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
