Chapter 2 Homework Questions and Answers
Terms in this set (18)
An atom of iron has the atomic number 26. This means that it has
Helium is not a reactive molecule because its:
first-level shell is full with two electrons.
One important difference between covalent and ionic bonds is that:
in covalent bonds two atoms share electrons, whereas in ionic bonds one atom gives one or more electrons to the other atom.
Water molecules form which type of bond with other water molecules?
Why do coastal areas have milder, less variable climates than inland areas?
Large bodies of water, especially oceans, can absorb huge amounts of heat from the sun during warm times of the year, reducing temperature increases on the land. Similarly, during cold times of year the ocean slowly cools, giving off heat that reduces the temperature drop on shore.
Certain molecules act like bank accounts for H+ ions because they can absorb excess H+ ions to keep a solution from becoming too acidic and release H+ ions to keep the solution from becoming too basic. Such molecules are called:
A chemical compound that releases OH− into a solution is called:
A solution's acidity is a measure of:
the H+ (free-floating protons) it contains.
Which of the following is a polysaccharide?
cellulose, the primary component of plant cell walls
Which of the following statements about fiber is FALSE?
Fiber in the diet slows the passage of food through the intestines.
All lipids are
not soluble in water
An unsaturated fatty acid is one in which:
carbon-carbon double bonds are present in the hydrocarbon chain.
Phospholipids assemble spontaneously into bilayers driven by the attraction of their "tail" portions to each other and of their "head" portions to each other. The tail regions are:
What can happen if an enzyme is altered, even slightly?
Its active site may change, causing the enzyme to stop functioning.
DNA is made of:
All macromolecules important in living systems contain
The Russian-American biochemist Phoebus Levene was the first to determine that nucleotides may contain one of four different nitrogen-containing bases. Levene believed that the nitrogen-containing bases occurred in equal amounts in DNA. What is the actual proportion of these bases?
DNA contains equal amounts of adenine and thymine, and equal amounts of guanine and cytosine.
One of the four nucleotide bases in DNA is replaced by a different base in RNA. Which base is it, and what is it replaced by?
thymine, replaced by uracil