Studied by 9 people
Describe the different steps of the signal transduction pathway
-Environmental or developmental signal (can be internal or external)
-Receptor (or sensor)
-Signal transmission/transduction
-Response (by an effector)
Distinguish between negative and positive feedback mechanisms
Positive feedback
-Keeps a process going that has a cutoff point
-does NOT maintain homeostasis
-An effector (provides response or effect) continues to stimulate a sensor/receptor so that a greater change occurs in the internal environment
Negative feedback
-Primary homeostatic mechanism
-Keeps variable close to set point
Demonstrate how the hydrogen ion gradient across the thylakoid membrane is produced
As electrons move through the proteins that reside between PSII and PSI, they lose energy. This energy is used to move hydrogen atoms from the stromal side of the membrane to the thylakoid lumen.
-will be used to synthesize ATP in a later step.
Explain how ATP is produced through photophosphorylation
light energy is used to pump protons across the thylakoid (mediated by flow of electrons through an electron transport chain) This stores energy in a proton gradient. As the protons flow back through an enzyme called ATP synthase, ATP is generated from ADP and inorganic phosphate.
Explain the importance of Rubisco in the carbon reactions/Calvin cycle
-Carbon fixation is catalyzed by Rubisco
-accounts for 50% of soluble protein in leaves
-also catalyzes RuBP + O2 reaction
-nitrogen source?
Describe the relationship between the light reactions and the carbon reactions/Calvin cycle
Outputs of one are used as the Inputs of the other
Describe the inputs and outputs for the carbon reactions/Calvin cycle
Inputs
-ATP
-NADPH
-CO2
Outputs
-ADP + P
-NADP+
-sugar (G3P for C3 plants)
If your blood glucose levels drop, the negative feedback response to maintain homeostasis would be...
convert glycogen into glucose
TRUE or FALSE
Positive feedback mechanisms help to maintain homeostasis.
FALSE
Use the following figure to answer this question.
Which wavelength of light in the figure is most effective in driving photosynthesis?
420 nm
Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light.
Which of the following statements describes a relationship that Engelmann's experiment helped to determine?
A) the relationship between wavelength of light and the rate of aerobic respiration
B) the relationship between wavelength of light and the amount of heat released
C) the relationship between wavelength of light and the rate of photosynthesis
D) the relationship between carbon dioxide concentration and the rate of photosynthesis
C) the relationship between wavelength of light and the rate of photosynthesis
Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light.
What did Engelmann conclude about the congregation of bacteria in the red and blue areas?
A) Bacteria congregated in these areas due to an increase in the temperature of the red and blue light.
B) Bacteria congregated in these areas because these areas had the most oxygen being released.
C) Bacteria are attracted to red and blue light and thus these wavelengths are more reactive than other wavelengths.
D) Bacteria congregated in these areas due to an increase in the temperature caused by an increase in photosynthesis.
B) Bacteria congregated in these areas because these areas had the most oxygen being released.
A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. Suppose a plant has a unique photosynthetic pigment and the leaves of this plant appear to be reddish yellow.
What wavelengths of visible light are absorbed by this pigment?
blue and violet
(anything but red and yellow)
What is the function of the pigment molecules in a light-harvesting complex in the thylakoid membranes?
They absorb and transfer light energy to the reaction-center chlorophyll.
What are the products of cyclic electron flow during the light reactions of photosynthesis?
ATP
Which of the following statements summarizes the metabolic results of photorespiration?
It produces carbon dioxide and consumes ATP and oxygen.
Discuss the role of ATP in energy transfer in the cell
-allows the cell to store energy briefly and transport it within the cell to support endergonic chemical reactions.
-Energy derived from glucose catabolism is used to convert ADP into ATP.
-Two processes of ATP regeneration are substrate-level phosphorylation and oxidative phosphorylation through the process of chemiosmosis.
-Energy must be infused into the system to regenerate ATP.
Describe how a proton (H+) gradient is established and maintained by the electron transport chain and used in the process of chemiosmosis
-a series of redox reactions is used to pump hydrogen ions across the mitochondrial membrane.
-The uneven distribution of H+ ions establishes both concentration and electrical gradients
-hydrogen ions pass through the inner mitochondrial membrane by an integral membrane protein called ATP synthase.
-the proton gradient is used for the addition of a phosphate to ADP, forming ATP
The mechanism of photophosphorylation is most similar to which of the following processes?
A) substrate-level phosphorylation in glycolysis
B) oxidative phosphorylation in cellular respiration
C) the Calvin cycle
D) reduction of NADP+
B) oxidative phosphorylation in cellular respiration
In photosynthetic cells, synthesis of ATP by chemiosmosis occurs during ________.
photosynthesis and respiration
Which of the following statements best describes the relationship between photosynthesis and cellular respiration?
A) Cellular respiration runs the biochemical pathways of photosynthesis in reverse.
B) Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.
C) Photosynthesis occurs only in plants; cellular respiration occurs only in animals.
D) Photosynthesis is catabolic; cellular respiration is anabolic.
B) Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.
In mitochondria, an electron transport chain pumps protons from the matrix into the intermembrane space, whereas in chloroplasts, an electron transport chain pumps protons from the ________.
stroma to the thylakoid space
The oxygen consumed during cellular respiration is directly involved in which of the following processes or events?
A) glycolysis
B) accepting electrons at the end of the electron transport chain
C) the citric acid cycle
D) the oxidation of pyruvate to acetyl CoA
B) accepting electrons at the end of the electron transport chain
In glycolysis, for each molecule of glucose oxidized to pyruvate, ________.
two molecules of ATP are used and four molecules of ATP are produced
Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate and sent to the mitochondria to start the Krebs/citric acid cycle?
A) acetyl CoA
B) ATP
C) citrate
D) water
A) acetyl CoA
Where does glycolysis occur in plant and animals cells?
cytoplasm
Even though plants cells carry out photosynthesis, they still use their mitochondria for oxidation of pyruvate. Under what conditions will plant cell mitochondria be active in this process?
in all cells, with or without light
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30-32
Discuss the ways in which carbohydrate metabolic pathways, glycolysis, and the citric acid cycle interrelate with protein and lipid metabolic pathways
Describe the absorptive state and the major events associated with this state
called the fed state and lasts about 4 hours after eating
anabolism exceeds catabolism
excess nutrients stored as fats and sometimes carbs
glucose → glycogen for storage
triglycerides are used for energy by adipose tissue, the liver, and skeletal and cardiac muscles
triglycerides → glycerol and fatty acids → triglycerides for storage
removal of the amino group produces keto acids- energy in the citric acid cycle
amino acids → fat in the liver
amino acids are used for protein synthesis
absorptive state controlled by insulin
Describe the post-absorptive state, and the major events associated with this state
fasting state
gi tract is empty, energy sources are supplied by the breakdown of body reserves
catabolism exceeds anabolism
maintains blood glucose
glucose sparing
proteins → amino acids
glycogen → glucose
triglycerides → glycerol and fatty acids
sympathetic nervous system- controlled by several hormones (more complex)
Discuss homeostatic imbalances (diabetes mellitus is an example)
Type 1
inadequate insulin production
Type 2
abnormal insulin receptors
both result in
proteins and fats are used for energy
unavailability of glucose to most body cells
excessively high blood glucose levels (hyperglycemia)
glucose loss in urine
can lead to metabolic acidosis, protein wasting, weight loss
may lead to coma and death
Why isn’t it sufficient to reduce only dietary fat intake to prevent new fatty deposits from forming in the body?
Acetyl CoA is a starting point for fatty acid synthesis.
TRUE OR FALSE. The preferred energy fuel for the brain is fat.
FALSE
TRUE OR FALSE. Carbohydrate and fat pools are oxidized directly to produce cellular energy, but amino acid pools must first be converted to a carbohydrate intermediate before being sent through cellular respiration pathways.
TRUE
When proteins undergo deamination (removal of amino group), the waste substance found in the urine is mostly ________.
urea
Glycogen is formed in the liver during the ________
absorptive state
Lipogenesis occurs when ________.
cellular ATP and glucose levels are high
Which of the following statements is FALSE?
A) The amino acid pool is the body's total supply of amino acids in the body's proteins.
B) Fats and carbohydrates are oxidized directly to produce cellular energy.
C) Amino acids can be used to supply energy only after being converted to a citric acid cycle intermediate.
D) Excess carbohydrate and fat can be stored as such, whereas excess amino acids are oxidized for energy or converted to fat or glycogen for storage.
A) The amino acid pool is the body's total supply of amino acids in the body's proteins.
If you were to jog one kilometer a few hours after lunch, which stored fuel would you probably tap?
liver glycogen and muscle glycogen
A fasting animal whose energy needs exceed those provided in its diet will draw on its stored resources in which order?
liver glycogen, then muscle glycogen, then fat
Humans store glucose in the form of ________________; plants store glucose in the form of ________________.
glycogen; starch
Which of the following glucose storage forms is the most difficult for human digestive systems to break down?
A) glycogen
B) cellulose
C) starch
D) triglycerides
B) cellulose
Explain how contraction and relaxation of the chambers of the heart create pressure gradients and how these gradients cause the flow of blood in relation to anatomy
All chambers in diastole
– Blood flows passively through atria and into ventricles
– Both AV valves open
– Note both atria and ventricles fill with blood
– But not all blood leaves atria
Atrial systole
– Ventricles (still in diastole) swell with extra blood that has been pumped in by atria
Ventricular systole (atrial diastole)
– Right and left AV valves pushed shut
– Blood forced into arteries through pulmonary and aortic semilunar valves
– ventricles contract from the bottom up
Now back to all chambers in diastole
– as ventricles enter diastole, a little blood sucked back in
– however right and left semilunar valves snap shut
Analyze how the major regions of an EKG correlate with the conduction system function and contraction (i.e., P wave = SA node excitement and atrial depolarization)
P wave- SA node excitement and atrial depolarization
PR segment- atrial depolarization is complete, the impulse is delayed at the AV node
QRS complex- ventricular depolarization, atrial repolarization
ST segment- ventricular depolarization is complete
T wave- ventricular repolarization begins at the apex
after the T wave- ventricular repolarization is complete
Describe the afferent signals to the brain, including three types of receptors, and how they affect heart rate
Propriocenters- sensory input from muscles and tendons
informs the brain on changes in physical activity
Baroreceptors- sensory input from blood vessels
informs the brain on changes to pressure in vessels
Chemoreceptors- sensory input from blood vessels
informs the brain on changes in carbon dioxide or oxygen levels in the blood
important in respiratory system but has some affect on heart rate
Compare and contrast the efferent responses that affect heart rate and how they alter the SA node activity including the neurotransmitters associated with these responses
Sympathetic system
cardioacceleratory system- increased heart rate
Postganglionic neuron secretes norepinephrine (NE)
Adrenergic receptors on cells of the SA node bind to NE
Cause an increased rate of action potentials of SA node
Maximum heart rate is 230 beats/minute
Limit of SA node excitation
Parasympathetic system
cardioinhibitory system- decreased heart rate
Postganglionic neuron secretes acetylcholine (ACh)
Cholinergic receptors on cells of the SA node bind ACh
Allow potassium to leave the cell → hyperpolarizing reaction
The rate of action potentials decrease
Normal heart rate is about 75 beats/minute
Without nervous control, the heart rate would be about 100 beats/minute
Describe the roles of the sympathetic and parasympathetic nervous systems in controlling heart rate
Sympathetic
blood pressure is too low
visceral motor neurons cause
increase heart rate by activating cardioacceleratory neurons
vasoconstriction which is the constriction of blood vessels regulated by the sympathetic release of norepinephrine or epinephrine
Parasympathetic
blood pressure is too high
visceral motor neurons cause
decrease heart rate by activation of cardioinhibitory neurons
vasodilation which is the dilation of blood vessels due to a decrease in norepinephrine
If the right AV valve does not close completely and allows blood to pass through when it should be shut, then you could expect:
the output of the right ventricle to be decreased.
The semilunar valves prevent blood from flowing backwards into the...
ventricles
Normal heart sounds are caused by which of the following events?
closing of the heart valves
Without SA node activity, what type of heart surgery would be indicated?
inserting an artificial pacemaker
Which of the following develops the greatest pressure on the blood in the aorta?
A) systole of the left atrium
B) diastole of the right ventricle
C) systole of the left ventricle
D) diastole of the right atrium
C) systole of the left ventricle
Among the following choices, which organism likely has the highest systolic pressure?
A) mouse
B) human
C) hippopotamus
D) giraffe
D) giraffe
TRUE or FALSE
The heart muscle (myocardium) receives its nutrients from the blood moving through the left atrium and ventricle.
FALSE
TRUE or FALSE
The left side of the heart pumps the same volume of blood as the right.
TRUE
The atrioventricular (AV) valves are closed ________.
when the ventricles are in systole
During exercise, which of the following would occur on an electrocardiogram (ECG/EKG) compared to an individual at rest?
A) the T wave would decrease
B) the P-R interval would decrease
C) the time from one R to the R of the next heartbeat would decrease
D) the S-T segment would decrease
C) the time from one R to the R of the next heartbeat would decrease
Explain how oxygen and carbon dioxide are transported in the blood
Oxygen transport
-98% bound to hemoglobin in red blood cells
-2% dissolved in blood plasma
-high pressure in alveoli, low in body cells, so oxygen goes into body cells
CO2 transport
-10% dissolved in blood plasma
-20% bound to hemoglobin
-70% in the form of Plasma bicarbonate
More important in determining the respiratory rate
-high pressure in body cells, lower in alveoli, so co2 goes into alveoli
Describe the factors that affect oxygen loading and unloading from hemoglobin
O2 pressure
-O2 saturation increases as the partial pressure of O2 increases
-starts to level off and plateau as partial pressure of O2 increases
pH differences
-hemoglobin retains less O2 at lower pH
-lower pH has a higher CO2 concentration
Analyze how changes in carbon dioxide levels alter pH (based on protons and the carbonic acid equation)
-CO2 increase, decreases pH by increasing H+ ions
-CO2 decrease, increases pH by decreasing H+ ions
Explain how the respiratory system works with the cardiovascular system to help regulate pH
-When the pH is too low, the chemoreceptors signal the respiratory system to increase ventilation and remove carbon dioxide.
-The chemoreceptors initiate the contraction of the diaphragm and intercostal muscles.
-High pH leads to a decrease in breathing rate
Contraction of the intercostal muscles causes which of the following to occur?
A) The diaphragm moves downward.
B) The rib cage is compressed.
C) The thoracic cavity volume decreases.
D) The ribs and sternum move upward.
D) The ribs and sternum move upward.
If the pH of the blood has decreased, this means that the ________.
amount of carbon dioxide has increased
During most daily activities, the human respiration rate is most closely linked to the blood levels of ________.
carbon dioxide
Which of the following events would you predict as carbon dioxide is released from your muscles into the surrounding capillary bed?
Oxygen delivery to muscle is increased when more carbon dioxide is produced by the muscle.
The partial pressure of carbon dioxide is 45 mm Hg in the blood and 40 mm Hg in the alveoli.
What happens to the carbon dioxide?
It diffuses into the alveoli.
Oxygen saturation (loading/unloading) of hemoglobin depends on...
Oxygen pressure differences in the tissues and pH differences in the blood
Define water potential and explain how it is influenced by solutes
Water potential is the water’s capacity to perform work.
Water flows from regions of higher water potential to regions of lower water potential
Adding solute causes water to diffuse to the place with the solute
Adding positive pressure causes the water to move away from the pressure
Adding negative pressure causes the water to move toward the pressure
Overall, water moves from an area of high water potential to low water potential
Describe how water potential, evapotranspiration, and stomatal regulation influence how water is transported in plants
Evapotranspiration- the loss of water from the plant through evaporation at the leaf surface
Creates a negative pressure at the leaf surface (water potential)
Pulls water from the roots up towards the leaf
Happens during the day when the stomata are open, at night the stomata close and transpiration stops.
Stomata are open when there is a K+ influx, closed when the K+ is moving out
Plants do not have a circulatory system like that of some animals. If a water molecule in a plant did "circulate" it would require…
both the xylem and the phloem
Plants need to control stomatal opening primarily so they can…
prevent water from leaving the plant cell.
Most of the water taken up by a plant is...
lost through transpiration.
The opening of stomata is thought to involve...
movement of K+ into the guard cells.
For sucrose to be moved from a leaf (source) cell to a root (sink) cell, sucrose is first actively transported into the phloem from the source cell. What happens next?
Water diffuses from the xylem to the phloem.
Discuss the role of the autonomic nervous system in regulation of body systems
regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal.
The sensory (afferent) and motor (efferent) divisions are part of the...
peripheral nervous system
The region of the neuron that carries the nerve impulse away from the cell body is called the...
axon
For a neuron at resting membrane potential…
A) a higher concentration of potassium ions is found outside the membrane
B) a higher concentration of potassium ions is found inside the membrane
C) a higher concentration of sodium ions is found inside the membrane
D) the inside of the membrane is positive relative to the outside of the membrane
B) a higher concentration of potassium ions is found inside the membrane
The "threshold" potential of a membrane is the…
minimum depolarization needed to operate the voltage-gated sodium and potassium channels.
Why does hyperpolarization of the neuron membrane occur?
The potassium channels close more slowly, allowing more potassium to flow from inside to outside the membrane.
If you wanted to inhibit a signal from propagating along the axon, which of the following ion channels would you want to ONLY open?
potassium
The following steps refer to various stages in transmission of the signal at a chemical synapse.
Neurotransmitter binds with receptors associated with the postsynaptic membrane.
Calcium ions rush into neuron's cytoplasm.
An action potential depolarizes the membrane of the presynaptic axon terminal.
The ligand-gated ion channels open.
The synaptic vesicles release neurotransmitter into the synaptic cleft.
3 → 2 → 5 → 1 → 4
Which cardio center in the brain is paired with the correct division of the autonomic nervous system transmitting that signal to the heart?
A) cardioacceleratory center : parasympathetic system
B) cardioacceleratory center : sympathetic system
C) cardioinhibitory center : sympathetic system
B) cardioacceleratory center : sympathetic system
Describe the importance of aquaporins in the plasma membrane
Integral membrane proteins that form water-selective channels across membrane
Accounts for observed higher rates of water movement than diffusion alone
Describe how osmosis is used in regulating stomatal opening
Changes in turgor pressure inflate or deflate guard cells, changing the stoma size
Guard cell turgor pressure is controlled by the regulation of K+ movement
Stomata Open
K+ influx
Water follows
Increase Turgor pressure
Stomata Close
K+ efflux
Water follows
Decrease Turgor pressure
Analyze how changes to the function of the nephron loop may disrupt water conservation
Descending limb is only permeable to water
Osmolarity of medulla increases moving away from cortex
Water moves via osmosis through aquaporins and is reabsorbed into the blood concentrating the filtrate in nephron
Ascending limb is only permeable to ions (primarily Na+ and Cl-)
In thin segment, NaCl, which had become concentrated in descending limb, diffuses out of nephron (helps maintain high osmotic concentration)
In thick segment, NaCl is actively transported out and filtrate becomes more dilute
Explain how the nephron and respiratory system works together to help balance blood pH
The Distal convoluted tubule (DCT)
Important site of proton (H+) reabsorption or secretion
Lungs can rid the body of excess acid very rapidly (seconds to minutes) through the conversion of HCO3– into CO2, which is then exhaled
Rapid but has limited capacity in a significant acid challenge
Kidneys can rid the body of both acid and base.
Renal capacity is large but slow (minutes to hours). The cells of the DCT actively secrete H+ into the forming urine as Na+ is reabsorbed.
The body rids itself of excess H+ and raises blood pH.
List the four hormones that affect renal function
– directly effected by ADH and aldosterone
– indirectly effected by renin and angiotensin
Describe where each hormone is produced, its target tissue and ultimate physiological effect
Renin
Macula densa cells detect the dilute filtrate
trigger JG cells to release renin from the kidneys
Angiotensin
Renin activates a protein called angiotensinogen in blood which is a precursor to angiotensin I.
Angiotensin I is activated to angiotensin II by ACE, primarily in the lungs
Angiotensin II results in increased blood pressure via vasoconstriction and thirst
released by liver
Aldosterone
angiotensin II triggers the release of aldosterone
stimulates reabsorption of sodium ions in the DCT and collecting duct
water follows because of osmosis, more water in blood increases pressure
released by adrenal glands
ADH
is triggered by water moving into the blood and increasing pressure.
ADH leads to more water reabsorption in the kidneys
released by pituitary gland
Plants may move Na+ into their cells to reduce the water potential and allow water to move from the soil into the cells. But too much Na+ can be toxic. Which of the following is NOT a process for plants to deal with high levels of Na+?
A) compartmentalization of Na+ in vacuoles
B) excretion of Na+ though salt glands
C) disrupting cell membranes
D) reduction of Na+ influx into the cell
C) disrupting cell membranes
There is a build-up of carbon dioxide in the blood (respiratory acidosis). What will occur in the distal convoluted tubule (DCT) of the nephron to negate the acidosis?
Secretion of more protons
If the DCT is unable to secrete protons in the situation described in Q1, what will happen to the respiratory rate?
The respiratory rate will increase.
Alcohol blocks the production of antidiuretic hormone (ADH) from the hypothalamus. When you drink alcohol, what happens?
More water is eliminated in the urine and you become dehydrated.
Why is water reabsorption in the descending limb of the nephron and the collecting duct passive?
There is more NaCl in the surrounding tissue compared to the nephron.
In this example in this figure, Net Filtration Pressure (NFP) is 10mm Hg toward the nephron (out of the blood).
What would happen if Blood Hydrostatic Pressure (BHP) changed to 45mm Hg and the other pressures remained constant?
Filtration would stop
What effect would you expect the drug furosemide, which blocks transport of Na+ and Cl– in the ascending limb of the loop of Henle, to have on urine volume?
increase urine volume
Which part of the nephron helps to regulate the pH of the blood?
Distal Convoluted Tubule (DCT)
Which of the following actions requires energy?
A) Transport of the filtrate through the nephron.
B) Transport of water into the medulla.
C) Transport of sodium chloride into the nephron loop.
D) Transport of sodium chloride into the medulla.
D) Transport of sodium chloride into the medulla.
What is the main result of the "salty medulla" created by the nephron loop?
Reabsorption of water in the descending limb of the nephron
Note
Flashcard