Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 702
TLS Online TPP Program

#Question id: 720

How would a homopolymer of alanine be more likely to form an alpha helix in water or in a hydrophobic medium?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. In an aqueous environment, the formation of intrachain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms. In an hydrophobic environment, these groups are stabilized by interaction with water, and so there is no energetic reason to form an a helix. Thus, the alpha helix would be more likely to form in a aqueous environment.

  2. In a hydrophobic environment, the formation of intrachain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms. In an aqueous environment, these groups are stabilized by interaction with water, and so there is no energetic reason to form an alpha helix. Thus, the alpha helix would be more likely to form in a hydrophobic environment.

  3. In both hydrophobic environment as well as aqueous environment, the formation of intrachain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms.

  4. In a aqueous environment, the formation of interchain hydrogen bonds stabilizes the amide hydrogen atoms and carbonyl oxygen atoms of the polypeptide chain, and so an alpha helix forms. In an hydrophobic environment, these groups are stabilized by interaction with water, and so there is no energetic reason to form an alpha helix. Thus, the alpha helix would be more likely to form in a aqueous environment.

More Questions
TLS Online TPP Program

#Question id: 12970

#Unit 10. Ecological Principles

In deep-sea hydrothermal vents near the Galapagos Islands, bacteria obtain energy by oxidizing hydrogen sulphide released from the vents. Giant tube worms, which lack mouths and digestive systems, harbour the bacteria in their tissues and use them as a source of organic molecules. Clams obtain energy by filtering bacteria directly from the water, and numerous crabs and octopi feed on the clams. In this unique ecosystem, the bactena are playing the role of
TLS Online TPP Program

#Question id: 12971

#Unit 10. Ecological Principles

One group of ecologists has suggested that producers are limited by competition for resources, primary consumers (herbivores) are limited by predation, and secondary consumers (carnivores) are limited by food. If this were true, at which of the following trophic levels would one expect to find substantial evidence for competitive exclusion?
TLS Online TPP Program

#Question id: 12972

#Unit 10. Ecological Principles

Under  some  circumstances a  population  can  split  into  two  or  more  species  without  the  existence of  geographic barriers. All of the following genetically determined behaviours could provide conditions leading to speciation EXCEPT
TLS Online TPP Program

#Question id: 12973

#Unit 10. Ecological Principles

The oceans affect the biosphere in all of the following ways except 
TLS Online TPP Program

#Question id: 12974

#Unit 10. Ecological Principles

Which lake zone would be absent in a very shallow lake?
TLS Online TPP Program

#Question id: 12975

#Unit 10. Ecological Principles

Which of the following is true with respect to oligotrophic lakes and eutrophic lakes?