Chapter Three - Protists Part 1

Question 1

Name a supergroup in Domain Eukarya

Answer 1

Supergroup Archaeplastida

Question 2

Name two groups of protists in Supergroup Archaeplastida

Answer 2

Red Algae and Green Algae

Question 3

Name another supergroup in Domain Eukarya

Answer 3

Supergroup SAR Clade

Question 4

Name the seven groups of protists in Supergroup SAR Clade

Answer 4

Diatoms, Golden Algae, Brown Algae, Dinoflagellates, Ciliates, Radiolarians and Foraminiferans.

Question 5

What is included in Domain Eukarya?

Answer 5

Animals, plants, fungi and a wide variety of other organisms often
collectively termed “protists.”

Question 6

What are protists?

Answer 6

a diverse group of unicellular, colonial, and multicellular eukaryotes.

Question 7

Name the four supergroups of eukaryotes

Answer 7

Excavata, “SAR”
clade, Archaeplastida and Unikonta.

Question 8

What are supergroups?

Answer 8

Are informal taxonomic categories that do not fit into the traditional Linnaean system (Domain, Kingdom, Phylum, Class, etc.). The major Kingdoms (Plantae, Animalia, and Fungi) are classified within some of these supergroups.

Question 9

All supergroups are categorised within what domain?

Answer 9

Domain Eukarya

Question 10

Protists are an extremely diverse group of organisms. What does the term “protists” refer to?

Answer 10

Refers to eukaryotes that
are not animal, plants, or fungi. Most protists are unicellular but there are also
some colonial (growing in clusters or filaments) and multicellular species.

Question 11

Name three types if protists

Answer 11

Photoautotrophs, Heterotrophs and Mixotrophs.

Question 12

What are photoautotrophs?

Answer 12

Protists containing
chloroplasts which they use to convert solar energy into chemical energy in the form of
sugars. They are often referred to as algae or phytoplankton.

Question 13

What are Heterotrophs?

Answer 13

Heterotrophic protists obtain nutrition by absorbing organic molecules or ingesting
food particles from the environment.

Question 14

What are mixotrophs?

Answer 14

Protists that can photosynthesize AND ingest nutrients from the environment.

Question 15

How do protists differ from each other?

Answer 15

They have structural and nutritional
diversity and vary in their life cycle and reproductive strategies. Some unicellular protists can only reproduce asexually while others can reproduce both asexually and sexually.

Question 16

What is the difference between algae and plants?

Answer 16

Unlike algae, all plants are defined as having terrestrial ancestors, even though some plants are now aquatic. All plants are multicellular eukaryotes while algae can be unicellular, filamentous, multicellular, or colonial. Algae may have plant-like structures but those structures do not contain true plant tissues.

Question 16

What are gamete producing structures called in algae?

Answer 16

Gametangia (singular: gametangium).

Question 16

What are sperm-producing gametangia called?

Answer 16

Antheridia

Question 17

What are egg-producing gametangia called?

Answer 17

Oogonia

Question 18

What two groups of protists are included in supergroup archaeplastida?

Answer 18

Red algae and green algae

Question 19

Describe red and green algae

Answer 19

They are photoautotrophic and include unicellular, colonial, and multicellular species.

Question 20

Describe Red Algae

Answer 20

They are marine seaweeds, especially characteristic of warmer waters, although
some red algae inhabit freshwater and even terrestrial habitats. Red algae can reproduce both asexually and sexually.

Question 21

Why is red algae red?

Answer 21

Due to the presence of an accessory photopigment (phycoerythrin) which masks the green of chlorophyl.

Question 22

How do red algae play an important ecological role?

Answer 22

Much like the reef
building coral species, coralline red algae species secrete a hard shell of calcium carbonate onto the surface of their cells for increased structural support building reef.

Question 23

What types of species of green algae are there?

Answer 23

There are unicellular, filamentous, multicellular and colonial species.

Question 24

Where can green algae be found?

Answer 24

In freshwater or marine aquatic habitats but some can also be found growing on terrestrial surfaces such as buildings, tree trunks, and sidewalks.

Question 25

How are green algae characterised?

Answer 25

By the presence of chloroplasts which have much the same ultrastructure and chlorophyll composition as plants. This similarity, along with data from molecular systematics, makes it clear that green algae are the algae most closely related to plants. They can reproduce both asexually and sexually.

Question 26

What does the SAR clade stand for?

Answer 26

Stramenopila, Alveolata, and Rhizaria.

Question 27

How is the SAR clade grouped?

Answer 27

On the basis of molecular evidence as well as the hypothesis that two of these groups, stramenopiles and alveolates, have some algal species that are derived from an ancestor that had a secondary endosymbiotic relationship with red algae.

Question 28

Describe protists in the SAR clade

Answer 28

They are unicellular, colonial, and multicellular species. Most protists in this clade are photoautotrophic plankton or algae while some species, the ciliates and the shelled amoebas (in clade Rhizaria), are heterotrophic.

Question 29

Describe Diatoms in the SAR clade

Answer 29

Diatoms are unicellular photoautotrophic stramenopiles abundant in both marine and freshwater plankton. Diatoms contain yellow-brown carotenoids in addition to chlorophyll. Diatoms exist in a variety of unique shapes but all share a translucent appearance because they are surrounded by a glass-like wall.

Question 30

Further describe Diatoms encasing, what happens when they die and Diatomaceous Earth.

Answer 30

Diatoms are encased with a unique glass-like cell wall, a frustule, made of silica which consists of two overlapping parts. When diatoms die, the silica frustules do not decompose and accumulate in thick layers in the sediment of freshwater and marine environments. Diatomaceous earth, which consists of fossilized diatom frustules, is commercially mined for use as filtering material (e.g. in swimming pool filters). Diatomaceous earth can also be used as a non-toxic insecticide because the fine, white, sediment can block tiny breathing pores in the exoskeleton of insects causing the animals to suffocate.

Question 31

Describe Golden Algae in the SAR clade

Answer 31

They are photoautotrophic stramenopiles found in marine, freshwater, and terrestrial habitats. Like diatoms, golden algae contain yellow-brown carotenoids but not all species of golden algae appear yellow or brown in color. This group of protists include unicellular, filamentous, and colonial species.

Question 32

What does the term coenocytic refer to?

Answer 32

Refers to structures that have multiple nuclei, but no divisions between cells.

Question 33

Describe Brown Algae in the SAR clade

Answer 33

They are large, multicellular marine stramenopiles commonly called “seaweeds” (some red and green algae also are seaweeds). Unlike the diatoms and golden algae, brown algae exhibit many plant-like structures

Question 34

Describe kelp

Answer 34

Kelp is the most well known form of brown algae. It grows in vast kelp forests in temperate coastal waters.

Question 35

What is the plant-like body of these seaweeds is referred to?

Answer 35

Thallus

Question 36

Name some anatomical structures of kelp

Answer 36

Blades (lamina), Holdfast (root-like structure), Stipe (stem-like structure), and Floats (pneumatocysts).

Question 37

Describe Dinoflagellates in the SAR clade

Answer 37

They are type of unicellular algae. They are photoautotrophic alveolates abundant in both marine and freshwater plankton, although there are also some heterotrophic species.

Question 38

What can some species of unicellular photoautotrophic protists experience?

Answer 38

Explosive population growth (algal blooms) in response to certain environmental factors. ex. “red tide” blooms which releases toxins that result in massive fish and invertebrate kills.

Question 39

How do dinoflagellates move?

Answer 39

Dinoflagellate cells are biflagellate (have two flagella) and some are surrounded by overlapping protective “armor” plates made of cellulose. Perpendicular grooves in the “armor” contain the flagella. Movement of the flagellum housed in the transverse groove, the one used for locomotion, causes the cell to spin like a top as it moves through the water (dinos = whirling). The other flagellum is used in steering.

Question 40

What are cilia used for?

Answer 40

Used for locomotion and feeding. Most ciliates are free-living, freshwater species.

Question 40

Describe Cilates in the SAR clade

Answer 40

They are heterotrophic, unicellular alveolates that are characterized by having small, hair-like cellular extensions called cilia covering all or part of their cell surface.

Question 41

How is reproduction in ciliates carried out?

Answer 41

By asexual fission or a unique sexual process called conjugation which involves two separate nuclei the micronucleus and macronucleus.

Question 42

What is a prominent feature when looking at ciliates?

Answer 42

The central vacuole is a prominent feature when viewing live ciliates which is used in osmoregulation.

Question 43

Describe Radiolarians in the SAR clade

Answer 43

The clade Rhizaria (in the SAR clade) includes two groups of “shelled” amoebas both of which are unicellular and heterotrophic. Unlike the ciliates, amoebas have pseudopodia (= false + feet), irregular cellular extensions used in moving and feeding.

Question 44

What happens in shelled amoebas?

Answer 44

Pseudopodia extend through pores in a hard “shell” called a test, which the amoeba secretes around itself. Their pseudopodia are thread-like in shape.

Question 45

What are radiolarians?

Answer 45

They are planktonic rhizarians found in marine environments with a test composed of silica. When these protists die, their tests sink to the bottom where they eventually contribute to the formation of sedimentary rock.

Question 46

Describe Foraminiferans (forams) in the SAR clade

Answer 46

They are rhizarians found in both marine and freshwater habitats. Unlike the radiolarians, foraminiferans have a test composed of calcium carbonate. The pores in their tests are called foramina. The tests of dead forams settle to the bottom where they contribute to the formation of chalk. The calcium carbonate tests of forams fossilize easy and have left an extensive record that dates all the way back to the Cambrian period.