Chapter 28: Protists (3)

Question 1

What are the characteristics of dinoflagellates?

Answer 1

They are abundant components of both
marine and freshwater phytoplankton

• Nutrition: diverse group of aquatic
  – phototrophs,
  – mixotrophs, and
  – heterotrophs

Question 1

What are “red tides”?

Answer 1

Toxic “red tides” are caused by periods
of dinoflagellate blooms

Question 2

What are the characteristics of Apicomplexans?

Answer 2

• Apicomplexans are parasites of animals, and some cause serious human diseases
• One end, the apex, contains a complex of
  organelles specialized for penetrating host
  cells and tissues
• Most have sexual and asexual stages that
  require two or more different host species for completion

Question 3

Apicomplexans spread as infectious cells called _______.

Answer 3

• They spread as infectious cells called
  sporozoites

Question 4

What are the characteristics of Ciliates?

Answer 4

• Ciliates, a large varied group of protists, use cilia to move and feed
• They have large macronuclei and small micronuclei
• Genetic variation results from conjugation, in which two individuals exchange haploid micronuclei

Question 5

What are the characteristics of rhizarians?

Answer 5

• Many species in the rhizarian clade are amoebas
• Rhizarian amoebas differ from amoebas in other clades by having threadlike pseudopodia
• Rhizarians include radiolarians, forams, and cercozoans

Question 6

What is psudeopodia?

Answer 6

• Amoebas are protists that move and feed by pseudopodia, extensions of the cell surface

Question 7

What are the characteristics of radiolarians?

Answer 7

• Marine protists called radiolarians have delicate, symmetrical internal skeletons that are usually made of silica
• Pseudopodia of radiolarians radiate from the central body
• Radiolarians use pseudopodia to engulf microorganisms through phagocytosis

Question 8

What are the characteristics of forams?

Answer 8

• Foraminiferans, or forams, are named for
  porous, generally multichambered shells, called tests
• Many forams have endosymbiotic algae

Question 9

What is the function of pseudopodia in forams?

Answer 9

Pseudopodia extend through pores in the tests and function in
– swimming
– feeding
– tests formation

Question 10

What can fossilized forams be used for?

Answer 10

The magnesium content in fossilized forams can be used to estimate changes in ocean temperature over time

Question 11

______and _______are the closest
relatives of land plants

Answer 11

Red algae and green algae are the closest
relatives of land plants

Question 12

What are the groups under archaeplastida?

Answer 12

Archaeplastida is the supergroup that includes

– red algae,
– green algae, and
– land plants

Question 13

Red algae are reddish in colour due to accessory pigment called ________, which masks the green of chlorophyll

Answer 13

Red algae are reddish due to accessory pigment called phycoerythrin, which masks the green of chlorophyll

Question 14

_________ are the most abundant large algae in coastal waters of the tropical oceans

Answer 14

Red algae are the most abundant large algae in coastal waters of the tropical oceans

Question 15

What are the characteristics of green algae?

Answer 15

• Green algae are named for their grass-green chloroplasts
• Plants are descended from green algae
• Green algae are a paraphyletic group

Question 16

What are the two groups under green algae?

Answer 16

The two main groups are:
– chlorophytes and
– charophyceans

Question 17

What are the characteristics of Most chlorophytes?

Answer 17

Most chlorophytes live in fresh water, although many are marine
* Includes more than 7000 species

• Other chlorophytes live:
  – in damp soil,
  – as symbionts in lichens, or
  – in environments exposed to intense visible and ultraviolet radiation

Question 18

How did Larger size and greater complexity evolve chlorophytes?

Answer 18

1. formation of colonies from individual cells
2. formation of true multicellular bodies by cell division and differentiation (e.g., Ulva)
3. repeated division of nuclei with no cytoplasmic division (e.g., Caulerpa)

Question 19

What are the 2 key roles protists play in their habitats?

Answer 19

Protists play two key roles in their habitats:
– that of symbiont and
– that of producers

Question 20

What are some examples of protist symbionts?

Answer 20

Some protist symbionts benefit their hosts

– dinoflagellates nourish coral polyps that build reefs
– wood-digesting protists digest cellulose in the gut of
termites