Test Exam I.2
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Majority of cyanobacteria are __. Some can be __; others may exhibit __.
How can they exhibit this?
- true branching
How? Cells start dividing on a different plane (ex: they usually divide horizontally and then divide vertically)
They also exhibit __. How can that be explained?
- false branching
- a break in the filament, causing separation (one continues to divide; another doesnt; this forms a branch)
If both pieces continue to divide: a pair of false branches
All in all, branches are mainly formed due to __.
Sometimes, the filaments are __. In a few, there may be a __ around a __.
What may this do?
a change in direction
- gel matrix around a group of filaments
may help survival and moisture to be retained= resistant to drying
What are the characteristics needed to be considered multicellular?
- differentiated cells (specialized)
Cyanobacteria have __. The only "body type" with this is __.
What are the two cells?
1) heterocyst: occur in trichomes of some species; bigger than )and develop from) vegetative cells; round, thicker wall; not as granular; lighter in color
1) function in __.
2) contain __ where there is a __ (beetween __) called __.
3) How many __ there are varies.
4) What does it do?
- 1) nitrogen fixation
- 2) polar nodules/ cytoplasmic connection/ heterocyst and neighboring vegetative cell/ microplasmodesmata
- 3) polar nodules
- 4) connects cells
1) occurs mainly in __.
3) What does this reaction do?
4) It takes __ to break the strong __ between __ of __.
N2 + 12 ATP--> 2 NH3 + 12 ADP + 12 Pi
make N available for the whole organism
alot of energy (12 ATP)/ triple bond/ two nitrogen molecules/ N2 gas
__ catalyzes nitrogen fixation. Very sensitive to __. A majority of cyanobacteria can't __.
What happens if the oxygen producing level is lower?
In heterocysts, you don't find __.
Nitrogenase is inactivated when __.
- fix nitrogen
less pigments--> higher in color
an oxygen-binding pigment
oxygen is present
Heterocysts and False Branching
1) The cxn between __ and __ is a __.
2) This is where __.
3) What does this explain?
- 1) heterocysts/ vegetative cells/ point of weakness
- 2) some branches form (between heterocysts and vegetative cells)
- 3) why only one part of a branch forms
- - if there are double branches, there may not have been a heterocyst at all
A few __ can fix nitrogen.
- 1) enormous
- 2) sometimes next to a heterocyst
- 3) very granular/ stacked with storage food (major function)
- 4) resistant to adverse survival mechanisms; they can survive adverse conditions
__ can develop from vegetative cells.
Not a __; more of a __.
Longest __ is __ years.
reproductive structure; survival structure
87 years (average: 70-80 years)
No __ in cyanobacteria.
Some filamentous forms demonstrate a __.
- It may be due to __.
Not considered a __.
- how do they move?
One species of cyanobacteria (__) is capable of __.
sliding/ gliding/ swaying/ or twisting motion
extrusions of mucilage from pores
form of motility
move at the whim of currents
- no __, but instead __, leading to __, which are __.
- no __ or __.
- each cy. has __.
true sex. reproduction/ asex/ production of clones/ genetically identical
mitosis or binary fission
one molecule of DNA
attached to membrane--> cell increases in length--> formation of cell wall and membrane--> two new cells
in colonies, they either do it together or separately
Reproduction by formation of __.
- process of binary fission but the cells aren't identical in size
Reproduction through __.
- filaments grow--> buffeted around--> break off--> new organism
Two basic forms of reproduction are __
What are cy.
- special fragmentation
- - not very common
binary fission and fragmentation
cy. are the simplest organisms
varies, but vast majority livein freshwater lakes (majority), rivers, streams
- 20% marine
- a few on moist soil, bare soil, or rock (usually next to a stream)
Explain their attachment.
Free floating or attached to other things (epiphytes)
What does epiphyte refer to?
means upon a plant, but refers to attachment to rocks and other things as well
If floating, they are important as __.
Cy are an important __ and are right at the __.
They occur at a wider range of habitats and __.
source of food/ baseof the food chain
tolerate alot more than euk might not
Example of extreme conditions.
thermophilic (extreme heat) (true cant tolerate this)
- really cold (but so can true algae)
- high salilinty and really acidic and basic conditions
2) very often, they are found __.
2a) When this occurs, they __.
both organisms benefit
inside the cell of an organism
in here, they lack a cell wall- act as chloroplasts, giving rise to endosymbiosis idea
Sym. cy. can grow with __ and have a __.
Aquatic ferns have __ containing cy. that __.
- fungal cells (lichens)
- unique structure
- leaf cavities
- fix nitrogen (cy benefit by receiving mroe light)
__ is a cy. that contains __.
-Can be grouped with __ of __.
How do terrestrial plants benefit?
through the N fixation
A majority of cyanobacteria have neither __ nor __.
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