Four of the following are key characteristics for the survival of a species. Which one is the exception?
A. Ability to acquire energy and nutrients
B. Response to environmental change
C. Reproduction
D. Inability to change
E. Ability to grow and adapt through changes in DNA
Answer: D
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Mendel found that pea plants expressing a recessive
trait a. were pure-breeding. b. appeared only in the first generation of a cross between two pure-breeding plants expressing contrasting forms of a trait. c. disappeared after the second generation. d. could be produced only if one of the parents expressed the recessive trait. e. were none of these.
The genomes of free-living spirochaetes are larger than those living in animal hosts. Why might this be so?
A. Free-living spirochetes will need genes to code for additional proteins to synthesize or obtain their own food from the environment around them. Parasitic spirochetes obtain nutrients from the animal host, and may not need to move towards those nutrients either. B. The spirochetes in animal hosts are different species entirely. As different species, they would naturally have smaller genomes. C. A smaller genome implies simplicity-the spirochetes living in animal hosts have fewer needs, so they need fewer genes. D. It isn't so-all spirochetes would have the same size genomes, since they're all the same species of microbe.
Archaeans like Sulfolobus have multiple origins of replication. This suggests that they
a. in this regard, are more like bacteria than eukaryotes. b. in this regard, are more like eukaryotes than bacteria. c. have a unique form of chromosomal replication. d. have multiple plasmids, whose replication must be coordinated. e. have multiple chromosomes.
Microorganisms use hydrogen bonds to attach themselves to the surfaces that they live upon. Many of them lose hold of the surface because of the weak nature of these bonds and end up dying or being washed away
Why don't microbes just use covalent bonds instead? A. Covalent bonds are always permanent bonds; the microbes could never get OFF their surface if they used them. B. Covalent bonds depend on completely giving up or completely accepting an electron to form the bond. This isn't possible for many microbes without dramatically altering their basic molecular composition. C. Covalent bonds typically require enzymes to form/break, whereas hydrogen bonds don't. If covalent bonds were used, it would require much more energy and molecules to be contributed from the cell. Hydrogen bonds don't have these requirements. D. Covalent bonds may have more specific and stringent requirements for what atoms can bond with. This makes for stronger bonds, but also decreases the overall potential for bonds that could readily be created between the microbe and its desired surface. E. C and D