Lecture 11: Algae

Question 1

Algae

Answer 1

Photosynthetic protists who
gained oxygenic
photosynthesis via primary
or secondary endosymbiosis

Question 2

How much of Earth’s oxygen does algae produce?

Answer 2

• 30% by algae
• 20% by prokaryotes such as
  cyanobacteria
• 50% by land plants

Question 3

Algal Blooms

Answer 3

Rapid growth of ‘algae’ due to increase in nutrients from fertilized agriculture lands, untreated factory waste water, etc.

Question 4

Which two organisms cause algal blooms

Answer 4

Caused by both algae and cyanobacteria

Question 5

how do algal blooms affect the environment?

Answer 5

• Water hypoxia through bacterial decomposition
  of dead algae
• Mechanically damaging gills
• Production of algal toxins

Concerns for environmental conservation and economic damage by affecting aquacultures and tourism.

Question 6

what is increasing algal blooms

Answer 6

climate change

Question 7

Alveolate in the SAR supergroup

Answer 7

• Unicellular algae
• About half are chemoheterotrophs, others are
  photoautotrophs/mixotrophs

Question 8

Algal bloom of dinoflagellates causes

Answer 8

red tide

Question 9

Photoautotrophic dinoflagellates contain ___ as one of their photosynthetic pigments

Answer 9

carotenoids

Question 10

what group do Haptophytes belong to?

Answer 10

‘Unresolved’ group in the eukaryotic
phylogenetic tree. Compromises of mostly marine, unicellular photoautotrophs and mixotrophs

Question 11

morphology of Haptophytes

Answer 11

• Two flagella for motility plus a haptonema for surface attachment and/or predation
• Surface of haptophytes are covered with small scales made of polysaccharides

Question 12

some Haptophytes have ___ scales

Answer 12

• Some haptophytes like Emiliana hyxleyi have hard, calcified scales

Question 13

Stramenopiles, of SAR supergroup morphology

Answer 13

• Straw-hair (Latin, Stramen-pilos), as
  many members have flagellum with fine, hairlike projections
• Diatoms, a unicellular, photoautotrophic Stramenopile
• One of the most abundant photosynthetic organisms in oceans and lakes
• Diatoms have glass-like cell wall made of silicon dioxide for mechanical protection vs. predation

Question 14

Diatoms of various shapes are distributed in

Answer 14

aquatic systems such as oceans, rivers and lakes

Question 15

Diatoms are well preserved due to their

Answer 15

silica shell

Question 16

Forensic limnology isolates diatoms from crime scenes to better understand the case. However why isn’t it useful as legal evidence?

Answer 16

Not as useful as legal evidences due to the amount of variation in samples

Question 17

Brown algae (seaweeds)

Answer 17

Multicellular photoautotrophic
Stramenopile, and the largest, most
complex algae

Question 18

Brown algae (seaweeds) morphology

Answer 18

Have organ-like structures which are analogous to plants:
* Blades: increase surface area (leaf-like)
* Stipe: support the blades (stem-like)
* Holdfast: anchor the alga (root-like)
* Can get up to 60 m tall
* Some have gas-filled floats to help the blades get closer to the water surface
* Plant-like reproduction cycle

Question 19

Diploid

Answer 19

Cell with a pair of chromosomes (2n)
* n=23 for human, 46 chromosome total

Question 20

Haploid

Answer 20

Cell with a single set of chromosome (n)

Question 21

Human example for sexual reproduction

Answer 21

1. Diploid adult (n=46) produces haploid, unicellular gametes (sperm/egg, n=23) via meiosis
2. Haploid sperm (n=23) fuses with haploid egg (n=23), producing a diploid, unicellular zygote (n=46)
3. Diploid zygote divides by mitosis to grow into diploid adult (n=46)

Question 22

For reproductive cycle of animals,
multicellularity only occurs

Answer 22

during the diploid stage

Question 23

Alternation of generation

Answer 23

Plants and some algae produce multicellular bodies in both diploid and haploid stages

Question 24

Sporophyte

Answer 24

Spore-producing, diploid
multicellular form

Question 25

Gametophyte

Answer 25

Gamete-producing, haploid multicellular form

Question 26

Alteration of Generation process

Answer 26

1. Diploid sporophyte produces haploid spores by meiosis 2. Haploid spores divide by mitosis to become the haploid gametophyte 3. Haploid gametophyte produces haploid gametes by mitosis 4. Two haploid gametes fuses, producing a diploid, unicellular zygote 5. Diploid zygote grows by mitosis to become the diploid sporophyte

Question 27

Brown algae spores are called

Answer 27

zoospores since they can move with flagella

Question 28

About half of zoospores develop into

Answer 28

haploid multicellular female gametophyte, the other half develop into male gametophyte

Question 29

Female and male gametophytes produce

Answer 29

gametes (egg and sperm), which meet and fertilize into the diploid zygote

Question 30

Archaeplastida

Answer 30

* Direct ancestors of primary endosymbiosis * The 'source organisms' of secondary endosymbiosis

Question 31

'Green algae' is a ___ group which is missing the Embryophytes (___)

Answer 31

paraphyletic (plants)

Question 32

Two main groups of green algae:

Answer 32

* Chlorophytes: the sister group to the clade Streptophyta (Charophytes + plants) * Charophytes: the closest relative to land plant

Question 33

Charophytes, Green algae

Answer 33

* Closest relative to plants * Determined by molecular phylogeny of nuclear, mitochondrial and plastid DNA, as well as morphological features

Question 34

Charophytes and plants:

Answer 34

* Both synthesize cell wall using ring-like protein structure, embedded in plasma membrane * Both have flagellated sperm * Both have similar nuclear, mitochondrial and chloroplast DNA * Both have sporopollenin

Question 35

Sporopollenin

Answer 35

tough layer which surrounds charophytes zygotes to prevent it from drying out

Question 36

Sporopollenin eventually enabled ___

Answer 36

ancestral charophytes to live permanently on land, above water surface

Question 37

Plants have sporopollenin walls which encase

Answer 37

plant spores Note the difference: Charophyte sporopollenin encases their zygotes, plant sporopollenin encases their spores.

Question 38

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Answer 38

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