Protists

Question 1

What are stramenopiles

Answer 1

• Under the group chromalveolates
• “Straw” “Hairs”
• AKA: -Heterokont=different flagella
• 2 flagella (one long and hairy, one short and smooth)*
• group is monophyletic*
• includes Diatoms, brown algae, yellow/green algae, golden algae and oomycetes
• chloroplasts evolved through 2 ES

Question 2

What are Diatoms/under what groups are they?

Answer 2

• under the chromalveolates (stramenopiles)
• cell walls made of silica
• 2 frustules that act like “shells” (serve as protection)
• upper is called epitheca
• lower is called hypotheca
• no flagella
• photoautotrophs, some -heterotrophs
• asexual and sexual
• create resting stages in stressful situations

Question 3

Describe the reproduction method of Diatoms

Answer 3

• sexual (gametic meiosis–>diploid dominant)
• asexual (undergo size reduction, one frustule is given from parental cell to the daughter cell and a new half is created
• since the upper frustule is bigger than lower, the sizes of each daughter cells eventually get smaller and smaller, until sexual reproduction occurs

Question 4

Why are Diatoms important?

Answer 4

• they are paleo-ecological indicators of environmental change by the sediments in the silica cell walls (track things like climate change through sediment change)
• 25% of global Carbon fixation

Question 5

Brown Algae:

Answer 5

• Fucoxandthin: brown-coloured pigment
• basic form is a thalus
• they have an “anchor” part of their structure called holdfast, stipe (stem), blades
• unique feature: has adjacent cells linked by plasmodesmata
• alternation of generation: sporophyte and gametophyte
• covered in mucilage as a protective barrier
• Defines ecology of near-shore and intertidal habitats
• unicellular and colonial

Question 6

Green/Yellow Algae

Answer 6

• non-motile fresh water,soil
• asexual
• normally single celled

Question 7

Golden Algae

Answer 7

• Asexual: zygotic meiosis; haploid is dominant
• photosynthetic but also vigorous eaters (eat bacteria and can live in low-nutrient water)
• normally single celled

Question 8

Oomycetes:

Answer 8

• aquatic and terrestrial habitats
• used to have photosynthetic ability but lost it
• thought to have been a fungi but the 2 flagella placed it under stramenophiles
• they can have homothalic (sexual organs on different organisms) or heterothalic, having both sexes on same individual
• hyphae are 2n

Question 9

Alveolates

Answer 9

• 3 major subgroups
• means, “with cavities”
• single celled
• some photosynthetic, some not

Question 10

Dinoflagellates

Answer 10

• single celled
• 2 flagellas
• most have thecas (cellulose plates)
• some have penduncle (“3rd flagella” that extends to get food)
• Reproduction: longitudinal cell division, sex, cysts
• release toxins for preditor protection
• bioluminescent

Question 11

Zooanthellae

Answer 11

helps for coral growth

Question 12

Zygotic meiosis

Answer 12

Haploid organisms producing haploid gametes (an entity), which release haploid gametes that fuse together to create diploid zygotes
-through meiosis, haploid organism is produces

Question 13

Gametic meiosis

Answer 13

Diploid organisms produce haploid gametes which fuse to create diploid zygotes
-no meiosis after this; organism remains diploidq

Question 14

Sporic meiosis

Answer 14

• haploid spores divide to produce gametophyte, which is a haploid entity
• gametophyte produces haploid gametes that fuse and become diploid zygote
• zygote grows and becomes an entity (sporophyte)
• releases spores that undergo meiosis to become haploid spores

Question 15

Parasites (Apicomplexans)

Answer 15

• are under alveolates
• no flagella/cilia
• complex life cycle (different stages in hosts)
• plasodium has N stage in humans and 2n in mosquitos
• sporic meiosis

Question 16

Cryptomonads

Answer 16

-important for understanding secondary ES

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