Midterm Key

Marine Botany Midterm 2015
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
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
Marine Botany Midterm 2015
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 ______
Thylakoids in stacks of 3 ______ Ochrophyta ______
g. Bacteria ___________ neither _______
h. Mastigonemes _______ Ochrophyta __________
Haplontic forms ______ Chlorophyta ________
Chloroplast has 2 membranes _____ Chlorophyta _________
k. Kleptoplasmids ________ Chlorophyta _______
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
Marine Botany Midterm 2015
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
6) intercalary growth:
Growth in both directions away from a meristem, usually between stipe and blade or blade and
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,
Marine Botany Midterm 2015
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 Pmax ?
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
Marine Botany Midterm 2015
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
1N gametes
in zygote
1N gametophytes
1N zoospores
Bryopsidales- diplontic2N 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?_
1N gametophytemitosis1N gametes (2 flagella look the same)fuse2Nzygote2N
sporophytemeiosis1N zoospores ( four flagella)grow into 1N gametophyte
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
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
Marine Botany Midterm 2015
Short Ans wer (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 lowestBut 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
Marine Botany Midterm 2015