Bio Final
Define a stimulus.
An external cue that elicits physiological or behavioral response.
Would an external ear infection (such as swimmers ear) or an internal ear infection be more likely to affect a person's balance? Why?
An internal ear infection would be more likely to affect a person's balance because balance in mammals is maintained by hair cells in the inner ear that perceive head position and motion.
What is a motor unit? How would the nervous system stimulate a muscle to generate a very strong contraction (2 factors)?
- A motor unit consists of a single motor neuron and all the muscle fibers it controls. - Fast-twich fibers are fast and enable brief, rapid, power contractions. - Slow fibers, often found in muscles that maintain posture, can sustain long contractions. It has less sarcoplasmic reticulum and pumps Ca2+ slowly. - Muscle fibers are organized into motor units. Within each muscle some motor unites contain hundreds of fibers while others contain just a handful.
Describe the steps that take place in the muscle fiber to generate a contraction.
-Action potential travels down motor neuron axon -Voltage gated Ca++ channels open -Ca++ stimulates release of acetylcholine from vesicles into synaptic cleft -Acetylcholine binds receptors, opens Na+ channels -Voltage gated Na= channels open AP! -Action potential travels along T-tubules through sarcoplasmic reticulum -Voltage gated Ca++ channels open -Ca++ binds to troponin, realeasing actin binding sites -Myosin binds to actin, contracting muscle fiber
. Which of the following is responsible for MOST of the water taken up by plant roots: a. it is lost through the stomata during transpiration b. it is used to make sugar during photosynthesis c. it is lost from the vascular system through guttation d. it is used to make CO2 during respiration e. It is used up by moving sugar and nutrients around in the phloem
A
Which of the following statements about eukaryotes is FALSE: a. All eukaryotes have membrane-bound organelles, including the nucleus. b. Chloroplasts evolved from symbiosis between a eukaryote and photosynthetic bacteria. c. Mitochondria evolved from symbiosis between a proto-eukaryote and a bacterium. d. All modern eukaryotes evolved from symbiosis between another organism and a bacterium. e. All eukaryotes are multicellula
A,D,E
What is the role of each of the following in generating a muscle contraction: Actin Myosin Tropomyosin Ca++ Sarcoplasmic reticulum Voltage-gated Ca++ channel T-tubule Acetylcholine Motor neuron ATP.
Actin-structural protein. Myocin-motor protein, binds to actin, pulls toward center. Tropomyosin- on the actin when cell at rest. it covers the binding site. Ca++ shifts tropomyosin and frees binding sites. Sarcoplasmic reticulum when cell at rest. when action potential is recieved, voltage gated ion chanels open and Ca++ is released. T-tubules come in and allow action potential to interact with sarcoplasmic reticulum. Acetylcholine is a neurotransmitter. Motor neuron releases acetylcholine. ATP needed.
Define an action potential. How does the charge across the neuron's membrane change during an action potential? What is the role of Na+ in generating the action potential? Why is Na+ such a useful ion for this purpose (think about how the resting potential is maintained)?
Action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls. Following a consistent trajectory, this occurs because of a rush of sodium. Neurons membrane potential increases. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. This then helps to get back to resting potential.
Describe the steps at the motor plate that take place when a motor neuron stimulates a muscle fiber to contract.
Action potential travels down motor neuron axon. Voltage gated ca++ channels open. Ca++ stimulates release of acetylcholine from vesicles into synaptic cleft. Acetylcholine binds receptors, opens na+ channels and action potential is generated.
How do animals without bones or other hard parts generate movement? What is a hydrostatic skeleton? Give an example of an animal with a hydrostatic skeleton.
Animals with Hydrostatic skeletons consistent of fluid filled chambers, when muscle contracts, forces chamber to change shape. An earth worm has a hydrostatic skeleton, which are divided into sections so when one section contracts the others relax driving movement.
Describe three functions of astrocytes, a type of glial cell. What is the function of the other glial cells (oligodendrocytes, and Schwann cells).
Astrocytes give structural support for neuron. They help regulate extracellular ion and neurotransmitter concentrations. Causes dilation of nearby blood vessels. During development, facilitate formation of tight junctions among brain caillary cells-blood brain barrier. Oligodendrocytes are part of central nervous system. Schwann cells are part of the peripheral nervous system, form myelin sheaths.
Why do electrical impulses travel down axons unidirectionally and not back up towards the axon hillock?
Electrical impulse travels down the axon through a wave of depolarization. K+ moves out but Na+ channels stay closed so doesn't Na flows in. This allows for an elecctrochemical gradient to flow down the neuron.
How do neurons integrate stimuli/information from multiple sources?
By electrical synapses direct movements of Na+ ions through gap junctions, or chemical synapses. Release of direct neurotransmitters opens or closes ligand-gated ion channels. Release of indirect neurotransmitters causes ion channels to open or close due to intracellular signaling. Long-term potentiation and depression through change in abundance of ion channels making neurons more or less responsive.
Explain the role of Ca++ in contraction of a muscle fiber. Draw a diagram that includes the sarcoplasmic reticulum, actin, myosin, tropomyosin, and troponin. Indicate where Ca++ ions are when the muscle is relaxed and when it is contracting. What causes release of Ca++ from the sacroplasmic reticulum? How does Ca++ get back into the sarcoplasmic reticulum?
Ca++ stimulates release of acetylcholine from vesicles into synaptic cleft. When muscle cells are at rest Ca++ is stored in sarcoplasmic reticulum. Ca++ binds to troponin, releasing actin binding sites so myosin binds to actin. The action potential travels along t-tubules through sarcoplasmic reticulum. voltage gated ca++ channels open.
Compare the metabolic potential (ability to burn organic molecules rapidly) of these animals that all live in a pond together: a freshwater annelid (a kind of worm) with a closed circulatory system, a crayfish with an open circulatory system, and a dragonfly larva with an open circulatory system and a tracheal system.
Closed circulatory system is best. Crayfish depends on envoirnment to get oxygen and get rid of CO2. Dragon fly will depend on tracheal system, has a faster metabollic rate.
Which of the following would transmit electrical impulses most rapidly: a. narrow, unmyelinated neuron b. wide, unmyelinated neuron c. narrow, myelinated neuron d. wide, myelinated neuron
D: wide,myelinated neuron
What are some other sensory modalities besides those mediated by mechanoreceptors, hair cells, and photoreceptors? Describe at least two animal sensory modalities that people do not have.
Electric fields:surrounds electively charged particles and exerts force on other electrically charged particles Echolocation: the location of objects by reflected sound, in particular that used by animals such as dolphins and bats.
What is the function of each of the following components of a neuron: Dendrite Cell body Axon hillock Axon terminus Synapse?
Dendrites are responsible for passing information that is gathered from other neurons. Cell body is responsible for the production of proteins for the dendrites and axons. Axon hillock initiates the propagation of the action potential down the axon, determines rate. Axon terminals have the role of sending nerve signals to different parts of the body, as they contain synapses where neurotransmitters are unconfined for communication purposes with other neurons. Synapse is where a neuron communicates with next neuron in the network.
Describe 3 functions of vertebrate hairs cells.
Describe 3 functions of vertebrate hair cells. vibrations of hair cells are responsible for balance, detection of water currents, and hearing.
Define diffusion & osmosis. Describe TWO examples of physiological processes IN PLANTS that depend on diffusion or osmosis. Describe TWO examples of physiological processes IN ANIMALS that depend on diffusion. Your answers should include the substance that is diffusing, and explain why there is a concentration gradient in this substance. Does diffusion require an input of energy or does it occur spontaneously?
Diffusion is movement from higher conc. to lower conc.(doesn't require energy). Osmosis is the passive movement of water molecules from a region of high solute concentration to a region of low solute concentration through a semi-permeable membrane. In plants diffusion explains the movement of CO2 in leaves, osmosis happens when plants absorb water from soil due to the soil having higher water conc. In animals diffusion happen when CO2 diffuses from blood which is high in CO2 compared to the lungs, and in the gut when digested food goes into the blood in capillary of villus in small intestine. And heat from the arteries to the veins.
Define each of the following: Electric field Electroreceptive Passive electroreception Electroreceptor Weakly electric fish Strongly electric fish Electric organ Electrocytes
Electric field: surrounds electrically charged particles and exerts force on other electrically charged particles Electroreceptive: is the biological ability to perceive natural electrical stimuli. Passive electroreception: detects signals naturally produced by other animals. Weakly electric fish:animal produces weak electric field around it using electric organ and detects alterations of this field Strong electric fish: Strongly electric fishes use fields to stun/kill prey. Electric Organ:Where charge is stored in animal body? Electrocytes: Stacked to generate charge
How does an electrical synapse differ from a chemical synapse? What is the name for the structures that allow communications between neurons at electrical synapses? What are some advantages and disadvantages of electrical over chemical synapses?
Electrical synapses conduct nerve impulses faster, but, unlike chemical synapses, they lack gain—the signal in the postsynaptic neuron is the same or smaller than that of the originating neuron. By electrical synapses direct movements of Na+ ions through gap junctions or chemical synapses, Release of direct neurotransmitters opens or closes ligand-gated ion channels. Release of indirect neurotransmitters causes ion channels to open or close due to intracellular signaling. Long-term potentiation and depression through change in abundance of ion channels making neurons more or less responsive. Gap junctions are the structures that allow communications between neurons at electrical synapses.
Explain the difference between strongly and weakly electric fishes. Which one should I be scared of? What type of cells did electrocytes evolve from? What is the neurotransmitter used to communicate between the nervous system and electrocytes? What cross-membrane protein due electrocytes uses to generate a charge gradient?
Electrocytes evolved from muscle cells. Weak electrical fishes generate an electrical field and detect changes to it. Sharks are only electroreceptive. They don't generate any more of an electric field than any other animal their size, but they can detect electric fields made by other animals. Weak electrical fish use there electric receptors to detect such as a shark, and Strongly eletrical fish are able to shock an organism such as an electric eel ? Acetylcholine is transmitter Charge gradient is created by Na+/K+ ATPase (sodium-potassium pump). Rapid APs in many, many stacked electrocytes creates current
Compare and contrast the roles of the endocrine system and the nervous system in communicating within animals' bodies. How are their functions similar and different? How do the nervous system and endocrine system interact?
Endocrine system communicates long distances within body on relatively long time scales. Nervous system comunnicates very rapidly by signaling (milliseconds). They have similar chemical signaling mechanisms operating at multiple scales within animals bodies. The secretion of hormones from the pituitary gland (which is part of the endocrine system) is closely controlled by the brain, especially by the hypothalamus (which is part of the nervous system).
Explain the evidence that eyes have evolved multiple times within the animals.
Evidence shows that animals inheried the ability to detect light. Rhodopsin found in non-animal eukoryotes and in almost all animal lineges. Eyes coming in many different forms but essential mainly detect light to form some sort of image.
Which of the following require animals to use energy: Excretion of hyperosmotic urine Diffusion of ammonia across gill of fish Uptake of salt by freshwater fish Maintenance of a cell's resting membrane potential Generation of an action potential in a neuron where the resting potential is established Building uric acid from ammonia Excretion of H+ into the distal tubule of the kidney Diffusion of oxygen from aveoli into capillaries in lungs Filtration by protonephridia of flatworm
Excretion of hyperosmotic urine takes energy. Uptake of salt by gills of freshwater fish takes energy. Maintenance of a cells resting membrane potential takes energy. Excretion of salt by gills of saltwater fish takes energy. Converstion of ammonia to urea and uric acid takes energy. Filtration by protonephridia of flatworm.
Define an eye and explain the difference between an eye and an eyespot.
Eye: Detects light with enough spatial resolution to form a picture of the world Eyespot: Perceiving only direction can easily be developed into pin-hole eyes
How are movements generated in plants? Compare and contrast these mechanisms with those responsible for animal movements:
Gravitropism: Movement or growth in response to gravity. Heliotropism: Movement of growth in response to sunlight Thigmotropism: Movement or growth in response to touch contact.
Describe an example of a counter-current system in animal physiology and state what substance is transferred between flows in your example. Draw a cartoon illustrating the how the relative concentration or quantity of this substance varies along each of the two flows. How would the transfer of this substance differ in a CONcurrent system? A drawing of the concurrent system may help you illustrate this.
Heat transfer between artery and veins is a counter current system within the human body, in a concurrent system the heat transfer between the would be 100% and 0% on one end and by the end of the system it will reach an equilibrium.
Does hyperpolarization make a neuron more or less likely to generate an action potential?
Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold
Explain how each of the following affect animals' ability to acquire oxygen and expel wastes through diffusion: Body size Metabolic rate Skin permeability Terrestrial vs. Aquatic habitat.
Increasing size means increasing need for oxygen. Faster metabolic rate needs more oxygen. Less permeable skin harder for oxygen to diffuse. Terrestrial animals usually have impermeable skin to avoid drying out. Gasses diffuse much slower in water.
Draw a crude diagram of an eye with a lens, indicating the path of light as it enters the eye, passes through a lens, and forms an image on the back of the eye (retina). Indicate where refraction (bending of light) occurs, and why it is important for image formation.
Is need to focus the image.
For each of the following, what is the motor protein and what is the structural protein: Movement of flagella Movement of cilia Contraction of muscle fiber
MOVEMENT OF FLAGELLA MOVEMENT OF CILIA - Motor: Dynein -Structure: Axoneme CONTRACTION OF MUSCLE FIBER - Motor: Myosin
Which of the following require an animal to expend energy: Maintenance of cell resting potentials . Generation of action potential in electrically excitable cell with resting potential already established. Regeneration of resting potential after action potential. Sequestration of neurotransmitter from synaptic cleft back into membrane-bound vesicles of the presynaptic neuron. Diffusion of sodium into a cell with a normal resting membrane potential
Maintenace of cell resting potential, Regen of resting potential after action potential Sequestration of neurotransmitter from synaptic cleft back in to membrane-bound vesicles of the presynaptic neuron.
Define homeostasis. List 5 conditions for which at least some animals are homeostatic regulators, and describe an example of how an animal regulates this condition. For each of the conditions you listed, do you think most plants are regulators or conformers?
Maintenance of stable conditions within the body that are suitable for metabolism. Temp: Maintaned through metabolism pH:? Glucose: ? Solute: Kidney filtration for urine production? Oxygen concentrations: Gas exchange within the lungs? Most are regulators.
Define a mechanoreceptor. Describe 3 different examples of specific mechanoreceptors in animals. List some other ways that animals use mechanoreceptors to get information about their environment.
Mechanoreceptor: sense physical deformation(Stimulated by distortion of plasma membrane) caused by forms of mechanical energy such as pressure, touch, stretch, motion, and sound.
How would each of the following affect a muscle cell's ability to contract? • Oubain • Tetrodotoxin • Poison that prevents breakdown of acetylcholine within neuromuscular synapses (motor plate) • Drug that elevates background Ca++ concentrations in muscle cells
OABAIN - With oubain, neuron cannot generate action potential, nor membrane resting potential. Will affect other cells in the body. TETRODOTOXIN - Tetrodotoxin prevents action potentials which are going to generated, which will make the animal very sick and possibly die because the nervous system cannot function. Respiratory paralization. POISON - Excitatory postsynaptic potential would not stop being produced because acetylcholine, while in excitatory state, produces this after binding with the lgand-gated ion channel DRUG THAT ELEVATES - Contractions would continue. The action of Ca+ binding to troponin, causing tropomyosin to pull away from actin and reveal binding sites on actin, and never ending binding of myosin and actin.
What is the role of each of the following in animal photoreception: opsin proteins, retinal, rhodopsin, dark pigments, Pax-6.
Opsins are membrane-spanning proteins that are coupled to Retinal a light-absorbing molecule, a complex of these is rhodopsin. Pax-6 gene is required for eyespot or eye formation
Compare photosynthesis and cellular respiration. What are the inputs and products of each? What organelles are involved? What constraints does cellular respiration place on both plants and animals? Describe a plant adaptation that allows plants to use cellular respiration for metabolic energy in a non-green (i.e. non-photosynthesizing) part of the plant.
Photosynthesis in chloroplasts: CO2 + H20 + light ----> c6h12o6 (carbs) + o2 + h2o... Cellular Respiration in mitochondria: c6h12o6 (carbs) + o2 ----> co2 + h2o + energy. Since cellular respiration needs oxygen and carbs, this is a constraint. HELP
Describe each of the 4 optical mechanisms for image formation in animal eyes that we talked about in class. For each, provide an example of an animal that uses that mechanism.
Pinhole eye(chameleon)- Allows very little light in Lensed eye(annelids)- Takes advantage of refraction to focus image Compound eye(insects)- Form by many simple refracting lenses, great for seeing movement mirrored eye (last found only in scallops)-
Describe the physical basis of sound. What aspects of sound do we interpret as intensity and pitch?
Pitch is determined by frequency of sound waves. Loudness determine by intensity of sound waves.
Compare and contrast mechanisms for communication within plants' bodies to communication mechanisms within animals' bodies. What are the major mechanisms the organisms uses to communicate within its body? How fast are they? What kind of information is communicated? How is the role of hormones similar and different in plants and animals?
Plant: Response mechanisms include circadian rhythms: 24 hour cycle, Induced defenses: chemicals/structures produced in response to damage, Tropisms: growth response that causes plant to bend toward or away from stimulus, Hormones: such us auxin, cytokinins, ethylene, and gibberelins. these hormones tell cells to divide, elongate... Light as a cue such as blue, red and far red light. Animals: Nervous system: very rapid signaling (milliseconds), Endocrine system: communicating long distances on relatively long time scale (seconds to days). Neurohormones: produced by specialized cells in nervous system in response to neural cues, act as hormones.
What constraints does photosynthesis place on plant's physiology?
Plants need cellular respiration to release stored chemical energy and to make ATP so that other cells can use energy. Cellular respiration needs oxygen and carbs, that means that the plant needs to be able to get oxygen and carbs. Photosynthesis needs CO2 and water. Plant doesn't have water available, stoma will close, CO2 won't come in, and this will not help with photosynthesis.
Compare and contrast plants' and animals' abilities to sense light, the type of information they gather about their environment from light, and their responses to light. What molecules are used to detect light? Where on the organism are they found? What, if any, complex morphological structures are involved? What wavelengths of light are intercepted? What type of information about the organism's environment does it gather from light? What are some physiological or behavioral responses and how does information from light trigger them?
Plants use Phytochrome to detect red/blue light which come is the form of Pr/Pfr, an example of these can be could be found in their leaves/stomata? not sure a morphological structures, the intercept wavelength ~400nm to ~700nm? An example of info it can get from the light is competition between the plants?not sure? Animals have eyes to detect light, the eyes take in light then refrect to make an image? not sure of morphological structures? Not sure of wavelengths? The type of info could be the environment itself? A response could be that when light is high some animals go out of their homes to heat their bodies?
Compare and contrast plants' and animals' responses to environmental conditions. What are some examples of stimuli or cues that plants respond to? What stimuli or cues do animals respond to? Pick an example of a plant response to the environment, and describe what molecules or cells are responsible for the plant sensing the correct cue, and describe the plant's response. Is it a change in growth, physiology, or behavior? How is the necessary information communicated within the plant? Pick an example of an animal response to the environment, and describe what molecules or cells are responsible for the animal sensing the correct cue, and describe the animal's response.
Plants: Can respond to light by moving toward or away from it if needed, Phytochrome detects the light a sends signals on what the plant should do, this is classified as a change in growth sense phototropism is growth toward or away from light . Animals: Can respond to heat such as if a object is too hot it will hurt that organism, the nervous system picks the cue up and sends the corresponding message where needed?
Compare and contrast water balance in land plants and terrestrial animals. What are the major sources and sinks of water for each? How is water loss linked to gas exchange in each? Explain at least 1 adaptation for conservation of water in each.
Plants: They get water from roots. They loose water from stoma through evaporation and transpiration. They lose water when stoma open for gas exchange. One adaptation is stoma on underside of leaf, waxy cuticle...... Animals: When they breath they take in oxygen, release co2. but at the same time it will lose water through evaporation during breathing. Also lose water through urine. Get water from metabolism (h2o produced from cellular respiration) drinking and eating food. Adaptation is our noses, cool air holds less water than warm air, air around us is always colder, water is deposited in our nose when breathing out.
Define negative feedback. Describe two examples of negative feedback loops involving hormones used to regulate physiological conditions within the body. Define positive feedback. Describe one example of a positive feedback loop involving one of the hormones we have learned about. Why is negative feedback much more common than positive feedback in animal physiology?
Positive: stimulus produces a response that increases the stimulus. example: when baby suckles nerves in breast are stimulates to communicate with hypothalamus, secretes oxytocin into bloodstream which stimulates milk to flow which means more suckling and more milk until baby is full. Negative: stimulus produces a response that decreases the stimulus. when osmoreceptor cells in the hypothalamus detect increase in osmolarity of the blood, the release of ADH is triggered. this increases permeability and water re-absorption helps prevent further osmolarity increase. we also get thirsty and drink to reduce blood osmolarity to the set point Negative: FSH controls sperm production, LH controls testosterone production, GnRH facilitates the release of FSH an LH, stopping that would cause problems for males because they need testosterone, so supplementation is required, testosterone is need to keep males hormonally balance, so GnRH->LH(sperm)&FAH(Test)->body->X->GnRH. So if something extreme happens to your body, the negative feedback system acts to reverse the extreme effect ( not help it to become more extreme).
Which of the following require the organism to expend energy: Relationships with mycorrhizae (plant is organism of interest) Maintenance of body temperature in endotherms Maintenance of complex, highly structured plant or animal bodies through time, and evolution of new, more complex body forms during the history of life Photorespiration Incorporation of CO2 into organic sugars in CAM or C4 photosynthesis Excretion of salt ions across the gill of a SALTWATER fish Excretion of ammonia across the gill of a FRESHWATER fish Production of hyperosmotic urine (urine more concentrated in solutes than body fluids) by the mammalian kidney
Relationships with Mycorrhizae. Maintenance of body temp in endotherms. Maintenance of complex highly structured plant or animal bodies through time and evolution of new more complex body forms during the history of life. Photo-respiration incorporation of CO2 into organic sugars in CAM or C4 photosynthesis,. Production of hyper-osmotic urine
Which of the following require an animal to expend energy: Binding of myosin and actin during muscle contraction. Release of Ca++ from sarcoplasmic reticulum during muscle contraction. Sequestration of Ca++ in sarcoplasmic reticulum during muscle relaxation. Unlinking of myosin and active during muscle relaxation . Detection of pressure by vertebrate hair cell. Sequestration of neurotransmitter from synaptic cleft back into membrane-bound vesicles of the presynaptic neuron.
Release of Ca++ from sarcoplasmic reticulum during muscle contraction. - Doesn't require energy. Unlinking of myosin and active during muscle relaxation. (Answer may be wrong)
Define sensation and perception. In what part of the nervous system does each of these take place?
Sensation is conversion of energy (stimuli) into change in membrane potential that changes frequency of action potentials. Perception is interpretation of this information by the central nervous system.
What fish has the best passive electroreception? How does it use this sense? Electroreceptors evolved from what other type of sensory cell?
Sharks are passive electroreceptive fish, and are the most sensitive to electrical fields of any animal, which it detects through activity of their nerves and muscles? Evolved from mechanosensory lateral line organs
If you got to design your own animal, what structures would you give it to allow it to perceive gravity? How would they work?
Statocysts are responsible for balance Vertebrate hair cells are responsible for balance, detection of water currents, and hearing?
Explain how tetrodotoxin, which blocks voltage-gated Na+ channels, and oubain, which disables the Na+/K+ pump would each affect the function of an isolated neuron. What would likely be the effect of each of these toxins on a whole, living animal?
Tetrodotoxin would cause neurons to not be able to generate action potential. so they wont be able to send any kind of electrical signals. Oubain would paralyze the animal. cause cells not to be able to maintain resting potential so they cant integrate info, using neurons electrical impulses.
Which of the following tend to INCREASE with animals' body size: The RATIO of the animal's surface area to its volume The TOTAL surface area of the respiratory membrane The metabolic rate (rate of cellular respiration per g animal tissue) The TOTAL oxygen consumption Gut complexity Food consumed daily/body mass
The TOTAL surface area of the respiratory membrane. The TOTAL oxygen consumption. Gut complexity
Define refraction.
The bending of light to a single point
Define membrane potential. What is the role of each of the following in creating a resting membrane potential in cells: Na+, K+, sodium-potassium pump, ion channel, diffusion, Cl-. Does the maintenance of a cellular membrane potential require energy? Why or why not?
The difference in electrical charge on inside and outside of membrane. Charged ions diffuse slowly across membrane, can't dissolve in lipid bilayer. This allows cells to maintain gradient, uses energy. Resting potential is maintained by 1) Na+/K+ pump keeping more Na outside, more K inside. 2) K+ diffuses out of cell through ion channels in response to conc gradient. 3) Loss of K+ ions leaves negative charge inside cell membrane, + charge outside.
Some have argued that the human eye is so complex it could not have been produced by evolution. Give an argument to refute this statement based on comparative morphology and function of eyes among animals (and protists!):
The evidence of eyes being produced by evolution can be seen when you look at all the different animal lineages that have eyes, and how rhodopsin is found in non animal Eukaryotas.
In the disease multiple sclerosis, the body's immune system attacks myelin around nerves. Why does loss of myelin disrupt nerve function?
The myelin sheath serves as an insulator and means of conduction. Plus, this "insulation" increases the diameter of the axon, and a bigger diameter means the faster the conduction. When myelin degrades, conduction of signals along the nerve can be impaired or lost, and the nerve eventually withers
What would be the consequence of a poison that prevented voltage-gated sodium channels to experience a refractory period after opening?
The na+ channels would stay open.
What is the primary function of each of the following: Nervous system Endocrine system Circulatory system Tracheal system Malphigian tubules Kidneys of freshwater fish Mammalian nose
The nervous system is the major controlling, regulatory, and communicating system in the body. The endocrine system is the collection of glands, each of which secretes different types of hormones that regulate metabolism, growth and development etc. The circulatory system is a vast network of organs and vessels that is responsible for the flow of blood, nutrients, oxygen and other gases, and hormones to and from cells. Tracheal system exchange oxygen and carbon dioxide between their tissues and the air by a system of air-filled tubes called tracheae. Malphigian tubules a tubular excretory organ, numbers of which open into the gut in insects and some other arthropods. Kidney is responsible for preventing excess solute loss as they contain more salts within their blood than the water located around thier bodies. Mammalioan nose: osmoregulatory organ removes excess NaCl from the blood by countercurrent exchange
Why does the complexity of digestive, respiratory, and excretory systems tend to increase with animals' size?
The organism needs more surface area.
How do each of the following contribute to efficient photosynthesis by plants? Stomata True vascular tissue Auxin Root nodules harboring nitrogen fixing bacteria Mycorrhizae Circadian rhythms
The stomata need to be open for release of oxygen and intake of CO2 so that photorespiration doesnt occur, it can also be on underside of leaf. Auxin is needed for the plant to grow because it promotes cell elongation. Root nodules harboring nitrogen fixing bacteria is useful because N is one of the most limiting nutrients for plant growth and is need for photosynthesis (lots of N goes to rubisco). Circadian rhythms are important because this is how plants know to open/close stomate during day/night. Mycorrhizae are important because they extend the volume of soil resulting to an increased plant nutrient supply
Compare visual perception and hearing in mammals and insects. How do their abilities differ? Draw and/or describe the organs that insects use for hearing and vision and explain why these lead to different abilities than those of mammals.
There are many animals with simpler forms of eyespots and eyes, including many forms that are intermediate between the complex vertebrate eye and a simple eyespot, and these are all functional and beneficial for the creatures/animals that have them. Then you can go on to describe the eyespot of the Euglena, eyespot of a flatworm, cup, pinhole, and lensed eyes in various animals, particularly mollusks.
How do animals without bones or other hard parts generate movement? What is a hydrostatic skeleton? Give an example of an animal with a hydrostatic skeleton.
These animals generate movement with muscle. Hydrostatic skeleton is a structure of soft-bodied animals consiting of fluid filled cavity surrounded by muscles. Ex: earthworm.
Organophosphate pesticides interfere with removal of acetylcholine from synaptic clefts through inhibiting the enzyme acetylcholinesterase. How would this effect the postsynaptic neuron? This chemical is used primarily to kill insects on farm fields. Would you expect it to be specific to insects or to be toxic to humans as well?
This would cause a build up making the organisms muscles contract more. And it is both toxic to insects and humans alike, it may not show short term effects but it will cause long terms affect due to being stored in organism fat.
Which of the following require the organism to expend energy: Transport of water through plant xylem Transport of sugar through plant phloem Uptake of nutrients through plant roots Symbiosis of plant with N-fixing bacteria (plant is organism of interest) Transpiration Movement of potassium ions to open and close guard cells Building complex organic molecules such as tannins from simple sugars formed during photosynthesis
Tranport sugar through phloem. Symbiosis of plant N-fixing bacteria. Building complex organic molecules such as tannins. Movement of potassium ions into guard cells.
What would be the effect of using a drug to block ligand-gated ion channels of the postsynaptic neuron at an electrical synapse?
Usuallly neurotransmitters bind to ligand gated ion channels. This drug would reduce this communication. This would make it less likely to generate action potential.
How do voltage-gated Na+ and K+ channels respond to changes in membrane potential during an action potential? How does each of them contribute to the depolarization of the membrane during the action potential and the restoration of the resting potential afterward?
Voltage gated ion channels are shut when the membrane potential is near the resting potential of the cell, but they rapidly begin to open if the membrane potential increases to a precisely defined threshold value. When the channels open Na+ flows in, which changes the electrochemical gradient, membrane potential rises. More Na+ channels open, producing a greater electric current across the cell membrane, and so on. Then all channels open, Na+ floods in, resulting in a large upswing in the membrane potential. Causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. Sodium channels close, sodium ions can no longer enter the neuron. K+ channels are activated and K+ leaves returning the electrochemical gradient to the resting state. Refractory period occurs, due to additional potassium currents. Mechanism that prevents an action potential from traveling back the way it just came.
How do the physical properties of water create challenges for gas exchange by aquatic animals?
Water that is fully saturated with oxygen still has 0.2 to 1 % oxygen, compared with 22% for air Gasses diffuse 10,000x more slowly in water than air Boundary layers are much thicker in water than air Colder water holds more oxygen at saturation than warmer water does.
Draw a vertebrate hair cell. How are vibrations of the hairs translated into a change in action potentials in associated neurons?
When there is no fluid movement, the action potential is at one rate. Fluid moving in one direction causes more action potential to be generated because of the increase in neurotransmitters. Fluid moving in the other direction has less action potential because of lack neurotransmitters. When hairs move, the hair cell moves and changes the synapse so different a amount of neurotransmitters is at the synapse.
Cephalopods (octopuses and squids) are unique among invertebrates in being able to use lensed eyes to produce focused images of objects at varying distances. Explain how the lensed eyes of cephalopods are similar to and different from those of terrestrial vertebrates.
cephalopods, lenses are moved back and forth by muscles - they also use refraction (all lensed eyes do). In general there are a lot of similarities with vertebrate eyes - cornea, lens, iris, ability to focus on objects at different distances.
Several psychoactive drugs (for example selective serotonin reuptake inhibitors (SSRIs) used to treat depression) inhibit clearing of specific neurotransmitters from the synaptic gap by the presynaptic cell and other accessory cells. If such a drugs acts on a fast, direct, excitatory neurotransmitter, how is this likely to affect the postsynaptic cell? How might the membrane potential of the postsynaptic cell change as a result?
if neurotransmitters are not cleared from synaptic gap, na+ channels wouldnt open and Action potential wouldnt be generated.
How would a drug that elevated Ca++ concentrations in muscle cells affect their contractions?
muscle cell will make muscle easier to contract.
