The arrangement being tested is how the two DNA strands orient their backbones. In DNA, the sugar-phosphate backbones run in opposite directions along the helix: one strand goes 5' to 3' while the other goes 3' to 5'. This antiparallel orientation is essential for proper base pairing and for enzymes like DNA polymerase, which add nucleotides to the 3' end during synthesis. If the strands were parallel (same direction), the geometry wouldn’t support the standard Watson-Crick pairing in the helix and would disrupt replication and transcription. Complementary describes which bases pair, not the overall backbone direction, so it doesn’t describe the orientation of the backbones. So the term antiparallel best captures how the backbones are arranged.

Funnels are designed to pour liquids into containers with small openings by using a wide mouth and a narrow spout. The broad top catches and holds the liquid, while the slim stem guides it precisely into a bottle, flask, or test tube without splashing. This combination makes pouring into narrow openings much easier and safer, reducing spills. Beakers have wide mouths but no narrow spout, so they’re not ideal for directing liquid into small mouths. A graduated cylinder is built for measuring rather than guiding pours into another container. A pipette excels at delivering precise, small volumes but isn’t the general tool for transferring larger amounts into containers with narrow openings. So the funnel best fits the described use.

Genetic testing is used to detect alterations in the genetic material or its direct products. It looks for changes in chromosomes, in specific genes, or in the proteins encoded by those genes. For example, chromosomal changes like extra copies or missing segments, gene mutations that alter function, or abnormal protein variants can indicate a genetic condition or carrier status. This distinguishes it from measuring physical traits or cellular functions, such as how readily a cell membrane lets substances through, which is a physiological property rather than a genetic change. It also isn’t about whole-body measurements like blood pressure or heart rate, or about energy production directly, which are influenced by many factors beyond the genome. Therefore, identifying changes in chromosomes, genes, or proteins captures what genetic testing is designed to reveal.

Rh compatibility centers on whether red blood cells carry the D antigen. People who are Rh-negative lack this antigen, so if they receive Rh-positive blood, their immune system can recognize the D antigen as foreign and make anti-D antibodies. Those antibodies can then cause a reaction if the person is exposed to Rh-positive blood again in the future. To prevent this sensitization, the safest and most consistent practice is to transfuse Rh-negative patients with Rh-negative blood. Rh-positive blood can be given to Rh-positive recipients because their immune system already tolerates the D antigen. The other options would risk sensitization or are simply not necessary for someone who is Rh-positive.

Nucleic acids are polymers built from repeating units called nucleotides. Each nucleotide contains a sugar (deoxyribose in DNA or ribose in RNA), a phosphate, and a nitrogenous base. Nucleotides link together via phosphodiester bonds to form long chains that store and transmit genetic information. This is distinct from other biomolecules: proteins are made from amino acids, lipids from fatty acids, and carbohydrates from monosaccharides. So the building blocks are nucleotides.