AP BIO Chapter 12 Human Phsiology

Question 1

Digestion:
Gastric enzyme works best at a pH of 
A) 2
B) 6
C) 8
D) 11

Answer 1

A) gastric enzymes are strongly acidic and activate the gastric enzyme pepsinogen. Other enzymes, such as intestinal enzymes, are activated in an alkaline pH.

Question 2

Where does the digestion of fats occur?
A) large intestine
B) esophagus
C) stomach
D) small intestine

Answer 2

D) fats are digested by lipase a in the small intestine.

Question 3

Where does the reabsorption of water used during digestion occur?
A) large intestine
B) esophagus
C) stomach
D) small intestine

Answer 3

A) the large intestine is the site of digestion of undigested wastes, vitamin production, and water reabsorption.

Question 4

In which structure is there no digestion?
A) large intestine
B) esophagus
C) stomach
D) small intestine

Answer 4

B) there is no digestion in the esophagus

Question 5

In which structure is digestion completed?
A) large intestine
B) esophagus
C) stomach
D) small intestine

Answer 5

D) all digestion and absorption of nutrients is completed in the small intestine

Question 6

Which structure contains the microvilli?
A) large intestine
B) esophagus
C) stomach
D) small intestine

Answer 6

D) the microvilli are cytoplasmic extensions of the villi. Millions of villi line the endothelium of latter sections of the small intestine.

Question 7

Which is TRUE of the stomach?
A) the pyloric sphincter is at the top of the stomach
B) the stomach lining releases Pilates to begin fat digestion
C) hydrochloric acid activates the enzyme pepsinogen
D) the pH of the stomach varies from acid to basic depending on what must be digested

Answer 7

C) the lower esophageal sphincter is at the top of the stomach; the pyloric sphincter is at the bottom of the stomach. The stomach releases inactive pepsinogen, which is activated by the acid environment, and digests proteins. The pH of the stomach is very acidic. The stomach is stimulated by the hormone gastrin.

Question 8

The hormone gastrin is released by the \_\_\_\_and has its effect on the\_\_\_\_
A) duodenum; stomach
B) duodenum; pancreas
C) stomach;gastric lining
D) stomach; small intestine

Answer 8

C) this is a statement of fact. See table 13.1

Question 9

The lacteals is found in the ___, and is involved with___
A) stomach; the release of hormones
B) duodenum; the hydrolysis of lipids
C) small intestine; the absorption of fatty acids
D) colon; the reabsorption of water

Answer 9

C) the lacteal is inside the villi that line the inside of the small intestine. The duodenum is the first 12inches (30cm) of small intestine and is the site of digestion, not absorption. “Colon” is another name for large intestine.

Question 10

Absorption of nutrients occurs in the
A) duodenum of the colon
B) duodenum of the small intestine
C) latter part of the small intestine
D) latter part of the large intestine

Answer 10

C) digestion occurs in the duodenum - first part of the intestine, and absorption occurs in the latter part.

Question 11

Gas Exchange :
Which is CORRECT about gas exchange in humans?
A) As humans inhale, the pressure in the chest cavity decreases and air is drawn in the large
B) air is forced down the windpipe when a person inhales
C) the breathing rate is controlled by the hypothalamus in the brain
D) hemoglobin carries CO2 and O2 in fairly equal amounts

Answer 11

A) humans breath by negative pressure. When we inhale, the chest cavity expands as the diaphragm contracts & lowers. This increase in volume causes a decrease in internal pressure, and air is drawn into the lungs because the intestinal pressure is less than the external pressure.

Question 12

Tracheal tubes are found in
A) earthworms
B) hydra
C) fish
D) insects

Answer 12

D) spiracles, openings in the exoskeleton of the insects, connect to tracheal tubes that lead to the hemocoel or sinuses where diffusion of respiratory gases occur. the respiratory surface is internal.

Question 13

Breathing in humans is usually regulated by
A) the number of red blood cells
B) the amount of hemoglobin in the blood
C) inherent genetic control
D) CO2 levels and pH sensors

Answer 13

D) the breathing rate is controlled by the medulla in the brain, which is primarily sensitive to CO2 levels in the blood. The other choices are FALSE.

Question 14

All of the following statements about the normal direction of the flow of blood are correct EXCEPT
A) lungs->pulmonary artery
B) right ventricle->tricuspid valve
C) aorta->aortic semilunar valve
D) vena cava->right atrium

Answer 14

A) from lungs, bloods into left atrium via pulmonary vein

Question 15

The pacemaker of the heart is
A) sinoatrial node
B) the atrioventricular node
C) the diastolic node
D) the semilunar node

Answer 15

A) the pacemaker of the heart is the sinoatrial node. From the sinoatrial node, the impulse passes to the atrioventricular node, then to the bundle of His.

Question 16

The Bohr effect on the oxyhemoglobin dissociation curve is produced directly by changes in
A) temperature
B) pH
C) CO2 levels
D) oxygen concentration

Answer 16

B) when the pH becomes more acidic, hemoglobin has less affinity for oxygen, so the hemoglobin will drop off some oxygen at the cells that have become slightly acidic due to an accumulation of CO2 from cell respiration.

Question 17

Which is TRUE of the human circulatory system?
A) the right ventricle of the heart has the thickest wall
B) veins has thick walls consisting of smooth muscle cells to assist in returning blood to the heart
C) blood flow is slowest in capillaries to maximize the diffusion of nutrients and wastes
D) the left and right ventricles contract alternately, which is responsible for the pulse sound

Answer 17

C) diffusion occurs in the thin-walled capillaries where the blood circulates slowly. All other choices are FALSE.

Question 18

In humans, the largest amount of the carbon dioxide produced by body cells is carried to the lungs as
A) CO2 attached to hemoglobin in the red blood cells
B) the bicarbonate ion dissolved in the plasma
C) the bicarbonate ion attached to hemoglobin
D) CO2 gas in solution in the plasma

Answer 18

B) although a small amount of CO2 is carried by the red blood cells, most is carried as bicarbonate ion.

Question 19

During ventricular systole, the \_\_\_valve(s) \_\_\_
A) semilunar; close
B) semilunar; open
C) AV; open
D) AV and semilunar; close

Answer 19

B) systole is the contraction of the ventricles of the heart. When the ventricles contract, blood is pushed out of the arteries thru the semilunar valves while the bicuspid and tricuspid valves remain closed.

Question 20

All of the following are true about blood EXCEPT
A) red blood cells live for about 120 days
B) white blood cells are formed in the bone marrow
C) platelets are not cells but are cell fragments
D) platelets derive from specialized cells knowns as neutrophil

Answer 20

D) platelets are fragments of cells known as megakaryocytes. All the other choices are TRUE.

Question 21

Chemical Signals:
Which hormone acts opposite parathormone?
A) calcitonin
B) glucagon
C) insulin
D) adrenaline

Answer 21

A) parathormone is released but he parathyroid and raises Ca levels in the blood. Calcitonin is released by the thyroid and lower Ca levels.

Question 22

The main target of anti-diuretic hormone is the
A) heart
B) kidney
C) liver
D) spleen

Answer 22

B) the target of anti-diuretic hormone (ADH) is the collecting duct of the nephron. If ADH is released, less urine is excreted.

Question 23

The hormone secreted by the adrenal cortex
A) reduces inflammatory response
B) is an amino acid
C) stimulates the adrenal medulla
D) lowers blood sugar

Answer 23

A) the hormone released by the adrenal cortex is cortisol, which reduces inflammation. The pharmaceutical version of cortisol is cortisone, which has the same function.

Question 24

Which hormones induces labor?
A) glucagon
B) adren-o-cortico-tropic hormone
C) Oxytocin
D) Thyroxin

Answer 24

C) oxytocin induces labor and the production of milk by the mammary glands.

Question 25

What hormone released by the posterior pituitary?
A) glucagon
B) adren-o-cortico-tropic hormone
C) Oxytocin
D) Thyroxi

Answer 25

C) oxytocin is produced in the hypothalamus and stored and released from the posterior pituitary.

Question 26

What hormone stimulates the adrenal gland?
A) glucagon
B) adren-o-cortico-tropic hormone
C) Oxytocin
D) Thyroxin

Answer 26

B) ACTH is tropic hormone. A tropic hormone is one that stimulates another endocrine gland to release a substance. ACTH stimulates the adrenal cortex to release a glucocorticoid-like cortisol.

Question 27

What hormone controls metabolic rate?
A) glucagon
B) adren-o-cortico-tropic hormone
C) Oxytocin
D) Thyroxin

Answer 27

D) the thyroid gland releases thyroxin, which controls the rate of metabolism.

Question 28

What hormone produced in the pancreas?
A) glucagon
B) adren-o-cortico-tropic hormone
C) Oxytocin
D) Thyroxin

Answer 28

A) glucagon is produced in the apha cells of the pancreas and raises blood sugar by breaking down glycogen that is stored in the liver.

Question 29

What hormone causes blood sugar levels to increase?
A) glucagon
B) adren-o-cortico-tropic hormone
C) Oxytocin
D) Thyroxin

Answer 29

A) glucagon is produced in the apha cells of the pancreas and raises blood sugar by breaking down glycogen that is stored in the liver.

Question 30

Tropic hormones
A) are those that are secreted by the liver
B) are those that are secreted by the thyroid
C) stimulate other glands
D) are released only by the hypothalamus

Answer 30

C) tropic hormones are released by one gland and stimulate another gland to release its hormone. For example, TSH is released by the anterior pituitary and stimulates the thyroid to release thyroxin.

Question 31

Excretion:
Which of the following processes of the kidney is the LEAST selective?
A) secretion
B) filtration
C) reabsorption 
D) the target of ADH

Answer 31

B) during filtration, all substances small enough to diffuse out of the glomerulus will do so. It is the least selective process occurring in the nephron.

Question 32

In humans, urea is produced in the 
A) kidneys
B) urinary bladder
C) urethra
D) liver

Answer 32

D) urea is a nitrogenous waste that is produced in the liver; urine is produced in the kidney.

Question 33

Which of the following is INCORRECTLY paired?
A) nephridia-earthworm
B) flame cell-bird
C) Malpighian tubules-insect
D) nephron-ape

Answer 33

B) the flame cell is a primitive excretory structure in Platyhelminthes like planaria. All freshwater Protista have contractile vacuoles that pump out water that continually leaks in. The other statements are all TRUE.

Question 34

Following a company picnic on a hot summer day where you ate traditional fare of hot dogs and hamburgers, ice cold beer, and played softball for an hour, you become very thirst. Which would probably contribute LEAST to your thirst?
A) eating salty food
B) drinking an ice cold beer
C) drinking lots of ice water
D) sweating

Answer 34

C) all of the other options would contribute to thirst. Alcohol,particularly, is dehydrating because it blocks production of antidiuretic hormone (ADH), thus causing the release of extra water in the urine.

Question 35

Which nitrogenous waste requires the least water for its excretion?
A) ammonia 
B) urea
C) nitrites
D) uric acid

Answer 35

D) uric acid is not soluble in water, therefore, it does not require water in order to be excreted from the body.

Question 36

The parts of kidney, where does filtration occur?
A) proximal and distal tubules
B) ascending loop of Henle
C) Bowman's capsule
D) Collecting tubule

Answer 36

C) filtration occurs in Bowman’s capsule.

Question 37

The parts of kidney: identify where secretion occurs
A) proximal and distal tubules
B) ascending loop of Henle
C) Bowman's capsule
D) Collecting tubule

Answer 37

A) secretion occurs in the proximal and distal tubules

Question 38

The parts of kidney, identify the area that is impermeable to the diffusion of water
A) proximal and distal tubules
B) ascending loop of Henle
C) Bowman's capsule
D) Collecting tubule

Answer 38

B) the ascending loop of Henle is impermeable to water.

Question 39

The parts of kidney, identify the target structure of ADH
A) proximal and distal tubules
B) ascending loop of Henle
C) Bowman's capsule
D) Collecting tubule

Answer 39

D) the target structure of ADH is the collecting tubule within the kidney.

Question 40

Nervous System:
Which of the following sequences describes the passage of a nerve impulse thru a simplex reflex arc in humans?
A) receptor->effector->Interneurons->motor neuron->sensory neuron
B) receptor->sensory neuron->Interneuron->effector->motor neuron
C) sensory neuron->effector->motor neuron->Interneuron->receptor
D) receptor->sensory neuron->interneuron->motor neuron->effector

Answer 40

D) the effector is a muscle or gland. The Interneuron is located in the spinal cord.

Question 41

The function of a Schwann cell is to
A) produce esterases to break down neurotransmitters
B) form the myelin sheath around the axon of a neuron
C) act as an Interneuron in the spinal cord
D) receive impulses and send them to the neuron

Answer 41

B) the Schwann cell forms the myelin sheath around the axon and nourishes the neuron. There are more Schwann cells in the nervous system than there are neurons.

Question 42

What is the function of cholinesterase in the transmission of an impulse?
A) it binds w postsynaptic receptors & blocks transmission of the impulse
B) it prevents the release of any more neurotransmitter from presynaptic vesicles
C) it enhances neurotransmission across the synapse
D) it breaks down Acetycholine, preventing continuous neurotransmission

Answer 42

D) there are several classes of esterase. They are all specific in action for a particular neurotransmitter.

Question 43

Which would be associated w the parasympathetic system?
A) increase in blood sugar
B) increase in adrenaline
C) increase in breathing rate
D) increase in digestion

Answer 43

D) the parasympathetic system is calming. It is active when you are relaxing or digesting food and it slows down when you are excited.

Question 44

The threshold potential of a particular membrane measures-70mV at time zero. After 10mins, it measures-90mV. What is the best explanation for what has happened to the membrane?
A) it became depolarized
B) the concentrations of Na+ & K+ became balanced
C) the membrane became hyperpolarized
D) the membrane became hypopolarized

Answer 44

C) the gradient is steeper at -90mV than it was at -75mV. The membrane is now hyperpolarized. The threshold is higher. Depolarizing the membrane and passing an impulse are more difficult.

Question 45

Which is an example of an effector?
A) hormone
B) gland
C) Interneuron
D) brain

Answer 45

B) an effector is a gland or muscle.

Question 46

If the threshold potential were measured at-75mV, what would be the value if the polarization across the membrane were increased?
A) -70mV
B) -80mV
C) zero
D) there would be no change because the membrane potential of a particular neuron can never change

Answer 46

B) the membrane potential reads zero when there is no differential between one side of the membrane and the other. The greater the differential, the more negative the potential.

Question 47

How do action potentials relay different intensities of information?
A) by changing the amplitude of the action potential
B) by changing the speed w which the impulse passes
C) by changing the frequency of the action potential
D) by changing the duration of the action potential

Answer 47

C) the only way a neuron distinguishes the intensity of the stimulus is by changing the frequency of the action potentials. A nerve response is all or none.

Question 48

Muscle:
Tendons connect
A) muscle to muscle
B) muscle to bone
C) ligaments to bones
D) ligaments to ligaments

Answer 48

B) this is a fact.

Question 49

The walls of arteries consists of
A) striated muscle and are under voluntary control
B) striated muscle are not under voluntary control
C) smooth muscle and are controlled by the somatic nervous system
D) smooth muscle and are controlled by the autonomic nervous system

Answer 49

D) the autonomic nervous system controls those things that are not consciously controlled. It controls smooth and cardiac muscles.

Question 50

What is the basic unit of function of a skeletal muscle fiber?
A) myosin filaments
B) actin filaments
C) the sarcomere
D) Z line

Answer 50

C) the sarcomere is the basic unit of contraction of skeletal muscle.

Question 51

What neurotransmitter at the synapse of a neuromuscular junction causes a muscle to contract?
A) GABA
B) norepinephrine 
C) dopamine 
D) Acetycholine

Answer 51

D) Acetycholine is the neurotransmitter at the neuromuscular junction.

Question 52

Which of the following is the name of a single muscle cell?
A) sarcomere
B) myofibril 
C) muscle fiber
D) sarcolemma

Answer 52

C) a single muscle cell is called a muscle fiber. It is a very large, multi-nucleated cell.

Question 53

All of the following are true about the contracting of skeletal muscle muscle cells EXCEPT
A) thick filaments are composed of actin
B) Ca++ ions are necessary for normal muscle contraction
C) the sarcolemma can propagate an action potential
D) the T-system connects the sarcolemma to the sarcolemma reticulum

Answer 53

A) thick filaments are composed of myosin, not actin. The other choices are TRUE about muscles.

Question 54

The main nitrogenous waste excreted by birds is
A) ammonia 
B) urea
C) uric acid
D) nitrite

Answer 54

C) uric acid is excreted as a crystal to conserve water by many terrestrial animals. However, humans and earthworms release nitrogenous waste in the form of urea.

Question 55

Essays questions :
Beginning at an axon at rest, describe the conduction of an impulse thru a neuromuscular junction to the contraction of a skeletal muscle.

Answer 55

See page 264

Question 56

Regulation and homeostasis are critical to living things.
A) explain what a feedback mechanism is and how it helps an organism to maintain homeostasis
B) explain the difference between positive feedback and negative feedback and give examples.

Answer 56

A) body maintain homeostasis by acting thru complex feedback mechanisms. A real-life example of a feedback system is the thermostat and a home heating system. You set the thermostat for a desired temperature. As soon as the temperature deviates from that set point, either the furnace or air-con turns on. In this way, the temperature in the building is maintained at a steady point.

B) Positive Feedback- enhances an already existing response to complete something. During childbirth, the pressure of the baby’s head against sensors near the opening of the uterus stimulates more uterine contractions, which causes increased pressure against the uterine opening, which causes yet more contractions. The positive feedback loop brings labor to an end and the birth of a baby.
Negative Feeback - is a colon mechanism in the endocrine system that maintains homeostasis. Example is how the body maintains proper levels of thyroxin. When the level of thyroxin in the blood is too low, the hypothalamus stimulates the anterior pituitary to release a hormone, thyroid-stimulating hormone (TSH) which stimulates the thyroid to release more thyroxin. When the level of thyroxin in the blood stream is adequate again, the hypothalamus stops stimulating the pituitary.