A
Kai is hiking on a trail when they suddenly encounter a bear. Before the bear notices them, Kai gains a sudden burst of energy and decides to run for safety. They were able to run away due to the release of a hormone from this gland?
Adrenal Medulla
Important notes:
Adrenal medulla - produces epinephrine which is a short term stress response hormone responsible for fight or flight
Adrenal cortex - produces aldosterone and cortisol which is a long term stress response hormone
Which gland is located in the neck and produces hormones regulating metabolism and growth?
Thyroid gland
Explanation: releases T3 and T4 which help with metabolism, and it works together with growth hormone to stimulate overall growth
Which of the following is a *FALSE* statement about the neuroregulation of muscle contraction?
a. Calcium binds to troponin to move the troponin-tropomyosin complex
b. Calcium is released from the sarcoplasmic reticulum into the sarcoplasm upon activation of calcium pumps.
c. Acetylcholine is released at the neuromuscular junction
d. The action potential is carried through the T tubule to the sarcoplasmic reticulum
e. All of the above are true
B. Calcium is released from the sarcoplasmic reticulum into the sarcoplasm upon activation of calcium pumps.
Calcium is release by calcium release channels
How do bony fish swimming in a school not collide with each other and turn in unison?
Hair cells and a cupula in the lateral line of the fish
Which of the following methods of molecule transport across membranes typically involve transport down a concentration gradient (from high to low concentration)?
A. Co-transport
B. Active transport
C. Diffusion
D. Facilitated Diffusion
A, C, D
Co-transport, Diffusion, Facilitated Diffusion
Which is NOT one of the ways our brain uses touch sensory systems to decode analogous world into digital signals
a. with the type of receptors used
b. with the action potential speed and amplitude coming from the sensory receptor cell
c. with the number (frequency) of action potentials send to brain from a given receptor cell
d. with the number of receptors that are activated
B
Explanation: Action potentials have to be all or nothing so there is no way to vary the speed and amplitude coming from the sensory receptor cell. In general, for all sensory systems the way signals are encoded is through frequency of action potentials, or the location (cells they come from)
Alya just ate a large slice of cake for dessert. In her body, her blood glucose level rises. What happens next in her body, and what type of feedback mechanism is this?
Insulin is released from her pancreas into her blood and glucagon release is inhibited; negative feedback
Explanation: When blood glucose rises, the pancreas releases insulin to turn glucose into glycogen and transports glucose into muscle and liver cells. When blood glucose levels fall, the pancreas releases glucagon which breaks down glycogen from the liver into glucose to raise blood glucose level. Neither one of these processes continues to infinity, and they are tightly regulated which is an example of negative feedback.
Which type of channel is primarily responsible for depolarizing the next node of Ranvier on an axon?
Voltage gated sodium channel
Explanation: Voltage gated sodium channels open immediately when the threshold potential is reached. Voltage gated sodium channels allow sodium into the neuron which causes the inside to become more positively charged than it was previously, which causes the spike shown in every action potential.
You are performing an experiment with seed germination to see if light wavelength makes a difference in germination period. You plan on recording the light color used on each group of seeds and the amount of time each group takes to sprout. However, you notice one group of seeds don’t sprout weeks after the other seeds have. Which light color were these seeds most likely grown under?
Far red light
Explanation: far red light inhibits growth/germination of a plant. When the receptor is in the Pr state, that means it has sensed far red light and will not allow the plant to germinate. This is because far red light indicates that the plant is under shade and does not have ample light to grow
How do plants respond to rain vs. a drought?
Intake of water activates the hormone gibberellin, which then signals to transcribe the gene encoding amylase, an enzyme that breaks down starches stored in the seed into simple sugars, and then germination proceeds.
When water is absent, germination in this pathway is blocked by a hormone called abscisic acid (also called ABA), which inhibits the activity of gibberellins.
What ensures unidirectionality of an action potential?
Refractory period of voltage gated Na+ channels
Explanation: Once the action potential hits the peak, VGSC’s are closed and VGPC’s open in order to repolarize the neuron. When the refractory period occurs these Na+ channels are still closed and it takes a lot more depolarization to get them to reopen in the phase because the voltage is below the threshold
Which of the following about plant behavior regulation is incorrect?
a. There are specialized cellular compartments that contain starch granules that move in response to gravity in the roots.
b. Intake of water activates the hormone gibberellin which signals to produce amylase that breaks down starches and proceeds germination.
c. When activated by blue light, auxin is found more on the shaded side of the plant.
d. Far-red light usually promotes stem elongation or growth.
e. All of them are correct
D
Explanation: red light → promotes growth in plants, far red light → inhibits growth and stem elongation
Which of the following best explains the shortening of light colored sections of a sarcomere while the dark bands stay the same length?
a. Light band, made out of thin filaments, shortens due to removal of actin monomers from the filament
b. Thick and thin filaments slide into each other making the region with only thin filaments smaller
c. As muscles contract, calcium rushes into the light band, making it appear darker.
d. Light bands do not get shorter because the sizes of the filaments do not change during contraction.
e. None of the above
B. Thick and thin filaments slide into each other making the region with only thin filaments smaller
Explanation: While the filaments themselves do not change length during a contraction (they just slide past each other), the dark colored band will cross over the lighter colored band making it look like the lighter colored band has gotten smaller or disappeared.
Caytie Anne slams the brakes to avoid crashing into the car in front of her, just barely missing the car. Her heart is beating rapidly in her chest, and her pupils are dilated. Which of the following divisions of the nervous system are responsible for these changes?
Autonomic, Sympathetic
Explanation: the autonomic nervous system is responsible for involuntary movements. For example if you choose to pick up a pencil that's the somatic nervous system, but your heartbeat is controlled involuntarily by the autonomic nervous system. The sympathetic nervous system is responsible for fight of flight, which is activated in stress responses like crashing your car. On the other hand, the parasympathetic nervous system is responsible for rest and digest after the sympathetic nervous system kicks in.
Dynein walks along which track?
Microtubule
Dynein → Microtubule Track
Myosin → Actin Filament (much smaller)
As a research assistant, you inject a dye into a tissue sample to observe cell communication. After a few hours, you notice that the dye does not spread very far and lights up only in a cluster of surrounding cells. Which kind of signaling could you label this behavior as?
Paracrine Signaling
Explanation: form of local cell to cell communication where signals are delivered to adjacent cells
In resting neurons, which ion is most likely to leak out of the membrane (i.e. has greatest membrane permeability)?
K+
Explanation: There are the highest number of potassium leak channels in the neuron. Since ions can only leave the neuron through leak channels, K+ has the greatest membrane permeability.
When walking along a pond, Sruthi observes a lotus looking withered with curled leaves. She later comes to find out this region has very recently experienced a drought. What could explain the lotus withered appearance?
a. Gibberellin enhances root growth
b. Auxin prevents water absorption
c. Ethylene causes localized cell death
d. ABA (abscisic acid) closes stomata
e. Cytokinins promote cell division
D. ABA closes the stomata
Explanation: The question tells us that the region the plant is in has recently experienced a drought. Since this means the plant has been dehydrated for long amounts of time, ABA is used to close the stomata. This way excess water will not be lost to the atmosphere. However, it also means the plant has very low turgor and will not be able to photosynthesize resulting in wilted leaves and mentioned.
Which are correct about EPSPs and IPSPs? (multiple select)
1. EPSPs make action potentials more likely in postsynaptic cells
2. EPSPs make action potentials less likely in postsynaptic cells
3. IPSPs make action potentials more likely in postsynaptic cells
4. IPSPs make action potentials less likely in postsynaptic cells
5. Simultaneous EPSPs and IPSPs could cancel each other out
6. Simultaneous EPSPs and IPSPs amplify each other
1, 4, 5
Explanation: Answer choice 1 is correct because EPSP’s are excitatory graded potentials. I like to think of making these making the neuron “excited” to fire so they cause a depolarization. If answer choice 1 is correct, than 2 cannot be correct. IPSP’s are inhibitory graded potentials so they inhibit the neuron and make it less likely to fire, therefore answer choice 4 is correct so 3 cannot be. Since EPSP’s make a neuron more likely to fire, and IPSP’s make them less likely to fire they can cancel each other out (like adding +10 + -10).
Describe how muscles contract using myosin and actin filaments (the sliding filament model)
Thin filaments that are attached to Z discs are pulled by thick filaments towards the center of the sarcomere. This reduces that distance between the Z discs and contracts the muscle cell.
In class you have found your blind spot.
A. Why do we have a blind spot?
B. Do all animals have blind spots?
C. What is the reason for us seeing everything in our visual field, if we have a known blind spot?
A. Why do we have a blind spot?
Inverted eye and/or no retina (photoreceptors) and Requires optical nerve to exit eye
B. Do all animals have blind spots?
No (1/1) Cephalopods have camera eye (1/1 extra credit)
C. What is the reason for us seeing everything in our visual field, if we have a known blind spot?
Stating that the brain compensates for this
Recall Peter Boysen-Jensen’s 1913 bending oat shoots experiments.
A. What is the specific stimulus AND hormone involved in phototropism?
B. According to the acid-growth hypothesis, if sensors are located at the tip of the plant, how does bending occur at the middle part of the plant during phototropism? Describe the pathway and steps that regulate this behavior.
C. Recall the experiment where the tip was cut, left on an agar cube for a while, and then that agar cube was placed slightly offset back on the shoot. What would happen if you did the same steps but put the agar (again offset) on a root instead? Explain
A. blue light (1/1), Auxin (1/1)
B. Unequal auxin distribution causes bending (1/1) by pumping out protons into the extracellular matrix (0.5/0.5) which degrades extracellular structures (0.5/0.5) and causes the cell to swell up (1/1)
C. auxin causes the root to bend towards the higher gradient (2/2)
A. Define signal transduction
B. Describe the general pathways of signal transduction and amplification for steroid vs non-steroid hormones
A. The process of converting extracellular signals to intercellular signals
B.Signaling in steroid hormones is different to non-steroid hormones. Signal transduction is only necessary for hydrophilic ligands that cannot cross the plasma membrane. Steroids are lipid-soluble, so they cross the membrane much more easily. Steroid hormones are received by a receptor in the cytosol, which then activates a signaling cascade to create a cell response through increased transcription. For hormones that bind to intracellular receptors, the amplification can occur during the process of both transcription or translation. For non-steroid hormones that bind to cell-surface receptors, the amplification can occur via second messengers that are produced or released in response to the hormone signal
A. define vestibular perception
B. give one way vestibular perception among animals and invertebrates are similar
C. one way that they are different.
A. The vestibular system is used for maintaining balance by detecting linear acceleration (gravity) and angular acceleration and deceleration.
B. Both systems use hair cells to perceive changes in orientation/balance
C. Hair cells are in the cupula for mammals, whereas they are in the statocyst for most invertebrates
Analog sensory information is often converted to digital action potentials for processing. Please explain the general mechanisms by which a stimulus is communicated for:
A. a light touch
B. different pitches of sound
A. Light touches cause fewer action potentials per second than are caused by a stronger touch by triggering receptors on near the skin surface
B. Different hair cells in the ear are activated by different frequencies (pitches) of sound waves