Marine Botany Midterm 2015

Transcription

1 Compare and Contrast the following items (20pts): 1) sporophyte vs gametophyte Both are alternate states of algal thallus type in the alternation of generation life history Sporophyte- diploid, 2N, multicellular release spores Gametophyte-haploid, 1N, multicellular releases gamete 2) Anterior vs posterior flagella in Phaeophyceae Both are found in Ochrophyta, Phaeophyceae and are attached laterally not apically Anterior flimmer flagella used for movement, long flagellum with two rows of stiff hairs, directed forward Posterior whiplash flagellum used for steering, short smooth flagellum, directed backward, contains flavin which functions as a photoreceptor 3) phycoplast vs. phragmoplast Used in determining which class an alga may be in within Chlorophyta. Refers to the orientation of microtubules in relation to the diving plane during cell division. Phycoplast: microtubules parallel to dividing plane -rare in algae Phragmoplast: double microtubules perpendicular to dividing plane-common in algae & land plants 4) haplontic vs diplontic Both used to describe different life histories in algae Haplontic: 1N thallus, the zygote is the only diploid stage, Chlorophyta only Diplontic: 2N thallus, the gametes are the only haploid stage- Chlorophyta & Ochrophyta 5) filamentous vs. pseudoparenchymatous construction Both are types of internal thallus morphologies in algae Filamentous- daughter cells remain attached to each other following cell division forming chains of cells, can be uniseriate or multiseriate Pseudoparenchymatous- form of thallus composed of interwoven continuous filaments, superficially resembles parenchyma 1

2 Match with the correct Division: Chlorophyta, Ochrophyta, both, or neither (12 points) a. Plantae Chlorophyta b. Chlorophyll C Ochrophyta c. Flowers neither d. Physode Ochrophyta e. Laminarin Ochrophyta f. Thylakoids in stacks of 3 Ochrophyta g. Bacteria neither h. Mastigonemes Ochrophyta i. Haplontic forms Chlorophyta j. Chloroplast has 2 membranes Chlorophyta k. Kleptoplasmids Chlorophyta l. Spores have 4 flagella Chlorophyta 2. (12 pts.) Describe why the following traits might be adaptive or advantageous to marine algae. Give a taxonomic example for each. a. Positive phototaxis in gametes - allows gametes to find each other at the surface of the water where there aren t any physical barriors, negative phototaxis in zygote- allows zygotes to settle at the bottom of the ocean where they may find suitable habitat to settle and grow- Chlorophyta, Ulvophyceae, Bryopsidales, Halimedia b. Producing tannins and terpenes-antiherbivory, antiepiphyte, antiendophyte, may also strengthen cell walls, block UVB protecting algae from radiation damage Ochrophyta c. A thallus morphology with lots of ruffles-more surface area leads to more diffusion, which increases nutrient uptake Ochrophyta of Chlorophyta 2

3 Define the terms below (20pts): 1) algae: Have chlorophyll A as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells (No flowers), limited cellular differentiation, no vascular system, much greater diversity of photosynthetic pigments, aquatic photsynthetic eukaryoes, polyphyletic group containing, cyanobacteria, diatoms, dinoflgellates, red, green and brown algae 2) physode: special vesicles in the cytoplasm of heterokonts that store tannins 3) utricles: Peripheral portions of siphons may be inflated and aggregated to form outer surface in coenocytic/ siphonous algae, swollen terminal end of siphon 4) coenocytic: One large multinucleate cell lacking crosswalls 5) plurilocular sporangia: structure where spores are formed that is divided into many small chambers :one spore/gamete per chamber 6) intercalary growth: Growth in both directions away from a meristem, usually between stipe and blade or blade and pneumatocyst 7) pneumatocyst: -a large float containing gas found in heterokontophyta -provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for Ps - can hold O2, CO2, CO 8) holocarpic reproduction: Entire thallus turns into gametes 9) pheromones: Chemical produced to elicit a specific behavior or physiological response from another individual, release by female gametes in phaeophyceae 10) alginic acid: Surrounds the microfibrils in the cell walls of phaeophyceae, function elasticity, flexibility, prevent desiccation and osmoregulation, 3

4 Create a dichotomous key to separate the following genera: Stephanocystis, Codium, Dictyota, Fucus, Chaetomorpha. You may not use taxonomic names of divisions, classes, or orders, but should instead use characteristics of the divisions, classes, orders or genera (10 pts) Codium & Chaetomorpha- Chl B, lutien,neoxanthin, starches (Amylose, Amylopectin), 2 membranes, thylakoids stacks 2-6, flagella-isokont, variable #, haplontic, counter clockwise basal body, cruciate microtubulae roots, cell wall, spindle closed, phragmoplast, furrow Codium- ceonocytic, siphonous, biflagellate, anisogamous,multinucleate, no division of cytoplasm with cell walls, clotting compounds, diplontic, utricles, gametangium, invasive on the east coast Chaetomorpha- large multinucleate cells, connected end to end with cross walls,chloroplasts- reticulate/discoid, isomorphic alt of gen, unbranched filaments, modified basal cell withr hizoidal extensions, crunchy Stephanocystis, Dictyota, Fucus- Chl C,fucoxanthin, sugars (Laminarian,Chrysolaminarian,Mannitol), 4 membranes, thylakoids stacks of 3, heterokont- one is hairy Stephanocystis, Fucus- diplontic, oogamous, parenchymatous, apical growth, receptical, conceptical, Fucus- midrib, 8 eggs per oogonium, found in the mid zone of the intertidal Stephanocystis-subtidal, perennial base, top portion grows annually contains catenate pneumatocysts Dictyota- isomorphis alt of gen, oogamous, parenchymatous, apical growth, 3 cells thick, tetraspores, dioecious, sperm, single hairy flagella, plurilocular & unilocular gametangia, spores no flagella 3. (10 pts.) In a single figure, draw a P-E curve for both a shade-adapted plant and a sun-adapted plant. Make sure to label the x- and y-axes, P-max, and photoinhibition. What is P max? Maximum production, highest photosynthetic rate- labled as highest point on each curve- dotted line to y-axis What is photoinhibition? Damage to photosystems due to high irradiance- labeled on graph where curve dips at the end What happens within the chloroplast that leads to differences in the P-E curve for sun vs shade adapted species? Sun adapted- smaller and fewer PSU Shade adapted- larger and bigger PSU 4

5 Draw a life history diagram as indicated below. Please label all stages of the life cycle, and include the ploidy (N or 2N) of all stages, when meiosis and mitosis occur, and sketch (very generally) what the algae look like. (20 pts) 1) Circle the order you are illustrating: Either Bryopsidales or Ulotrichales What type of life history does it exhibit? Ulotricales- haplontic 1N thallus (1N gametophyte) mitosis 1N gametes fuse 2N zygote meiosis occurs in zygote 1N codiolum stage 1N spores (zoospores) 1N thallus g syngamy 1N gametes 2N zygote meiosis occurs in zygote 1N gametophytes 1N codiolum stage 1N zoospores or Bryopsidales- diplontic- 2N thallus meiosis 1N gametes(both with 2 flagella ) fuse 2N zygote grows 2N thallus 2) Isomorphic Alternation of Generations: What order exhibits this life history?_ Ulvales,Cladophorales, 1N gametophyte mitosis 1N gametes (2 flagella look the same) fuse 2Nzygote 2N sporophyte meiosis 1N zoospores ( four flagella) grow into 1N gametophyte Ectocarpales, 1N gametophyte (plurilocular gametangia) mitosis 1N gametes (2 heterokont flagella female release ectocarpene ) fuse 2Nzygote 2N sporophyte (plurilocular/unilocular sporangia) meiosis 1N zoospores ( 2 heterokont flagella) grow into 1N gametophyte Dictyotales 1N gametophyte (female- unilocular gametangia, male-plurilocular gametangia) mitosis 1N gametes (maleone hairy flagella, female no flagella release ectocarpene ) fuse 2Nzygote 2N sporophyte (unilocular sporangia-tetraspore) meiosis 1N zoospores ( no flagella- 4 spores) grow into 1N gametophyte 5

6 Short Answer (20 pts): 1. What determines the upper and lower limits of algae in the intertidal? Upper limit- abiotic factors- tide, temperature, light intensity, sand & physiological tolerance of the species Lower limit- biotic factors- herbivory, competition 2. Explain how Lubchenco & Cubit changed the way people thought about heteromorphic life histories of certain marine algae as adaptations to variation in herbivory. Heteromorphic life histories was thought to be due to seasonal conditions, but proved that they were driven by herbivory. When herbivores were excluded upright morphs grew no matter the season. 3. Please discuss the theory disproved in the paper New light on Seaweed by Saffo and how algae cope with photosynthesizing with limited quality and quantity of light. Disproved Engelman s theory of chromatic adaptation-algae distribution based on seconday pigments and what light they absorb: greens highest, browns mid, reds lowest- But found that quantity not necessarily spectral quality of light matters Irradiance not spectral quality 1) produce more accessory pigments 2) produce more photosynthetic pigments 3) morphology matters- thicker fronds, arrangement of chloroplasts 4. Briefly discuss the key points of the endosymbiotic theory of organelle acquisition and how it relates to the origination of and relationship between the brown, red, and green algae. Heterotrophic eukaryote eats a photosynthetic bacteria (cyanobacteria) leads to formation of the chloroplast Results in photosynthetic eukaryote- chloroplast has 2 membranes- red and green algae Heterotrophic eukaryote eats photosynthetic eukaryote Nucleus from photosynthetic eukaryote is lost Results in photosynthetic eukaryote-chloroplast has 4 membranes- brown algae EXTRA CREDIT (2 points): Please compose a rhyming poem about your favorite species of algae 6

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