Practice 1 Flashcards
A person is suddenly frightened. Which of the following reactions occurs next?
A. Liver cells absorb glucose from the blood stream.
B. Blood vessels supplying skeletal muscles constrict.
C. Blood vessels supplying the intestines dilate.
D. Liver cells release glucose into the blood stream.
Option D is correct. Epinephrine causes liver cells to break down glycogen, which causes an increase in sugar in the blood stream.
A. Epinephrine causes liver cells to break down glycogen, which causes an increase in sugar in the blood stream, not the absorption of sugar from the blood.
B. Epinephrine causes blood vessels supplying skeletal muscles to dilate, which increases blood flow to muscle cells.
C. Epinephrine causes blood vessels supplying the intestines to constrict, restricting blood flow to the organs of the digestive system.
Which of the following is an example of positive feedback?
A. Oxytocin causes an increase in uterine muscle contractions, ultimately causing the posterior pituitary to release more oxytocin
B. An increase in blood glucose level causes the release of insulin, which results in the lowering of glucose levels in the blood and halting the release of insulin.
C. A drop in body temperature causes the hypothalamus to activate warming
mechanisms, which results in the increase of body temperature.
D. An increase in blood osmolarity causes the release of ADH, which causes urine to become more concentrated and osmolarity to decrease
Option A is correct. When a response reinforces a stimulus, causing an even greater response, positive feedback is occurring.
B. This is an example of negative feedback. The response of lower glucose levels reduces the initial stimulus and stops the pancreas from releasing insulin.
C. This is an example of negative feedback. The response of increasing body temperature reduces the initial stimulus and stops the hypothalamus from activating warming mechanisms.
D. This is an example of negative feedback. An osmolarity increase causes a response that decreases osmolarity and reduces the release of ADH.
Demyelinization results in which of the following?
A. Inhibited detection of a stimulus at the dendrites of a nerve cell
B. Disrupted propagation of an action potential along the axon of a nerve cell
C. Inhibited uptake of neurotransmitters at the synapse of a nerve cell
D. Disrupted ability of the Na +/ K+ pumps to depolarize a cell
Option B is correct. The myelin sheath, which is a lipid-based structure, insulates the axon, allowing rapid electrical conduction of the action potential down the axon. Deterioration of the myelin sheath disrupts this process.
A. The myelin sheath does not directly affect the reception of a stimulus at the dendrites.
C. The myelin sheath covers the axon and does not function in the reabsorption of neurotransmitters.
D. Na+ /K+ pumps still function even if the myelin sheath has deteriorated.
The nephridium in worms has a function most similar to which of the following organs in humans? A. Liver B. Spleen C. Lymph nodes D. Kidney
Option D is correct. Nephridia in segmented worms operate similarly to the nephron of the kidneys. Nephrons in the kidneys contain a collecting tubule that aids in urine production.
A. Liver cells make bile and help regulate blood sugar levels. They do not contain collecting tubules used to collect and concentrate filtrate.
B. The spleen functions to remove old, fragmented red blood cells and pathogens from the blood. Spleen cells do not contain collecting tubules used to collect and concentrate filtrate.
C. The lymph nodes filter out pathogens from interstitial fluid (lymph). The cells of the lymph nodes do not contain collecting tubules used to collect and concentrate filtrate.
Which of the following cell types is responsible for the production of soluble antibodies? A. Cytotoxic T-cell B. Macrophage cell C. Helper T-cell D. B-cell
Option D is correct. The production of antibodies by B-cells is part of the humoral response to antigens.
A. Cytotoxic T-cells destroy pathogens and infected cells.
B. Macrophages ingest and digest both non-self cells and dead cells.
C. Helper T-cells help cytotoxic T-cells and other immune cells.
Which of the following organ systems is responsible for transporting nutrients, wastes, and other substances throughout the human body? A. Respiratory B. Immune C. Nervous D. Circulatory
Option D is correct. The heart pumping blood through the arteries, capillaries, and veins provides the means of transporting substances throughout the body.
A. The respiratory system exchanges gases with the outside environment, bringing oxygen in and letting carbon dioxide out.
B. The immune system protects the body from pathogens (infectious agents) using a combination of white blood cells and
antibodies.
C. The nervous system, which includes the brain, spinal cord, and peripheral nerves, controls the actions of other body systems.
Which of the following is a characteristic of the human organism?
A. Autotrophic with a genome stored in DNA
B. Heterotrophic with a genome stored in DNA
C. Autotrophic with a genome stored in RNA
D. Heterotrophic with a genome stored in RNA
Option B is correct. Humans consume rather than manufacture nutrient molecules (heterotrophic), and human genes are encoded in DNA.
A. Humans consume rather than manufacture nutrient molecules.
C. Humans consume rather than manufacture nutrient molec ules, and human genes ar,e encoded in DNA.
D. Human genes are encoded in DNA.
Which of the following is the function of the lymph nodes in mammals?
A. Pump oxygen into tissue spaces.
B. Store extra glucose for emergencies.
C. Synthesize hemoglobin for erythrocytes.
D. Filter debris from intracellular spaces
Option D is correct. Lymph nodes filter debris, lymphocytes, and pathogens from intracellular fluid.
A. This is not a function of the lymph nodes. Oxygen diffuses to these areas from capillaries of the circulatory system.
B. This is not a function of the lymph nodes. Glucose is stored as glycogen in the liver and muscles of mammals.
C. This is not a function of the lymph nodes. Hemoglobin is synthesized in the red blood cells.
The bands in muscle sarcomere are formed by actin and which of the following other proteins? A. Myosin B. Dynein C. Keratin D. Laminin
Option A is correct. Myosin contains “heads” that contact actin and pull the actin fibers together in an ATP-dependent mechanism that causes muscles to contract.
B. Dynein is an ATP-dependent molecule that “walks” along micro tubules, causing them to move, but it is not part of the sarcomere.
C. Keratin is the fibrous protein of hair and nails and is not part of the sarcomere.
D. Laminin is a protein of the nuclear envelope and is not part of the sarcomere.
Which of the following structures within a human cell is responsible for recycling the materials no longer functional or needed within the cell? A. Ribosome B. Lysosome C. Mitochondrion D. Nucleolus
Option B is correct. Lysosomes are specialized vacuoles containing digestive enzymes.
A. The ribosome is not involved in recycling materials that are no longer functional or needed.
C. Mitochondria function in cellular respiration, facilitating the production of ATP.
D. The nucleolus functions in the assembly of ribosomes.
Which of the following is the correct structure and function of the cell membrane?
A. A double glycoprotein structure with embedded lipid bodies provides shape and rigidity to the cytoplasm.
B. A double layer of phosphate proteins with lipid channels allows molecules to pass from the inside to the outside of cells.
C. Nonpolar phosphate heads and polar lipid tails form a bilayer to control the transport of proteins.
D. A phospholipid bilayer with embedded proteins regulates molecules entering and leaving cytoplasm.
Option D is correct. The cell membrane consists of a phospholipid bilayer with polar phosphate heads, nonpolar lipid tails, and embedded proteins, which permit the movement of molecules across the membrane.
A. The double structure is not composed of glycoprotein.
B. The double layer is not composed of phosphate proteins.
C. The heads are polar and the tails are nonpolar; molecules pass through protein channels.
In which of the following areas does protein breakdown begin in the human body? A. Mouth B. Stomach C. Small intestine D. Large intestine
Option B is correct. The stomach is the first place in the digestive system in which proteinases are produced.
A. Carbohydrate digestion starts in the mouth, but protein breakdown does not.
C. Protein breakdown continues in the small intestine, but it does not start here.
D. Protein is generally digested by the time it enters the large intestine.
Which of the following chemical compounds prevents the lungs from collapsing? A. Mucus B. Surfactant C. Enzymes D. Buffers
Options B is correct. Surfactants are lipopolysaocharides that have a hydrophobic and hydrophilic layer. They keep the lungs inflated.
A. Mucin is a type of mucus produced by lung cells that absorbs water.
C. Enzymes are a catalytic protein and do not prevent the lungs from collapsing.
D. Buffers maintain acid-base balance and are not involved in lung function.
Which of these structures diverts food into the esophagus, and prevents it from entering the lungs? A. Uvula B. Soft palate C. Tonsils D. Epiglottis
Option D is correct. The epiglottis shuts off the tracheal opening, diverting food into the esophagus.
A. The uvula is found in the back of the throat and prevents food entry into the nasal passages.
B. The soft palate is found in the back of the buccal cavity. It helps in swallowing and prevents food entry into the nasal passages.
C. The tonsils are made of lymphatic tissue that does not typically interfere with food movement.
Which of these terms related to the respiratory system refers to the "voice box" for sound production? A. Pharynx B. Trachea C. Larynx D. Uvula
Option C is correct. The larynx is a cartilaginous structure containing the vocal cords, which is used to generate sound.
A. The pharynx is the muscular region at the intersection of the respiratory and digestive systems, not the voice box.
B. The trachea is the large tube containing cartilaginous rings through which air passes into and out of the lungs.
D. The uvula is a fleshy extension of the beck of the soft palate, hanging above the throat. It does not function in the production of sound.
Unlike skeletal muscle, cardiac muscle is highly resistant to lactate-mediated fatigue because cardiac muscle
A. uses aerobic respiration in mitochondria for energy.
B. operates with electrical energy supplied by the sinoatrial (SA) node.
C. primarily metabolizes glucose using the fermentation pathway.
D. does not need oxygen for the production of energy.
Option A is correct. Aerobic respiration (oxidative respiration) is almost exclusively used by the heart. The byproducts of this type of respiration are water (H2O) and carbon dioxide (CO2), not lactate .
B . The sinoatrial (SA) node, also known as the pacemaker, produces electrical impulses for heart contraction. It does not provide energy to the heart.
C. The lactose-producing fermentation pathway operates during oxygen deprivation in the skeletal muscle. It does not primarily operate in the heart.
D. The heart is highly sensitive to oxygen deprivation, and requires a steady oxygen supply for adenosine triphosphate (ATP) production by oxidative phosphorylation during aerobic respiration.
Which of the following arteries directly supplies oxygenated blood to the reproductive system? A. Common carotid artery B. Gonadal artery C. Femoral artery D. Subclavian artery
Option B is correct. The gonadal artery is the primary artery that supplies oxygenated blood to the gonads and male reproductive system. It is called the testicular artery in males and the ovarian artery in females.
A. The common carotid artery supplies oxygenated blood to the head.
C. The femoral artery supplies oxygenated blood to the lower limbs.
D. The subclavian artery supplies oxygenated blood to the upper limbs.
Which of the following options represents the chromosomal composition of a normal human zygote? A. 23 chromosomes B. 46 chromosomes C. 69 chromosomes D. 92 chromosomes
Option B is correct. The fusion of a sperm with 23 chromosomes and an egg with 23 chromosomes would result in a zygote with 46 chromosomes.
A. The unfertilized egg and the sperm each contain 23 chromosomes. This is the haploid chromosome number for a human.
C. 69 chromosomes represent the fusion of a diploid human cell with a haploid human cell. This is not the diploid chromosome number for a normal human zygote.
D. 92 chromosomes represent the fusion of
two diploid human cells. This is not the chromosome number for a normal human zygote.
