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Lecture 9

BIOLOGY 207 Lecture Notes - Lecture 9: Heterotroph, Sieve Tube Element, Ekman TransportPremium

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Bio 207 Lecture 9
Photosynthesis distribution
- Can use chlorophyll a as a proxy for measuring where the most photosynthesis occurs
- Primarily see it in coastal areas, hot spots for algae
o These places tend to be rich in nutrients come up from the bottom (upwelling)
Upwelling: nutrients that are below come to the surface, causing
photosynthetic organisms to bloom and heterotrophs to grow
Ekman transport (upwelling): Prevailing winds pushes water out at a right
angle from the top, so water from the bottom comes up (79)
o Also rich in what comes out of rivers from the land massesmay be natural or
artificial such as fertilizers
I. Stramenopiles, aka heterokonts
a. Found in all three zones of the water (open ocean, shallow coastal waters, and
intertidal zones)
b. Multi and single cellular
c. When flagella are present, they have hairs on their flagella
i. This is the distinguishing derived feature for this group
d. Made up of a couple of photosynthetic organisms, but also have a protest that it
fungus-like (chitin in their cell wall, dna derived from fungi)
II. Brown Algae, called Phaeophytes
a. Multicellular, make up kelp beds, which are anchored to the bottom of the ocean
i. Form underwater forests maybe 30-40 feet long
ii. Sedentary, large-bodied organism
b. Brown because of fucoxanthins (pigment), also have chlorophylls a & c
c. Chloroplasts with 3-4 membranes
d. Structure
i. Have a blade, which is very thin, the photosynthesizing part of the organism
ii. Attached to a stipe (40ft is reasonable)
iii. Holdfast at the bottom
e. Intercalary meristem: hot spots for mitotic growth and tissue regeneration
i. Are able to persist for a long time because of this, can replace eaten/tattered
tissue because of this
f. Pneumatocysts (air bladders): filled with metabolic gases which allow them to stay
g. In order to solve the problem of distributing food to the entire organism, have tube-
like structures (sieve tubes) that spread around everywhere
i. Convergent trait to trees (Not because they are related, just solved the problem
the same way)
h. Kelp life cycle how to get this sedentary, large organism to get to a new place?
i. Two phases:
1. Has a large, sedentary phase (diploid);
a. This is the sporophyte phase
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