Unit 1 Progress Check: MCQ

Which statement describes how water is pulled up through the xylem to the leaves of the plant?

As water exits the leaf, hydrogen bonding between water molecules pulls more water up from below.

Which of the following best describes the process that adds a monosaccharide to an existing polysaccharide?

A specific enzyme removes the hydrogen (HH) from the monosaccharide and the hydroxide (OHOH) from the polysaccharide, creating a bond between the two and creating a water (H2OH2O) molecule.

Water molecules are polar covalent molecules. There is a partial negative charge near the oxygen atom and partial positive charges near the hydrogen atoms due to the uneven distribution of electrons between the atoms, which results in the formation of hydrogen bonds between water molecules. The polarity of water molecules contributes to many properties of water that are important for biological processes. Which of the following models best demonstrates the arrangement of hydrogen bonds between adjacent water molecules?

/O\ /H H H--O \H

Figure 1 represents a segment of DNADNA. Radiation can damage the nucleotides in a DNADNA molecule. To repair some types of damage, a single nucleotide can be removed from a DNADNA molecule and replaced with an undamaged nucleotide. Which of the four labeled bonds in Figure 1 could be broken to remove and replace the cytosine nucleotide without affecting the biological information coded in the DNADNA molecule?

Bonds YY and ZZ at the same time

Which of the following would most likely occur if cattle lost the ability to maintain a colony of microorganisms in their digestive tract?

Cattle would no longer be able to use cellulose as a primary source of glucose.

A student wants to modify model 1 so that it represents an RNARNA double helix instead of a DNADNA double helix. Of the following possible changes, which would be most effective in making model 1 look more like RNARNA than DNADNA?

Changing the deoxyriboses to riboses by adding −OH−OH groups

Which of the following statements best describes the different functions of starch and cellulose in plants?

The differences in the assembly and organization of the monomers of these two polymers result in different chemical properties.

Which feature of model 1 best illustrates how biological information is coded in a DNADNA molecule?

The linear sequence of the base pairs

A study determined the effect of two different digestive enzymes, AA and BB, on these two polysaccharides. Table 1 presents the data from the study. Mammals do not produce digestive enzyme BB. However, sheep and cattle are two types of mammals that contain microorganisms in their digestive tract that produce enzyme BB. Question Based on Figure 1, which of the following best compares the atomic structures of starch and cellulose?

Starch and cellulose are composed of repeating glucose monomers; however, in cellulose every other glucose monomer is rotated 180 degrees.

As shown in the diagram, when environmental temperatures drop below freezing, a layer of ice typically forms on the surface of bodies of freshwater such as lakes and rivers. Which of the following best describes how the structure of ice benefits the organisms that live in the water below?

The water molecules in ice are farther apart than those in liquid water, so the ice floats, maintaining the warmer, denser water at the lake bottom.