, stamens, and carpels) are attached. tip of the stalk enlarges to form this.

Answer 267

One of the two clades of flowering plants; eudicot seeds contain two cotyledons, or seed leaves. Compare with monocot. include oaks, roses, mustards, cacti, blueberries, & sunflowers. Either herbaceous or woody (hickory tree). Leaves vary in shape but usually broader than monocots, have netted veins, parts usually occur in 4's or 5's or multiples thereof. Endosperm usually absent in mature seed, having being absorbed by the 2 cotyledons during seed development.

Answer 268

cell containing a diploid nucleus known as a zygote nucleus.

Answer 269

do not flower when night length is either too long or too short. Sugarcane and coleus are intermediate-day plants. These plants flower when exposed to days and nights of intermediate length.

Answer 270

A plant reproductive body consisting of a young, multicellular plant and nutritive tissue (food reserves), enclosed by a seed coat.

Answer 271

other environmental factors are also involved, including CO2 concentration. A low concentration of CO2 in the leaf induces stomata to open, even in the dark. The effects of light and CO2 concentration on stomatal opening are interrelated. water stress. During a prolonged drought, stomata remain closed, even during the day. Stomatal opening and closing are under hormonal control, particularly by the plant hormone abscisic acid. also regulated by an internal biological clock that in some way measures time. For ex:, after plants are placed in continual darkness, their stomata continue to open and close at more or less the same time each day.

Answer 272

—the epidermis and periderm--provides a protective covering over plant parts. In herbaceous plants, its a single layer of cells called the epidermis. Woody plants initially produce an epidermis, but it splits apart as a result of the production of additional woody tissues inside the epidermis as the plant increases in girth. Periderm, which replaces the epidermis in the stems & roots of older woody plants, composes the outer bark.

Answer 273

Production of two types of n spores, microspores (male) and megaspores (female). Compare with homospory.

Answer 274

The leaf epidermis contains minute openings, or stomata (sing., stoma), for gas exchange between leaf cells and the environment; the stomata are evenly spaced to optimize this gas exchange. Each stoma is flanked by two specialized epidermal guard cells, which are responsible for opening and closing the stoma Stomata are especially numerous on the lower epidermis of horizontally oriented leaves (an average of about 100 stomata per square millimeter) and in many species are located only on the lower surface. In contrast, floating leaves of aquatic plants, such as water lilies, have stomata only on the upper epidermis.

Answer 275

A monophyletic supergroup of eukaryotes with chloroplasts bounded by outer and inner membranes; include red algae, green algae, and land plants.

Answer 276

regulates the movement of water and minerals that enter the xylem in the root’s center. Structurally differs from the rest of the cortex. Endodermal cells fit snugly against one another, and each has a special bandlike region, called a Casparian strip, on its radial (side) and transverse (upper and lower) walls.

Answer 277

day-neutral plants, do not initiate flower- ing in response to seasonal changes in the period of daylight and darkness but instead respond to some other type of stimulus, ex- ternal or internal.

Answer 278

Archaeopteris, a progymnosperm that lived is one of the earliest known trees with “modern” woody tissue. ## Footnote Fossils of several progymnosperms w/ reproductive structures intermediate between those of spore plants & seed plants have been discovered. For EX, the evolution of microspores into pollen grains & of megasporangia into ovules (seed producing structures) can be traced in fossil progymnosperms. The fossil record indicates that progymnosperms probably gave rise to conifers & to another group of extinct plants called seed ferns, which were seed-bearing woody plants with fernlike leaves (FIG. 28-16b). The seed ferns, in turn, probably gave rise to cycads & ginkgo, as well as to several gymnosperm groups now extinct. The origin of gnetophytes remains unclear, although molecular data indicate that they are closely related to conifers.

Answer 279

specialized for structural support is sclerenchyma tissue, whose cells have both primary and secondary cell walls. The root of the word sclerenchyma is derived from the Greek word sclero, meaning “hard.” The secondary cell walls of sclerenchyma cells become strong and hard because of extreme thickening. Pits, which are thin areas where secondary walls did not develop, allow an exchange of substances between adjacent living sclerenchyma cells. Mature sclerenchyma cells are unable to stretch or elongate. At functional maturity, when sclerenchyma tissue is providing support for the plant body, its cells are often dead. ## Footnote Sclerenchyma tissue may be located in several areas of the plant body. Two types of sclerenchyma cells are sclereids and fibers. Sclereids are cells of variable shape common in the shells of nuts and in the stones of fruits such as cherries and peaches. The slightly gritty texture of pears results from the presence of clusters of sclereids. Fibers, which are long, tapered cells that often occur in patches or clumps, are particularly abundant in the wood, inner bark, and leaf ribs (veins) of flowering plants thick secondary walls of sclerenchyma cells are chemically different because they are rich in lignin, in addition to cellulose, hemicelluloses, and pectin.

Answer 280

A group of organisms that includes a recent common ancestor and all its descendants; a clade. Compare with polyphyletic group and paraphyletic group.

Answer 281

micro - An essential element that is required in trace amounts for normal growth. macro - An essential element required in fairly large amounts for normal growth.

Answer 282

the upper angle between a leaf and the stem to which it is attached.

Answer 283

Areas of localized cell division on the side of a plant that give rise to secondary tissues. Lateral meristems, including the vascular cambium and the cork cambium, cause an increase in the girth of the plant body. Trees and shrubs undergo both primary and secondary growth. These plants increase in length by primary growth and increase in girth by secondary growth. The increase in girth, which occurs in areas that are no longer elongating, is due to cell divisions that take place in lateral meristems, areas extending along the entire length of the stems and roots except at the tips. Two lateral meristems, the vascular cambium and the cork cambium, are responsible for secondary growth, which is the formation of secondary tissues: secondary xylem, secondary phloem, and periderm.

Answer 284

support columns, called bundle sheath extensions, that extend through the mesophyll from the upper epidermis to the lower epidermis. may be composed of parenchyma, collenchyma, or sclerenchyma cells.

Answer 285

The movement of organic materials (dissolved food) in the phloem of a plant.

Answer 286

Precipitation that is acidic as a result of both sulfur and nitrogen oxides forming acids when they react with water in the atmosphere.

Answer 287

which are unicellular, with a round or oval shape.

Answer 288

A term describing a plant that sheds leaves or other structures at regular intervals, e.g., during autumn. Compare with evergreen.

Answer 289

In many plants, the mesophyll is divided into two sublayers. In the lower portion, the cells are more loosely and irregularly arranged in a layer called spongy mesophyll. Photosynthesis also occurs here, but the primary function is to allow diffusion of gases, particularly CO2, within the leaf.

Answer 290

Guard cells are associated with special epidermal cells called subsidiary cells that are often structurally different from other epidermal cells. provide a reservoir of water and ions that move into and out of the guard cells as they change shape during stomatal opening and closing

Answer 291

A spore case, found in plants, certain protists, and fungi.

Answer 292

Adjacent to each sieve tube element is a companion cell that assists in the functioning of the sieve tube element. complete with a nucleus. This nucleus is thought to direct the activities of both the companion cell and sieve tube element. play an essential role in moving sugar into the sieve tube elements for transport to other parts of the plant.

Answer 293

Each pollen grain produces two cells sur- rounded by a tough outer wall. One cell eventually divides to form two male gametes, or sperm cells, and the other produces a pollen tube through which the sperm cells travel to reach the ovule.

Answer 294

a simple, dry fruit that develops from 2 or more fused carpels and splits open along 2 or more sutures or pores. Iris, poppy, and cotton

Answer 295

A leaf or stem that is modified for holding or attaching onto objects. EX: vines

Answer 296

The winter buds of a dormant woody plant are covered by bud scales, modified leaves that protect the delicate meristematic tis- sue of the bud from injury, freezing, or drying out.

Answer 297

An extinct group of plants that may have been the ancestors of gymnosperms. 2 derrived features: leaves w/ branching veins (megaphylls) & woody tissue ( secondary xylem, similar to that of the modern gymnosperms).reproduced by spores not seeds.

Answer 298

differential gene expression The expression of different subsets of genes at different times and in different cells during development. responsible for variations in chemistry, behavior, and structure among cells.

Answer 299

Free energy of water; the water potential of pure water is zero and that of solutions is a negative value. Differences in water potential are used to predict the direction of water movement (always from a region of less negative water potential to a region of more negative water potential). under normal conditions the water potential of the root is more negative than the water potential of the soil. Thus, water moves by osmosis from the soil into the root.

Answer 300

A sex cell; in plants and animals, an egg or sperm. In sexual reproduction, the union of gametes results in the formation of a zygote. The chromosome number of a gamete is designated n.

Answer 301

Primary growth is evident when a root tip is examined A protective layer of cells called a root cap covers the root tip. Directly behind the root cap is the root apical meristem, which consists of meristematic cells.

Answer 302

Development toward a more mature state; a process changing a young, relatively unspecialized cell to a more specialized cell.

Answer 303

Development in plants encompasses all the changes that take place during the entire life of an individual.

Answer 304

similar to a caryopsis in that it is simple and dry, does not split open at maturity, and contains a single seed. However, the seed coat of an achene is not fused to the fruit wall. Instead, the single seed is attached to the fruit wall at one point only, permitting an achene to be separated from its seed. The sunflower fruit is an example of an achene. One can peel off the fruit wall (the shell) to reveal the sunflower seed within.

Answer 305

The above ground portion of a plant, such as the stem and leaves.

Answer 306

A flower that lacks either stamens or carpels. Com-pare with perfect flower.

Answer 307

All 4 organs , normal order of whorls (circles) on the end of the flower stalk seplas → petals → stamens → carpels

Answer 308

2 polar nuclei in the central cell of the ovule fuse with the 2nd sperm cell to form the 1st cell of the triploid (3n) endosperm, the tissue with nutritive and hormonal functions that surrounds the developing embryonic plant in the seed. This process, in which two separate cell fusions occur, is called double fertilization. It is, with few exceptions, unique to flowering plants. (A type of double fertilization has been reported in two gymnosperm species, Ephedra nevadensis and Gnetum gnemon.)

Answer 309

The part of the stamen in flowers that produces microspores and, ultimately, pollen grains. saclike, where meiosis occurs to form microspores that develop into pollen grains.

Answer 310

a complex tissue composed primarily of relatively unspecialized living cells. Dispersed among these cells are more specialized guard cells and outgrowths called trichomes. In most plants, consists of a single layer of flattened cells. Epidermal cells generally contain no chloroplasts and are therefore transparent, so light can penetrate the interior tissues of stems and leaves. In both stems and leaves, photosynthetic tissues lie beneath the epidermis.

Answer 311

Unrestricted growth, as for example, in stems and roots. Compare with determinate growth.

Answer 312

A substance found in many plant cell walls that confers rigidity and strength, particularly in woody tissues.

Answer 313

formed from the ovaries of many flowers that grow in proximity on a common floral stalk. The ovary from each flower fuses with nearby ovaries as it develops and enlarges after fertilization. Pineapples, figs, and mulberries are multiple fruits.

Answer 314

A family of membrane-enclosed organelles occurring in photosynthetic eukaryotic cells; include chloroplasts, chromoplasts, and amyloplasts and other leukoplasts.

Answer 315

The simple body of analga, fungus, or nonvascular plant that lacks root, stems, or leaves, e.g., a liverwort thallus or a lichen thallus.

Answer 316

The outer bark of woody stems and roots; composed of cork cells, cork cambium, and cork parenchyma, along with traces of primary tissues. functions as a replacement for the epedermis

Answer 317

special protein aid on cell aid in water movement.

Answer 318

At the center of a eudicot primary root is the stele, or vascular cylinder, a central cylinder of vascular tissues. The outermost layer of the stele is the pericycle, which is just inside the endodermis. The pericycle consists of a single layer of parenchyma cells that give rise to multicellular lateral roots, also called branch roots. Lateral roots originate when cells in a portion of the pericycle start dividing. As it grows, the lateral root pushes through several layers of root tissue (endodermis, cortex, and epidermis) before entering the soil. Each lateral root has all the structures and features—root cap, root hairs, epidermis, cortex, endodermis, pericycle, xylem, and phloem—of the larger root from which it emerges. In addition to producing lateral roots, the pericycle is involved in forming the lateral meristems that produce secondary growth in woody roots (discussed later in the chapter).

Answer 319

The active transport of a substance from a region of low concentration to a region of high concentration by coupling its transport to the transport of a substance down its concentration gradient.

Answer 320

A type of water-conducting cell in the xylem of vascular plants.

Answer 321

Collectively,the petals of a flower.

Answer 322

In gymnosperms and flowering plants, a tube or extension that forms after germination of the pollen grain and through which male gametes (sperm cells) pass in to the ovule.

Answer 323

A plant hormone involved in various aspects of plant growth and development, such as cell division and delay of senescence.

Answer 324

multicellular. The body consists of long, branched, threadlike filaments called hyphae (sing., hypha)

Answer 325

The n, gamete producing stage in the life cycle of a plant. Compare with sporophyte generation.

Answer 326

the shoot apex or terminal bud located above the point of attachement of the cotyledon(s).

Answer 327

The water cycle, which includes evaporation, precipitation, and flow to the ocean; supplies terrestrial organisms with a continual supply of fresh water.

Answer 328

A lateral meristem that produces secondary xylem (wood) and secondary phloem (inner bark). Compare with cork cambium.

Answer 329

A band of waterproof material around the radial and transverse walls of endodermal root cells.

Answer 330

Climbing plants and epiphytes, which are plants that grow attached to other plants, have aerial roots that anchor the plant to the bark, branch, or other surface on which they grow. Some have aerial roots specialized for functions other than anchorage. may absorb moisture as well. Certain epiphytic orchids, for example, have photosynthetic roots.

Answer 331

Loss of water vapor by evaporation from aerial plant parts is called transpiration.

Answer 332

A corm is a short, erect underground stem that superficially resembles a bulb. Unlike the bulb, whose food is stored in underground leaves, the corm’s storage organ is a thickened underground stem covered by papery scales (modified leaves). Axillary buds frequently give rise to new corms; the death of the parent corm separates these daughter corms, which then become established as separate plants. Familiar garden plants that produce corms include crocus, gladiolus, and cyclamen.

Answer 333

Unlike the xylem in herbaceous eudicot roots, the xylem in many monocot roots does not form a solid cylinder in the center. Instead, the phloem and xylem are in separate, alter- nating bundles arranged around the central pith, which consists of parenchyma cells. Because virtually no monocots have secondary growth, no vascular cambium exists in monocot roots

Answer 334

ray A chain of parenchyma cells (one to many cells thick) that functions for lateral transport in stems and roots of woody plants.

Answer 335

The n spore in heterosporous plants that gives rise to a male gametophyte. Compare with megaspore.