Misc #3

Question 1

Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell’s plasma membrane.

Figure 1. A section of a cell’s plasma membrane, showing a channel protein and a concentration gradient across the membrane

An investigator wants to understand whether a newly found membrane protein is involved in membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport?

Answer 1

Add more of the proteins to the plasma membrane and measure the rate of the particle movement.

Question 2

Water is constantly diffusing into the cytosol of freshwater single-celled organisms. In order to maintain the proper solute concentrations in the cytosol, contractile vacuoles pump out the excess water. An experimenter placed single-celled organisms into various saline concentrations and recorded the ATP used by the contractile vacuole. The data are shown in the graph.

Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution?

Answer 2

Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum

Question 3

The transport of a substance across a plasma membrane of a specific organelle requires energy. The rate at which the transport takes place also depends on temperature. A scientist isolated the specific organelle and then used the following treatments to determine the conditions that will result in the maximal transport. All treatments contained the extracted organelle and were maintained at 25°C.

The data from this experiment indicate that maximal rate of transport of protein X at 25°C occurs at an ATP concentration of 1.0μm/mL.

Which procedure should be done next to gather data needed to meet the scientist’s objective?

Answer 3

Incubate samples containing 1.0μm/mL of ATP at four temperatures other than 25°C .

Question 4

DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids.

Which of the following best describes a structural difference between DNA and RNA?

Answer 4

The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.

Question 5

Figure 1 represents a nucleic acid fragment that is made up of four nucleotides linked together in a chain.

Figure 1. Nucleic acid fragment

Which of the following characteristics of Figure 1 best shows that the fragment is RNA and not DNA?

Answer 5

The identity of each nitrogenous base

Question 6

Which of the following conclusions is most clearly supported by the representations of nucleic acid #1 and nucleic acid #2 ?

Answer 6

Nucleic acid #1 contains adenine-thymine base pairs, whereas nucleic acid #2 does not.

Question 7

Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in Figure 1.

Figure 1. A model showing a cell engulfing a smaller cell

Which of the following provides evidence to best support the researchers’ claim?

Answer 7

The organelle has a double membrane.

Question 8

Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells?

Answer 8

Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell’s nucleus.

Question 9

The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host.

Which of the following observations best supports the model?

Answer 9

Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP

Question 10

Which of the following best describes the numbered areas?

Answer 10

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

Question 11

The model below shows the structure of a portion of a plasma membrane in an animal cell.

Which statement best explains the orientation of the phospholipid molecules in this model?

Answer 11

The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.

Question 12

A model of the plasma membrane showing several biological molecules, including a transmembrane protein, is shown in Figure 1.

Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?

Answer 12

Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.

Question 13

The molecular structures of linoleic acid and palmitic acid, two naturally occurring substances, are shown in the figure.

Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?

Answer 13

Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.

Question 14

Which of the following best describes the structures of carbohydrates?

Answer 14

They occur as monomers, chains of monomers, and branched structures.

Question 15

Which of the following best describes how amino acids affect the tertiary structure of a protein?

Answer 15

The interactions of the different R -groups with other R -groups and with their environment determine the tertiary structure of the protein.

Question 16

A model of a process involving nucleic acids is shown in Figure 1.

Which of the following best explains what process is represented in Figure 1 ?

Answer 16

New DNA strands are being synthesized in the 5’ to 3’ direction from their DNA templates.

Question 17

Figure 1 shows some relevant details of a model of how a deoxynucleotide, in this case dTMP, is added to a growing strand of DNA.

The features of this model provide evidence for which explanation of why all growing strands are synthesized in a 5′ to 3′ direction

Answer 17

The phosphate group, attached to the 5′ carbon of the dTMP , forms a covalent bond with the oxygen atom attached to the 3′ carbon of the growing strand.

Question 18

Figure 1 illustrates a model of the molecules involved in DNA replication and their placement relative to each other.

which of the following correctly explains where DNA replication will begin on the strand oriented 5’→3’, reading from left to right?

Answer 18

DNA replication will be initiated immediately to the left of the RNA , since DNA polymerase requires an RNA primer.

Question 19

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1.

A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researcher’s claim?

Answer 19

Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

Question 20

Ethylene causes fruits to ripen. In a signaling pathway, receptors activate transcription factors, which ultimately leads to ripening.

Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to ripening of fruit?

Answer 20

Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

Question 21

A student claims that the Y chromosome contains the sex-determining region gene, known as the SRY gene, which causes male fetuses to develop testes.

Which of the following provides correct information about cell signaling that supports the claim?

Answer 21

The SRY gene produces a protein that binds to specific regions of DNA in certain tissues, which affects the development of these tissues.

Question 22

The carbohydrates glucose, galactose, and fructose have the same chemical formula (C6H12O6) but different structural formulas, as represented in the figure.

Which of the following statements about glucose, galactose, and fructose is most likely true?

Answer 22

The carbohydrates have different properties because they have different arrangements of carbon, hydrogen, and oxygen atoms.

Question 23

Water and ammonia interact to form hydrogen bonds, as represented in the figure.

Which statement best helps explain the formation of the hydrogen bond represented in the figure?

Answer 23

The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.

Question 24

Figure 1 is a diagram of water molecules at the air-water interface at the surface of a pond.

Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water’s surface?

Answer 24

Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.

Question 25

A model that represents a process occurring in a cell of a particular organism is shown in Figure 1.

Which of the following correctly explains the process shown in Figure 1 ?

Answer 25

Initiation of transcription is occurring because a strand of RNA is being produced from a DNA template strand.

Question 26

Figure 1 represents part of a process that occurs in eukaryotic cells. There are untranslated regions (UTR) in this sequence.
Which of the following best explains the process represented by Figure 1 ?

Answer 26

The enzyme-regulated processing of pre‑ mRNA into mature mRNA

Question 27

Figure 1 represents part of a process essential to gene expression.

Which of the following best explains what strand X represents?

Answer 27

The antisense strand, because it is serving as a template