Free Practice Questions for NLN NEX Exam

Hyperextension refers to movement at a joint that goes beyond the normal anatomical position in the sagittal plane, specifically in a posterior direction. For example, bending the head backward farther than upright posture is considered hyperextension. Option B correctly describes this movement. Option A describes abduction, which occurs in the frontal plane. Option C describes flexion, which is anterior movement. Option D describes extension back to anatomical position, not beyond it. The NEX Science exam frequently tests anatomical terminology related to joint movement, and understanding directional planes (sagittal, frontal, transverse) is essential. Hyperextension differs from extension because it exceeds the normal range of motion, which can increase injury risk.

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Macromolecules are large, complex molecules essential for life. The four major classes of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates provide energy and structural support, lipids are involved in energy storage and membrane structure, proteins perform a wide range of functions including enzymes and transport, and nucleic acids store and transmit genetic information. DNA and RNA are examples of nucleic acids. The other answer choices—fatty acids, unsaturated fats, and phospholipids—are all types of lipids rather than separate macromolecule categories. The NEX Science exam often assesses whether students can distinguish between macromolecule categories and their subcomponents. Recognizing nucleic acids as one of the four major macromolecules is fundamental to understanding genetics, protein synthesis, and cell function.

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Dominant traits are more likely to be expressed when present. If one parent contributes more dominant alleles, the child may resemble that parent more closely. Dominance does not mean stronger genes, just that they mask recessive traits. The NEX Science exam emphasizes basic Mendelian inheritance and dominance relationships.

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Stage A in the diagram represents fertilization, where a sperm cell fuses with an egg to form a zygote. In humans, fertilization normally occurs in the fallopian tube, not in the uterus or vagina. After fertilization, the zygote undergoes cell division as it travels toward the uterus for implantation. The ovary produces and releases the egg but is not the site of fertilization. The NEX Science exam commonly tests understanding of reproductive anatomy and sequence of events in human development. Correctly identifying the fallopian tube as the site of fertilization is essential for understanding pregnancy, contraception, and reproductive health.

Veins contain one-way valves that prevent blood from flowing backward as it returns to the heart. These valves are especially important in veins of the arms and legs, where blood must move against gravity. When muscles contract, they push blood forward toward the heart, and the valves close behind it to prevent backflow. Without these valves, blood could pool in the veins, leading to conditions such as varicose veins. The valves do not obstruct blood flow under normal conditions, nor do they prevent blood from leaking into surrounding tissues—that function is related to capillary walls. The NEX Science exam often emphasizes understanding how anatomical structures support physiological function, making venous valves a key cardiovascular concept.

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The thymus, lymph nodes, and spleen are key components of the immune system. The immune system is responsible for defending the body against pathogens such as bacteria, viruses, and other foreign invaders. The thymus plays an important role in the maturation of T lymphocytes (T cells), which are critical for adaptive immunity. Lymph nodes filter lymphatic fluid and trap pathogens, allowing immune cells to recognize and respond to infections. The spleen filters blood, removes old or damaged red blood cells, and helps initiate immune responses to blood-borne pathogens. While the endocrine system regulates hormones, the cardiovascular system transports blood, and the integumentary system protects the body externally, none of these systems include the thymus, lymph nodes, and spleen as primary organs. The NEX Science exam often tests system identification by grouping organs with shared functions, making the immune system the correct choice.

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Sperm cells are produced in thetestes, specifically within tightly coiled structures called seminiferous tubules. The process of sperm production is known as spermatogenesis and requires hormones such as testosterone. Cowper’s glands and the prostate gland do not produce sperm; instead, they secrete fluids that contribute to semen and help protect and nourish sperm cells. The epididymis is responsible for sperm maturation and storage but does not produce sperm. The NEX Science exam often tests reproductive anatomy by asking students to distinguish between sperm production, maturation, and transport. Understanding the specific role of each male reproductive structure is essential. Since only the testes are responsible for the formation of sperm cells, option C is the correct answer.

Rods and cones are photoreceptor cells responsible for detecting light and color. These specialized cells are located in the retina, which is the innermost layer of the eye. The retina converts light energy into electrical signals that are transmitted to the brain via the optic nerve. Rods are more sensitive to low light and are important for night vision, while cones detect color and fine detail. The sclera is the tough, white outer layer of the eye that provides protection. The choroid contains blood vessels that supply nutrients to the eye, and the cornea is the transparent front portion that helps focus incoming light. Because rods and cones must directly receive light to function, they are located in the retina. This concept is commonly tested on the NEX Science exam in questions related to sensory organs and physiology.

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A mutation is a random change in the DNA sequence of an organism. Mutations can occur due to errors during DNA replication, exposure to radiation, or chemical agents. These changes may have no effect (silent mutations), cause harm (negative mutations), or provide an advantage (positive mutations). Recombination refers to the exchange of genetic material during meiosis, not random DNA changes. Duplication involves copying a segment of DNA, and replication is the normal process of copying DNA before cell division. The NEX Science exam often emphasizes that mutations are a source of genetic variation and can influence evolution and disease. Understanding the different possible effects of mutations is essential for topics related to genetics, cancer biology, and inheritance.

This question tests understanding of predator–prey relationships, a key ecology concept on the NEX Science exam. Wolves are the natural predators of moose on Isle Royale. When the moose population was initially high, there was an abundant food supply for wolves. This allowed the wolf population to increase significantly. As the number of wolves increased, predation pressure on the moose population also increased, leading to a sharp decline in moose numbers. This inverse relationship between predator and prey populations is a classic ecological pattern. There is no evidence in the question to suggest disease, human hunting, or breeding rate differences as the primary cause. Instead, the changes in population sizes are best explained by increased predation. The NEX often assesses whether students can interpret real-world ecological data and recognize how population dynamics are influenced by natural predator–prey interactions.

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