Topic 8

Question 1

What is evidence of endosymbiosis?

Answer 1

• self replicating (binary fission)
• resemble bacteria in size and structure
• circular DNA
• 2 cell membrane

Question 2

Describe the domain: Eukarya

Answer 2

• linear DNA
• membrane bound organelles (mitochondria and chloroplasts)
• larger than prokaryotes
• dynamic membrane -> ability to change shape
• diverse morphology -> well developed cytoskeleton

Question 3

Why are eukarya and prokarya sister taxa?

Answer 3

• absence of peptidogylcan
• several kinds of RNA polymerase
• presence of introns
• unbranched hydrocarbon membrane lipids
• branched hydrocarbon membrane lipids

Question 4

Explain the Oxygen Revolution

Answer 4

• began accumulating 2.7 billion years ago
• oxygen was toxic to most early taxa
• slowly adapted to oxygen rich atmosphere & began aerobic respiration

Question 5

What are some possible selective advantages of sexual reproduction?

Answer 5

• meiosis is adaptive, may be able to thrive if the environment changes
• genotypes of many parasites & pathogens evolve quickly

Question 6

How is diffusion related to the evolution of multicellularity?

Answer 6

hypothesis #1 - larger sizes are advantageous

- diffusion is effective only over short distances, you want a higher surface to volume ratio

Question 7

What are the nutritional modes of protists?

Answer 7

• protozoans: animal-like protists
• fungus-like protists
• algae: plant-like protists
• mixotrophs

Question 8

Name 4 Supergroups

Answer 8

• Excavata
• SAR Clade ( Stramenophiles, Alveolates, Rhizaria )
• Archaeplastida
• Unikonta

Question 9

Describe the Archaeplastids Group

Answer 9

• contains red and green algae, as well as land plants

- chloroplasts have two membranes

Question 10

Describe Red Algae

Answer 10

• pigment turns it red, masking green chlorophyll

- multicellular seaweeds

Question 11

Describe Green Algae

Answer 11

• chlorophytes -> chlorophyll produces green pigment, contains unicellular & multicellular species
• charophytes -> complex, multicellular organisms, closely related to land plants

Question 12

What are red and green algae closely related to?

Answer 12

plants !!

Question 13

Describe the Chromalveolata Group

Answer 13

• may have originated by secondary endosymbiosis
• controversial clade (stramenophiles and alveolates)
• only united by DNA

Question 14

Describe Apicomplexans

Answer 14

• mostly parasitic ( malaria )

- heterotrophic “protozoans”

Question 15

Describe Ciliates

Answer 15

• very large diverse group
• heterotropic
• reproduce using binary fission and sometimes conjugation
  ex) paramecium

Question 16

Describe Diatoms

Answer 16

• unicellular algae

- membrane made of silica ( super strong )

Question 17

Describe Dinoflagellates

Answer 17

• two flagella
• cell reinforced by cellulose plates
• aquatic phototrophs, heterotrophs & mixotrophs
• photopigment = red plastids
• some produce toxins
• some can glow
• “red tide”

Question 18

Describe the Excavata Group

Answer 18

• highly variable
• mostly heterotrophic “protozoans”
  ex) “sleeping sickness”, diaherra

Question 19

Describe Unikota

Answer 19

• lack plastid genes

- no chloroplasts

Question 20

Define asexual reproduction

Answer 20

• mitosis and cell division in eukaryotic organisms

- results in daughter cells that are genetically identical to the parents

Question 21

Why should we study protists?

Answer 21

• impact on human health and welfare
• ecological importance
• critical to understanding evolution of plants, fungi, and animals