Unit one Progress check

As shown in Figure 1, an amino acid must have which of the following properties in order to be incorporated into a polypeptide?

The ability to form a covalent bond with both its NH2NH2 group and its COOHCOOH group

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.

Mammals do not produce digestive enzyme B. However, sheep and cattle are two types of mammals that contain microorganisms in their digestive tract that produce enzyme B. Which of the following best describes the process that adds a monosaccharide to an existing polysaccharide?

A specific enzyme removes the hydrogen (H) from the monosaccharide and the hydroxide (OH) from the polysaccharide, creating a bond between the two and creating a water (H2O) molecule.

Figure 1 represents a segment of DNA. Radiation can damage the nucleotides in a DNA molecule. To repair some types of damage, a single nucleotide can be removed from a DNA. DNA 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 DNA molecule?

Bonds Y and Z at the same time (By breaking bonds Y and Z at the same time, the cytosine nucleotide could be removed from the DNA molecule and replaced with an undamaged cytosine without changing the biological information stored in the DNA.)

Which of the following best describes a structural similarity between the two molecules shown in Figure 1 that is relevant to their function?

Both molecules contain nucleotides that form base pairs with other nucleotides, which allows each molecule to act as a template in the synthesis of other nucleic acid molecules.

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. 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 RNA double helix instead of a DNA double helix. Of the following possible changes, which would be most effective in making model 1 look more like RNA than DNA?

Changing the deoxyriboses to riboses by adding −OH groups

Which of the following models best demonstrates the arrangement of hydrogen bonds between adjacent water molecules?

D.

Figure 1. A short segment of a double-stranded nucleic acid molecule Which of the following statements is correct about the molecule shown in Figure 1 ?

It is DNA because of the nucleotides present.

Which of the following is common feature of the illustrated reactions showing the linking of monomers to form macromolecules?

Monomers are joined by a covalent bond, and a water molecule is produced.

Which of the following describes a key difference among the 20 amino acids that are used to make proteins?

Some amino acids are hydrophobic.(Due to having nonpolar R-groups, 10 of the 20 amino acids are hydrophobic. Interactions between hydrophobic amino acids play an important role in determining protein structure and function.)

Mammals do not produce digestive enzyme B. However, sheep and cattle are two types of mammals that contain microorganisms in their digestive tract that produce enzyme B. 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.

How might this change affect the structure and function of the protein?

The R-group of the new amino acid, valine, has different chemical properties than the R-group of cysteine. This will cause the protein to misfold and not function properly in the cell.

Mammals do not produce digestive enzyme B. However, sheep and cattle are two types of mammals that contain microorganisms in their digestive tract that produce enzyme B. 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.

Based on the figure, which statement best describes the observed relationship between atmospheric CO2CO2 enrichment and plant growth under ideal and stressed conditions?

The increase in atmospheric CO2CO2 resulted in a greater increase in plant growth under stressed conditions than under ideal conditions.

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

The linear sequence of the base pairs

Which of the following is the most likely reason for the difference in leaf growth?

The phosphorus-starved plant was unable to synthesize both the required nucleic acids and lipids, limiting growth.

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.