Structure and Function in Plants and Animals

oligosaccharins

A type of elicitor that is derived from cellulose fragments released by cell wall damage released in response to bacterial or fungal infections.

axillary buds

a bud that grows from the axil of a leaf and may develop into a branch or flower cluster. the apex of a lateral shoot, so this structure can develop into a new shoot if the plant is damaged.

rhizome

a horizontal, underground stem that produces new leaves, shoots, and roots Irises, tubers, and many weeds reproduce using rhizomes, which are similar to runners, but with underground growth. Each node of a rhizome can produce a new individual shoot with flowers.

Liverworts

a nonvascular plant that's shaped like a human liver. found growing as a thick crust on moist rocks or soil along the sides of a stream. The liverworts are the most ancient group of land plants and can be found in nearly every terrestrial habitat on the planet. Despite their name, most liverworts are leafy, and only 20% of species have gametophytes with flattened, liver-shaped lobes. Liverworts have pores for gas exchange, but these pores don't open and close like stomata. Liverworts don't have a protective cuticle. They're able to reproduce asexually through the production of gemmae, which are small, lens-shaped leaf fragments released by the gametophyte.

tropism

A growth response of a plant toward or away from a stimulus The directional growth of a plant in response to stimuli such as light (phototropism), gravity (gravitropism), or touch (thigmotropism)

cross-pollination

a reproductive process in which pollen from one plant is transferred to the stigma of another plant involves pollen from one individual pollinating a flower of a different individual.

The upper and lower sides of a leaf are covered in

a single layer of cells that forms the epidermis; stomata are typically found in the epidermis on the underside of a leaf. Occasionally, plants that grow in extreme heat or cold may have an epidermis with more than one layer of cells.

Strigolactones

regulate apical dominance, seed germination, and mycorrhizal associations involved in a variety of functions, including germination and establishing mycorrhizae.

Green Algae (Chlorophyta and Strepophytes)

related to land plants, unicellular or multicellular; autotrophic, includes the algae in lichen, as well as spirogyra, sea lettuce and ulva The precise evolutionary history of the green algae is still under discussion, but genetic data supports classifying green algae into the chlorophytes and the streptophytes. The streptophytes include land plants and closely related green algae, while the chlorophytes are other green algae that also share many traits with land plants.

guard cells and stomata

- GUARD CELLS open STOMATA (pores in a leaf) which allow carbon dioxide, oxygen, and water vapor to pass. - The stoma and guard cells help to maintain water homeostasis Using active transport, photosynthesizing guard cells draw in potassium ions from the surrounding epidermal cells, and starch in these cells is converted to malate, causing water to enter the guard cells through osmosis This increases the turgor pressure of the guard cells, causing stomata to open. Stomata are typically open during the day when the sun is available for photosynthesis and the plant needs carbon dioxide. Water stress or extreme heat can reduce the turgor pressure in guard cells, causing the stomata to close to minimize water loss through transpiration and maintain homeostasis.

Some cells in the epidermis are further specialized to become guard cells, trichomes, or root hairs.

- Guard cells surround stomata, opening and closing them to regulate airflow and limit water loss. Stomata are generally located on the undersides of leaves, and there can easily be more than 1000 stomata per square centimeter. - Trichomes are cellular hair-like projections that cover the surface of a plant and are what makes a plant "fuzzy." Trichomes protect leaves from intense light or UV rays, insulate tissues against changes in temperature, reduce water loss through stomata, and secrete chemical defenses targeting herbivores. - Root hairs are hair-like extensions of epidermal cells that increase the surface area of the root so the plant can absorb a greater amount of water and nutrients.

Key Points 1

- Plants are found in nearly every ecosystem on land. - The haplodiplontic life cycle of plants consists of an alternation of generations between a multicellular diploid sporophyte stage and a multicellular haploid gametophyte. - The gametophyte is the dominant form for nonvascular plants and the sporophyte is the dominant form of seed plants. - Plants evolved a waxy cuticle, stomata, cell walls with cellulose and lignin, and a prolonged diploid life stage as they adapted to life on land. - Seeds, flowers, and fruits were important steps in the evolutionary history of plants. - Chlorophytes are aquatic green algae and can be unicellular, colonial, or multicellular. - Charophytes are a clade of streptophytes and a group of green algae closely related to land plants. - Bryophytes have a dominant gametophyte stage and fertilization requires water and have a rudimentary vascular system of conducting cells but lack the tracheid cells characteristic of vascular plants. - Seedless vascular plants like ferns have a dominant sporophyte stage and require water for fertilization. - Gymnosperms include Ginkgo, cycads, gnetophytes, and conifers. - The seeds of angiosperms are surrounded by carpels, which are modified leaves that develop into fruit. - Monocots are a major group of angiosperms characterized by the presence of a single cotyledon. - Dicots have two cotyledons.

gametophyte stage

- Produeces gametes through mitosis - Dominant form on nonvascular plants like mosses and liverworts - haploid

Key Points 2

- The root system anchors a plant into its substrate and absorbs water, minerals, ions, and other nutrients. - Leaves are the main photosynthetic organs. - Plants have three main types of tissues: dermal tissue lining the exterior surfaces, ground tissue forming internal tissue, supporting the plant, and storing nutrients, and vascular tissue to transport water and nutrients. - Xylem conducts water, dissolved minerals, and inorganic ions. Water flows through xylem against the force of gravity due to transpiration in the leaves and capillary action due to cohesion and adhesion. - Phloem conducts sugars made from photosynthesis as well as amino acids, hormones, and other molecules. Phloem is constructed of sieve tube elements and companion cells. The flow of phloem requires active transport and follows a pressure gradient from a photosynthetic source to a sink. - A root cap protects the apical meristem in the root. Some plants have modified roots for additional support, nutrient absorption, or nutrient storage. - Stems are made of nodes and internodes. - Some plants have modified stems, forming runners, bulbs, or rhizomes. - Photosynthesis primarily occurs within the palisade mesophyll in the leaves of dicots. Leaves of different plants are modified to maximize light absorption and minimize water loss. - Guard cells open and close stomata to allow gas exchange and minimize water loss through transpiration.

sporophyte stage

- dominant form in seed plants - produces spores trough meiosis - diploid

life cycle of angiosperms

1. Pollination happens when pollen grains from the anthers land on sticky stigma of a pistil. 2. The pollen tube grows from the pollen grain down trough the style and into the ovary to the ovule. (After reaching a receptive stigma on a compatible plant, one of the cells in a pollen grain grows a pollen tube while the generative cell remains behind. The pollen tube grows into the style to reach the embryo sac, which it enters through the micropyle.) 3. The sperm then travels down to the pollen tube and fertilizes the egg, the zygote develops into an embryo. (The generative cell divides to produce two sperm. One fuses with the egg to form a diploid zygote while the other joins with the polar nuclei to form a triploid cell. This double fertilization process is a hallmark of angiosperm reproduction.) 4. Parts of the ovary become the seed's cote and stored food, The ovary and other flower parts will form a fruit that surrounds the seed. (The triploid cell later forms the endosperm tissue and provides nutrients for the embryo.) Angiosperms exhibit an alternation of generations typical of all land plants, in which the gametophyte lives within a much larger sporophyte, and their life cycle involves the unique process of double fertilization. In angiosperms, the male and female gametophyte stages are housed in the stamen and carpel, and the gametophytes produce gametes through mitosis.

Double fertilization is a unique part of the angiosperm life cycle. Put the following steps in order

1. The megaspore divides to produce eight haploid nuclei in seven cells 2. A pollen grain on the stigma grows a pollen tube to reach the embryo sac 3. Two sperm cells are deposited into the embryo sac 4. The egg's fertilized to form a diploid-zygote; the polar nuclei cell is fertilized to form a triploid cell 5. The endosperm nourishes the embryo as it grows

5 major types pf plant hormones

1. auxins 2. cytokinins 3. gibberellins 4. ethylene 5. abscisic acid

3 main types of tissue meristem:

1. dermal tissue 2. ground tissue 3. vascular tissue

Two types of cells carry out conduction in the phloem:

1. sieve tube elements - long, cylindrical cells connected by porous plates, and mature sieve tube elements lack nuclei. 2. companion cells - provide energy to the sieve tube elements to support the active transport of the phloem components.

simple fruit

A fruit derived from a single carpel or several fused carpels. develops from a single ovary, an aggregate fruit is made from multiple ovaries within a single flower. often divided into dry and fleshy fruits, and dry fruits can be categorized as dehiscent and indehiscent Dehiscent fruits, which include legumes, grains, and nuts, naturally open at maturity to release their seeds, and indehiscent fruits don't open to release their seeds.

Cytokinins

A class of plant hormones that retard aging and act in concert with auxin to stimulate cell division, influence the pathway of differentiation, and control apical dominance. operate alongside auxins to promote cell division and differentiation, regulating growth. Cytokinins are produced in the roots and immature fruits. - regulate growth, promote cell division and differentiation

Gibberellins

A class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development. contribute to stem elongation and influence the utilization of stored nutrients during germination and seedling development. Gibberellins are produced in the tips of roots and shoots and seeds. - Impact the use of nutrients during germination and seedling development and is also involved in stem elongation

vascular cambium

A cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem. In dicots, a vascular cambium may be present between the xylem and phloem, allowing for secondary growth of the stem. Vascular cambium is a type of lateral meristem that produces xylem and phloem.

Angiosperms

A flowering plant which forms seeds inside a protective chamber called an ovary. There are around 300,000 species of flowering plants, called angiosperms. Carpels, which are modified leaves that develop into fruit, surround the seeds of angiosperms. Modified stems and leaves form flowers, which contain the gametophyte. The parts of a flower are attached in whorls around a stem. Green and leaflike sepals surround an inner whorl of petals, which are colorful and attractive to pollinators. The petals encircle stamens that produce the male gametophytes, pollen, on anthers, which in turn surround one or more carpels. The widened base of a carpel forms an ovary that contains one or more ovules and later ripens to become fruit. The upper tip of the carpel is referred to as the stigma. The stigma receives pollen, which then moves down the style to reach the ovary. thought to be monophyletic, descended from a common ancestor. Water lilies, magnoliids (including magnolia, laurel, avocado, cinnamon, and black pepper), and star anise are understood to be some of the oldest living groups of flowering plants Amborella trichopoda, a small New Caledonian shrub, is the only remaining species of an even older lineage that dates back 135 million years, and the now-extinct family Archaefructaceae is the oldest angiosperm found in the fossil record. But none of these lineages represents the most basal angiosperms since recent molecular evidence suggests that the flowering plants might have originated between 145 and 208 million years ago. The exact evolutionary origin of angiosperms remains a mystery.

multiple fruit

A fruit derived from an entire inflorescence. develop from several flowers' ovaries.

Conifers

A gymnosperm, or naked seed plant, that produces cones The largest and most diverse group of gymnosperms. include cedar, spruce, pine, fir, sequoia, yew, and larch. Conifers have needle- or scale-like leaves, which, due to their shape, minimize the evaporation of water. Most are evergreen, but a few, like bald cypress and tamarack, are deciduous and lose their leaves in the fall. The vascular system of conifers contains tracheid cells but no rigid vessel elements, making their wood relatively soft. Conifers are often found at high altitudes or in cold climates, and the bark of many conifers is thickened as an adaptation to freezing temperatures and fires. Some cones will only open after being exposed to fire.

stolons/runners

A horizontal above ground stem that takes root at various intervals. Runners are slender stems that grow along the ground, where every other node produces adventitious roots, leaves, and flowers

lateral meristems

A meristem that thickens the roots and shoots of woody plants. The vascular cambium and cork cambium are lateral meristems. causes a plant to become thicker.

Bryophytes

A moss, liverwort, or hornwort; a nonvascular plant that inhabits the land but lacks many of the terrestrial adaptations of vascular plants. the first plants to colonize land during the Ordovician period, over 450 million years ago. Ferns and gymnosperms increased in diversity during the middle of the Carboniferous, forming lush forests that spanned the globe. In the middle of the Cretaceous period, Angiosperms, or flowering plants, began to substantially increase in abundance, with their diversification aided by coevolution with pollinating insects like beetles and bees.

Ginkgophyta

A phylum of gymnosperms represented by a single extant species, Ginkgo biloba, characterized by fanlike leaves that turn gold and are deciduous in autumn. Ginkgo trees first appeared in the lower Jurassic and used to be widely distributed, especially throughout the Northern Hemisphere. Today, this phylum has only one species, Ginkgo biloba, which is often a cultivated resident of yards or city streets since it can no longer be found in the wild. Buddhist monks have cultivated the trees for centuries, contributing to the survival of the species. Ginkgo are dioecious, and most of the Ginkgo you see in cities are males because the females produce a fleshy seed that smells like rancid butter.

Gymnosperms

A plant that produces seeds that are exposed rather than seeds enclosed in fruits plants with "naked seeds" that are partially exposed on a scale for pollination but often later enclosed by sporophyte tissues, forming cones. Gymnosperms can be monoecious if both male and female sporangia are produced on a single plant, or dioecious if male and female sporangia are produced on separate plants. The sporophyte stage is dominant, and fertilization doesn't require water because the male gametophyte is a pollen grain. Gymnosperms are classified into four phyla, Ginkgophyta, Cycadophyta, Gnetophyta, and Coniferophyta.

gymnosperms

A plant that produces seeds that are exposed rather than seeds enclosed in fruits primarily pollinated by the wind

gametangia

A reproductive organ that houses and protects the gametes of a plant in which spores and gametes are produced.

Hornworts

A small, herbaceous, nonvascular plant that is a member of the phylum Anthocerophyta. The evolutionary history of hornworts is confusing. Even though hornworts are most likely an ancient group, there's no evidence of them in the fossil record until the Cretaceous period. This group is defined by the presence of a tall, thin, photosynthetic sporophyte extending beyond a filmy gametophyte. Hornwort sporophytes possess many stomata, and the base of the sporophyte consists of meristem cells that continually divide to increase the height of the sporophyte. Hornworts often form symbiotic relationships with nitrogen-fixing cyanobacteria.

Spermatophytes

All of the living and fossil seed plant phyla dominate most terrestrial ecosystems and provide most of the world's crops.

Explain the life cycle of an angiosperm. What does alteration of generations mean, and is the plant diploid or haploid in each stage of its life cycle? Describe the process of the gametophytes forming the zygote and endosperm in an angiosperm.

Alteration of generations, uniques to plants, means that plnts have two distinct stges in their life cycle. In the gametopyte stage, the plant is haploid and produces gametes. In the sporophyte stage, the plant is diploid and produces spores. For the gametophyte to form a zygote, angiosperms undergo double fertilization. In this process, the megaspore divides to produce the female gametophyte. In the embryo sac, which include the egg cell and the polar nuclei, which is the two nuclei within a single cell. A pollen grain deposits two sperm cells into the embryo sac. Once fertilizes the egg cell and forms the diploid zygote. The other sperm cell fertilizes the polar nuclei, forming a triploid cell that develops into the endosperm.

photomorphogenesis

Effects of light on plant morphology.

Apical meristem

Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length. found at the tips of the roots and shoots, and these cells continually divide to extend the plant's body.

Transpiration

Evaporation of water from the leaves of a plant the process of water vapor diffusing from a plant into the environment. The movement of water through the xylem is mostly driven by transpiration in the leaves, but solute pressure in the leaves and roots also drives it. When water exits a leaf through transpiration, this creates a negative pressure that pulls more water into the leaf from the xylem. Inside the xylem, water moves upward through capillary action.

Dicots

Flowering plant whose embryos have 2 cotyledons. "eudicots"—the true dicots include almost all other flowering plants: apples, cherries, citrus, legumes, oak trees, sunflowers, roses, and many more. This group comprises about 75% of all angiosperm. Eudicots are characterized by the presence of two cotyledons. Other features include a branched network of veins in the leaves, vascular bundles forming a ring, a root system that includes a central tap root, and flower parts usually arranged in fours or fives. Dicots can be woody or herbaceous.

Meristem tissue

Found mainly at the tips of the roots and shoots, where it can produce new cells for growth. -mostly undifferentiated or incompletely differentiated. - analogous to stem cells in animals and allow plants to grow

Drupes

Fruits that have a central pit enclosing a single seed. include peaches, cherries, coconuts, and walnuts, have a fleshy mesocarp, which is the middle layer of pericarp

parenchyma

Fundamental tissue composed of thin-walled living cells that function in photosynthesis and storage. The ground tissue of a plant largely consists of parenchyma cells that store nutrients, perform photosynthesis, and secrete chemicals.

Ferns and other seedless vascular plants

Gametophyte: Reduced, independent (photosynthetic and free-living) Sporophyte: Dominant arose during the Devonian period. During the Carboniferous geologic period, massive forests of club mosses (lycophytes) and horsetails towered as high as 100 feet above the earth. have true vascular tissue, with xylem and phloem to conduct water and nutrients. These organisms also have roots able to absorb water and nutrients from the soil. In addition, seedless vascular plants have true leaves, improving their photosynthetic efficiency compared to bryophytes.

Gnetophyta

Gnetum, Ephedra, Welwitschia thought to be closely related to angiosperms and have broad leaves and xylem with vessels. Ephedra viridis is a gnetophyte that grows in the western United States and Mexico. Ephedra is the natural source of the compound ephedrine and is a decongestant and stimulant.

True ferns

Largest group with around 11,000 species Have broad, frond like leaves the most abundant and diverse with over 20,000 living species. The sporophytes of ferns consist of rhizomes and fronds, which develop as "fiddleheads" before uncoiling to form leaves. The sporangia of ferns appear in clusters termed sori. Spores are released into the surrounding environment and germinate into heart-shaped gametophytes. Rhizoids, which also help transport water and nutrients, have anchored to their substrate. The gametophytes produce archegonia and antheridia. Sporophytes develop in the archegonia, which offers protection during the early stages of zygotic development

cork cambium

Lateral meristematic tissue that produces the outer covering of stems woody plants may also have a cork cambium that lies just beneath the epidermis. The cork cambium is a type of lateral meristem that produces cork tissue, which becomes impregnated with water-repellent substances, cuts off the nutrient supply to the epidermis, sloughs off, and dies, forming the outer bark.

palisade mesophyll

Layer of tall, column-shaped mesophyll cells just under the upper epidermis of a leaf the upper side of a leaf is comprised of densely packed, columnar parenchymal cells with many chloroplasts, and is the primary site of photosynthesis.

Phloem

Living vascular tissue that carries sugar and organic substances throughout a plant Phloem conducts the food products of photosynthesis, like sugars, as well as amino acids, hormones, and other molecules. Photosynthetic mesophyll cells produce sugar, which is actively pumped into phloem using ATP. Unlike xylem, phloem can flow in any direction, so the aqueous solution moves from a photosynthetic source, the leaves, to a sink, a part of the plant that needs nutrients, like the root system or new growth using active transport.

spongy mesophyll

Loose tissue beneath the palisade layer of a leaf; has many air spaces between its cells Beneath the palisade mesophyll is a layer of loosely packed spongy mesophyll that aids in gas exchange.

The epidermis forms the outer layer of a plant and is only one cell thick but provides valuable protection for the plant. Name 2 ways in which cells in the epidermis helps protect a plant, including at least one way that epidermal cells differentiate to become specialized cells.

Me: Epidermal cells secrete a fatty, waxy cuticle that protects against environmental stressors such as desiccation. Them: The epidermal cells secrete a waxy cuticle that prevents the plant from drying out. Some epidermal cells become guard cells, which surround stomata and control whether they are opened or closed to regulate air flow ad water loss to the environment. Other epidermal cells become trichomes, hair-like projection on the surface of the plant, which protect the plant from UV light and insulate the plant against temperature fluctuations. Trichomes also help protect the plant from herbivores and reduce the amount of water list through the stomata.

Jasmonates

Mediate plant defenses against insect herbivores; regulate a wide range of physiological processes like jasmonic acid are produced in response to herbivory and trigger the production and release of volatile chemicals that signal neighboring leaves and plants of an ongoing threat. These volatile compounds may also attract predators or other natural enemies.

Auxins

Plant hormones that lead to phototropism by elongating the dark side of the plant promote stem growth and elongation by increasing the flexibility of cell walls. They're also involved in fruit development and the regeneration of injured vascular tissue. Auxins can be found in the apical meristem and other young plant tissues. - Increase flexibility of cell walls to promote growth and elongation

vascular tissue

Plant tissue consisting of cells joined into tubes that transport water and nutrients throughout the plant body. - responsible for transporting water and nutrients within the body of the plant - The 2 main types of vascular tissue are xylem and phloem

meristem

Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth. undifferentiated or incompletely differentiated cells in a plant that can divide and develop into the specialized cells making up plant tissues, much like stem cells in animals.

Fertilization

Process in sexual reproduction in which male and female reproductive cells join to form a new cell Pollination, which for angiosperms is the transfer of pollen from an anther to a stigma, occurs through a variety of mechanical processes. Wind, water, gravity, insects, birds, and bats may all facilitate pollination

Shoot system

The aerial portion of a plant body, consisting of stems, leaves, and (in angiosperms) flowers. The shoot system consists of leaves, the main photosynthetic organs of a plant and sites of gas exchange, and stems, which support the leaves and house vascular tissue to circulate water and nutrients. The leaves and stems are vegetative parts of the plant because they're non-reproductive. Reproductive organs, seeds, flowers, and fruit are also part of the shoot system.

alteration of generations

The alteration of two or more different forms in the life cycle of a plant or animal. Because of the alternation of generations and the presence of the multicellular haploid gametophyte and the multicellular diploid sporophyte, this life cycle is called haplodiplontic.

mesophyll

The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis. The parenchyma cells that make up a leaf's internal tissue

ethylene

The only gaseous plant hormone. Among its many effects are response to mechanical stress, programmed cell death, leaf abscission, and fruit ripening. promotes the ripening of fruits by stimulating the formation of sugars from starches and acids. Because ethylene is a volatile gas, ethylene produced by one fruit can influence the ripening of neighboring fruits. Ethylene is also involved in the aging of other tissues, contributing to flower wilt and leaf fall. - promotes fruit ripening

Flowers are modified leaves that contain gametophytes.

The parts of a flower are attached in whorls around a stem. Leaflike sepals surround the colorful petals of a flower, which in turn encircle the male and female organs. Male stamens produce pollen on anthers, and one or more female carpels make up the pistil. A carpel consists of an ovary, style, and a sticky pollen-receiving stigma.

gametophyte

The stage in the life cycle of a plant in which the plant produces gametes, or sex cells. gametes, which are reproductive cells, are produced through mitosis. The male and female gametes fuse to form a diploid zygote, which then develops into the sporophyte

sporophyte

The stage in the life cycle of a plant in which the plant produces spores. The mature sporophyte produces spores through meiosis, and the spores undergo mitosis to produce the haploid gametophyte.

petiole

The stalk of a leaf, which joins the leaf to a node of the stem. Leaves develop from the apical meristem and are connected to the stem by a narrow petiole

pericarp

The thickened wall of a fruit. Each of the three layers of the ovarian wall, grow in various ways to produce different types of fruits, including drupes, berries, pomes, hesperidium, legumes, achenes, and nuts.

Monocots

angiosperms that have only one seed leaf a monophyletic group of angiosperms that includes orchids, grasses, palms, rice, corn, wheat, sugar cane, and bananas, among others. The characterizing feature of monocots is the presence of a single cotyledon, which is an embryonic leaflike organ that transfers nutrients for the developing embryo. Monocots also have parallel veins running the length of their leaves, scattered vascular bundles, fibrous roots, and flower parts typically arranged in threes or sixes. Monocots generally lack woody tissues.

abaxial surface

bottom of leaf

The female gametophyte

embryo sac Inside an ovule, a megaspore mother cell divides meiotically to produce four megaspores. Three of these megaspores disintegrate, leaving one that divides through mitosis to produce eight haploid nuclei within seven cells, while the integument of the ovule differentiates to form a membrane, altogether forming the embryo sac. The embryo sac is the female gametophyte of angiosperms. The egg is located near the micropyle, a small opening in the membrane, and surrounded by two cells called synergids. The two polar nuclei migrate to the ovule's center, fusing to form the central cell, and the three remaining cells, the antipodals, relocate to the far end of the ovule.

root systems

for anchoring and water/nutrient absorption The root system anchors a plant in its substrate and absorbs water, ions, and other nutrients.

Streptophytes

group that includes green algae and land plants Charophytes are a major clade of streptophytes closely related to land plants. The representative species Chara is often called muskgrass or skunkweed due to its odor. These organisms are similar in appearance to land plants, produce lignin, form plasmodesmata, which are cytoplasmic linkages connecting neighboring cells, and undergo mitosis and cytokinesis in a manner similar to land plants. Charophytes exhibit a haplontic life cycle rather than alternation of generations.

Rhizomes

horizontal underground stems horizontal networks of underground stems - horizontal networks of underground stems

abscisic acid

inhibits cell growth, helps close stomata involved in the abscission, or dropping of leaves and fruits, and plays a role in inducing dormancy in seeds and buds. Abscisic acid is produced in leaves, fruits, and root caps, and it accumulates during periods of environmental stress, like the colder temperatures and reduced daylight in autumn. - fruiting body or mushroom of some fungi

Bryophytes: Liverworts, Mosses, and Hornworts

lack vascular tissue; can't grow very large because they no strong supporting tissue to keep bodies ere; live in damp places because rhizoids cannot penetrate deep into soil to extract the moisture they need, no vascular tissue to transport nutrients to above and below photosynthetic parts The closest living relatives of the first land plants, appearing around 450 million years ago during the Ordovician. These plants are unspecialized but successful in many different environments, including the tundra. Even though bryophytes are often called nonvascular plants. This is misleading because, while they lack tracheids, the vascular cells that conduct water in all other land plants, they do possess other types of conducting cells. Bryophytes participate in symbiotic relationships with mycorrhizal fungi, and their lifecycle is dominated by a photosynthetic haploid gametophyte phase. Fertilization requires the presence of water because male gametes swim using a flagellum. Bryophytes are divided into the liverworts, the hornworts, and the mosses. require water for fertilization

sporangia

multicellular organs that produce spores specialized structures formed by seedless plants

suckers

new shoots sent up from roots that may form new plants asexually sprouts produced by roots, so if the aboveground portion of a plant is damaged or removed, fragments of the roots can produce a new plant. Plants that use suckers include raspberries, apples, bananas, and dandelions.

The gametophyte is the dominant form in ___

nonvascular plants (mosses, liverworts)

Chlorophytes

part of green algae; live in fresh water but many are marine inhabitants; some live in damp soil, other on glaciers and snowfields; some live symbiotically with fungi to form lichens include modern aquatic algae and can be unicellular, such as Chlamydomonas, colonial with cell specialization like Volvox, or multicellular like Ulva. These organisms primarily have a haplontic life cycle where the primary form is haploid, and only the zygote is diploid. In many situations, the zygote can act as a spore, remaining dormant until conditions are right for growth. Like land plants, the chloroplasts of chlorophytes have the pigments chlorophyll a, chlorophyll b, and carotenoids.

Cycadophyta

peaked in Mesoic (age of dinosaurs); over 75% of remaining species threatened Cycads are gymnosperms that resemble palm trees and thrive in tropical and subtropical environments. They were in high abundance during the Mesozoic, but only a few dozen species are still around today, several of which are facing extinction. Female cycads produce gigantic cones that can weigh as much as 100 pounds, and the males produce the largest sperm of any living organism. Unlike other gymnosperms, beetles, rather than the wind, facilitate pollination.

The male gametophyte

pollen grain Male gametophytes are produced in the anthers. Each anther contains very large numbers of diploid microspore mother cells that divide by meiosis to produce four haploid cells in a tetrad. The nuclei divide once more as the tetrad breaks up and each cell forms a double-layered cell wall. The result is a pollen grain consisting of a binucleated cell with an intricately sculpted outer wall. One of these nuclei is the generative nucleus, which will enter the ovary during fertilization. The other nucleus is the pollen tube nucleus. The thick outer wall makes the pollen grain waterproof and contains chemicals reactive with the stigma to signal the pollen to form a pollen tube and deliver the male nuclei to the egg cell.

the sporophyte dominates the life cycle of ___

seed plants (flowers, trees)

berries

simple fruits in which the entire ovary is fleshy and juicy throughout such as blueberries, grapes, and tomatoes have a fleshy, continuous pericarp covering one or more fused carpels. Note that blackberries and strawberries aren't true berries; blackberries are aggregate drupes and strawberries are accessory fruits, which are derived from other parts of the flower.

Mosses

soft, small, green and nonvascular and are found on the ground near water the largest group of bryophytes and can be found from the equator to extremely high latitudes. the most abundant plants in the Arctic and Antarctic circles, although the diversity of mosses is highest in the tropics. Even though many mosses can survive in the inhospitable conditions of the tundra or even periods of drought, most species are extremely sensitive to air pollution, so they can be rare around human settlements and are often used to monitor pollution levels. The gametophytes of mosses consist of small, leaflike structures organized around a central stalk. These tissues aren't true leaves because they lack vascular tissue. Rhizoids, a sort of rudimentary root, loosely anchors the gametophyte to its substrate, but this system isn't involved in the acquisition of water or nutrients. Instead, the leaflike structures directly absorb water and nutrients, or specialized cells may conduct them up the central axis. A female gametangium is called an archegonium and a male gametangium is an antheridium. The antheridia release sperm that will fuse with eggs in archegonia. The resulting zygotes develop into sporophytes, which remain attached to the gametophyte. In the sporangium, spore mother cells go through meiosis to generate spores.

mychorrhizae

specialized mutualistic associations between roots and fungi can be found in the root systems of about 70% of land plants

Brassinosteroids

steroid hormones in plants that have a variety of effects, including cell elongation, retarding leaf abscission, and promoting xylem differentiation. functionally similar to auxins and gibberellins and can influence these hormones as well.

Club Mosses (Lycophyta)

the earliest group of seedless vascular plants are basal to all other vascular plants. While they possess a vascular system consisting of tracheid cells, their leaves aren't vascularized. Horsetails, also called scouring rush, are characterized by their ribbed, nodular stem containing evenly spaced whorls of needle-like leaves. Whisk ferns are unique in that they've secondarily lost their roots and leaves. The thallus of whisk ferns consists of forked green stems terminating in small, yellow knobs that house the sporangia.

intercalary meristem

the growth region at the base of grass leaves that causes leaves to elongate at the leaf base and nodes of monocots and allows the leaves to grow from the base.

nodes

the points at which leaves are attached where leaves and axillary buds attach to the stem

epidermis

the primary component of a plant's dermal tissue. Even though this outer layer is only one cell thick, it creates a valuable protective covering for a plant. Epidermal cells secrete a fatty, waxy cuticle that protects against environmental stressors such as desiccation.

Germination

the process whereby seeds or spores sprout and begin to grow the emergence of the plant from the seed coat. Seeds offer enhanced protection of embryos and allow for periods of dormancy so germination can occur under optimal conditions. Seeds, which the protective seed coat surrounds, contain a food supply for the embryo. In dormant seeds, growth is arrested due to the presence of very little water, which reduces metabolic activity. In some plant species, dormant seeds may remain viable for hundreds of years. The seeds of many plants germinate once enough water is available or when temperatures rise in the spring. Some seeds require fire to germinate, and other seeds even need to pass through the digestive system of an animal first.

internodes

the stem segments between nodes a plain section of stem.

phenology

the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.

Fruits

the sweet and fleshy product of a tree or other plant that contains seed and can be eaten as food. Fruits play an important role in protecting seeds and facilitating seed dispersal. The protective seed coat develops from the outer integuments of the ovule, and fruit is formed after the ovary matures. Fruits are mature, ripened ovaries that typically develop after fertilization.

self-pollination

the transfer of pollen grains from an anther to the stigma of the same flower or to the stigma of another flower on the same plant a flower may pollinate itself, or pollen from a plant may pollinate another flower on the same plant

Dermal tissue

tissue of the plant that makes up the waxy outer layer of the plant - responsible for protecting the plant - Guard cells are a cell type in dermal tissue and some dermal cells have trichomes

Ground tissue

tissue system that makes up the majority of a plant - has parenchyma cells that store nutrients and perform photosynthesis. - Ground tissues also include collenchyma and sclerenchyma that physically support the plant

Collenchyma

type of ground tissue cell with a strong, flexible cell wall; helps support larger plants other ground tissue cells that produce strong fibers that provide support and protection

Sclerenchyma

type of ground-tissue cell with an extremely thick, rigid cell wall that makes ground tissue tough and strong possess a secondary cell wall reinforced with lignin, a polymer that lends rigidity and is an essential part of wood.

adaxial surface

upper surface of leaf

xylem

vascular tissue that carries water upward from the roots to every part of a plant major types of vascular tissue. conducts water, dissolved minerals, and inorganic ions like nitrates and phosphates from the roots up to the rest of the plant. It contains xylem parenchyma, tracheids, and vessel elements that function in conduction. Tracheids and vessel elements are composed of dead, hollowed-out cells with thick, lignified cell walls arranged into tall, interconnected tubes.