Biol 1407 Exam #2 New Review

30 & 33 Know green algae most closely related to land plants

2 groups of green algae are most closely related to land plants, Coleochaete and Chara. Have one multicellular haploid generation Coleochaete and Chara have a multicellular body that consists of haploid cells--unlike the multicellular body of animal cells, which consists of diploid cells. The diploid phase is generated by the fusion of haploid gametes to form a zygote, and the haploid phase is generated from diploid cells by meiosis.

30 & 33 Know two groups of seed plants: gymnosperm and angiosperm

2 monophyletic groups of seed plants: Gymnosperms: "naked seeds" Angiosperms: "enclosed seeds in fruit" Both groups are sporophyte dominant with a microscopic, dependent gametophyte Advantages of seeds: Seeds are better spores Survive better than unprotected spores Can be transported long distances; winged seeds Pollen grains are better sperm Make water unnecessary for fertilization Not flagellated; have wings Only 2 extant seed plants: Gymnosperms (with less than 1,000 species) 4 groups of woody plants Cycads Gingkos Conifers Gnetophytes Angiosperms (with more than 380,000 species) Produce seeds (naked or enclosed) and woody stems Common in cool or dry regions

Endosymbiosis; origin of mitochondria and chloroplast 27

27.2 The Endosymbiotic Hypothesis proposes that chloroplasts and mitochondria engulfed by eukaryotic cells were originally free-living bacteria. Chloroplasts resemble cyanobacteria Much of chloroplasts' nucleic acid has migrated to the cell's nucleus Mitochondria resemble proteobacteria Chloroplasts resemble photosynthetic bacteria, specifically cyanobacteria. Over a century ago, a Russian botanist (Konstantin Sergeevich Merezhkovsky) recognized this similarity and suggested that chloroplasts were once free-living cyanobacteria that became incorporated into a host. His radical hypothesis suggested that the symbiont (cyanobacteria) lived within another cell (a plant cell), making an endosymbiotic relationship between the two. In 1967, American biologist Lynn Margulis resurrected this hypothesis and used transmission electron microscopy to show the structural similarities in the photosynthetic membranes of cyanobacteria, algae, and chloroplasts. The chloroplasts were found to have two membranes, which makes sense when considering that one was once the cyanobacteria's membrane and the other was the membrane of the cell that engulfed it. The two also show similar biochemistry during photosynthesis. The cyanobacteria most closely related to chloroplasts have 2000 - 3000 genes, while the chloroplast itself (within a photosynthetic eukaryote) only has between 60 and 200 genes. The genes that were lost from the chloroplast genome were attributed to the evolution of the chloroplast over time. Some genes that were once needed for the free-living cyanobacteria may have been lost because they were no longer needed in the chloroplast other genes may have been lost if there were similar nuclear genes providing the same function and many other genes migrated to the nucleus of the host cell. It was believed that chloroplasts originated from endosymbiotic cyanobacteria only once in a common ancestor of green and red algae. Recently, a second case of cyanobacterial endosymbiosis has been discovered. A photosynthetic amoeba, Paulinella chromatophora, contains chloroplasts that originated from a different branch of cyanobacteria than the cyanobacteria that gave rise to the chloroplast in other photosynthetic eukaryotes. Research also suggests that the engulfment of cyanobacteria in Paulinella occurred long after the other endosymbiotic event that gave rise to chloroplasts. About a third to half of the ancestral genome remains present in this organism, suggesting that chloroplast evolution is still in progress. Mitochondria also originated from once free-living bacteria. They contain their own DNA, which closely resembles that of proteobacteria, and they have very few genes, indicating that most genes have either been lost or have migrated to the host's nucleus, where they still reside. Most eukaryotic cells contain mitochondria, with the exception of single-celled eukaryotic cells found in oxygen-free environments. It was once thought that the reason for this was because the endosymbiotic event that established mitochondria happened after the evolution of these eukaryotes. However, this has now been proven otherwise because of the mitochondrial genes found in the nucleus of these cells. In fact, every mitochondrial-free eukaryote examined to date has relic mitochondrial genes in its nuclear genome. It is now believed that eukaryotic cells that do not have mitochondria once had them, but have since lost them. Many have small organelles called hydrogenosomes that generate ATP by anaerobic processes. These organelles have little or no DNA, but genes of mitochondrial origin in the cell's nucleus code for proteins that function in the hydrogenosome. These organelles appear to be highly altered mitochondria adapted to life in oxygen-poor environments. HYPOTHESES OVER MITOCHONDRIA 1. Eukaryotic cells first evolved from an archaeon-like prokaryote and only then incorporated the proteobacterial cell that became a mitochondrion. 2. Eukaryotic cells evolved from a symbiosis between an archaeon and a proteobacterium. The proteobacterium became a mitochondrion

28 Understand diffusion and bulk transport

28.2 In complex multicellular organisms, bulk transport eliminates the problems of diffusion. Diffusion: Movement of molecules from areas of high to low concentration acting over small distances Main limitation of cell size Effective only over short distances Main limitation of cell size Bulk transport: Active process that allows multicellular organisms to nourish cells located far from external environment Eliminates problems of diffusion Diffusion is effective only over small distances and so it strictly limits the size and shape of bacterial cells. Diffusion also constrains how eukaryotic organisms function. Animals have developed various mechanisms for circumventing the limits imposed by diffusion. The large size of a sponge is achieved by placing metabolically active cells in close contact with the environment by the use of canals in their bodies. Jellyfish also have thin layers of tissue that are metabolically active, but the bell shape is thick because it contains inactive molecules. Bulk transport also circumvents the constraints of size imposed by diffusion. Bulk transport is seen in animals when pumping blood through the circulatory system to oxygenate tissues that are great distances from the lungs, during digestion, or during hormone signaling. Other complex organisms also rely on bulk transport. For example, trees must transport water upward from their roots to their leaves.

29 & 31 Know examples of and characteristics of Bryophytes

3.2 Bryophytes diverged before the evolution of vascular plants, and they grow in environments where the ability to obtain water from the soil does not provide a disadvantage. Paraphyletic group; 3 types of bryophytes:;Mosses, Liverworts, Hornworts Small, simple and tough plants; Have either a flattened thallus or upright leafy The bryophytes, which includes mosses, liverworts, and hornworts. Bryophytes do not actively control their hydration. These plants do not form roots and are totally dependent on the surface water to keep their photosynthetic cells hydrated. As their environment dries, so do they. Vascular plants, which do actively control their hydration by drawing up water from the soil. The descendants of the last common ancestor of the bryophytes also include vascular plants. "Bryon" means moss; small and tough plants; cannot retain water and cannot deliver water to other plant parts since they do not have vasculature Therefore, need moist environment Main component of life cycle ....the mat of moss....is gametophyte (haploid multicellular generation that produces gametes). Sporophytes are dependent on gametophyte. They live in all temperatures and altitudes, only plant to live in Antarctica. They do not need roots or soil for water; so they live on rocks and tree trunks/branches Peat moss covers large regions known as peat-lands, and has many practical uses, including fuel

32 Pathogens enter plants: damaged tissue or stomata

32.1 Plants have evolved mechanisms to protect themselves from infection by pathogens, i.e. viruses, bacteria, fungi, worms, and parasitic plants

32 Constitutive defenses versus inducible defenses

32.3 The production of defenses is costly, resulting in trade-offs between protection and growth. Plants produce 2 types of defenses: Constitutive defenses...which are produced whether or not a threat is present Inducible defenses....which are triggered when a plant detects that it is being attacked

32 Escape and radiate

32.4 Interactions among plants, pathogens, and herbivores contribute to the origin and maintenance of plant diversity. "Escape and radiate" form of plant evolution: plants undergo a burst of diversification following evolution of a new form of defense

30 & 33 Understand Alternation of Generations ;know sporophyte, gametophyte, sporangium, gametangium, the entire cycle, which is n or 2n

All land plants have life cycles with an alternation of gametophyte ("gamete-plant") and sporophyte ("spore-plant") generations 1 generation is the gametophyte: the multicellular organism with haploid cells (n) other generation is the sporophyte: the multicellular organism with diploid cells (2n) the 2 generations alternate, each producing the other The 2 plant forms are named for the type of reproductive cells they produce: Gametophytes (n) Form gametes by mitosis in gametangia Gametes: haploid reproductive cells that cannot develop directly into organisms Must unite sperm and egg gametes in water to form diploid zygote In mosses only, the haploid gametophyte is the dominant generation Sporophytes (2n) Produce spores by meiosis in sporangia Spore: haploid reproductive cell, but one that develops directly into an organisms (the haploid gametophyte) without fusing with another In all other plant groups (other than mosses/bryophytes), the sporophyte generation is the dominant one Sporangium: Multicellular jacket on sporophyte that produces/protects spores Sporopollenin Complex mixture of polymers A tough resistant covering to spores Provides environmental protection to spores

Know Superkingdom Amoebazoa 27

Ameobozoa are a group of eukaryotes with amoeba-like cells that move and gather food by means of pseudopodia. More than 1000 amoebozoan species have been identified. Amoebozoans play a role in soils as a predator on other microorganisms, and some can influence human health. Entamoeba histolytica is an anaerobic protist in the amoebozoa superkingdom that is responsible for the human disease, amoebic dysentery, which accounts for 50,000 to 100,000 deaths every year. Spread by contaminated drinking water, food, or eating utensils The amoebozoans of greatest biological interest are the slime molds (plasmodial slime molds and cellular slime molds). In plasmodial slime molds, haploid cells fuse to form zygotes that subsequently undergo repeated rounds of mitosis, but not cell division, to form colorful, often lacy structures visible to the naked eye. These structures, called plasmodia, are coenocytic, which means they contain many nuclei within one giant cell. Plasmodia generate sporangia that produce spores for dispersal. Cellular slime molds spend most of their life cycle as amoeboid cells feeding on bacteria in the soil. However, starvation can cause these cells to produce a chemical signal (cyclic AMP) that induces as many as 100,000 cells to aggregate into a large multicellular slug-like form. These slugs can move with the use of actin and myosin and forage for food. These structures also form sporangia that produce spores for dispersal.

32 Ants and acacia

Ant-plants....such as the bullhorn acacia....provide food and shelter for ants, which defend their host plant Several hundred plants have evolved a much closer relationship with ants. These "ant-plants" provide both food and shelter for an entire colony of ants, which then defend their host. An example of this relationship can be seen in the bullhorn acacia, which produces hollow spines at the base of each leaf, as well as protein- and lipid-rich food bodies on the tips of its expanding leaves. Symbiotic ants live in these spines and feed on the food bodies.

32 Biotrophic versus necrotrophic pathogens

Biotrophic pathogens :gain resources from living cells Necrotophic pathogens: kill cells before using them

29 & 31 Know what epiphyte is

Bryophytes are epiphytes: a plant that grows high in the canopy of other plants, or on branches or trunks of trees, without contact with the soil

30 & 33 Know what epiphyte is

Bryophytes are epiphytes: a plant that grows high in the canopy of other plants, or on branches or trunks of trees, without contact with the soil

29 & 31 Understand CAM photosynthesis

CAM:(crassulacean acid metabolism) plants Capture CO2 at night when evaporation rates are low During day, close their stomata & use overnight stored CO2 (as a 4-C organic acid) to supply Calvin cycle during day Results in less water vapor loss Drawback: rates of PS are low Found in habitats such as deserts Occurs in all 4 types of vascular plants, but most common in angiosperms A number of plants have evolved a mechanism to limit water loss whereby they open their stomata to capture CO2 at night when the air is cool and limits the rates of evaporation. This mechanism is called crassulacean acid metabolism or CAM. It is named after a family of plants that uses this pathway. CAM provides a system for overnight storage of CO2, converting CO2 into a form that will not diffuse away. 1. The storage form of CO2 is produced by the activity of the enzyme PEP carboxylase, which combines a dissolved form of CO2 with a 3-carbon compound called phosphoenol pyruvate (PEP). The resulting product is a 4-carbon organic acid that is stored in the cell's vacuole. 2. When the sun comes up the next morning, the stomata close, conserving water. 3. At the same time, the 4-carbon organic acids are retrieved from the vacuole and decarboxylated. This newly released CO2 does not escape because the stomata are closed. 4. Instead, the CO2 diffuses into the chloroplast, where it is incorporated into carbohydrates by the Calvin cycle, which needs light in order to have a continual supply of ATP and NADPH. The drawback to CAM photosynthesis is that the rates of photosynthetic carbohydrate production tend to be low because ATP is needed to drive the uptake of organic acids into the vacuole, and because only so much of the 4-carbon acid can be stored in the vacuole. This type of photosynthesis is found in habitats such as deserts and among the epiphytes (a plant that grows high in the canopy of other plants or on branches or trunks of trees). It occurs in all four types of vascular plants, although it is most common in angiosperms.

29 & 31 Know term transpiration, stomata, cavitation, lignin, endodermis, mycorrhize

CO2 uptake in leaves for PS is at the cost of water vapor loss Called transpiration...evaporative loss of water vapor from leaves Waxy cuticle on the outside of epidermis slows rate of transpiration, but also slows inward diffusion of CO2 Stomata are small pores in epidermis that open and close Allow CO2 to enter leaf. But also allow water vapor to diffuse out Mycorrhizae are symbioses between roots and fungi that enhance nutrient uptake, particularly phosphorus. In return, the fungi receive carbohydrates produced in leaves and transported to roots by the phloem. Mycorrhizae are of two main types: Ectomycorrhizae, which produce a thick sheath of fungal cells that surround the root tip. Some of these cells penetrate the walls of root cells, producing a dense network that surrounds individual root cells. The root and fungal cells are then able to exchange carbon and nutrients through their plasma membranes. Endomycorrhizae, which do not form structures that are visible on the outside of the root. Instead, they form highly branched structures, called arbuscules, that protrude into the interior of root cells. Despite this invasion, the plasma membranes of both fungal and root cells remain intact. The arbuscules increase the contact area between the two cell types, enhancing carbon and nutrient exchange.

Choanoflagellates 27

Chanoflagellates are a group of unicellular protists characterized by a ring of microvilli that form a collar around the cell's single flagellum. About 150 choanoflagellate species have been described from marine and freshwater environments, where they prey on bacteria. These species are the most evolutionarily similar protistan species to animals. Molecular sequence comparisons confirm the close relationships between animals and choanoflagellates. Many genes once thought to be unique to animals have now been identified in choanoflagellates.

28 Know properties of complex multicellularity (6)

Complex multicellularity: Have differentiated cells and tissues Most cells are completely surrounded by other cells Red and brown algae Land plants Fungi Animals Properties of complex multicellular organisms: 1. Adhesion molecules 2. Specialized structures for cell communication 3. Tissue and organ differentiation.........including reproduction 4. Only some cells in contact with external environment 5. Helps organisms avoid predators 6. Cell or tissue loss can be fatal for organism Complex multicellular organisms include red and brown algae, land plants, fungi, and animals. Plants and animals differ in many ways, but they have some fundamental features in common: Highly developed mechanisms for adhesion between cells Specialized structures for cell communication Tissue and organ differentiation A small subset of cells contribute to reproduction Cell or tissue loss can be lethal for the organism Presence of both interior and exterior cells These are common characteristics of most complex multicellular organisms. There are three general requirements for complex multicellular life: Cells must stick together. Cells must communicate with one another. Cells must participate in a network of genetic interactions for cell division and differentiation.

30 & 33 Know 4 types of gymnosperm; know conifers

Connifers: Tallest and oldest trees on Earth Wind-pollinated Mainly evergreen Found primarily in cool to cold environments Gnetophytes: Small group Contains only 3 genera and few species Independently evolved xylem vessels Gingkos: Single living species of a group distributed globally before evolution of angiosperms Wind pollinated Produces tall, branched trees Cycads: Produce large leaves on stout, unbranched stems They now occur in small, fragmented populations....primarily in tropics and subtropics Insect pollinated All form symbiotic relationships with nitrogen-fixing bacteria

30 & 33 Know what sphagnum moss is

Dominant plant of peat bogs Produces water-holding cells that allow it to soak up water and to acidify environment Helps slow decomposition, so much carbon build-up

29 & 31 Know what sphagnum moss is

Dominant plant of peat bogs Produces water-holding cells that allow it to soak up water and to acidify environment Helps slow decomposition, so much carbon build-up Bryophytes are epiphytes: a plant that grows high in the canopy of other plants, or on branches or trunks of trees, without contact with the soil

30 & 33 Know the life cycle evolution in land plants

Early land plants evolved a life cycle in which 1 generation (phase) of the life cycle released sperm into a moist environment and the following generation dispersed offspring through air. Called Alternation of Generations

Know phylogeny of photosynthesis 27

Eukaryotes acquired PS multiple times by repeated episodes of endosymbiosis Proven by DNA comparisons of chloroplast DNA Cyanobacteria

28 Understand Evo-Devo, regulatory genes and homeotic genes

Evolutionary-developmental biology (Evo-Devo) A new field of research that looks at both individual development and evolutionary patterns i.e.Regulatory genes (homeotic genes) play an important role in butterfly wing coloration Mutations in these genes can account for differences in wing colorations among species. Regulatory genes play a role in the evolution of complex multicellular organisms. Many of the genes involved in development manage other genes. A molecular signal induces the expression of a gene, and the protein product is then prompted to express or repress another gene. An example of this can be seen in butterfly wing color patterns. Regulatory genes (homeotic genes) play an important role in butterfly wing coloration, and mutation in these genes can account for differences in wing colorations among species. The gene, Distalless, which is responsible for the eye pattern on some wings, is fused to genes for GFP protein. Therefore, the expression of Distalless can be traced by GFP visualization. Evolutionary-developmental biology (evo-devo), is a field of research that looks both at individual development and evolutionary patterns in an attempt to understand the developmental changes that allowed organisms to diversify and adapt to changing environments. The immense diversity can be seen in the world.

Fossil record of protists 27

Fossils in sedimentary rocks as old as 1.8 bya have signs of eukaryotic cells Earliest fossil eukaryotes are 1.2 bya and red algae Eukaryotic fossils diversified 800 mya when Oxygen increased and sulfide decreased

28 Know communication in animals and plants

Gap Junctions: protein channels in animals that allow ions and signaling molecules to move from one cell to another Plasmodesmata: intracellular strands of cytoplasm in plants that extend to neighboring Cells to allow communication

Understand eukaryotic life cycles 27

Green Algae, Chlamydomonas are haploids. Diatoms are diploids In animals, as in diatoms, the only 1n phase is the gamete. Plants have 2 multicellular phases in their life cycle; One 1n and one 2n Called Alternation of Generation The cell cycle of eukaryotes differs based on whether the organism reproduces sexually or asexually. Cells with one copy of each gene are haploid, while sexual fusion between two haploid cells results in a diploid cell (two copies of each gene). The life cycle of sexually reproducing eukaryotes alternates between haploid and diploid states. The life cycles of single-celled eukaryotes differ in the proportion of time spent as haploid (1N) versus diploid (2N) cells. Green Algae, Chlamydomonas are haploids. Diatoms are diploids In animals, as in diatoms, the only 1n phase is the gamete. Plants have 2 multicellular phases in their life cycle; One 1n and one 2n Called Alternation of Generation (a and b) The life cycles of single-celled eukaryotes differ in the proportion of time spent as haploid (1n) versus diploid (2n) cells. (c) The life cycles of animals have many mitotic divisions between formation of the zygote and meiosis. (d) Vascular plants have two multicellular phases. Sexual reproduction involves meiosis and the formation of gametes, and the subsequent fusion of gametes during fertilization (Chapters 11 and 42). Sex promotes genetic variation in two simple ways. First, meiotic cell division results in gametes or spores that are genetically unique. Each gamete has a combination of alleles different from the other gametes and from the parental cell as a result of recombination and independent assortment. Second, in fertilization, new combinations of genes are brought together by the fusion of gametes. Interestingly, a few eukaryotic groups have lost the capacity for sexual reproduction. The best-studied of these eukaryotes are tiny animals called bdelloid rotifers. The genetic diversity of these organisms is actually high, maintained by high rates of horizontal gene transfer. Meiotic cell division results in cells with one set of chromosomes. Such cells are haploid. Sexual fusion brings two haploid (1n) cells together to produce a diploid (2n) cell that has two sets of chromosomes. The life cycle of sexually reproducing eukaryotes, then, necessarily alternates between haploid and diploid states. Under the right conditions, however—typically, starvation or other environmental stress—two cells fuse, forming a diploid cell, or zygote. The zygote formed by these single-celled eukaryotes commonly functions as a resting cell. It covers itself with a protective wall and then lies dormant until environmental conditions improve. In time, further signals from the environment induce meiotic cell division, resulting in four genetically distinct haploid cells that emerge from their protective coating to complete the life cycle. As shown in Fig. 27.3b, some single-celled eukaryotes normally exist as diploid cells. An example is provided by the diatoms, single-celled eukaryotes commonly found in lakes, soils, and the oceans. Diatom cells are mostly diploid and reproduce asexually by mitotic cell division to make more diploid cells. Because their mineralized skeletons constrain growth, diatoms become smaller with each asexual division. Once a critical size is reached, meiotic cell division is triggered, producing haploid gametes that fuse to regenerate the diploid state as a round, thick-walled cell. This cell eventually germinates to form an actively growing, skeletonized cell. In diatoms, then, short-lived gametes constitute the only haploid phase of the life cycle. The two life cycles just introduced, of Chlamydomonas and diatoms, are similar in many ways. In both, haploid cells fuse to form diploid cells, and diploid cells undergo meiotic cell division to generate haploid cells. Both life cycles also commonly include cells capable of persisting in a protected form when the environment becomes stressful. Why some single-celled eukaryotes usually occur as haploid cells and others usually occur as diploid cells remains unknown—a good question for continuing research.

30 & 33 Know seed plants: gymnosperms and angiosperms

Gymnosperms: Gymnosperms bear "naked seeds" (not in fruit), typically on cones Key features of life cycle: Dominance of sporophyte generation Development of seeds from fertilized ovules (female gametophyte) Role of pollen (male gametophyte) in transferring sperm to ovules I.e. conifers (pine trees), ginkos, cycads Ovule: haploid female gametophyte; found on ovulate cones on the tree (sporophyte) The ovule will become the seed when pollinated Pollen grains: haploid male gametophytes; found on pollen cones Airborne, resistant sperm cells that lack flagella; have wings instead Fertilization by pollen transforms ovule into seed Gymnosperms are wind pollinated

32 Know at least 1 example of each level of biological defense

Hairs are a common mechanical defense, and many times these hairs are also armed with chemical irritants. Grasses and other plants also have a mineral defense consisting of silica plates, which wear down insect mouthparts so the insects feed less efficiently and grow more slowly. Some tropical trees have prickles, spines, or thorns. Even the simple toughness of a leaf has a large impact on the probability of it being eaten. The photos show prickles on the beach palm (left), hairs on the leaves of nettle (center), and Arabidopsis (right

30 & 33 Bryophytes have dominant haploid gametophyte with a dependent sporophyte

In mosses only, the haploid gametophyte is the dominant generation

30 & 33 Seedless vascular plants: sporophyte dominant with small, close to ground gametophytes

In mosses, the sporophyte (2n) grows directly out of the gametophyte's (n) body (dependent sporophyte) Sporophyte for mosses is for dispersal

30 & 33 Understand the advantages of seeds over spores; know seed structure

In seed-producing plants: male gametes are never exposed to the environment the relationship between sporophyte and gametophyte is reversed from that in bryophytes: the gametophyte is reduced to a few cells dependent on the sporophyte. seeds are produced, which are able to disperse away from the parent plant.

29 & 31 Know phylogeny of plants

Land plants form a monophyletic group All members share a common ancestor not shared with any other species Evolved from green algae 2 major groups of land plants: Bryophytes, i.e. mosses, liverworts, hornworts Vascular plants Bryophytes: nonvascular plants Do not actively control their hydration. Do not form roots and are totally dependent on the surface water to keep their photosynthetic cells hydrated. Vascular plants More than 95% of all land-plant species found today. Contains four main subgroups: Ferns and horsetails....seedless vascular Lycophytes........seedless vascular Gymnosperms: including pine trees and other conifers.....naked seeds Angiosperms: flowering plants that include oak trees, grasses, and sunflowers.....enclosed seeds Actively regulate the hydration of their PS cells Land plants originated from aquatic green algae 470 mya. These first plants were small and resembled their algal ancestors. They had no way of obtaining water from the soil and had a limited capacity to restrict water loss from cells. Today, descendants of those first land plants dominate terrestrial habitats. These are vascular plants that have evolved the ability to carry out photosynthesis, grow to extreme heights, and control the gain and loss of water. Land plants form a monophyletic group (all members share a common ancestor not shared with any other species) descended from green algae. The land is covered by two groups of plants: The bryophytes, which includes mosses, liverworts, and hornworts. Bryophytes do not actively control their hydration. These plants do not form roots and are totally dependent on the surface water to keep their photosynthetic cells hydrated. As their environment dries, so do they. Vascular plants, which do actively control their hydration by drawing up water from the soil. The descendants of the last common ancestor of the bryophytes also include vascular plants. Vascular plants make up more than 95% of all land-plant species found today. This group of plants contains four main subgroups: Ferns and horsetails....seedless vascular Lycophytes........seedless vascular Gymnosperms: including pine trees and other conifers.....naked seeds Angiosperms: flowering plants that include oak trees, grasses, and sunflowers.....enclosed seeds

29 & 31 Anatomy of leaf

Leaf is the principal site of photosynthesis. Flattened portion is called a blade. Attached to the plant by a petiole. Outer waxy covering: cuticle (to prevent water loss). Tiny holes: called stomata with guard cells 3 major parts of a leaf: The epidermis: sheets of cells that line the upper and lower surfaces The mesophyll: loosely packed photosynthetic cells; contain chloroplasts The vascular tissue that form veins: the xylem and phloem

Know green algae diversity 27

Live mainly in freshwater Great diversity All have: Chlorophyll a and b in chloroplasts with 2 membranes Unique attachment for flagella Phytoplankton: the species that live as PS cells in seawater Chlorophyte branch of green algae includes seaweeds such as sea lettuce seen globally on seashores as flotsam Streptophyte branch of green algae....closest relatives of land plants Land plants and algal relatives form the branch of Viridoplantae. This branch includes green algae. Green algae is diverse, with about 10,000 species living in freshwater. Green algae range from tiny single-celled flagellates to meter-scale seaweeds. They all have both chlorophyll a and chlorophyll b in chloroplasts with two membranes and a unique attachment for flagella. It is thought that green algae originated as small flagellated cells in seawater. The species that live as photosynthetic cells in the water are called phytoplankton (a). The chlorophyte branch includes seaweeds such as sea lettuce and large, complex seaweeds found in tropical and temperate oceans (e). Chlorophyte green algae has played a role in studies of photosynthesis (a) and multicellularity (d). For humans, the more important branch of green algae is the one that diversified on land, called streptophytes (b and c).

32 Know all 7 biological defenses

Mechanical Defense Chemical Defense 1. Alkaloids 2. Terpenes 3. Phenols

30 & 33 Characteristics of monocots versus eudicots

Monocots : Single cotyledon: embryonic seed leaf Vascular bundles scattered throughout stem Parallel venation Flower parts occur in 3's (3, 6, 9, 12...) Root is called a fibrous root Do not form a vascular cambrium i,.e. grasses, wheat, corn, rice, coconut palms, bananas, ginger and orchids Most of our food supply comes from monocots Eudicots : Pollen grains with 3 openings through which the pollen tube can grow Diverse; majority of flowering plants i.e. legumes, roses, cabbage, pumpkin, coffee, tea, cacao, maples, oaks, magnolias Root called a taproot Netlike venation Dicot flowers have 4 or 5 petals Vascular bundles arranged in a ring

Know superkingdom Opisthokonta 27

Most diverse superkingdom: Protists, including choanoflagellates (our closest protistan relative) Protists : eukaryotes that do NOT have features of animals, plants or fungi Algae: photosynthetic protists Protozoa: heterotrophic protists Fungi Animals Animals fall in within the superkingdom Opisthokonta, Of the 1.8 million species described in the past 250 years, 75% of them fall into the superkingdom, Opisthokonta. This superkingdom includes 1.3 million animal species (mostly insects and their relatives), fungi (75,000 species), and protists, including choanoflagellates.

29 & 31 Know the differences between phloem and xylem

Movement generated by: PHLOEM Plant generated, by movement of solutes at sources XYLEM Driven by environment, difference in hydration between soil and air Movement: PHLOEM Pushed up or down XYLEM Pulled up Cell anatomy: PHLOEM Cell membrane, cytoplasm, SER, mitochondria XYLEM Cell wall Needed for photosynthesis PHLOEM Yes XYLEM Yes Subject to risks PHLOEM Leaks from turgor pressure Damage by insects due to high sugar content XYLEM Collapse Cavitation

32 Hypersensitive response

Once a pathogen has been detected, plants protect themselves by: Reinforcing their natural barriers, strengthening their cell walls, closing stomata, and plugging their xylem Producing an antimicrobial compound Launching a hypersensitive response: actively killing the cells surrounding the infection

Know 7 superkingdoms of eukaryotes 27

Opisthokonts Amoeozoans Archaeplastids Stramenopiles Alveolates Rhizarians Excavates

29 & 31 Know plant diversity; over 90% angiosperms

Over 400,000 extant species Over 90% are angiosperms Land plants date back to 465 mya Angiosperms are newest from140 mya Evolution of angiosperms resulted in rapid plant diversity Moist tropical rain forests dominated by angiosperms provided new types of habitats into which other plants could evolve 33.1 Plant diversity is dominated by angiosperms, which make up about 90% of all extant plant species.

29 & 31 Know phloem anatomy, turgor pressure

Phloem transports carbohydrates to the non-PS parts of plant. Occurs through sieve tubes: formed from elongate cells that are connected end to end by sieve plates Sieve plates contain large pores that allow phloem sap to flow from 1 sieve tube cell to another Phloem transports its carbs from source(leaf cell) to sink (roots, young leaves, developing fruit) Phloem transport can be either up or down A difference in turgor pressure drives the movement of phloem sap from source to snk The outer vascular tissue, called phloem, transports carbohydrates from leaves to the rest of the plant body. Transport of carbohydrates takes place in the phloem. Phloem consists of multicellular sieve tubes composed of highly modified cells called sieve elements that are connected end-to-end. During development, sieve elements lose much of their intracellular structure, including the nucleus and vacuole. At maturity, they retain the plasma membrane, which encloses a modified cytoplasm containing only smooth endoplasmic reticulum and a small number of organelles, including mitochondria. Cellular functions such as protein synthesis are carried out by an adjacent companion cell, to which the sieve element is connected by numerous plasmodesmata. Sieve elements are linked by sieve plates, which are modified end walls with large pores. Phloem sap is the sugar-rich solution that flows through both the lumen of the sieve tubes and the sieve-plate pores. Phloem transports carbohydrates, amino acids, inorganic forms of nitrogen, ions, hormones, protein signals, and RNA. Phloem transports its molecular cargo from source (leaf cell) to sink (root cell). Sources are regions of the plant that produce or store carbohydrates (e.g., leaves, tubers). Sinks are regions that need carbohydrates to fuel growth and respiration (e.g., roots, young leaves, developing fruits). Phloem transport can be either up or down depending on the where the source and sink are relative to each other. The active loading of solutes from sources brings water into sieve tubes by osmosis, which increases the turgor pressure. At sites of use, the removal of solutes leads to an outflow of water and a drop in turgor pressure. It is the difference in turgor pressure that drives the movement of phloem sap from source to sink.

Know superkingdom Archaeplastida 27

Photosynthetic group Includes land plants Divided into 3 major groups: Glaucocystophytes Red algae Viridoplantae: Green algae and land plants Archaeplastida This is where you find the land plants and whose 300,000 described species dominate eukaryotic biomass on the planet. One group of archaeplastids are the glaucocystophytes, a small group of single-celled algae found in freshwater ponds and lakes. Glaucocystophyte chloroplasts appear to retain more features of the ancestral cyanobacterial endosymbiont than any other algae, containing both peptidoglycan in their walls and photosynthetic pigments of biliproteins, which are also found in cyanobacteria.

29 & 31 Plant hierarchy; 3 plant organs; 3 plant tissues, plant cells, nodes versus internodes ***********

Plants are organized by hierarchy: Organs, tissues, cells (largest to smallest) Plant bodies have 3 major organs: Shoots: Leaves: major photosynthetic organs Stems: bear leaves and flowers (in angiosperms) Roots: anchor the plant and absorb water and mineral through root hairs; store food Leaves: attached to stem nodes Main organ for photosynthesis Axillary buds: give rise to branches Plant organs: may be adapted for specialized functions Plants have 3 tissue systems continuous throughout the plant: Dermal tissue: outer covering protection; absorption of water (Plant's outer protection In nonwoody plants: it is a single tissue called epidermis (a layer of tightly packed cells) In leaves and stem: cuticle (waxy epidermal covering) helps prevent water loss In woody plants: protective tissue called periderm replaces the epidermis in older regions of stems and roots) Vascular tissue: xylem and phloem; help long-distance transport of substances (Transport of water and minerals; and transport of food Xylem and phloem Water-conducting cells of xylem: Tracheids Vessel elements Have thick walls Dead at at functional maturity Phloem: Sieve-tube elements Living, but highly modified cells Lack internal organelles Function in the transport of sugars through the phloem of angiosperms)) Ground tissue: bulk of plant; tissue that does PS, storage, metabolism, and regeneration; found between dermal and vascular tissues (Neither dermal nor vascular tissue; but important for specialized functions such as PS, storage, support, etc Ground tissue internal to vascular tissue: pith Ground tissue external to vascular tissue: cortex Parenchyma cells: unspecialized and thin-walled cells; keep ability to divide Photosynthesizing cells, storage cells Found in ground tissue of leaves, stems, fruit, storage roots Collenchyma cells: unevenly thickened walls; support young, growing plant Found in ground tissue Sclerenchyma cells: have thick, lignified (woody) walls that support mature, non-growing parts of plant; rigid cells that can't elongate; dead at maturity; ) Stems (shoots): repeating sections of nodes (where 1 or more leaves are attached) and internodes (regions of stems in between nodes)

32 SAR

Plants can acquire immunity called systemic acquired resistance (SAR) to pathogens after being exposed to the pathogen in another part of the plant. Evidence for systemic acquired resistance was found in an experiment carried out by plant pathologist A.F. Ross. He infected tobacco plants with TMV (tobacco mosaic virus), which turned leaves a mottled yellow. One week later, he exposed another leaf on the same plant to the virus.

29 & 31 Understand indeterminate growth

Plants show indeterminate growth A type of growth in which the organism continues to grow as long as it lives Meristems: rapidly dividing, undifferentiated cells that remain all through the life of plant Continues to divide producing undifferentiated cells, which may eventually differentiate Plants do NOT have a pre-programmed body There are constants, life leaf shape and branching patterns But you can never predict where a new branch will form Plants continue to grow throughout their lives

29 & 31 Plant primary growth, apical meristems

Primary plant growth: lengthens roots and shoots Root apical meristem: located at tip of root; generates cells for a growing root axis and the root cap. Supplies cells to increase in length Shoot apical meristem: located in the apical bud, where it gives rise to alternating internodes and leaf-producing nodes. Supplies cells for increase in length Eudicot stems: have vascular bundles in a ring Monocot stems: have scattered vascular bundles Mesophyll cells: adapted for photosynthesis Stomata: epidermal pores formed by a pair of guard cells Allow for gas exchange and major site of water loss

29 & 31 Plant secondary growth, lateral meristems, vascular cambium, cork cambium

Secondary plant growth: increases width of stems and roots in woody plants Lateral meristems: located near edge of plant, usually in a cylinder Supplies cells for plant to increase its diameter Secondary growth found in all woody plants and only in dicots Vascular cambium: adds secondary xylem (wood) and secondary phloem during secondary growth Older layers of secondary xylem (heartwood) become inactive Younger layers (sapwood) still conduct water Cork cambium: gives rise to a thick covering, called periderm, which consists of cork cambium plus layers of cork cells it produces. Replaces epidermis.

30 & 33 Know seedless vascular plants: includes ferns, lycophytes; know their characteristics

Seedless vascular plants: Lycophytes Ferns and horsetails First plants to grow tall Have tubes; xylem for water and phloem for food Dominant lifecycle is diploid sporophyte, with a tiny independent gametophye Seedless vascular plants dominated early forests Their growth helped global cooling at end of Carboniferous period Decaying remnants of ferns/first forests eventually became coal Seedless vascular plants: Ferns, horsetails, lycophytes Depend on swimming sperm for fertilization and dispersal of spores into air 1st plants to grow tall....xylem and phloem present in sporophyte generation Large PS diploid sporophyte is dominant generation; height is crucial for spore dispersal Gametophytes are small and close to ground to increase chances of fertilization

30 & 33 Know examples and characteristics of vascular seedless plants

Seedless vascular plants: Lycophytes Ferns and horsetails Seedless vascular plants: Ferns, horsetails, lycophytes Depend on swimming sperm for fertilization and dispersal of spores into air 1st plants to grow tall....xylem and phloem present in sporophyte generation Large PS diploid sporophyte is dominant generation; height is crucial for spore dispersal Gametophytes are small and close to ground to increase chances of fertilization

28 Know about simple multicellularity

Simple multicellular organisms: All cells are undifferentiated; they each have full range of functions All cells are in direct contact with external environment Unicellular eukaryotes evolved first Then simple multicellular eukaryotes evolved The 36 remaining branches exhibit at least some cases of simple mulitcellularity in the form of filaments, hollow balls, or sheets of little-differentiated cells. In the form of filaments, hollow balls, or sheets of undifferentiated cells Simple multicellularity involves: 1. Adjacent cells stick together, but few specialized cells 2. Most cells have full range of functions 3. Every cell is in direct contact with external environment Properties of these multicellular organisms include: Adhesion molecules that cause adjacent cells to stick together but where there is little communication or transfer of resources between cells and little differentiation of specialized cell types Most of the cells retain a full range of functions including reproduction Every cell is in contact with the external environment

27 Know characteristics of single-celled heterotroph

Single-celled eukaryotic heterotrophs can engulf particulate food. The cells engulf food particles and package them inside a membrane vesicle and transport them to the cytoplasm in a process called phagocytosis. Within the cytoplasm, enzymes break down the particles into molecules that can be processed by the mitochondria. The dynamics of the cytoskeleton and membrane system, as well as the compartmentalization of metabolism, help explain why eukaryotic cells have so many shapes and prokaryotic cells have so few. Membrane dynamics Compartmentalized metabolism Genome organization/complex gene regulation Genetic diversity by means of sexual reproduction Life cycles 1. Nucleus 2. Predation (Endocytosis) 3.Dynamic membrane (Changes shapes) 4. Can move effectively 5 .Many single-celled eukaryotes normally exist in the haploid stage and reproduce asexually by mitotic cell division (Fig. 27.3a) 6. Eukaryotes compartmentalize their energy metabolism into mitochondria and chloroplasts; frees the rest of cell to interact with environment 7. Eukaryotic cells have a nucleus—that is their defining characteristic. Moreover, the metabolic processes that power eukaryotic cells take place only in specific organelles—aerobic respiration in the mitochondrion (Chapter 7) and photosynthesis in the chloroplast (Chapter 8). Only limited anaerobic processing of food molecules takes place within the cytoplasm. Many single-celled eukaryotes feed on bacteria or other eukaryotic cells, and animals, in turn, ingest larger foodstuffs, including other animals and plants. In consequence, eukaryotes can exploit sources of food not readily available to bacterial heterotrophs, which feed on individual molecules. This ability opens up a great new ecological possibility—predation—increasing the complexity of interactions among organisms. The structural flexibility of eukaryotic cells also allows photosynthetic eukaryotes to interact with their environment in ways that photosynthetic bacteria cannot. Unicellular algae (which are eukaryotes) can move effectively through surface waters vertically as well as horizontally and therefore can seek and exploit local patches of nutrients. The innovations of dynamic cytoskeletal and membrane systems gave eukaryotes the structure required for larger cells with complex shapes and the ability to ingest other cells. Thus, early unicellular eukaryotes did not gain a foothold in microbial ecosystems by outcompeting bacteria and archaeons. Instead, they succeeded by evolving novel functions. Along with the capacity to remodel cell shape, eukaryotes evolved complex patterns of gene regulation, which in turn enabled unicellular eukaryotes to evolve complex life cycles and multicellular eukaryotes to generate multiple, interacting cell types during growth and development. These abilities opened up still more possibilities for novel functions, which we explore in this and later chapters.

30 & 33 Know the term sporopollenin

Sporopollenin Complex mixture of polymers A tough resistant covering to spores Provides environmental protection to spores

28 Know about choanoflagellates

The closest protistan relatives of animals are unicellular microorganisms called choanoflagellates. Their genome has genes that code for many of the same protein families that promote adhesion in animals. Although they are generally unicellular, simple multicellular structures can be induced by molecular signals in a number of species. Surprisingly, these signals were caused by their prey, bacteria. When they detect their food bacteria, these organisms form a mulitcellular structure. The function is unknown at this time, but these observations support the hypothesis that they facilitate predation.

29 & 31 Know examples and characteristics of vascular seedless plants

The descendants of the last common ancestor of the bryophytes also include vascular plants. Vascular plants make up more than 95% of all land-plant species found today. This group of plants contains four main subgroups: Ferns and horsetails....seedless vascular Lycophytes........seedless vascular

Know superkingdom Excavata 27

This superkingdom is defined by a feeding groove structure named excavata Includes imporatant parasites of animals, I.e. Giardia, Trypanosome euglenid Euglenids: PS species with plastids derived from green algae by secondary endosynbiosis

28 Understand blastula, gastrulation, gastrula

Unconstrained by cell walls, animal cells can move relative to one another. When fertilized eggs undergo several rounds of mitosis, they form a ball of undifferentiated cells called a blastula. Blastula cells migrate, becoming reorganized into a hollow ball that folds inward at one location to form a layered structure called the gastrula. Gastrula formation brings new populations of cells into direct contact with one another, inducing patterns of molecular signaling and gene regulation that begins the process of growth and tissue specification. Gradients in signaling molecules define top, bottom, front, back, left, and right. Plants do much the same thing, but because animal cells can't move during development, cell division and tissue differentiation occur throughout the developing animal body. i.e. during animal development, embryos undergo gastrulation, a process in which cells migrate inward to form a layered structure called a gastrula

30 & 33 Know double fertilization of angiosperms; angiosperm seeds with endosperm

Unique to angiosperms 2 sperm unite with 2 cells of female gametophyte Formation of a 2n zygote and 3n endosperm (nourishes the zygote/embryo Pollination: Pollen carried by pollinator to stigma Pollinators....bees, hummingbirds, butterflies Fly to flower to eat nectar; get pollen on their legs from anthers Pollen Tube Germination: Pollen lands on sticky stigma Pollen has 2 types of cells: Tube cell: burrows down to ovules Generative cell: divides to form 2 sperm cells which travel down to ovule Fertilization: 2 sperm cells enter ovule 1 sperm cell fertilizes egg cell...becomes diploid zygote 2nd sperm cell joins two polar nuclei to become triploid endosperm; nutrient for zygote Called Double Fertilization

29 & 31 Know xylem anatomy

Xylem: formed from cells that lose all their cell contents as they mature Xylem have thick, lignified cell walls Water flows into xylem conduits across small thin-walled regions called pits. Pits allow the passage of water, but not air, from 1 conduit to another Tracheids: unicellular xylem conduits Vessels: multicellular conduits Pulling water through xylem creates risk of mechanical failure: By inward collapse of conduit walls Cavitation: where an air bubble expands to fill entire conduit The inner tissue, called xylem, transports water from the roots to the leaves. Water travels with ease through xylem because of the structure of the water-transporting cells within this tissue. As they develop, these cells become greatly elongated. When they complete their growth, they secrete a thick additional wall that contains lignin, a chemical compound that increases mechanical strength. Finally, the nucleus and cytoplasm are lost, leaving behind only the cell walls. The thick walls form a hollow conduit though which water can flow. Water enters and exits xylem conduits through pits. Pits contain only the thin, water-permeable cell wall that surrounded each cell as it grew. Pits allow the passage of water but not air from one conduit to another. Xylem conduits can be formed from a single cell or from multiple cells stacked to form a hollow tube. Unicellular conduits are called tracheids, and multicellular conduits are called vessels. Because tracheids are the product of a a single cell, they are typically 4−40 μm in diameter and no more than 2−3 cm long. Vessels are made up of individual cells called vessel elements. Vessels can be much wider and longer than tracheids, ranging from 5−500 μm, and lengths can be up to several meters. Water enters a tracheid through pits, travels upward through the conduit interior, and then flows outward through other pits into an adjacent, partially overlapping tracheid. Water also enters and exits a vessel through pits. In contrast to tracheids, however, once the water is inside the vessel, little or nothing blocks the flow of water from one cell to the next. However, at the end of a vessel, the water must flow through pits if it is to enter an adjacent vessel and thereby continue its journey from the soil to the leaves. The forces that pull water from the soil in plants must be able to lift water against gravity and pull water from the soil, even when it is dry. These forces must also be greater than the physical resistance associated with moving water through the plant itself. When stomata are open, water evaporates from the walls of cells lining the intercellular air spaces of leaves. The partial dehydration of the cell walls creates a force that pulls water toward the sites of evaporation. Once generated, this force is transmitted through the xylem, beginning in the leaf veins, then down through the stem, and down through the roots to the soil. Water can be pulled through the xylem because of the strong hydrogen bonds that form between water molecules. This mechanism of water transport only works if there is a continuous column of water in the xylem that extends from the roots to the leaves. In order to pull water from the soil, xylem must be constructed in such a way that it does not to collapse. If you suck on a drinking straw too hard, it will collapse inward, blocking flow. This is the same for xylem. Therefore, vascular plants make conduit walls rigid with lignin to reduce the risk of collapse. A second risk is cavitation. Cavitation occurs when the water in a conduit is abruptly replaced by water vapor. Cavitation disrupts the continuity of the water column, so cavitated conduits can no longer transport water from the soil. Cavitation results when microscopic gas bubbles that are present in the water expand under the pulling forces exerted by the leaves. These bubbles are formed in one of two ways: An air bubble is pulled through a pit because of lower pressure in the water compared to the air. Gases come out of solution as the water within the xylem freezes. As the water thaws, cavitation occurs.

32 Virulent versus avirulent pathogens

s Not all infections have a significant effect on the host plant.  Virulent pathogens are able to overcome the host's defenses and lead to disease. Avirulent pathogens damage only a small part of the plant because the host is able to contain the infection.