Algae

Question 1

What are algae?

Answer 1

A diverse group of not necessarily closely related photosynthetic organisms.

Question 2

What are cyanobacteria?

Answer 2

Photosynthetic prokaryote bacteria that produce oxygen.

Question 3

Since they do not all share a common ancestor, the group of algae is ________

Answer 3

Polyphyletic

Question 4

What are some of the major groups that are considered algae?

Answer 4

Green algae

Brown algae

Red algae

Diatoms

Dinoflagellates

Coccolithophores

Question 5

Describe coccolithophores.

Answer 5

Unicellular eukaryotic protists, have calcium carbonate (calcite) plates, alternation of diploid and haploid phases, reproduce asexually by binary fission. Global distribution, important carbon sinks and photosynthesizers.

Question 6

Describe dinoflagellates.

Answer 6

Flagellate unicellular eukaryotic protists, some are photosynthetic, important as endosymbionts for corals, anemones, jellyfish, Tridacna clams, etc.

They have thecal plates and chloroplasts. Asexual reproduction by mitosis.

They have diverse nutritional strategies: phototrophy, mixotrophy, heterotrophy.

Create harmful algal blooms and bioluminescence.

Question 7

Algae chloroplasts contain ______ like that in cyanobacteria and presumably represent reduced endosymbiotic cyanobacteria

Answer 7

circular DNA

Question 8

Describe green algae

Answer 8

The division contains both unicellular and multicellular species. Some conduct sexual reproduction, which is oogamous or isogamous. All members of the clade have motile flagellated swimming cell

Question 9

Describe red algae

Answer 9

The red algae form a distinct group characterized by having eukaryotic cells without flagella and centrioles, chloroplasts that lack external endoplasmic reticulum and contain unstacked (stoma) thylakoids, and use phycobiliproteins as accessory pigments, which give them their red color.

Red algae store sugars as floridean starch, which is a type of starch that consists of highly branched amylopectin without amylose, as food reserves outside their plastids. Most red algae are also multicellular, macroscopic, marine, and reproduce sexually.

The red algal life history is typically an alternation of generations that may have three generations rather than two.

Question 10

Describe brown algae

Answer 10

A large group of multicellular mostly marine seaweeds.

Question 11

What is a holdfast?

Answer 11

Rootlike structure used for anchoring algae to the substrate but which is not used for uptake of nutrients or water.

Question 12

What is a stipe?

Answer 12

A stalk or stemlike structure present in an alga. The tissues within the stipe are divided into three distinct layers or regions. These regions include a central pith, a surrounding cortex, and an outer epidermis, each of which has an analog in the stem of a vascular plant. In some brown algae, the pith region includes a core of elongated cells that resemble the phloem of vascular plants both in structure and function.

Sometimes hollow and filled with air for buoyancy.

Question 13

What is a lamina aka blade aka frond?

Answer 13

Flattened portion that resembles a leaf.

Question 14

How does brown algae grow?

Answer 14

Through cell division at an apical tip.

Question 15

Describe the cell walls of brown algae.

Answer 15

The cell wall consists of two layers; the inner layer bears the strength, and consists of cellulose; the outer wall layer is mainly algin, and is gummy when wet but becomes hard and brittle when it dries out

Question 16

How do brown algae reproduce?

Answer 16

Most brown algae, with the exception of the Fucales, perform sexual reproduction through sporic meiosis. Between generations, the algae go through separate sporophyte (diploid) and gametophyte (haploid) phases

Question 17

Describe diatoms.

Answer 17

A major group of microalgae, and are among the most common types of phytoplankton. Diatoms are unicellular, although they can form colonies in the shape of filaments or ribbons (e.g. Fragilaria), fans (e.g. Meridion), zigzags (e.g. Tabellaria), or stars (e.g. Asterionella).

Diatoms are producers within the food chain. A unique feature of diatom cells is that they are enclosed within a cell wall made of silica (hydrated silicon dioxide) called a frustule.[7] These frustules show a wide diversity in form, but are usually almost bilaterally symmetrical, hence the group name. The symmetry is not perfect since one of the valves is slightly larger than the other, allowing one valve to fit inside the edge of the other.

Question 18

Describe the life cycle of diatoms

Answer 18

Reproduction among these organisms is primarily asexual by binary fission, with each daughter cell receiving one of the parent cell’s two frustules (or theca). This is used by each daughter cell as the larger frustule (or epitheca) into which a second, small frustule (or hypotheca) is constructed.

Question 19

Describe crustose coralline algae.

Answer 19

They are characterized by a thallus that is hard because of calcareous deposits (calcite) contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but other species can be purple, yellow, blue, white or gray-green.

Question 20

Why is CCA important?

Answer 20

Many corallines produce chemicals which promote the settlement of the larvae of certain herbivorous invertebrates, particularly abalone. Larval settlement is adaptive for the corallines because the herbivores remove epiphytes which might otherwise smother the crusts and preempt available light.

Question 21

How is CCA involved in reef building?

Answer 21

They provide calcareous material to the structure of the reef, help cement the reef together, and are important sources of primary production.

Coralline algae are especially important in reef construction, as they lay down calcium carbonate as calcite. Although they contribute considerable bulk to the calcium carbonate structure of coral reefs, their more important role in most areas of the reef, is in acting as the cement which binds the reef materials into a sturdy structure.

Question 22

What organisms benefit from ocean acidification?

Answer 22

Seagrasses, algae and other photosynthetic organisms