Black-and-white camera film, in the old days of film photography, was very sensitive to blue light but not to red light. Blue skies would often show very little detail, because the film couldn’t record all that it was seeing. To compensate, photographers would put a red filter on the lens, darkening the sky enough that the film could record its fluffy clouds.

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#Question id: 55

#Unit 1. Molecules and their Interaction Relevant to Biology

The standard free energy change for the reaction A → B is −15.0 kJ · mol−1. What is the equilibrium constant for the reaction at 25°C?

#Question id: 56

#Unit 1. Molecules and their Interaction Relevant to Biology

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

#Question id: 57

#Unit 1. Molecules and their Interaction Relevant to Biology

A(n) ________ has charge but negligible mass, whereas a(n) ________ has mass but no charge.

#Question id: 58

#Unit 1. Molecules and their Interaction Relevant to Biology

A covalent chemical bond is one in which ________.

#Question id: 59

#Unit 1. Molecules and their Interaction Relevant to Biology

Nitrogen (N) normally forms three covalent bonds with a valence of five. However, ammonium has four covalent bonds, each to a different hydrogen (H) atom (H has a valence of one). What do you predict to be the charge on ammonium?

#Question id: 64

#Unit 1. Molecules and their Interaction Relevant to Biology

Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what way(s) do these molecules differ from each other? Testosterone and estradiol ________.