CH 24 HW Flashcards
Miller and Urey’s experiments that attempted to recreate conditions on early Earth were significant because ________ ?
they showed that organic molecules such as amino acids could be produced from inorganic molecules
Why do some scientists believe that RNA, rather than DNA , was the first genetic material?
RNA has both information storage and catalytic properties.
The earliest organisms were most likely _______?
Prokaryotic
Which of the following is the correct sequence of events in the origin of life (formation of the first simple cells)?
synthesis of organic molecules, synthesis of organic macromolecules, formation organic molecules, formation of DNA-based genetic systems
Which of these questions regarding the origin of life on Earth is currently the most challenging and would have the greatest impact on our understanding if we were able to answer it?
How did RNA sequences come to carry the code for amino acid sequences?
Which of the following is likely the greatest impact that early cyanobacteria had on Earth?
increasing the atmosphere’s oxygen concentration though photosynthesis
Which of the following was present when life first evolved on Earth?
Water
The abiotic synthesis of ____, such as amino acids and nitrogenous bases, may have occurred near volcanoes or around deep-sea vants.
small organic molecules
The abiotic synthesis ____, may have occurred as organic monomers splashed onto hot rocks and spontaneously joined into chains.
Polymers
The first ____ may have formed when collections of organic molecules became isolated within membranes.
Protocells
The first genetic material was probably self-replicating _____.
RNA
Once some protocells contained self-replicating molecules, ____ could have begun to shape their properties as those that reproduced more efficiently would have increased in number.
Natural Selection
At some point, ____, a more stable molecule, became the genetic material.
DNA
The earliest evidence of life on Earth is 3.5-billion-year-old fossils of ____, which were built up by ancient photosynthetic prokayotes.
Stromatolites
What is function of fimbriae?
They are used to attach the cell to its substrate or to other prokaryotes.
Select the valid comparison between eukaryotes and prokaryotes.
- The total biomass of eukaryotes is approximately ten times the total biomass of prokaryotes.
- Eukaryotes are far more metabolically diverse than prokaryotes.
- Prokaryote cells have simpler internal structure and genomic organization than eukaryotic cells.
c) Prokaryote cells have simpler internal structure and genomic organization than eukaryotic cells.
What structure can allow a bacterium to persist, often over extended periods of time, in environments that nutrients, are dehydrating, or are freezing, or very hot?
Capsules or Endospores
If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, but does contain the large circular chromosome, the regenerated bacterium will probably also?
lack antibiotic-resistant genes
With regards to obtaining carbon and energy, you are a ____, while a photosynthetic cyanobacterium is a ____.
chemoheterotroph, photoautotroph
The energy source is sunlight and the carbon source is carbon dioxide CO2 what is the mode of nutrition?
PhotoAutotroph
The energy source is sunlight the carbon source is organic compounds what is the mode of nutrition?
PhotoHeterotroph
The energy source is chemicals the carbon source is carbon dioxide what is the mode of nutrition?
ChemoAutotroph
The energy source is chemicals the carbon source is organic compounds what is the mode of nutrition?
ChemoHeterotroph
Binary fission is a form of what and why?
A form of asexual reproduction because a single individual is the sole parent and passes copies of all its genes to its offspring.
During binary fission, DNA replication begins at the ? and continues where?
origin of replication, and continues all the way around the circular chromosome.
When DNA replication is complete and the bacterium has reached twice its original size, the ____ grows inward, dividing the parent cell into two daughter cells.
Plasma membrane
In theory, the two daughter cells are ____ to each other and the parent cell
genetically identical
However, mistakes made during DNA replication sometimes result in ____, changes to the nucleotide sequence of DNA.
Mutations
The rapid reproduction and large population sizes of many bacterial populations mean that even a small mutation can lead to considerable ____.
Genetic variation
Carrying the F factor in a plasmid is apart of which type of F cell?
F+ Cell
May donate a plasmid to another cell is apart of which type of F cell?
F+ Cell
Carries the F factor in its circular chromosome is apart of which type of F cell?
Hfr cell
May donate genes from its chromosome to another cell is apart of which type of F cell?
Hfr cell
May become F+ after conjugation with an F+ cell is apart of which type of cell?
F- cell
May become recombinant after conjugation with an Hfr cell is apart of which type of F cell?
F- cell
May receive genetic material, but cannot donate genetic material is apart of which type of F cell?
F- cell
Say there is a type of bacteria that attaches to the human intestinal lining using a feature that also protects it from bacteriophages and dehydration. The bacterium is not susceptible to the penicillin family of antibiotics, lacks plasmids and contains relatively little peptidoglycan. The cell also lacks F factors and F plasmids. Which mechanism(s) of genetic recombination can possibly take place?
conjugation
transduction
transformation
transformation only
Azotobacter is a genus of bacteria that live in soil and have the following characteristics:
They are bacilli.
They are gram-negative.
They are obligate aerobes.
They can fix nitrogen. (Unlike some other nitrogen-fixing bacteria, which associate with the roots of plants, Azotobacter species are free-living.)
Select the statements that are TRUE for bacteria in the genus Azotobacter.
*They appear purple after Gram staining.
*They can carry out anaerobic respiration in an environment that lacks O2.
*They use O2 for cellular respiration.
*They can convert atmospheric nitrogen to ammonia.
*They are shaped like rods.
*They have a relatively thin layer of peptidoglycan in their cell wall.
*They require amino acids or other organic molecules as a source of nitrogen.
*They have the appearance of coils or corkscrews.
*They are poisoned by O2.
*They use O2 for cellular respiration.
*They can convert atmospheric nitrogen to ammonia.
*They are shaped like rods.
*They have a relatively thin later of peptidoglycan in their cell wall.
What is one of the most diverse characteristics in prokaryotes?
Metabolism
How are archaea most similar to bacteria?
the shape of their chromosomes and plasmids
What is bioremediation?
the use of organisms to remove pollutants from the environment
What is a common ecological role of prokaryotes?
recycling soil nutrients and breaking down organic matter
What role do bacteria typically play in the environment?
decomposers, converters and producers
