BIOL 114 Exam 4

Nonvascular plants

(Also called bryophytes) Lack vascular tissue - specialized groups of cells that conduct water and nutrients from one part of the plant body to another. Mosses are one group of nonvascular plants.

Cuticle

- A watertight barrier that coats the aboveground parts of today's land plants and helps them resist drying. - If biologists had to point to one innovation that made the transition to land possible, it would be the random mutations that led to the production of cuticle. *Covering surfaces with wax creates a problem, however, regarding the exchange of gases across those surfaces (cuticle is almost impervious to CO2 and water). Most plants solve this problem with a structure called a stoma (plural = stomata).

Life cycles of fungi. See pg. 626-627

- CHYTRID LIFE CYCLE: chytrids are the only type of fungi with species that exhibit alternation of generations. 1) haploid adults form gametangia, in which male and female swimming gametes are produced by mitosis. 2) gametes from the same individual or different individuals fuse to form a diploid zygote. 3) the zygote grows into a diploid sporophyte. *The life cycle continues when meiosis occurs in the sporophytic mycelium, inside a structure called a sporangium. The haploid spores produced by meiosis disperse by swimming. - ZYGOMYCETES LIFE CYCLE: form yoked hyphae that produce a spore-forming structure. - BASIDIOMYCOTA LIFE CYCLE: have reproductive structures with many spore-producing basidia. - ASCOMYCOTA LIFE CYCLE: have reproductive strictest with many spore-producing asci.

Zygote

- Eggs are also retained in the green algal lineages that are most closely related to land plants: In Charophyceae and other closely related groups, sperm swim to the egg, fertilization occurs, and the resulting ZYGOTE stays attached to the parent. - Either before or after fertilization, the egg or zygote receives nutrients from the mother plant. But the parent dies each autumn as the temperature drops. The zygote remains on the dead parental tissue, settles to the bottom of the lake or pond, and overwinters. In spring, meiosis occurs and the resulting spores develop into haploid adult plants.

Angiosperms v gymnosperms

- Flowering plants v seed plants that do not flower (both seed plants) - Gymnosperms and angiosperms produce pollen grains that are transported via wind or insects and that then produce sperm. - Among seed plants there was a major divergence in how seeds develop--either naked (in gymnosperms) or protected inside a capsule (in angiosperms).

Flower, stamen, carpel, ovary, petal

- Flowering plants, or angiosperms, are the most diverse land plants living today. Their success in terms of geographical distribution, number of individuals, and number of species revolves around a reproductive organ--the FLOWER. - Most flowers contain two key reproductive structures: the stamens and carpels illustrated on the left-hand side of Fig. 31.19. Stamens and carpels are responsible for heterospory. - A STAMEN includes a structure called an anther, where microsporangia develop. Meiosis occurs inside the microsporangia, forming microspores. Microspores than divide by mitosis to form pollen grains. - A CARPEL contains a protective structure called an OVARY, where the ovules are formed. *The presence of enclosed ovules inspired the name angiosperm ("encased seed") as opposed to gymnosperm ("naked seed"). - As in gymnosperms, ovules contain the megasporangia. A cell inside the megasporgangium divides by meiosis to form the megaspore, which then divides by mitosis to form the female gametophyte. After a pollen grain lands on a carpel and produces sperm, fertilization takes place, as shown in Fig. 31.19. *Angiosperm fertilization is unique, however, because it involves two sperm cells. One sperm fuses with the egg to form the diploid zygote, while a second sperm fuses with two nuclei in the female gametophyte to form a triploid nutritive tissue called ENDOSPERM. The involvement of two sperm nuclei is called DOUBLE FERTILIZATION. *The evolution of the flower, then, is an elaboration of heterospory. The key innovation was the evolution of the ovary, which helps protect female gametophytes from insects and other predators. - Once stamens and carpels evolved, they became enclosed by modified leaves called SEPALS and PETALS. The four structures then diversified to produce a fantastic array of sizes, shapes, and colors--from red roses to blue violets. Specialized cells inside flowers also began producing a wide range of scents.

Sporopollenin

- Fossilized spores are surrounded by a sheetlike coating. Under the electron microscope, the material appears almost identical in structure to a waxy material called sporopollenin. - Sporopollenin also encases spores and pollen from modern land plants and helps them resist drying.

How do fungi reproduce? What are some reproductive adaptations of fungi?

- Fungi also produce reproductive organs, which are thick, fleshy structures. Mushrooms, puffballs, and other dense, multicellular structures that arise from mycelia do not absorb food, instead they function in reproduction. - In many fungi, including some entire lineages, sexual reproduction has never been observed. In those lineages that do reproduce sexually, important morphological differences among lineages are seen. - Most fungal species that undergo sexual reproduction produce one of four types of distinctive reproductive structures: 1) Swimming gametes and spores. 2) Zygosporangia. 3) Basidia. 4) Asci.

Fungi

- Fungi are eukaryotes that grow as single cells or as large, branching networks of multicellular filaments. Familiar fungi include the mushrooms you've encountered in the woods, the molds and mildews in your home, the organism that causes athlete's foot, and the yeasts used in baking powder and brewing. - Along with the land plants and the animals, the FUNGI are one of three major lineages of large, multicellular eukaryotes that occupy terrestrial environments. - Certain fungi and a handful of bacterial species are the only organisms capable of digesting both the lignin and cellulose that make up wood. Without fungi, Earth's surface would be piled so high with dead tree trunks that there would be almost no room for animals to move or plants to grow. - Because they recycle key elements such as C, N, and P, and because they transfer key nutrients to plants and animals, fungi have a profound influence on ecosystem productivity and biodiversity.

Identify traits that unify the fungi as a group and separate them from the other lineages (what differentiates a fungus from an animal?)

- Fungi lack complex, long-distance transport systems like those found in plants and animals. One advantage of most fungi having pores in septa is that nutrients can move rapidly from regions of uptake to regions of mycelial growth. Because nutrients and some organelles can flow through the entire mycelium--at least to a degree--the fungal mycelium is intermediate between a multicellular land plant or animal and an enormous single-celled organism. - As consumers, fungi digest their food (dead or living) outside of their body, unlike animals.

Heterospory

- In addition to sporophyte-dominated life cycles, another important innovation found in seed plants is called HETEROSPORY--the production of two distinct types of spores by different structures. - All of the nonvascular plants and most of the seedless vascular plants are homosporous. Homospory is the production of a single type of spore. Homosporous species produce spores that develop into bisexual gametophytes that produce both egg and sperm. - If these gametes are isolated in nature, they can self-fertilize and produce offspring. - If two bisexual gametophytes are close enough for the exchange of sperm outcrossing is favored because it increases genetic variation. *The evolution of heterospory was a key event in land plant evolution because it made possible one of the most important adaptations for life in dry environments--pollen.

Vessel Element

- In fossils dated to 250-275 million years ago, biologists have documented the most advanced type of water conducting cells observed in plants. - VESSEL ELEMENTS are shorter and wider than tracheids, and their upper and lower ends have gaps where both the primary and secondary cell wall are missing. - The width of vessels and the presence of open gaps reduce resistance and make water movement more efficient. - In vascular tissue, vessel elements are lined up end to end to form a continuous pipe-like structure. *In the stems and branches of some vascular plant species, tracheids or a combination of tracheids and vessels form the extremely strong support material called wood.

Plasmogamy & karyogamy

- In many fungi, the process of sexual reproduction begins when hyphae from two different mating types fuse to form a hybrid cell. When the cytoplasm of two individuals fuses in this way, PLASMOGAMY is said to occur. When two or more genetically distinct nuclei exist within a single mycelium, it is HETEROKARYOTIC. - Most hyphae in heterokaryotic mycelia are dikaryotic--they are divided by septa, and each cell contains two nuclei, one from each mating type. - In a eukaryotic or heterokaryotic mycelium, one or more pairs of unlike nuclei may eventually fuse to form a diploid zygote. The fusion of nuclei is called KARYOGAMY. The nuclei that are produced by karyogamy then divide by meiosis to form haploid spores. *During asexual reproduction, spore-forming structures are produced by a haploid mycelium, and spores are generated by mitosis. As a result, offspring are genetically identical to their parent.

Lignin

- Lignin is a complex polymer built from six-carbon rings. It is extraordinarily strong for its weight and is particularly effective in resisting compressing forces such as gravity. - The evolution of lignified cell walls gave stem tissues the strength to remain erect in the face of wind and gravity. - Today, the presence of lignin in the cell walls of water-conducting cells is considered the defining feature of vascular tissue. The evolution of vascular tissue allowed early plants to support erect stems and transport water from roots to aboveground structures.

Hyphae, septa, mycelium

- Mycelia constantly grow in the direction of food sources and die back in areas where food is running out. The body shape of a fungus can change almost continuously throughout its life. Because of their small size, fungal mycelia can penetrate tiny fissures in soil and absorb nutrients that are inaccessible to plant roots. - The filaments within a mycelium are called HYPHAE. Hyphae are long, narrow filaments that branch frequently. Because mycelia are composed of complex, branching networks of extremely thin hyphae, fungi have the highest surface-area-to-volume ratios observed in multicellular organisms and are therefore the best at absorption. (*Downside = prone to drying out). - In most terrestrial fungi, each filament is divided into cells by cross-walls called SEPTA. Septa do not close off the cells along hyphae completely. Instead, gaps called pores enable a wide variety of materials, even nuclei and organelles, to flow from one compartment to the next. *Some fungal lineages have hyphae that are coenocytic--meaning that they are not divided into separate cells and thus lack septa.

Gametophyte v sporophyte dominant life cycles

- Nonvascular plants, such as mosses, are gametophyte dominant (haploid). - In contrast, ferns and other vascular plants are sporophyte dominant (diploid). *The transition from gametophyte dominated life cycles to sporophyte dominated life cycles is one of the most striking of all trends in land plant evolution.

Differentiate the three morphological categories of land plants

- Nonvascular plants: (Also called bryophytes) Lack vascular tissue - specialized groups of cells that conduct water and nutrients from one part of the plant body to another. Mosses are one group of nonvascular plants. - Seedless vascular plants: Have vascular tissue but do not make seeds. Instead, they make microscopic spores that are carried by wind to new habitats. Ferns are an example of seedless vascular plants. - Seed plants: Have vascular tissue. A seed consists of an embryo and a store of nutritive tissue, surrounded by a tough protective layer. The flowering plants, or angiosperms ("encased seeds"), are a group of seed plants.

Tracheid

- Once simple water-conducting tissues evolved, evolution by natural selection favored more complex tissues that were more efficient in providing support and transport. - In fossils that are about 380 million years old, biologists find the advanced water-conducting cells called tracheids. - Tracheids are long, thin, tapering cells that have a thickened, lignin-containing SECONDARY CELL WALL in addition to a cellulose-based PRIMARY CELL WALL; and pits in the sides and ends of the cell where the secondary cell wall is absent, where water can flow efficiently from one tracheid to the next. *The secondary cell wall gave tracheids the ability to provide better structural support, but water could still move easily through the cells because of the pits. Today, all vascular plants contain tracheids.

Chitin

- Protein found in the cell walls of fungi. - Also produced by animals.

Parasite v mutualist v commensal

- Some fungi specialize in absorbing nutrients from living organisms. When fungi absorb these nutrients without providing any benefit in return, they lower the fitness of their host organism and act as PARASITES. Ex: athlete's foot or yeast infections. - Most of the fungi that live in association with other organisms benefit their hosts, however. In these cases, fungi are not parasites but MUTUALISTS. *Scientists categorize the symbiotic relationships as mutualistic if they benefit both species, parasitic if one species benefits at the expense of the other, or commensal if one species benefits while the other is unaffected.

Stomata

- Stomata consist of an opening surrounded by specialized guard cells. The opening, called a pore, opens or closes as the guard cells change shape. - When guard cells lose water, they become flaccid or limp and the stomata close. Pores are normally closed at night to limit water loss from the plant when CO2 uptake is not needed. - But when guard cells absorb water and become turgid or taut, they open the pore. - Open stomata allow CO2 to diffuse into the interior of leaves and stems where cells are actively photosynthesizing. *Stomata are present in all land plants except liverworts, which have pores but no guard cells. These data suggest that the earliest land plants evolved pores that allowed gas exchange to occur at breaks in the cuticle-covered surface. Later, the evolution of guard cells gave land plants the ability to regulate gas exchange--and control water loss--by opening and closing their pores.

Fruit

- The evolution of the ovary was an important event in land plant diversification, but not only because it protected the female gametophytes of angiosperms. It also made the evolution of fruit possible. - A FRUIT is a structure that is derived from the ovary and encloses one or more seeds. Tissues derived from the ovary are often nutritious and brightly colored. Animals eat these types of fruits, digest the nutritious tissue around the seeds, and diapers seeds in their feces. *The evolution of flowers made efficient pollination possible; the evolution of fruits made seed dispersal possible.

Gametangia

- The fossilized gametophytes of early land plants contain specialized reproductive organs called gametangia. - Although members of the green algae group Charophyceae (stonewarts) also develop gametangia, the gametangia found in land plants are larger and more complex. - The evolution of an elaborate gametangium was important because is protected gametes from drying and from mechanical damage. - Gametangia are present in all land plants living today except angiosperms, where structures inside the flower perform the same functions.

Pollen, Pollination

- The nonvascular plants and the seedless vascular plants have sperm that swim to the egg and perform fertilization. For a sperm cell to swim, there has to be a continuous sheet of water between the male and female gametophytes, or a raindrop has to splash sperm onto a female gametophyte. - In species that live in dry environments, these conditions are rare. The land plants made their final break with their aquatic origins and were able to reproduce efficiently in dry habitats when a structure evolved that could move their gametes without the aid of water. - In heterosporous seed plans, the microspore germinates to form a tiny male gametophyte that is surrounded by a tough coat of sporopollenin, resulting in a POLLEN GRAIN. - Pollen grains can be exposed to the air for long periods of time without dying from dehydration. They are also tiny enough to be carried to female gametophytes by wind or animals. Upon landing near the egg, the male gametophyte releases the sperm cells that accomplish fertilization. - Biologists hypothesize that flowers are adaptations to increase the probability that an animal will perform POLLINATION--the transfer of pollen from one individuals stamen to another individuals carpel.

Retaining offspring: land plants are nourished by their parent

- The second innovation that occurred early in land plant evolution involved the eggs that formed inside the archegonia. Instead of shedding their eggs into the water and soil, land plants retain them. - In contrast to the zygotes of most green algae, the zygotes of all land plants begin to develop on the living parent plant, forming a multicellular embryo that remains attached to the parent and can be nourished by it. *Green algae zygotes develop after the parent plant dies.

Alternation of generations

- When alternation of generations occurs, individuals represent a multicellular haploid phase or a multicellular diploid phase. - The multicellular haploid stage is called the gametophyte; the multicellular diploid stage is called the sporophyte. - The two phases of the life cycles are connected by distinct types of reproductive cells--gametes and spores. - Although alternation of generations is observed in a wide array of eukaryotic lineages and in some groups of green algae, it does not occur in the algal groups most closely related to land plants. - Fig. 31.12 - alternation of generations steps: 1) The sporophyte (diploid zygote, retained on parent) produces spores by meiosis. Spores are haploid. 2) Spores germinate and divide by mitosis to develop into multicellular, haploid gametophytes. 3) Gametophytes produce gametes by mitosis. Both the gametophyte and the gametes (egg and sperm) are haploid, but gametophytes are multicellular while gametes are unicellular. 4) Two gametes unite during fertilization to form a diploid zygote. 5) The zygote divides by mitosis and develops into a multicellular, diploid sporophyte. *In green algae that are related land plants, only the zygote is diploid.

Spore (fungi)

- When conditions dry, the fungal mycelium may die back partially or completely. Reproductive cells called SPORES that are produced by sexual or asexual reproduction are resistant to drying, however. As a result, spores can endure dry periods and then germinate to form a new mycelium when conditions improve. Mycelial growth is dynamic, changing with moisture availability or food supply. - In certain species that live primarily in water or wet soils, the gametes produced during sexual reproduction have flagella, as do the spores produced during asexual reproduction. These are the only motile cells known in fungi. Species with swimming gametes are usually known as CHYTRIDS.

Compare and contrast zygotes and spores

- zygotes and spores are both single cells that divide by mitosis to form a multicellular individual. Zygotes develop into sporophytes, spores develop into gametophytes. - zygotes are diploid and spores are haploid. - zygotes result from the fusion of two haploid cells, such as a sperm and egg, but spores are not formed by the fusion of gametes. - spores are produced by meiosis inside structures called sporangia; gametes are produced by mitosis inside gametangia.

Three key morphological traits that link animals and fungi

1) Most animals and fungi synthesize the tough structural material called chitin. Chitin is a prominent component of the cell walls of fungi. 2) The flagella that develop in chytrid spores and gametes are similar to those observed in animals: As in animals, the flagella in chytrids are single, are located at the back of reproductive cells, and move in a whiplike manner. 3) Both animals and fungi store food by synthesizing the polysaccharide glycogen. (Green plants, in contrasts, synthesize starch as their storage product.)

Seed

A seed consists of an embryo and a store of nutritive tissue, surrounded by a tough protective layer. *A seed is a structure that, like a bird's egg, includes an embryo and a food supply surrounded by a tough coat that allows for effective dispersal of embryos. Spores are an effective dispersal stage in nonvascular plants and seedless vascular plants, but they lack the stored nutrients found in seeds.

Mold

Black bread molds are zygomycetes.

Yeast

Compared with animals and land plants, fungi have simple bodies. Only two growth forms occur among them: 1) single-celled forms calledYEASTS, and 2) multicellular, filamentous structures called MYCELIA. Many species of fungus grow either as yeasts or as a mycelium, but some regularly adopt both growth forms.

How does fertilization occur?

Compared with green plants, protists, and animals, fertilization in fungi has important and unique features: - Only some chytrids produce gametes, which are not considered eggs and sperm. Both male and female gametes are motile, and female gametes are only slightly larger than male gametes. - In all other lineages of fungi, fertilization occurs in two distinct steps: 1) fusion of hyphae and 2) fusion of nuclei from the fused hyphae. These two steps can be separated by long time spans and even long distances.

Asci

Cups, morels, and some other types of fungi form reproductive structures, specialized sac-like cells called ASCI at the ends of hyphae, on the surfaces of the fungi, each producing eight spores. Species with ascu are traditionally known as ascomycetes, or "sac fungi."

Sporangia

Fossilized spores that are 475 million years old have recently been found in association with spore-producing structures, called sporangia, that are similar to sporangia observed in some non-vascular plants.

Extracellular digestion

Fungi perform extracellular digestion--digestion that takes place outside the organism. The simple compounds that result from enzymatic action are then absorbed by the hyphae. Most animals also perform extracellular digestion, but it takes place in a digestive tract.

Mycorrhizae

Fungi that live in close association with plant roots are said to be mycorrhizal ("fungal-root"). Plant species grow three to four times faster in the presence of its normal fungal associations than they do without them.

Saprophyte

Fungi that make their living by digesting dead plant material are called saprophytes. When trees die, certain fungi are the organisms that break down wood into sugars and other small organic compounds. Fungi use these molecules as food, as do many microorganisms. In addition when fungi die or are eaten, the molecules are passed along to a wide array of other organisms.

Ecosystem services

Green algae and land plants provide ecosystem services because they enhance the life-supporting attributes of the atmosphere, surface water, soil, and other physical components of an ecosystem. Green plants alter the environment in ways that benefit many other organisms.

Seedless vascular plants

Have vascular tissue but do not make seeds. Instead, they make microscopic spores that are carried by wind to new habitats. Ferns are an example of seedless vascular plants.

Seed plants

Have vascular tissue. A seed consists of an embryo and a store of nutritive tissue, surrounded by a tough protective layer. The flowering plants, or angiosperms ("encased seeds"), are a group of seed plants.

Gametophyte v Sporophyte

In alternation of generations, the multicellular HAPLOID stage is the GAMETOPHYTE; the multicellular DIPLOID stage is the SPOROPHYTE.

Antheridia v Archegonia

In both the Charophyceae and the land plants, individuals produce distinctive male and female gametangia: - The sperm-producing gametangium is called an ANTHERIDIUM. - The egg-producing gametangium is called an ARCHEGONIUM. *In terms of their function, antheridia and archegonia are analogous to the testes and ovaries of animals.

Zygosporangia

In some species, haploid hyphae from two individuals meet and become joined, like oxen with a yoke. Cells from yoked hyphae fuse to form a distinctive spore-producing structure called a zygosporangium. Species with a zygosporangiym are known as zygomycetes.

Nectar

Instead of leaving pollination to an undirected agent such as wind, the hypothesis is that natural selection favored structures that reward an animal--usually an insect--for carrying pollen directly from one flower to another (reward = nectar). *Attractants = scent, flower shape, and flower color.

Lichen

Lichens are a mutualistic partnership usually between a species of ascomycete and either a cyanobacterium or an alga.

The transition to land: how do plants reproduce in dry conditions?

Life cycles of sexually reproducing eukaryotes, including plants, serve several functions: - increase genetic variability as a result of meiosis and fertilization. - increase the number of individuals. - disperse the individuals to new habitats. *Sporopollenin-encased spores (resist drying out on land) were one of the innovations that made the initial colonization of land possible. Two other innovations that occurred early in land plant evolution were instrumental for efficient reproduction in a dry environment: (1) gametes were produced in complex, multicellular structures; and (2) the embryo was retained on the parent (mother) plant and was nourished by it.

Spore (plant)

Most of the fossils dating from the period of the earliest land plants (475 MYA) are microscopic. They consist of the reproductive cells called spores and sheets of a waxy coating called a cuticle.

Basidia

Mushrooms, brackets, and puffballs form specialized club-like cells called BASIDIA at the ends of hyphae, each producing four spores. Species with basidia are traditionally called basidiomycetes or "club fungi."

Describe how fungi obtain nutrients. What adaptations aid them in obtaining nutrients?

Mycelial growth is an adaptation that supports external digestion and the absorptive lifestyle of fungi.

Endophyte

Mycorrhizae aren't the only type of symbiotic fungi found in plants, however. Researchers have also become interested in fungi that live in close association with the aboveground tissues of land plants--their leaves and stems. Fungi that live in the aboveground parts of plants are called ENDOPHYTIC. - Recent research has shown that some endophytes increase the drought tolerance of their host plants. Endophytes found in some grasses also produce compounds that benefit plants. The compounds deter or even kill herbivores. In exchange for these benefits, endophytes absorb sugars from the plant. *CONCLUSION: endophytes are mutualistic.

EMF v AMF

Not long after associations between fungi and the roots of land plants were discovered, researchers found that two types of plant-mycorrhizal interactions are particularly common, involving ectomycorrhizal fungi (EMF) and arbuscular mycorrhizal fungi (AMF). The two major types of mycorrhizae have distinctive morphologies, geographic distributions, and functions. - EMF are usually species from the Basidiomycota, though some ascomycetes participate. The hyphae of EMF penetrate decaying material and release enzymes called peptidases that cleave the peptide bonds between amino acids in dead tissues. The amino acids released by this reaction are absorbed by the hyphae and transported to spaces between the root cells of trees, were they can be absorbed by the plant. - AMF include species from the Glomeromycota. AMF are also called endomycorrhizal fungi, because they penetrate the interior of root cell walls. The key point is that the hyphae of AMF penetrate the cell wall and make direct contact with the PM of root cells. The highly branched hyphae inside the plant cell wall are thought to be an adaptation that increases the surface area available for exchange of molecules between the fungus and its host. *CONCLUSION: Mycorrhizal fungi are mutualistic.

Discuss the adaptations that have allowed plants to colonize land, both in terms of surviving the dry conditions and in reproducing.

Once green plants made the transition to survive out of water, growth on land offered a bonanza of resources: - Light: The water in ponds, lakes, and oceans absorbs and reflects light. As a result, the amount of light available to drive photosynthesis is drastically reduced even a meter or two below the water's surface. - CO2: the most important molecule required by photosynthetic organisms--is more abundant in the atmosphere and diffuses more readily there than it does in water. Natural selection favored early land plants with adaptations that solved the drying-out problem. These adaptations arose in 3 steps: (1) preventing water loss, which kept cells from drying out and dying; (2) providing protection from harmful UV radiation; and (3) moving water from tissues with direct access to water to tissues without direct access. - (1) Preventing water loss = cuticle and stomata - (2) Providing protection from UV Irradiation: Water absorbs UV radiation --> Most land plants today accumulate UV-absorbing compounds, called flavonoids (plant pigments), to protect their DNA from damage (since they aren't surrounded by water anymore). - (3) The importance of upright growth: in a terrestrial environment, individuals that can grow erect have much better access to sunlight than individuals that are incapable of growing erect. But two problems have to be overcome for a plant to grow erect: (1) transporting water from tissues that are in contact with wet soil to tissues that are in contact with dry air, against the force of gravity; and (2) becoming rigid enough to avoid falling over in response to gravity and wind. VASCULAR TISSUE SOLVED BOTH PROBLEMS.

In a schematic of alternation of generations, identify the sequence of events and label the stages and their ploidy (Fig. 31.12)

See Fig. 31.12

Place adaptations and innovations on the plant phylogenetic tree (Fig. 31.9 & 31.23)

See Fig. 31.9 and 31.23

Distinguish the 6 groups of fungi (fig 32.8)

See pg. 619 - Microsporidia contains the single-celled, parasitic eukaryotes called microsporidians. They are fungi (previously thought to be a sister taxa to fungi). - The chytrids and zygomycetes are poorly resolved. Swimming gametes and the zygosporangium evolved more than once. Or both structures were present in a common ancestor but then were lost in certain lineages. - Chytrids make chytrid-like motile gametes or spores, and zygomycetes make zygote with tough outer coat. - Glomeromycota are a monophyletic group that make a spore with tough outer coat. The adaptations that allow these species to live in association with mycorrhizae (AMF) evolved only once. - Basidiomycota are a monophyletic group that make a club-like basidium. The basidium evolved only once. - Ascomycota are a monophyletic group that make sac-like ascus. The ascus evolved only once. *What drove the diversification of fungi? - The evolution of novel methods for absorbing nutrients from a diverse array of food sources.

Identify how unicellular and multicellular fungi differ in body structure(s)

Single celled fungi are called yeasts. Multicellular fungi have web-like bodies called mycelia. *See pg. 615, Fig. 32.4

Vascular tissue

Specialized groups of cells that conduct water and nutrients from one part of the plant body to another.

Diversification of gymnosperms

The fourth internal in land plant history is characterized by seed plants called gymnosperms ("naked seeds"). Because gymnosperms grow readily in dry habitats, biologists infer that both wet and dry environments on the continents became blanketed with green plants for the first time during this interval. *Gymnosperms came before angiosperms.

Compare and contrast green algae and land plants

The green algae are a paraphyletic group that totals about 7000 species. Their bright green chloroplasts are similar to those found in land plants. Specifically, green algal chloroplasts have a double membrane and contain chlorophylls a and b. And like land plants, green algae synthesize starch in the chloroplast as a storage product of photosynthesis. They also have a cell wall that is composed primarily of cellulose. - Green algae are important primary producers in nearshore ocean environments and in all types of freshwater habitats. They are also found in several types of more exotic environments, including snowfields at high elevations, pack ice, and ice floes. These habitats are often splashed with bright colors due to large concentrations of unicellular green algae. Although these cells live at near-freezing temperatures, they make their own food via photosynthesis. - In addition, green algae live in close association with an array of other organisms, e.g., the algae supply protists with food, the protists provide protection for the algae.

Similarities between green algae and land plants

The green algae have long been hypothesized to be closely related to land plants, because key traits are similar in the two groups: - Their chloroplasts contain the photosynthetic pigments chlorophyll a and b and the accessory pigment B-carotene. - They have similar arrangements of the internal, membrane-bound sacs called thylakoids. - Their cell walls, sperm, and peroxisomes are similar in structure and composition. - Their chloroplasts synthesize starch as a storage product. *Biologists hypothesize that land plants evolved from multicellular green algae that lived in freshwater habitats.

Green algae

The green algae include species that are unicellular, colonial, or multicellular, and that live in marine, freshwater, or moist terrestrial habitats. The vast majority are aquatic. Although some land plants also live in ponds or lakes or rivers, the vast majority live on land.

Embryo

The retention of the embryo was such a key event in land plant evolution that the formal name of the group is Embryophyta--literally, the "embryo plants." The retention of the fertilized egg in embryo-bytes is analogous to pregnancy in mammals, where offspring are retained by the mother and nourished through the initial stages of growth.

Micro v megasporangia

The two types of spore-producing structures in heterosporous species are often found on the same individual: 1) Microsporangia are spore-producing structures that produce microspores. Microspores develop into male gametophytes, which produce the small gametes called sperm. 2) Megasporangia are spore-producing structures that produce megaspores. Megaspores develop into female gametophytes, which produce the large gametes called eggs. *Thus, the gametophytes of seed plants are either male or female, never both.

Describe the roles and importance of fungi

They nourish the plants that nourish us. They affect global climate change, because they are critical to the carbon cycle on land. Unfortunately, many fungi can cause debilitating diseases in humans and crop plants.

The carbon cycle and fungi

Two components of the carbon cycle on land: 1) The fixation of carbon by land plants--meaning that carbon in atmospheric CO2 is reduced to form sugar, which is then used to synthesize cellulose, lignin, and other complex organic compounds in the bodies of plants. 2) The release of CO2 from nearly all organisms as the result of cellular respiration--meaning the oxidation of glucose and production of the ATP that sustains life. The fundamental point is that, for many carbon atoms, saprophytic fungi connect the two parts of the carbon cycle. *If fungi had not evolved the ability to digest lignin and cellulose soon after land plants evolved the ability to make these compounds, carbon atoms would have been sequestered in wood for millennia instead of being rapidly recycled into glucose molecules and CO2.

Heterotroph

gains carbon from consuming other organisms.