ATI TEAS 7 — All Questions

Which organ system is primarily responsible for transporting oxygen and nutrients throughout the body?

• a.Digestive system
• b.Circulatory system✓
• c.Integumentary system
• d.Skeletal system

The circulatory (cardiovascular) system uses the heart, blood, and vessels to transport oxygen, nutrients, and waste throughout the body. The digestive system breaks down food, and the skeletal system provides structure.

What is the basic structural and functional unit of all living organisms?

• a.The atom
• b.The cell✓
• c.The tissue
• d.The organ

The cell is the smallest unit that can carry out all life processes and is the fundamental building block of all living organisms. Atoms are units of matter, while tissues and organs are groups of cells.

Which part of the cell is responsible for producing energy in the form of ATP?

• a.Ribosome
• b.Nucleus
• c.Mitochondria✓
• d.Cell membrane

The mitochondria are the powerhouse of the cell, generating ATP through cellular respiration. The nucleus stores DNA, and ribosomes synthesize proteins.

During inhalation, the diaphragm contracts and moves in which direction?

• a.Downward✓
• b.It does not move
• c.Sideways
• d.Upward

When the diaphragm contracts, it flattens and moves downward, increasing the volume of the chest cavity and drawing air into the lungs. During exhalation it relaxes and moves upward.

Which type of blood vessel carries blood away from the heart?

• a.Capillaries
• b.Arteries✓
• c.Venules
• d.Veins

Arteries carry blood away from the heart to the body's tissues. Veins return blood to the heart, and capillaries are the tiny vessels where exchange of gases and nutrients occurs.

What is the pH value that is considered neutral on the pH scale?

• a.10
• b.14
• c.7✓
• d.0

On the pH scale as it is normally used, 7 is neutral: pure water at 25 degrees Celsius has a pH of 7. Values below 7 are acidic and values above 7 are basic (alkaline). The familiar 0-to-14 range is a working convention for dilute solutions in water, not a hard limit of the scale.

Which macromolecule serves as the primary source of quick energy for the body?

• a.Carbohydrates✓
• b.Nucleic acids
• c.Lipids
• d.Proteins

Carbohydrates are broken down into glucose, the body's main and most readily available source of energy. Proteins build tissue and lipids store energy long-term.

In the scientific method, what is a hypothesis?

• a.A tool for measuring the result
• b.A conclusion drawn after the experiment
• c.A testable prediction✓
• d.A proven fact

A hypothesis is a testable, tentative prediction that an experiment can support or refute, and it is written before data is collected. A conclusion drawn after the experiment comes at the other end of the process, and a hypothesis is neither a proven fact nor a tool for measuring the result.

Which organ is the primary site of nutrient absorption in the digestive system?

• a.Stomach
• b.Large intestine
• c.Esophagus
• d.Small intestine✓

The small intestine, with its finger-like villi, is where most nutrient absorption occurs. The stomach mainly digests food, and the large intestine absorbs water and forms waste.

How many chromosomes are found in a typical human body (somatic) cell?

• a.48
• b.23
• c.46✓
• d.44

A typical human somatic cell contains 46 chromosomes, arranged in 23 pairs. Gametes (egg and sperm) contain 23 chromosomes each.

Which of the following is an example of a chemical change?

• a.Boiling water
• b.Rusting iron✓
• c.Melting ice
• d.Cutting paper

Rusting iron forms a new substance (iron oxide), making it a chemical change. Melting, cutting, and boiling are physical changes that do not alter chemical composition.

The central nervous system consists of which two structures?

• a.Peripheral nerves and muscles
• b.Arteries, veins and capillaries
• c.Heart and lungs
• d.Brain and spinal cord✓

The central nervous system is made up of the brain and spinal cord, which process and coordinate information. Peripheral nerves running outside the brain and spinal cord belong to the peripheral nervous system, while arteries, veins and capillaries belong to the circulatory system and the heart and lungs to other systems entirely.

What is the process by which plants convert sunlight into chemical energy?

• a.Cellular respiration
• b.Photosynthesis✓
• c.Digestion
• d.Anaerobic fermentation

Photosynthesis is the process by which plants use sunlight, water and carbon dioxide to make glucose and oxygen. Cellular respiration runs the other way, releasing energy from glucose rather than capturing sunlight; digestion and anaerobic fermentation do not use light at all.

Which subatomic particle carries a negative electrical charge?

• a.Electron✓
• b.Atomic nucleus
• c.Neutron
• d.Proton

Electrons carry a negative charge and occupy the space around the nucleus. Protons carry a positive charge and neutrons carry none; both sit inside the atomic nucleus, which is therefore positively charged overall.

Which system includes the bones and provides support and protection for the body?

• a.Skeletal system✓
• b.Endocrine system
• c.Muscular system
• d.Nervous system

The skeletal system is made up of bones that provide structural support and protect internal organs. It also works with muscles to allow movement.

What is the main function of red blood cells?

• a.Carry oxygen✓
• b.Produce antibodies
• c.Fight infection
• d.Form blood clots

Red blood cells contain hemoglobin, which binds and transports oxygen from the lungs to the body's tissues. White blood cells fight infection and platelets help form clots.

In a controlled experiment, the variable that is deliberately changed by the researcher is called the:

• a.Randomized control group
• b.Dependent or outcome variable
• c.Independent variable✓
• d.Constant

The independent variable is the factor the researcher deliberately manipulates in order to observe its effect. The dependent or outcome variable is what gets measured in response, a randomized control group is the comparison group that receives no manipulation, and a constant is held the same for every group.

Which gas do humans primarily exhale as a waste product of cellular respiration?

• a.Hydrogen
• b.Nitrogen, 78% of inhaled air
• c.Oxygen
• d.Carbon dioxide✓

Cellular respiration produces carbon dioxide as its waste product, and humans exhale it. Oxygen is inhaled and consumed to release energy from glucose. Nitrogen makes up about 78% of inhaled air but is breathed straight back out unchanged, so it is not a waste product.

Which of the following best describes the role of enzymes in the body?

• a.They provide structural support to cells
• b.They transport oxygen in the blood
• c.They speed up chemical reactions✓
• d.They store genetic information

Enzymes are biological catalysts: they lower activation energy and speed up chemical reactions without being consumed. Structural support comes from proteins such as collagen and keratin, oxygen is transported in the blood by hemoglobin, and genetic information is stored in DNA.

The kidneys are the primary organs of which body system?

• a.Digestive system
• b.Nervous system
• c.Urinary system✓
• d.Respiratory system

The kidneys are the main organs of the urinary (renal) system, filtering blood to remove waste and excess water, forming urine. They also help regulate blood pressure and electrolytes.

An atom that has gained or lost electrons and therefore carries a charge is called a(n):

• a.Ion✓
• b.Molecule
• c.Isotope
• d.Compound

An ion is an atom or group of atoms with a net electrical charge due to gaining or losing electrons. Isotopes differ in neutron number, not charge.

Which chamber of the heart pumps oxygenated blood to the entire body?

• a.Right atrium
• b.Left ventricle✓
• c.Right ventricle
• d.Left atrium

The left ventricle is the heart's strongest chamber and pumps oxygenated blood through the aorta to the whole body. The right ventricle pumps blood to the lungs.

Which of the following correctly orders levels of biological organization from smallest to largest?

• a.Cell, tissue, organ, organism✓
• b.Tissue, cell, organ, organism
• c.Organ, tissue, cell, organism
• d.Organism, organ, tissue, cell

The correct order from smallest to largest is cell, tissue, organ, organism. Cells form tissues, tissues form organs, and organs form the whole organism.

Which of the following is a function of the liver?

• a.Detoxifying harmful substances✓
• b.Producing insulin for blood sugar
• c.Pumping blood through the whole body
• d.Filtering air

The liver detoxifies harmful substances, produces bile and stores glycogen. Insulin for blood sugar control is produced by the pancreas, pumping blood through the whole body is the heart's job, and the lungs, not the liver, handle air.

In genetics, an allele that is expressed only when two copies are present is called:

• a.Mutant
• b.Recessive✓
• c.Dominant
• d.Codominant

A recessive allele is expressed only when an individual has two copies of it. A dominant allele is expressed even when only one copy is present.

What is the primary purpose of a control group in an experiment?

• a.To change the independent variable
• b.To guarantee the hypothesis is correct
• c.To provide a baseline for comparison✓
• d.To measure only the dependent variable

A control group does not receive the experimental treatment and serves as a baseline for comparison. Comparing the experimental group to it helps isolate the effect of the independent variable.

Which part of the neuron receives signals from other neurons?

• a.Axon
• b.Myelin sheath
• c.Synapse
• d.Dendrites✓

Dendrites are branch-like extensions that receive incoming signals from other neurons. The axon carries signals away from the cell body toward other cells.

Which of the following bonds involves the sharing of electrons between atoms?

• a.Hydrogen bond
• b.Metallic bond
• c.Ionic bond
• d.Covalent bond✓

A covalent bond forms when atoms share electrons. An ionic bond involves the transfer of electrons, resulting in oppositely charged ions that attract.

The hormone insulin, which lowers blood glucose levels, is produced by the:

• a.Adrenal glands
• b.Pancreas✓
• c.Liver
• d.Thyroid

Insulin is produced by beta cells in the pancreas and helps lower blood glucose by promoting its uptake into cells. The thyroid regulates metabolism.

Which process describes the movement of water across a semipermeable membrane from an area of low solute concentration to high solute concentration?

• a.Osmosis✓
• b.Combustion
• c.Filtration
• d.Active transport

Osmosis is the passive diffusion of water across a semipermeable membrane from low to high solute concentration until equilibrium is reached. It requires no energy input.

Which type of muscle tissue is found in the walls of the heart and contracts involuntarily?

• a.Cardiac muscle✓
• b.Voluntary muscle
• c.Smooth muscle
• d.Skeletal muscle

Cardiac muscle is found in the heart and contracts involuntarily and rhythmically. Skeletal muscle is voluntary, and smooth muscle forms the walls of hollow organs and blood vessels. Note that the three muscle tissue types are skeletal, cardiac, and smooth; "voluntary" describes how a muscle is controlled, not a tissue type.

Which of the following is a metric unit of mass?

• a.Meter
• b.Newton
• c.Gram✓
• d.Liter

The gram is the metric unit of mass you will meet most often on this exam; the SI base unit is the kilogram, which is 1,000 grams. Liters measure volume, meters measure length, and newtons measure force (weight), not mass.

Which body system works with the nervous system to maintain homeostasis by releasing hormones?

• a.Endocrine system✓
• b.Lymphatic system
• c.Skeletal system
• d.Muscular system

The endocrine system releases hormones into the bloodstream to regulate processes such as growth and metabolism. It works alongside the nervous system to maintain homeostasis.

If a student measures the boiling point of pure water at sea level, the expected temperature is approximately:

• a.0 degrees Celsius
• b.100 degrees Celsius✓
• c.98.6 degrees Fahrenheit
• d.100 degrees Fahrenheit

Pure water boils at 100 degrees Celsius (212 degrees Fahrenheit) at sea level. Zero degrees Celsius is the freezing point, 98.6 degrees Fahrenheit is normal body temperature, and 100 degrees Fahrenheit is only about 38 degrees Celsius, far below boiling.

Which valve separates the right atrium from the right ventricle?

• a.The mitral valve
• b.The aortic valve
• c.The pulmonary semilunar valve
• d.The tricuspid valve✓

The tricuspid valve sits between the right atrium and right ventricle. The mitral valve occupies the matching position on the left side, while the pulmonary semilunar and aortic valves guard the exits of the two ventricles rather than the entrances.

Which vessel carries deoxygenated blood away from the heart toward the lungs?

• a.The aorta
• b.The pulmonary vein
• c.The pulmonary artery✓
• d.The superior vena cava

The pulmonary artery is the one artery carrying oxygen-poor blood, moving it from the right ventricle to the lungs. Pulmonary veins return oxygen-rich blood to the heart, the aorta distributes oxygen-rich blood to the body, and the vena cava brings blood into the heart rather than away from it.

Which structure acts as the heart's natural pacemaker?

• a.The sinoatrial node✓
• b.The Purkinje fibers
• c.The bundle of His
• d.The atrioventricular node

The sinoatrial node in the right atrium fires fastest and therefore sets the rhythm. The atrioventricular node, bundle of His, and Purkinje fibers conduct that signal onward and can pace the heart only if the sinoatrial node fails.

Which type of blood vessel is the site where oxygen and nutrients pass into the tissues?

• a.Capillaries, whose walls are one cell thick✓
• b.Veins, because they contain one-way valves
• c.Arterioles, because they control blood flow
• d.Arteries, because they carry blood at the highest pressure

Capillary walls are a single layer of endothelium, thin enough for substances to diffuse across. Arteries and arterioles distribute blood under pressure and veins return it, but none of those has walls thin enough for exchange.

Which component of blood is primarily responsible for clotting?

• a.Red blood cells
• b.Plasma proteins called albumins
• c.Platelets✓
• d.White blood cells

Platelets, also called thrombocytes, aggregate at an injury and trigger the clotting cascade. Red cells carry oxygen, white cells defend against infection, and albumin maintains osmotic pressure rather than forming clots.

Why is the wall of the left ventricle thicker than the wall of the right ventricle?

• a.It receives blood directly from the lungs
• b.It contains more valves than the right side
• c.It must pump blood to the whole body✓
• d.It holds a much larger volume of blood

The left ventricle generates the higher pressure needed for systemic circulation, so its muscular wall is thicker. Both ventricles eject roughly the same volume, each has one outflow valve, and receiving blood from the lungs is the job of the left atrium.

A blood pressure reading is written as 120/80. What does the lower number represent?

• a.The number of heartbeats per minute
• b.Pressure while the ventricles contract
• c.The volume of blood pumped per beat
• d.Pressure while the ventricles relax✓

The lower figure is diastolic pressure, measured between contractions when the ventricles fill. The upper figure is systolic pressure during contraction, and neither number reports heart rate or stroke volume.

Which mineral is a required part of the hemoglobin molecule?

• a.Potassium
• b.Calcium
• c.Iron✓
• d.Sodium

Each hemoglobin molecule holds four iron-containing heme groups, and the iron is what binds oxygen. Calcium supports bone and clotting, while sodium and potassium are electrolytes involved in fluid balance and nerve signaling.

In which structures of the lungs does gas exchange with the blood actually occur?

• a.The alveoli✓
• b.The bronchi
• c.The pleural membranes
• d.The trachea

Alveoli are thin-walled air sacs wrapped in capillaries, which is where oxygen and carbon dioxide diffuse. The trachea and bronchi are conducting airways only, and the pleural membranes reduce friction as the lungs move.

Which structure closes over the opening of the larynx during swallowing?

• a.The epiglottis✓
• b.The vocal cords
• c.The soft palate
• d.The uvula

The epiglottis folds down over the laryngeal opening so food passes into the esophagus instead of the airway. The soft palate and uvula close off the nasal passages, and the vocal cords produce sound rather than sealing the airway during swallowing.

By what process do oxygen and carbon dioxide move across the alveolar membrane?

• a.Active transport requiring ATP
• b.Filtration driven by blood pressure
• c.Simple diffusion down concentration gradients✓
• d.Endocytosis by the alveolar cells

Each gas moves passively from where it is more concentrated to where it is less concentrated, which is diffusion and requires no energy. Active transport, filtration, and endocytosis all describe other mechanisms that do not govern alveolar gas movement.

Which sequence correctly traces inhaled air from the throat to the gas-exchange surface?

• a.Trachea, alveoli, bronchioles, bronchi
• b.Trachea, bronchi, bronchioles, alveoli✓
• c.Bronchioles, bronchi, trachea, alveoli
• d.Bronchi, trachea, alveoli, bronchioles

Air passes down the trachea, divides into the bronchi, narrows into bronchioles, and ends at the alveoli. The other sequences place a smaller branch before the larger one it comes from, which reverses the branching pattern of the airway.

What is the primary function of surfactant in the lungs?

• a.It carries oxygen from the alveoli into the bloodstream
• b.It triggers the cough reflex when irritated
• c.It traps dust particles entering the airway
• d.It reduces surface tension so alveoli stay open✓

Surfactant lowers the surface tension of the fluid lining the alveoli, preventing them from collapsing at the end of expiration. Hemoglobin carries oxygen, mucus and cilia trap particles, and sensory nerves trigger coughing.

Which enzyme in saliva begins the chemical digestion of starch in the mouth?

• a.Amylase✓
• b.Trypsin
• c.Lipase
• d.Pepsin

Salivary amylase starts breaking starch into smaller sugars while food is still being chewed. Pepsin acts on protein in the stomach, trypsin acts on protein in the small intestine, and lipase acts on fats.

In which organ does the chemical digestion of protein begin?

• a.The mouth
• b.The stomach✓
• c.The esophagus
• d.The large intestine

Hydrochloric acid in the stomach converts pepsinogen to pepsin, which starts splitting proteins. The mouth begins starch digestion instead, the esophagus only transports food, and the large intestine mainly absorbs water.

What is the primary role of bile in digestion?

• a.It emulsifies fats into smaller droplets✓
• b.It neutralizes stomach acid entering the intestine
• c.It chemically breaks peptide bonds in protein
• d.It absorbs vitamins through the intestinal wall

Bile is a detergent rather than an enzyme; it breaks large fat globules into small droplets so lipase can reach more surface. Pancreatic bicarbonate neutralizes acid, proteases break peptide bonds, and absorption is carried out by the intestinal lining.