HESI A2 Biology practice test

Answer: B — Hydrogen bonding between water molecules.

Because water molecules are polar, they form hydrogen bonds with each other. Much of the heat added to water goes into breaking these bonds before the temperature can rise, which gives water its high specific heat.

Checked against: OpenStax Biology 2e, 2.2 Water

Answer: C — Amino acids.

Proteins are chains of amino acids linked by peptide bonds. Monosaccharides build carbohydrates, nucleotides build nucleic acids, and fatty acids are components of many lipids.

Checked against: OpenStax Biology 2e, 3.4 Proteins

Answer: D — Dehydration synthesis.

In dehydration synthesis a hydrogen from one monomer and a hydroxyl group from the other are removed as water, forming a covalent bond. Hydrolysis is the reverse: water is added to break the bond.

Checked against: OpenStax Biology 2e, 3.1 Synthesis of Biological Macromolecules

Answer: B — Ribosomes.

Prokaryotes have a plasma membrane, cytoplasm, DNA in a nucleoid region, and ribosomes. They lack a nucleus and other membrane-bound organelles such as mitochondria and endoplasmic reticulum.

Checked against: OpenStax Biology 2e, 4.2 Prokaryotic Cells

Answer: A — It loses water and shrinks.

A hypertonic solution has a higher solute concentration than the cell's cytoplasm, so water moves out of the cell by osmosis and the cell shrinks (crenates).

Checked against: OpenStax Biology 2e, 5.2 Passive Transport

Answer: C — Cytoplasm.

Glycolysis, the splitting of glucose into two pyruvate molecules, happens in the cytoplasm and does not require oxygen. The citric acid cycle occurs in the mitochondrial matrix and the electron transport chain in the inner mitochondrial membrane.

Checked against: OpenStax Biology 2e, 7.2 Glycolysis

Answer: A — Water.

In the light-dependent reactions, water is split to replace electrons lost by chlorophyll, and the oxygen atoms from water are released as O2.

Checked against: OpenStax Biology 2e, 8.2 The Light-Dependent Reactions of Photosynthesis

Answer: D — Anaphase.

In anaphase the cohesin proteins holding sister chromatids together are broken, and each chromatid is pulled to an opposite pole. In metaphase chromosomes line up at the center, and in telophase new nuclear envelopes form.

Checked against: OpenStax Biology 2e, 10.2 The Cell Cycle

Answer: B — 23.

Meiosis halves the chromosome number: a diploid cell with 46 chromosomes produces haploid cells with 23 chromosomes each, so that fertilization restores 46.

Checked against: OpenStax Biology 2e, 11.1 The Process of Meiosis

Answer: C — They lower the activation energy of the reaction.

Enzymes bind substrates at their active site and lower the activation energy needed to reach the transition state. They are not consumed and do not change the overall energy released or absorbed.

Checked against: OpenStax Biology 2e, 6.5 Enzymes