1) Explain the importance of a control group in scientific experiments.
2) Briefly discuss the differences between prokaryotic and eukaryotic cells.
7) The origin of life on Earth would not have been possible if the primitive atmosphere contained __________.
8) How does energy flow differ from chemical cycling?
17) What process results in offspring that are adapted to their current environment?
20) Discuss the validity of the following statement (providing your reasoning): Cutting the tails off mice for 100 generations will result in a strain of mice with genes for short tails.
It appears that you are studying for an exam, so I'll try to be brief but complete in my responses to these questions. In case you need them, I'll include links to any references I use.
1) - experiments are performed to investigate the effect of a single or multiple variables on a system.
- the investigator needs to ensure that experimental results are due to the effect of the variable of interest and not due
to unrelated variables.
- controls contribute to the elimination of alternate explanations of experimental results.
2) Prokaryotes (bacteria of the domains Archaea and Eubacteria): First cells to evolve; always exist as single cells or
colonies, do not exhibit true multicellularity; have only a cell membrane, no other membrane-bound organelles; genetic
material is a naked chromosome within the cytosol; ribosomes are the only organelles; reproduce by binary fission to
produce identical daughter cells.
Eukaryotes: more structurally complex, most are multicellular; presence of a nucleus (membrane-bound organelle,
separates genetic material (DNA) from the rest of the cell; contain internal membrane-bound organelles, reproduce in
several ways, including meiosis (sexual reproduction) and mitosis (cell division producing identical daughter cells).
5) A biologist's working definition of "species" often includes the following: "a group of organisms capable of interbreeding
and producing fertile offspring of both genders, and separated from other such groups with which interbreeding does
Roles in scientific experiments are explained.