TEAS Test of Essential Academic Skills - Set 4 - Part 2

Correct Answer: Sublimation

Sublimation is the phase change in which a solid converts directly into a gas without passing through a liquid state. Dry ice, which is solid carbon dioxide, undergoes sublimation as it warms in open air. Option a is incorrect because vaporization is the change from a liquid to a gas, including evaporation and boiling. It involves a liquid state in between solid and gas, not a direct transition from solid to gas. Option b is incorrect because condensation is the change from a gas to a liquid. It is the opposite direction of vaporization and does not involve a solid phase or a transition from solid to vapor. Option c is incorrect because deposition is the change from a gas directly to a solid, the reverse of sublimation. Frost forming on a cold surface is an example of deposition rather than sublimation in nature.

Correct Answer: Seven

Pure water has a pH of seven, which is considered neutral on the pH scale. At this pH, the concentrations of hydrogen ions and hydroxide ions in solution are equal, balancing acidic and basic character of water. Option a is incorrect because a pH of zero indicates a very strong acid such as battery acid. Pure water does not contain enough hydrogen ions in solution to reach this extremely acidic pH value at standard conditions. Option b is incorrect because a pH of three is acidic and corresponds to substances like vinegar or orange juice. Pure water has fewer hydrogen ions and a higher, neutral pH at standard conditions in chemistry. Option d is incorrect because a pH of fourteen represents a very strong base such as drain cleaner. Pure water does not contain a high concentration of hydroxide ions and is not strongly basic at all.

Correct Answer: Lipids

Lipids include triglycerides, phospholipids, and steroids. They are characterized by being insoluble in water and play roles in energy storage, forming cell membranes, and serving as precursors to certain hormones such as testosterone and estrogen. Option b is incorrect because proteins are made of amino acids linked by peptide bonds. They serve as enzymes, antibodies, and structural components, but do not include triglycerides, phospholipids, or steroids in their classification. Option c is incorrect because carbohydrates include sugars and polysaccharides such as starch, glycogen, and cellulose. Carbohydrates are made of carbon, hydrogen, and oxygen in a different ratio and are not lipids in any way. Option d is incorrect because nucleic acids include DNA and RNA, which store and transmit genetic information. They are made of nucleotides, not fatty acids and glycerol or fused carbon ring structures of steroids.

Correct Answer: Temperature

Increasing temperature gives solute and solvent particles more kinetic energy, which speeds up collisions and helps the solute dissolve more quickly. For most solid solutes, higher temperature also raises overall solubility in water based solutions. Option a is incorrect because pressure mainly affects gas solubility, not the dissolving rate of solid medications in liquid. Warming the vial does not significantly change the pressure inside the closed container of medication during preparation. Option b is incorrect because solute polarity is a fixed property of the medication's chemical structure. The nurse cannot change polarity simply by warming the vial; warming only affects the movement of the particles. Option c is incorrect because warming the vial does not change how much solvent is present. The volume of solvent stays roughly the same, but the warmer particles move and interact more rapidly with each other.

Correct Answer: Resists changes in pH

A buffer solution resists changes in pH when small amounts of acid or base are added. Buffers usually contain a weak acid and its conjugate base, which absorb extra hydrogen or hydroxide ions to maintain a stable pH. Option a is incorrect because a buffer does not always raise the pH. Its purpose is to keep the pH stable, neutralizing any added acid or base rather than continually pushing the solution in one direction over time. Option c is incorrect because a buffer does not always lower the pH. Buffers stabilize pH against both acids and bases, working in either direction to maintain a relatively constant hydrogen ion concentration in solution. Option d is incorrect because buffers can be set at many pH values, depending on the weak acid and conjugate base used. Blood, for example, is buffered near a pH of seven point four.

Correct Answer: Osmosis

Osmosis is the diffusion of water molecules across a selectively permeable membrane from an area of lower solute concentration to higher solute concentration. It is a passive process that does not require any cellular energy input. Option a is incorrect because active transport moves substances against their concentration gradient using energy from ATP. Water typically moves passively across membranes, so its movement is not classified as active transport in the cell. Option b is incorrect because endocytosis is the bulk movement of materials into the cell by the membrane folding inward to form a vesicle. It does not refer specifically to water moving across the membrane by diffusion. Option d is incorrect because exocytosis is the bulk export of substances from the cell when a vesicle fuses with the plasma membrane. It does not describe the passive movement of water through a membrane.

Correct Answer: Covalent

A covalent bond forms when two atoms share one or more pairs of electrons. This bonding is common between two nonmetals and produces molecules such as water, oxygen gas, and carbon dioxide in nature and biology. Option b is incorrect because hydrogen bonds are weak attractions between a hydrogen atom and an electronegative atom in another molecule. They are intermolecular forces rather than true bonds formed by direct electron sharing in molecules. Option c is incorrect because an ionic bond forms when one atom transfers electrons to another, creating a positive cation and a negative anion. Ionic bonds involve electron transfer rather than electron sharing between two atoms. Option d is incorrect because metallic bonds occur in pure metals, where valence electrons are loosely shared across many atoms in a sea. This differs from covalent bonds between two specific atoms sharing electron pairs.

Correct Answer: Virus

Influenza, the common cold, and chickenpox are all caused by viruses. Viruses contain genetic material wrapped in a protein coat and must invade a host cell to replicate, which is why antibiotics do not treat them. Option a is incorrect because bacteria cause illnesses such as strep throat, tuberculosis, and certain urinary tract infections. None of the diseases listed in the question are caused by bacterial agents requiring antibiotic therapy in patients. Option b is incorrect because fungi cause infections such as athlete's foot, ringworm, and yeast infections. Influenza, the common cold, and chickenpox are not associated with fungal pathogens or fungal cell biology in any way. Option c is incorrect because protozoa cause illnesses such as malaria and giardiasis. The respiratory and skin diseases listed in the question stem are caused by viral agents, not by single-celled eukaryotic protozoans like Plasmodium.

Correct Answer: Toward the reactants

According to Le Chatelier's principle, adding heat to an exothermic reaction is like adding a product. The system shifts to absorb the extra heat by favoring the reverse reaction, producing more reactants over time at equilibrium. Option a is incorrect because shifting toward products would be expected if temperature were lowered, removing heat that the forward reaction releases. Adding heat instead pushes an exothermic system in the reverse direction toward more reactants. Option c is incorrect because changing temperature alters the rates of forward and reverse reactions unequally. The equilibrium position must shift to compensate for the disturbance, so the system does not remain unchanged after heating significantly. Option d is incorrect because reactions do not stop at equilibrium; both directions continue at equal rates. Adding heat changes the rates and shifts the position of equilibrium but does not halt the reaction altogether at any point.

Correct Answer: A phospholipid bilayer with proteins

The plasma membrane is a phospholipid bilayer with proteins embedded throughout. The fluid mosaic model describes this structure, in which proteins drift within the fluid phospholipid sea and serve transport, signaling, and structural roles for the cell. Option a is incorrect because the plasma membrane is not a solid layer of proteins. Phospholipids form the bulk of the membrane, while proteins are embedded within or attached to the surfaces of the lipid bilayer. Option b is incorrect because the plasma membrane is a bilayer, not a single phospholipid layer. The two layers face inward with hydrophobic tails and outward with hydrophilic phosphate heads in the membrane. Option d is incorrect because a rigid wall of cellulose describes a plant cell wall, not the plasma membrane. The plasma membrane is flexible and made of phospholipids and proteins rather than cellulose fibers in plants.

Correct Answer: Insertion or deletion of a base

A frameshift mutation occurs when a base is inserted into or deleted from a gene. This shifts the reading frame for every codon downstream of the change, usually altering the protein sequence severely from that point onward. Option b is incorrect because replacing one base with another produces a substitution, also called a point mutation. Substitutions affect only one codon and may be silent, missense, or nonsense, but they do not shift the reading frame. Option c is incorrect because a silent change codes for the same amino acid as before. Silent mutations leave the protein unchanged, so they do not produce the dramatic frame shift seen in true frameshift mutations of genes. Option d is incorrect because loss of a hydrogen bond is a transient event during DNA replication and transcription. It does not change the underlying DNA base sequence, so it cannot cause a frameshift mutation in the gene.

Correct Answer: Protons and neutrons

The nucleus of an atom contains positively charged protons and uncharged neutrons. These two particles account for nearly all the mass of an atom, while electrons orbit outside the nucleus in shells around the central nucleus. Option a is incorrect because electrons are not located inside the nucleus. Electrons occupy shells surrounding the nucleus and contribute very little mass compared to the protons that share the nucleus with neutrons. Option b is incorrect because electrons are found in shells around the nucleus, not within it. Neutrons do reside in the nucleus, but the nucleus does not contain electrons in its dense central region of the atom. Option c is incorrect because electrons are not in the nucleus at all. The nucleus holds protons and neutrons, while electrons remain outside in shells determined by their respective energy levels around the nucleus.

Correct Answer: Type A or type B only

The father with type AB passes either an A allele or a B allele. The mother with type O passes only the recessive i allele. Children inherit one A or B paired with i, producing type A or type B. Option a is incorrect because type AB requires both an A allele and a B allele. The mother only has i alleles to give, so no child can inherit the two different codominant alleles needed for type AB blood. Option b is incorrect because type O requires two recessive i alleles. The father with AB does not carry an i allele to pass on, so no child from this couple can have type O blood at all. Option d is incorrect because both type AB and type O are impossible in this cross. Type AB requires alleles the mother lacks, and type O requires alleles the father lacks, so neither outcome occurs in offspring.

Correct Answer: Adding a catalyst

A catalyst lowers the activation energy required to begin a reaction, which allows more particle collisions to be productive. Catalysts speed up reactions without being consumed and are not part of the final products of the reaction. Option a is incorrect because lowering temperature reduces particle kinetic energy and slows down reactions. Fewer collisions occur and those that do happen carry less energy, decreasing the overall reaction rate noticeably under standard conditions. Option c is incorrect because decreasing reactant concentration places fewer particles in a given volume. Fewer collisions occur per unit time, which slows the reaction rather than speeding it up under standard laboratory conditions. Option d is incorrect because reducing the surface area of a solid limits how much of it is exposed to other reactants. Less contact area means fewer collisions and a slower reaction overall in any system.

Correct Answer: Codominance

Codominance occurs when both alleles in a heterozygote are fully and equally expressed in the phenotype. The classic example is type AB blood, where both A and B antigens appear on the surfaces of red blood cells. Option b is incorrect because complete dominance occurs when one allele completely masks another in the heterozygote. Only the dominant phenotype appears, while the recessive allele is hidden, unlike codominant expression of both alleles. Option c is incorrect because incomplete dominance produces a blended intermediate phenotype, such as pink flowers from red and white parents. The two alleles are not both fully expressed but rather mixed together into one trait. Option d is incorrect because polygenic inheritance involves many genes contributing to one trait, such as height or skin color. It does not describe the simultaneous full expression of two alleles at a single gene locus.

Correct Answer: Monosaccharide

Monosaccharides such as glucose, fructose, and galactose are the building blocks of carbohydrates. They link together to form disaccharides like sucrose and polysaccharides like starch, glycogen, and cellulose for energy and structural roles in cells. Option a is incorrect because amino acids are the building blocks of proteins, not carbohydrates. They contain an amino group, a carboxyl group, and a side chain, joined together by peptide bonds during protein synthesis at ribosomes. Option b is incorrect because glycerol is a small molecule that combines with fatty acids to form triglycerides. It is part of lipid structure, not a building block used to construct carbohydrate polymers in cells of any organism. Option c is incorrect because nucleotides are the building blocks of nucleic acids such as DNA and RNA. They contain a sugar, a phosphate group, and a nitrogenous base rather than only carbohydrate structural components in a chain.

Correct Answer: Holds the maximum dissolved solute

A saturated solution holds the maximum amount of solute that can dissolve in the solvent at the given temperature. Any additional solute will not dissolve and will simply settle to the bottom of the container as undissolved material. Option a is incorrect because a solution that contains less solute than the solvent can hold is unsaturated, not saturated. More solute could still dissolve into an unsaturated solution under the current temperature conditions of the system. Option b is incorrect because a solution holding more solute than would normally dissolve is supersaturated. Supersaturated solutions are unstable and form when a saturated solution is cooled or otherwise changed in conditions over time. Option d is incorrect because a solution by definition must contain a solvent. Without a solvent, there is nothing for the solute to dissolve in, and the system would not be classified as a solution at all.

Correct Answer: Viruses lack structures antibiotics target

Antibiotics target bacterial structures such as cell walls, ribosomes, and metabolic pathways. Viruses lack these structures because they are not cells, so antibiotics have nothing to act on, leaving viral infections untreated by antibiotic therapy alone. Option a is incorrect because antibiotics specifically target bacteria, not fungi. Fungal infections are treated with antifungal medications, which act on structures unique to fungal cells, such as their ergosterol-containing membranes and chitin walls in the cell. Option c is incorrect because increasing the dose would not change the outcome. Even at high concentrations, antibiotics still cannot affect viruses, since the drug mechanisms target bacterial cellular structures absent from any viral particle. Option d is incorrect because antibiotics primarily target bacteria, not protozoa. Antiprotozoal medications are used for protozoan infections, while antibiotics specifically attack the cell walls and ribosomes of bacterial pathogens

Correct Answer: Salt

In a saltwater solution, salt is the solute because it is the substance being dissolved, and it is present in a smaller amount. Water is the solvent because it is the dissolving medium and the larger component of the mixture. Option b is incorrect because water is the solvent, not the solute, in a saltwater solution. The solvent is the substance present in the larger amount and is responsible for dissolving the smaller component into solution. Option c is incorrect because the container is not part of the solution. The solute and solvent are the two substances mixed together, while the container only holds the resulting solution and does not participate in dissolving anything. Option d is incorrect because dissolved air may be present in trace amounts but is not the substance that defines saltwater. The relevant solute that gives saltwater its identity is the dissolved salt, not the dissolved air molecules.

Correct Answer: Metaphase

During metaphase, the chromosomes align along the cell's equator, also called the metaphase plate. Spindle fibers attach to centromeres and prepare to pull sister chromatids toward opposite poles in the next phase, which is anaphase. Option a is incorrect because prophase is the phase in which chromosomes condense and become visible. The nuclear envelope breaks down and the spindle apparatus begins to form, but chromosomes have not yet lined up at the cell's middle. Option b is incorrect because telophase is the final stage in which nuclear envelopes reform around each set of chromosomes. By telophase, the chromosomes have already separated and reached opposite poles of the dividing cell. Option d is incorrect because anaphase is the phase in which sister chromatids separate and move to opposite poles. The chromatids have already left the middle alignment by this stage of cell division during mitosis.