Describe the ongoing research concerning the relationship between species richness and community
stability. What research supports or fails to support this relationship? What will be an ideal response?
Concepts to Consider: The traditional view supports increasing species richness as a cause of
community stability; experimental and field research supports this view, including: 1) studies in
monocultures such as agricultural areas that are susceptible to disruptions due to lack of species
richness, and 2) studies by Tilman and Downing in Minnesota grasslands; however, typical community
structure does vary from year to year, indicating a natural variation in species densities. Also note
criticisms of this study that suggest using established ecosystems, rather than plots, in order to avoid
additional confounding variables.
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Denitrifying bacteria are often facultative anaerobes, capable of performing other forms of respiration or fermentation as well as nitrate reduction
Indicate whether the statement is true or false.
The phospholipids of plasma membranes have
a. a hydrophobic head and a hydrophilic tail. b. a hydrophobic head and a hydrophobic tail. c. a hydrophobic head and two hydrophobic tails. d. a hydrophilic head and two hydrophobic tails. e. a hydrophilic head and two hydrophilic tails.
Choose the correct formula for the reaction that takes place between hydrogen and oxygen to produce
water. a. H2 + O2 ? H2O b. H + O ? H2O c. 2H2 + O2 ? 2H2O d. 2H2O + O2 ? 4H2O e. 2H2 + 2O2 ? 2H2O
One of the questions early geneticists had to answer was how only four nucleotides can specify placement of 20 amino acids in proteins. Today we know that _________, a sequence of three adjacent nucleotides, determine the insertion of a specific amino acid in a polypeptide chain
a) codon b) karyotype c) reverse transcritption d) glycerol