1.What is a \'stromatolites\' and what might be a possible relationship between
ID: 35961 • Letter: 1
Question
1.What is a 'stromatolites' and what might be a possible relationship between their formation in early earth and atmospheric changes? What is the significance of this atmospheric change?
2.Describe the three modes that prokaryotes can 'obtain' new genes. Be sure to identify similarities and differences between the three modes. How does the concept of new gene introduction change the view that prokaryotes are asexual species?
3.which statement below best explains why the free O2 in the atmosphere, may have led to a greater diversity of eukaryotic forms?
A. More O2 would have increased metabolism and ATP production which may have increased growth and reproductive rates and therefore species evolution
B. More O2 would have balanced against greater concentrations of toxic gases thus increasing the survivorship of species and therefore species evolution
C. More O2 would have led to the development of complex polymers which would have given rise to more complex forms of life and species evolution
4. Which statement below best describes why the protists are considered a group at an evolutionary 'crossroads'?
A. Protistans represent a diverse group that provided the building blocks for the fungi, plants and animals
B. Protistans represent a mix of prokaryotic and eukaryotic life forms
C. Protistans have the ability to rapidly exchange genetic information between different species thus blurring the lines between distinct evolutionary units of life
Explanation / Answer
Answer:
1) stromatolites are layered mounds, columns, and sheet-like sedimentary rocks. They were originally formed by the growth of layer upon layer of cyanobacteria, a single-celled photosynthesizing microbe that lives today in a wide range of environments ranging from the shallow shelf to lakes, rivers, and even soils. Cyanobacteria are prokaryotic cells (the simplest form of modern carbon-based life) in that they lack a DNA-packaging nucleus. Bacteria, including the photosynthetic cyanobacteria, were the only form of life on Earth for the first 2 billion years that life existed on Earth.cyanobacteria were ultimately responsible for one of the most important "global changes" that the Earth has undergone. Being photosynthetic, cyanobacteria produce oxygen as a by-product. Photosynthesis is the only major source of free oxygen gas in the atmosphere. As stromatolites became more common 2.5 billion years ago, they gradually changed the Earth's atmosphere from a carbon dioxide-rich mixture to the present-day oxygen-rich atmosphere. This major change paved the way for the next evolutionary step, the appearance of life based on the eukaryotic cell (cell with a nucleus).
2)
Binary fission is a type of reproduction in which the chromosome is replicated and the resultant prokaryote is an exact copy of the parental prokaryate, thus leaving no opportunity for genetic diversity.this shows it is asexual reproducution.
Transformation is a type of prokaryotic reproduction in which a prokaryote can take up DNA found within the environment that has originated from other prokaryotes.
Transduction is a type of prokaryotic reproduction in which a prokaryote is infected by a virus which injects short pieces of chromosomal DNA from one bacterium to another.
Conjugation is a type of prokaryotic reproduction in which DNA is transferred between prokaryotes by means of a pilus.
3) A. More O2 would have increased metabolism and ATP production which may have increased growth and reproductive rates and therefore species evolution.
4)B. Protistans represent a mix of prokaryotic and eukaryotic life forms
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