Review these Biology Hesi A2 Set 2 nursing practice questions with answer choices and explanations.
A cell has damaged lysosomal enzymes. Which activity would most directly be impaired?
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Explanation: Lysosomal enzymes digest materials delivered to these organelles.
A cell loses most of its ATP supply. Which process is most likely to be affected immediately?
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Explanation: Energy-dependent transport requires ATP directly or depends on gradients maintained using ATP.
A secretory vesicle reaches the plasma membrane and releases its contents outside. Which event occurred?
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Explanation: Exocytosis releases vesicle contents when its membrane fuses with the plasma membrane.
Why do mature human red blood cells obtain ATP mainly through glycolysis?
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Explanation: Mature red blood cells have no mitochondria and rely on glycolysis for ATP.
What is the fluid mosaic model of membrane structure?
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Explanation: Many membrane lipids and proteins can move laterally within the bilayer.
A cell needs to copy a gene into an RNA message. Which process is required?
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Explanation: Transcription produces RNA using DNA as the template.
A DNA template segment is 3'-TAC-5'. What complementary RNA sequence is produced?
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Explanation: RNA bases pair with the template: T with A, A with U, and C with G.
A protein's amino acid sequence changes after a DNA mutation. Why can its function change?
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Explanation: Protein shape and chemical properties depend partly on amino acid sequence.
What is a chromatid?
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Explanation: After replication, a chromosome consists of two sister chromatids until they separate.
Which stage of meiosis includes pairing of homologous chromosomes?
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Explanation: Homologous chromosomes pair during prophase I, allowing crossing over.
A diploid organism has eight chromosomes. How many chromosome pairs does a typical diploid cell contain?
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Explanation: The diploid number is eight, arranged into four homologous pairs.
An individual is homozygous recessive for two genes, represented as aabb. Which allele combination can its normal gametes carry?
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Explanation: Each gamete receives one allele of each gene; this individual can contribute only a and b.
A parent has blood-group genotype IAi and the other has genotype ii. What is the expected chance of a blood-group O child?
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Explanation: Half the expected offspring receive i from both parents, producing blood group O.
Why are identical twins usually much more genetically similar than fraternal twins?
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Explanation: Identical twins arise when one early embryo separates, so their inherited genomes are initially nearly identical.
Which structure contains most of a cell's hereditary instructions and regulates gene expression?
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Explanation: The nucleus stores most cellular DNA and is a major site of gene regulation.
Which skin layer contains blood vessels, many sensory receptors, and sweat glands?
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Explanation: The dermis supports and nourishes skin and houses these structures.
What is the main protective role of melanin?
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Explanation: Melanin contributes to skin pigmentation and reduces some ultraviolet damage.
Which cells build new bone matrix?
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Explanation: Osteoblasts form bone matrix and support its mineralization.
Which cells break down bone during normal remodeling?
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Explanation: Osteoclasts resorb bone, working with bone-forming cells in remodeling.
What does synovial fluid mainly do in a movable joint?
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Explanation: Synovial fluid reduces friction and supports the articular cartilage.
What happens when a skeletal muscle contracts?
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Explanation: Sliding filaments shorten sarcomeres while individual filament lengths remain essentially unchanged.
Which mineral ion triggers key steps in skeletal muscle contraction?
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Explanation: Calcium binds regulatory proteins that permit actin-myosin interaction.
Which eye structure changes shape to help focus light on the retina?
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Explanation: The lens adjusts its curvature to focus on objects at different distances.
Which eye structure contains light-sensitive rods and cones?
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Explanation: Retinal photoreceptors detect light and begin signals that reach the brain.
Which ear structure contains receptors important for hearing?
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Explanation: Hair cells within the cochlea convert vibrations into signals for hearing.
Which hormone promotes increased blood calcium when the level falls?
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Explanation: Parathyroid hormone helps raise calcium through effects on bone, kidneys, and vitamin D activation.
Which organs release estrogen and progesterone as major reproductive hormones?
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Explanation: The ovaries produce these hormones as part of reproductive regulation.
Where does human fertilization most commonly occur?
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Explanation: Fertilization usually occurs in the ampulla region of a uterine tube.
Which organ supports exchange of nutrients, gases, and wastes between maternal and fetal circulations?
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Explanation: The placenta permits exchange across a barrier; maternal and fetal blood do not normally mix directly in bulk.
Which vitamin is particularly important for normal DNA synthesis and early neural-tube development?
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Explanation: Folate participates in nucleotide synthesis and supports normal early embryonic development.
Which vitamin deficiency can cause scurvy?
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Explanation: Vitamin C deficiency impairs collagen formation, producing features such as bleeding gums and poor tissue repair.
Which condition in children is associated with inadequate vitamin D and poor bone mineralization?
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Explanation: Vitamin D deficiency can impair calcium balance and mineralization of growing bones.
Which immune response mainly involves antibodies acting in body fluids?
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Explanation: Humoral adaptive immunity depends on antibodies produced by activated B-cell descendants.
Which antibody class is especially associated with protection at mucosal surfaces?
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Explanation: IgA is prominent in secretions such as saliva and helps protect mucosal surfaces.
Which antibody class normally crosses the placenta and provides some fetal protection?
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Explanation: Maternal IgG can cross the placenta, providing temporary passive immunity.