Test Exam I.2
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Test Exam I.2
Majority of cyanobacteria are __. Some can be __; others may exhibit __.
How can they exhibit this?
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?
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 __.
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.
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.
- not very common
binary fission and fragmentation
cy. are the simplest organisms
varies, but vast majority livein freshwater lakes (majority), rivers, streams
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)
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 __.