Khan M

Meningitis and the flu share many early symptoms. Which of the following could explain why a doctor could misdiagnose meningitis as the flu during flu season? Bottom-up information processing High signal detection threshold for meningitis Gestalt principle of similarity Low just noticeable difference

A high signal detection threshold (loosening the criteria for meningitis) would mean that the doctor would be more likely to diagnose meningitis. Bottom-up information processing means that the doctor would start with no prior knowledge and create the diagnosis only from information gained from the patient. This would block the confounding caused by flu season, and be more likely to lead to the correct diagnosis. The just noticeable difference refers to the amount of change required to register in one's perception of a stimulus. If the doctors had a low just noticeable difference to distinguish flu from meningitis, they would be more likely to notice that their patient had a more serious disease and address that concern. The Gestalt principle of similarity would explain why the similar symptoms of flu and meningitis would be grouped in the doctor's mind, potentially leading to a misdiagnosis.

Which of these is the correct order to the steps of the phototransduction cascade in reaction to light? A rod turns from on to off => turns a bipolar cell off-center => activates a retinal ganglion cell. Retinal changes conformation => α unit bonds with PDE => the rod hyperpolarizes and turns on. A rod changes conformation => α unit bonds with PDE => the rod hyperpolarizes and turns off. A rod turns from on to off => turns a bipolar cell on-center => activates a retinal ganglion cell.

A rod turns from on to off => turns a bipolar cell ON-center Retinal changes confirmation => α unit bonds with PDE => the rod hyperpolarizes and turns OFF. A rod turns from on to off => turns a bipolar cell on-center => activates a retinal ganglion cell.

What would occur if all available hydrogen ions were used by ATP synthase? It would decrease the levels of inorganic phosphate in the intermembrane space It would increase the levels of inorganic phosphate in the mitochondrial matrix It would increase the ph of the mitochondrial matrix It would increase the ph of the mitochondrial intermembrane space

ATP synthase binds with inorganic phosphate in the mitochondrial matrix not in the intermembrane space ATP synthase activity decreases the levels of inorganic phosphate in the mitochondrial matrix ATP synthase consumes hydrogen ions available in the intermembrane space, thus it would increase the ph of the mitochondrial intermembrane space

With respect to their relative pH, how do the cytosol, intermembrane space of the mitochondria, and the mitochondrial matrix compare? pH of mitochondrial matrix < pH of cytosol = pH of intermembrane space pH of intermembrane space < pH of mitochondrial matrix < pH of cytosol pH of mitochondrial matrix > pH of cytosol > pH of intermembrane space pH of cytosol > pH of intermembrane space = pH of mitochondrial matrix

ATP synthase in the inner mitochondrial membrane is powered by the proton motive force. The proton motive force is due to the concentration gradient of hydrogen ions between the intermembrane space and the mitochondrial matrix. pH = -log[H^+] ​ The hydrogen ions move down their concentration gradient from the intermembrane space to the matrix, therefore, the concentration must be higher in the intermembrane space, and thus the pH of the intermembrane space must be lower. If a significant gradient existed between the cytosol and the intermembrane space, it would destroy the gradient between the intermembrane space and the matrix, and halt the production of ATP. Although it is more permeable than the inner membrane, the outer membrane of the mitochondria is not permeable to all ions/solutes so it cannot be considered continuous with the cytosol. In reality, the pH of the cytosol ranges around 7-7.4, near "neutral" range, and is much less acidic than the intermembrane space of the mitochondria. pH of mitochondrial matrix > pH of cytosol > pH of intermembrane space.

A constant electric field moves a positive point charge from one position to another position so that the change in electric potential is -450\ \text{V}−450 Vminus, 450, space, V. Which of the following must increase during this movement? The charge's velocity The charge's potential energy The charge's electric potential The charge's acceleration

According to the question stem, there is an electric potential difference between the two positions. The negative change in electric potential indicates that the point charge moves from a position of higher electric potential to a position of lower electric potential. The point charge displacement as a result of a constant electric field indicates that the point charge moves to a more favorable, downstream position. This indicates that the charge loses potential energy and gains kinetic energy during the movement. Just like a ball dropped from a height due to the force of gravity, the point charge moves to its new location due to the force generated by the electric field on the charge. In both situations, the object being moved will increase in velocity during its movement.

The role of adenylate cyclase is: To cyclize AMP in order to generate second messengers To aid in signal amplification via conversion of GTP to GDP To activate G protein-coupled receptors via phosphorylation To degrade steroid hormones, terminating their function

Adenylate cyclase has no role in hormone degradation. It has no role in GTP → GDP conversion. Adenylate cyclase aids in conversion of ATP to cAMP, which acts as a second messenger.

Back side

Aisha is pulling with 20N, so in order for this system to be in equilibrium, Saul and Lorenzo together must be pulling with the same force in the opposite direction. That vector would represent the hypotenuse of the right triangle where Saul's force is the adjacent side and Lorenzo's opposite. Hint #22 / 6 One big clue to solving this problem is that the angle is equal to arctan(1.33). 1.33 is the value of the opposite side divided by the adjacent side. Hint #33 / 6 Let's represent the decimal by a fraction, which would be 4/3. So the ratio of the opposite side to the adjacent side is 4:3. Hint #44 / 6 Either by Pythagorean theorem or by past memorization, the hypotenuse will have the value of 5, and we have our 3-4-5 triangle. Hint #55 / 6 As we said, Aisha represents the hypotenuse, which has a value of 20N. Divide that by the calculated value for the hypotenuse to obtain the factor to multiply the other sides. That factor is 4.

A previously unknown cell type is discovered in the central nervous system of a laboratory strain of mice. In cell-culture experiments, researchers find that the cell type can self-renew, but can only differentiate into one other cell type. Which of the following best characterizes this cell type? Multipotent embryonic stem cell Unipotent somatic stem cell Multipotent somatic stem cell Unipotent embryonic stem cell

All stem cells must have the ability to reproduce copies of themselves as well as differentiate into other cell types. Some stem cells, such as the ones that replenish the skin, are unipotent, meaning that they are capable of differentiating into only one cell type. The unknown cell type that the researchers discovered is best characterized as a unipotent somatic stem cell type.

Inducible system

Always off unless molecule binds to repressor and stops it

Which of the following force pairs represents an action-reaction pair? Downward force of gravity on a falling object and upward force of air resistance at terminal velocity Component of gravity along the plane of the incline on the block and static frictional force up along the plane Force of the horse on the cart and force of the cart on the horse Weight of the book and normal force of the table

An action-reaction pair must consist of forces that are of the same type (field or contact) and that act on different objects. Weight is a field force, and normal force is a contact force, so they are not of the same type and act on the same object, i.e. book. At terminal velocity, the force of gravity equals the force of air resistance, but they are not the same type and act on the same object, i.e. falling object. Gravity along the plane of the incline and the static frictional force are equal, but they are not the same type and act on the same object, i.e. block. The only action-reaction pair is the force of the horse on the cart and force of the cart on the horse.

Which factor may help determine the antigenicity of a virus? The internal proteins The whole capsid The size of the virus Some of the capsomeres

Antigenicity refers to the part of the virus that stimulates white blood cells. Internal proteins are not in direct contact with white blood cells, and therefore would not express antigenicity of any kind. The whole capsid is not entirely recognized by white blood cells. The capsomers are recognized by white blood cells, and therefore determine the virus antigenicity.

Small nucleolar RNA (snoRNA)

Are a class of small RNA molecules that primarily guide chemical modifications of other RNAs, mainly ribosomal RNAs, transfer RNAs and small nuclear RNAs.

Which of these is NOT a direction in auditory space? A Elevation B Azimuth C Distance D Loudness

Auditory space is defined as the area extending around the head in all directions that is used to perceive sound. Elevation describes the relative height of the sound above or below a plane extending outward from between the ears. The azimuth is the angle left or right from a symmetry line equidistant from the ears. Loudness is a perception based on a sound's frequency and sound pressure level, not a direction in auditory space.

What is the correct order of steps in a common G-Protein coupled receptor (GPCR) signal transduction? The answer does not include all steps. I. Formation of ligand-receptor complex II. Release of neurotransmitter into synapse III. Alpha subunit regulates target protein IV. Intracellular phosphorylation cascade V. G protein acquires GTP VI. Dissociation of G protein subunits VII. Cross-phosphorylation of G proteins VIII. Hormone binds to GPCR I, V, VI, III, IV I, V, III, IV, VI II, I, V, VII, III, IV VIII, I, V, VII, III, IV

Be careful not to assume G protein-coupled receptors (GPCRs) serve any one specific function (such as neurotransmitter signaling or hormone signaling). GPCRs are widespread and diverse, serving a large variety of functions in different tissue types. There are three main stages of cell signaling: reception, transduction, and response. In the reception phase of a GPCR system, the ligand-receptor complex forms and a conformational change on the inside of the receptor allows G protein to exchange GDP for GTP. G proteins contain three subunits: alpha, beta, and gamma. Typically, when a GPCR receives a signal the alpha subunit dissociates from beta and gamma and regulates a target protein. Regulation of the target protein typically leads to an intracellular phosphorylation cascade. This would be the transduction stage. The correct order of steps in a GPCR system is I, V, VI, III, IV. (The response stage is not included in these steps.)

5' cap

Binding site for translation on ribosomes for eukaryotes

Helicase

Breaks hydrogen bonds

Caspase enzymes mediate apoptosis by attacking which of the following? The cysteine residues in cytochrome c enzymes The cysteine residues in cytoplasmic proteins The aspartate residues in cytoplasmic proteins The cysteine residues in BCL-2 family proteins

Caspase enzymes are proteolytic enzymes found in the cytoplasm. Caspase enzymes are activated by cytochrome c. Caspase enzymes have cysteine-rich active sites that target aspartate residues in cytoplasmic proteins. Caspase enzymes mediate apoptosis by attacking the aspartate residues in cytoplasmic proteins.

Back side

Choose 1 answer: Divided attention Selective attention Joint attention Directed attention Selective attention is the ability to maintain attention while being presented with masking or interfering stimuli. Joint attention is the focusing of attention on an object by two separate individuals. Divided attention occurs when an individual must perform two tasks which require attention, simultaneously. Directed attention allows attention to be focused sustainably on a single task, in this case a single orientation of the Necker cube.

Conservative mutation vs. non conservative mutation

Conservative mutations: Result in an amino acid change. However, the properties of the amino acid remain the same (e.g., hydrophobic, hydrophilic, etc)

Which direction is positive torque?

Counterclockwise

CpG methylation

CpG methylation diminishes the oncogenic potential of cells. CpG island methylation does not have a role in the differentiation of cells. However, once cells are done differentiating, their DNA needs to be turned off, or silenced. CpG methylation permanently, or stably, silences the DNA of cells that have completed the process of differentiation.

What is the basic order of events in the digestion and mobilization of dietary fats? Degradation by lipases→ emulsified by bile→ incorporation into chylomicrons→ absorption and conversion into triacylglycerols Emulsified by bile→ degradation by lipases→ absorption and conversion into triacylglycerols→ incorporation into chylomicrons Degradation by lipases→ absorption and conversion into triacylglycerols→incorporation into chylomicrons→ emulsified by bile Emulsified by bile→ incorporation into chylomicrons→ absorption and conversion into triacylglycerols→ degradation by lipases

Dietary fats are insoluble in aqueous solution, and cannot be absorbed by the intestinal mucosa. Bile is secreted from the gallbladder to emulsify dietary fat particles to form finely dispersed, soluble micelles. The formation of micelles allows for intestinal lipases to degrade the dietary particles so that they may be absorbed and used to form TAGs. The triacylglycerols are incorporated with cholesterol and apolipoproteins within the intestinal mucosa. The correct order is: emulsified by bile→ degradation by lipases→ absorption and conversion into triacylglycerols→ incorporation into chylomicrons.

Function of an activator?

Enhances interaction between RNA polymerase and the promoter

Which of the following describes the relationship between the straight chain forms of D-glucose and D-galactose, given that they are non-cyclic molecules that differ only in stereochemical configuration at the fourth carbon? They are anomers They are enantiomers They are meso-compounds They are epimers

Epimers are stereoisomers that differ in stereochemical configuration only at one stereocenter. Enantiomers are a pair of molecules that are mirror images of each other. Anomers are epimers that are in their cyclic state. The straight-chain forms of D-glucose and D-galactose are epimers.

How do the majority of fatty acids enter the outer membrane of the mitochondria? Transferase facilitated entry of free fatty acids Transferase facilitated entry of carnitine bound fatty acids Free diffusion of hydrophobic free fatty acids Free diffusion of carnitine bound fatty acids

Even though they are predominantly hydrophobic, most dietary fatty acids are too large for free diffusion across membranes, which presents a kinetic barrier to their transport. Although a high FFA concentration outside of a cell may establish a gradient such that their transport into the cell is energetically favorable, the energy required for the movement of large molecules is substantial. Coupling the transfer of large molecules to energetically favorable reactions allows this barrier to be overcome. Three reactions allow for FA entry into the mitochondria, in a process known as the carnitine shuttle. First, acyl-CoA synthetase links coenzyme A with the fatty acid, made favorable by the hydrolysis of two bond in ATP (to make AMP). Second, fatty acid acyl-CoA is attached to carnitine via carnitine acyltransferase I, and the acyl-carnitine enters the outer membrane. The majority of fatty acids enter the outer membrane of the mitochondria via transferase facilitated entry of carnitine bound fatty acids.

DNA Polymerase 3 proof reading ability

Exonuclease, 3-5, lays nucleotide in place

Fecundity

Fecundiity is the maximum number of children a woman can possibly have in her lifetime but it is usually never reached due to factors such as the economic cost of children, the woman's education, and birth control

Newtons laws

First regards inertia

genetic drift

Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance (sampling error). Genetic drift occurs in all populations of non-infinite size, but its effects are strongest in small populations.

Consider the whole gestational period. When does fertilization normally occur? Week 1 of gestation At the very beginning of gestation Prior to gestation occur Week 2 of gestation

Gestation begins with the uterus getting ready for implantation Fertilization occurs after the beginning of gestation Fertilization occurs in week 2 of gestation

Which cytoskeletal structure is linked with the movements of a macrophage? Glycocalyx Microtubules Microfilaments Cilia and flagella

Glycocalyx does not generate movement and it is also not present in macrophages. Cilia and flagella generate movement but not in a macrophage. Microtubules make cilia and flagella. Microfilaments are responsible for the amoeboid movement of macrophages.

Mismatch repair

Happens after replication and is endonuclease

Small nuclear RNA (snRNA)

Help with processign of pre-mRNA

Catalytic efficiency

How many substrates and products can turn into product in one second at its maximum speed.

Back side

If the force acts downwards to the left or upwards to the right of the fulcrum, then there is a counterclockwise (CCW) torque. If the force acts downwards to the right or upwards to the left of the fulcrum, then there is a clockwise (CW) torque. Forces will act from the center of mass if possible, and the fulcrums are the top right edge of Block 2 and the left edge of the desk. If Block 2 were shifted to the left, the center of mass moves to the left of the fulcrum, so the weight creates a CCW torque, not CW. The weight of Block 1 acts to the right of the same fulcrum downwards creating a CW torque, not CCW. If Block 1 were shifted to the right, as the center of mass moves to the right of the fulcrum, it will create a CW torque that topples off Block 1. However, the small normal force from Block 2 has been decreasing as Block 1 moved to the right. The weight of Block 1 acts to the left of the fulcrum downwards, and the weight will produce a CCW torque, not CW. There is a normal force from Block 2 on Block 1 that acts to the left of the fulcrum upwards, producing a CW torque.

A team of zoologists discover that direct cell-cell communication plays a key role in the early cardiac development of monitor lizards, and that the molecules responsible for this communication are downregulated in adolescents and adults using a proprietary assay they developed in their lab. Which of the following universally known assays would most directly confirm this difference between embryonic monitor lizards and more fully grown monitor lizards? Enzyme-linked Immunospot (ELISPOT), to detect secretory products of cells Northernblot, to detect specific RNA sequences in a sample Immunohistochemistry, to detect cell-surface proteins and glycoproteins Southernblot, to detect specific DNA sequences in a sample

Immunohistochemistry, to detect cell-surface proteins and glycoproteins

Shine delgarno sequence

In prokaryotes, used for translation, ribosome binds to.

Researchers compare the rate of production of daughter cells produced per differentiation event in a population of multipotent somatic stem cells that is undergoing stochastic differentiation with the rate found in a population undergoing obligate asymmetric replication. What would they find? Daughter cells produced per differentiation event would be the same in each group Daughter cells produced per differentiation event would be three times that of the latter Daughter cells produced per differentiation event would be half that of the latter Daughter cells produced per differentiation event in the former group would be twice that of the latter

In stochastic differentiation, a stem cell differentiates into two daughter cells (the original stem cell ceases to exist), and a nearby stem cell undergoes mitosis to create two stem cells: there is a net gain of two daughter cells, while the number of stem cells remains constant. In obligate asymmetric replication, a stem cell differentiates into one daughter cell while also continuing to exist. There is a net gain of one daughter cell, while the number of stem cells remains constant. Therefore, daughter cells produced per differentiation event in the former group would be twice that of the latter.

Marr's stages of vision describes how a 2D image on the retina is transformed to a 3D object. Which of these is NOT one of Marr's 4 stages of vision? Primal Sketch 3D object-centered description 1D sketch 2.5D sketch

In the primal sketch stage, edges, and texture are identified and used to create a basic scene outline. In the 2.5D sketch stage, surfaces and scenes are related to one another. In the 3D object-centered description stage, the object is able to be recognized from any angle or visualized as a 3D map. The Marr's first stage of vision is called either the grey level description or the input image, not 1D sketch.

If two genes experience independent assortment, which assumption is most likely true? The expression of one gene does not affect the expression of the other. They are located in close proximity on the same chromosome. Crossing over between the genes does not occur. The genes are located on different chromosomes or are far apart on the same chromosome.

Independent assortment is Mendel's second law. It describes the tendency for traits to be passed on independently of each other. During meiosis, chromosomes are mixed up so that each gamete has a random set of chromosomes. Genes on different chromosomes are split up independently. If two genes experience independent assortment, they are most likely located on different chromosomes.

Which of the following is not a mechanism for induction of cell differentiation? Choose 1 answer: Choose 1 answer: INCORRECT Paracrine signalling INCORRECT Formation of gap junctions INCORRECT Direct contact CORRECT (SELECTED) Autocrine signalling

Induction occurs when entities external to a cell initiate the process of differentiation. Autocrine signalling refers to cell signalling that occurs when secreted cytokines from a cell interact with receptors on the secreting cell Autocrine signalling is not a mechanism for induction of cell differentiation

The tympanic reflex helps prevent damage from loud sounds. How does the tensor tympani work to protect one's hearing? The tensor tympani loosens the tympanic membrane. This allows the vibrations to pass more easily through the ear. The tensor tympani produces sounds by vibrating. This allows the ear to adapt to loud sounds. The tensor tympani tightens the tympanic membrane. This changes the frequency of the sound to a frequency outside the range of hearing. The tensor tympani dampens loud sounds by tightening the tympanic membrane. This slows down transduction.

It is not possible to adapt to loud sound. Over time intense vibration from loud sounds causes damage to hair cells and loss of hearing. Strong vibrations in the ear could damage the hair cells, regardless of whether they are within the audible range. The tensor tympani dampens loud sounds by tightening the tympanic membrane. This slows down transduction.

Can fatty acids and amino acids be used in gluconeogenesis?

Just amino acids

Lac operon

Lactose binds to repressor and allows it to become transcribed

Leptin and ghrelin

Leptin - full Ghrelin - hungry

Enhancer

Loop the DNA around to it brings DNA ploymerase close to a spot to be transcribed

Malformation of the peripheral nervous system is linked to specific groups cell formed during neurulation, and these cells are derived from one of 3 embryonic germ layers. What is this specific group of cells, and which embryonic layers are they derived from? Neural tube cells, ectoderm Neural layer cells, mesoderm Neural crest cells, ectoderm Neural fold cells, endoderm

Mesoderm does not form peripheral nervous system. Endoderm does not form peripheral nervous system. Neural tube cells form the spine and brain. Neural crest cells are derived from the ectoderm and will form the peripheral nervous system.

Diplopia is the scientific term for double vision, a condition in which the patient perceives two images of the same entity, usually displaced horizontally or vertically. Which of the following perceptual cues is most affected by diplopia? Convergence Interposition Binocular disparity Motion parallax

Monocular cues, such as motion parallax and interposition, would not be affected by diplopia. Binocular disparity relies on the different images seen by each eye to determine depth, but still takes each image as a separate piece of information. Convergence relies on both eyes working together to create a single image that helps to determine depth. Patients suffering from diplopia will have impaired depth perception due to the loss of this mechanism.

Which statement represents a key difference between a G protein-coupled receptor and a receptor tyrosine kinase? A receptor tyrosine kinase acts as an enzyme to its intracellular substrate. A single ligand can activate multiple signal transduction pathways through a receptor tyrosine kinase. A receptor tyrosine kinase is more likely to activate gene transcription. A G protein-coupled receptor can be activated by a diverse array of ligands.

Most membrane receptor proteins, including most G protein-coupled receptors and receptor tyrosine kinases, are activated by a single specific ligand. G protein-coupled receptors usually do not have enzymatic activity themselves, whereas receptor tyrosine kinases do have enzymatic activity ("kinase" signifies that it phosphorylates a substrate). Activated receptor tyrosine kinases cross-phosphorylate, resulting in a dimer with several phosphorylated tyrosines that can serve as docking sites for a variety of proteins. Since activated receptor tyrosine kinases can serve as docking sites for a variety of proteins, a single ligand can activate multiple signal transduction pathways. GPCRs can also activate multiple signal transduction pathways from a single ligand. Thus, the only answer choice that represents a major difference between receptor tyrosine kinases and G protein-coupled receptors is that a receptor tyrosine kinase acts as an enzyme to its intracellular substrate, while a G protein-coupled receptor does not.

Muscle cells will have increased amounts of which organelles? Smooth endoplasmic reticulum and mitochondria Rough endoplasmic reticulum and ribosomes Mitochondria and chloroplasts Rough endoplasmic reticulum and smooth endoplasmic reticulum

Muscle cells use a lot of energy very quickly when they are active. Muscles contain sarcoplasmic reticulum, a modified endoplasmic reticulum that helps store calcium. Sarcoplasmic reticulum is modified smooth endoplasmic reticulum. Muscle cells contain more mitochondria (for energy) and smooth endoplasmic reticulum (for efficient contractions) than other cells of the body.

Oxidative phase of PPP produces what?

NADPH

Lyase

No water or oxidation/reduction

Can acetyl-CoA travel across the mitochondrial membrane?

No, but citrate can, then gets converted to acetyl coA and OAA

Does cDNA have introns?

No, comes from proteins

Is an acetal part of reducing sugar

No, must be hemiacetal, sucrose is non reducing

Translocation

Occurs between non homologous chromosomes, otherwise it would be crossing over.

At which point in development do we start to observe a significant increase of the size of embryo? During organogenesis During fertilization During early cleavage During blastulation

Organogenesis is not the first observable growth of the embryo. The sperm is so small in relation to the egg that fertilization does significantly increase the size of the embryo. During cleavage cells get smaller after each division, thus during blastulation is when we begin to observe the embryo growing in size.

The rate of osmosis across a cell membrane depends upon which of the following? I: Intracellular solute concentration II: Extracellular solute concentration III: Polarity of solutes IV: Molecular weight of solutes V: The presence of aquaporins I, II, and V I and II I, III, and IV I, II, III, IV, and V

Osmotic pressure is a colligative property. A colligative property is a property that is dependent on the ratio of solute to solvent concentration, but not the identity of the solute (or the solvent). Aquaporins are channel proteins that allow water to flow through a membrane. The polarity and molecular weight of the solutes do not affect osmosis. The rate of osmosis depends on ratio of intracellular to extracellular concentration as well as the presence of aquaporins in the cell membrane - answers I, II, and V.

What is the name of the phenomenon in which a white blood cell engulfs a pathogen? Which cytoskeletal structures are involved in this process? Phagocytosis and microtubules. Pinocytosis and microtubules. Exocytosis and microfilaments. Phagocytosis and microfilaments.

Phagocytosis and microfilaments

The blind spot is the area where the optic nerve connects to the retina. The 'night blind spot' occurs under conditions of low light and can extend 5 to 10 degrees from the center of the person's field of view. What is the cause of the 'night blind spot'? Mesopic vision, used in low light, does not receive input from the fovea due to the lack of rods. Photopic vision, used in low light, does not receive input from the fovea due to the lack of rods. Scotopic vision, used in low light, does not receive input from the fovea due to the lack of rods. Scotopic vision, used in low light, does not receive input from the fovea due to the lack of cones.

Photopic vision occurs at levels of high light levels. Mesopic vision occurs at dawn or dusk and involves both rods and cones. Scotopic vision occurs at levels of very low light. The fovea is dense with cones and does not contain rods. Scotopic vision, used in low light, does not receive input from the fovea due to the lack of rods.

F x v =?

Power

Selective serotonin reuptake inhibitors (SSRIs), used to treat depression, block a specific protein in the pre-synaptic neuron to keep the neurotransmitter in the synaptic cleft for a longer period of time. What sort of protein do they block? A neurotransmitter channel A sodium-neurotransmitter symporter A neurotransmitter ATP pump A phagocytosis-inducing protein

Primary active transport is very costly to the cell, and is used sparingly. Neurotransmitter are recycled through neurotransmitter reuptake, and so the cell must be specific about what it is uptaking. A sodium-neurotransmitter symporter couples the energy released by sodium moving down its gradient to also bring the neurotransmitter into the cell. These are the proteins blocked by many SSRIs.

Oogenesis, the process that creates female gametes, is halted at prophase I until puberty. Which of the following describes the DNA content of a female's gametes during her childhood? 46 chromosomes, 92 chromatids 23 chromosomes, 23 chromatids 46 chromosomes, 46 chromatids 23 chromosomes, 46 chromatids

Prophase I is the first step of the first division of meiosis. A chromatid is a single copy of the genetic information, while chromosomes are counted by the number of centromeres. In prophase I the cell has undergone DNA replication, but has yet to divide, leaving it with 46 chromosomes and 92 chromatids.

Start of transcription

RNA polymerase attaches to promoter

The electron transport chain is an important chemical reaction of cellular respiration. What would occur if oxygen was not present in the electron transport chain (anaerobic conditions)? A The anaerobic reaction would be endergonic with magnitude of ΔG smaller than in the presence of oxygen. B The anaerobic reaction would be exergonic with magnitude of ΔG smaller than in the presence of oxygen. C The anaerobic reaction would be exergonic with magnitude of ΔG larger than in the presence of oxygen. D The anaerobic reaction would be endergonic with magnitude of ΔG larger than in the presence of oxygen.

Release of free energy is typical of exergonic reactions. Electron transport chain is characterized by decreasing free energy levels on each step. Oxygen is the final electron acceptor in electron transport chain, its absence would reduce the overall free energy released, thus this exergonic reaction would have a smaller magnitude ΔG in the absence of oxygen.

DNA polymerase 1 proof reading ability

Removes RNA primer, exonuclease, 5-3

Which of the following cells is not capable of entering replicative senescence? Skin cells Cardiac muscle cells Pluripotent stem cells Brush border cells

Replicative senescence is a state that mitotically active cells enter into when they have reached their Hayflick limit (when their telomeres have become very short). Cardiac muscle cells are not mitotically active (they don't divide). Cardiac muscle cells are not capable of entering replicative senescence.

Scalar X Scalar =?

Scalar

Vector x Scalar =?

Scalar

Silent mutation

Silent mutations are mutations in DNA that do not significantly alter the phenotype of the organism in which they occur. Silent mutations can occur in non-coding regions (outside of genes or within introns), or they may occur within exons. When they occur within exons they do not result in a change to the amino acid sequence of a protein (a "synonymous substitution"), in which case there is no change in phenotype.

Where do chylomicrons and VLDL's come from

Small intestine and liver respectively.

Which of the following best exemplifies the Gestalt principles of grouping? A medical student scheduling classes in the morning and labs in the afternoon. A patient with the flu thinking they have meningitis because the symptoms are similar. A hospital breaking up departments into Cardiology, Infectious Disease, etc. A doctor making a diagnosis based on all of the symptoms a patient presents with.

The Gestalt principles of grouping hold that the brain process the whole, rather than the sum of its parts. The principles of grouping focus on the whole, rather than the parts, so any example of breaking up into parts (classes, departments, etc), is not an example of Gestalt grouping. The doctor who processes all of the information about a patient (labs, physical exam, medical history, etc) is using all of the information to create a single diagnosis. This exemplifies Gestalt grouping, as opposed to jumping to conclusions from a single blood test or physical symptom.

Which of these is NOT a reason why low tones are represented near the apex, while high tones are represented near the base of the cochlea? The base of the basilar membrane is much stiffer than the apex. Pressure changes in the cochlea cause a peak amplitude at a certain area of the basilar membrane as a function of the frequency of the sound. The base of the basilar membrane is narrower than the apex. Pressure changes in the cochlea cause a greater stiffening at the base than the apex.

The base of the basilar membrane is 100 times stiffer than the apex. The base of the basilar membrane is three to four times more narrow than the apex. Pressure changes in the cochlea cause a greater stiffening at the base than the apex.

Which of the following statements about the systemic effect of bacterial cells are true? Gram-negative bacteria are more likely to cause systemic effects because their outer membrane protects them from several antibiotics, making treatment more difficult. Gram-positive bacteria are more likely to cause system effects because the peptidoglycan in their cell walls is tough and hard for medicine to penetrate. Gram-positive bacteria are more likely to cause systemic effects because the lipopolysaccharide (LPS) in their membranes can act as a toxin to the circulatory system. Gram-negative bacteria are more likely to cause systemic effects because their lack of an outer membrane means they can more quickly infect host cells.

The cell envelopes of gram-negative bacteria have more layers than those of gram-positive bacteria. Lipopolysaccharide is found in an outer membrane layer. Gram-negative bacteria are considered to be more dangerous, because components of the outer membrane make them more resistant to antibiotics and the host's immune system. Additionally, the lipopolysaccharide found in its outer membrane is an endotoxin that damages the host.

The lungs, spine and muscles are derived from 3 different germ layers. What would be the correct order of formation of the embryological cells from which these tissues are derived from? A Embryological cells that will form spine will form first, followed by the muscles and then lungs B Embryological cells that will form muscles will form first, followed by the lungs and then spine C Embryological cells that will form muscles will form first, followed by the spine and then lungs D Embryological cells that will form spine will form first, followed by the lungs and then muscles

The correct order of formation of germ layers is first ectoderm then endoderm followed by mesoderm. Lungs are derived from endoderm. Spine is derived from ectoderm. Muscles are derives from mesoderm, hence embryological cells that will form spine will form first, followed by the lungs and then muscles.

If the cytoskeletal model of cell movement is true, which of the following would one not expect to find in motile macrophages as compared to stationary macrophages, assuming all else to be equal? Increased levels of mRNA Increased levels of DNA polymerase activity Increased levels of ribosome activity Increased levels of gene transcription

The cytoskeletal model of cell movement holds that cells move by synthesizing actin chains. Actin is a protein. One would not expect to find increased levels of DNA polymerase activity in motile versus stationary macrophages, since DNA polymerase is only active during cell division (don't confuse DNA polymerase with RNA polymerase).

With respect to the binding of regulatory compounds, what properties define an enzyme as being allosteric? Choose 1 answer: Choose 1 answer: Reversible, noncovalent binding of regulatory compounds Reversible, covalent binding of regulatory compounds Irreversible, covalent binding of regulatory compounds Irreversible, noncovalent binding of regulatory compounds

The effect of modulators on enzyme activity is dependent upon cellular conditions, such that they may bind at high intracellular concentrations, or diffuse out at low concentrations. Allosteric enzymes bind modulators at specific sites, and are characterized by conformational changes upon binding. Covalent bonds are not readily reversible. Allosteric enzymes bind modulators in a reversible fashion. Allosteric enzymes bind modulators in a reversible, non-covalent fashion.

How do the electron transport chain and chemiosmosis affect the acidity of the intermembrane space and mitochondrial matrix? The electron transport chain and chemiosmosis decrease the acidity of intermembrane space and mitochondrial matrix, respectively The electron transport chain decreases the ph of the mitochondrial matrix and chemiosmosis increases the ph of intermembrane space The electron transport chain and chemiosmosis increase the acidity of intermembrane space and mitochondrial matrix, respectively The electron transport chain does not change the ph of the mitochondrial matrix and chemiosmosis increases the acidity of intermembrane space

The electron transport chain creates a proton gradient This proton gradient results in more hydrogen ions in the intermembrane space Chemiosmosis moves hydrogen protons into the mitochondrial matrix Higher levels of hydrogen ions represent increased acidity The electron transport chain and chemiosmosis increase the acidity of intermembrane space and mitochondrial matrix, respectively

The cone of confusion arises from an ambiguity in the sound information that reaches the ear. What is the cause of this ambiguity? A None of the points on the cone of confusion have the same interaural level difference or interaural time difference. B All of the points on the cone of confusion have the different interaural level differences but the same interaural time difference. C All of the points on the cone of confusion have the same interaural level difference and interaural time difference. D None of the points on the cone of confusion have the different interaural level differences but the same interaural time difference.

The interaural time difference describes the difference in time it takes a sound to reach the left vs the right ear. The interaural level difference describes the difference in sound pressure level between the ears. The head dampens the overall sound to the far ear and reduces the intensity of the high frequency tones, but not the low frequency tones. All of the points on the cone of confusion have the same interaural level difference and interaural time difference.

Repressible system

The lac operon is an example of an inducible system. With repressible systems, the binding of the effector molecule to the repressor greatly increases the affinity of repressor for the operator and the repressor binds and stops transcription.

Back side

The lac operon that controls lactose digestion in prokaryotes normally operates at a very low basal level, and is upregulated by the presence of its substrate. Lactose is a dimer of galactose and glucose. The absence of glucose leads to an increase in cAMP, because now the cell must rely much more heavily on the lac operon for energy. This sets off a cascade of events that upregulate the enzymes that cleaves lactose. The presence of lactose and absence of glucose will lead to the most galactose and thus will dye the most strongly blue (Answer B).

If the forces acting on an object are balanced, then which of the following must be true about the object? The object experiences forces of equal magnitude on all of its sides. The object experiences no net acceleration. The object is at rest The magnitude of the normal force must equal that of its gravitational force.

The magnitude of the normal force does not have to equal its gravitational force. It is possible for there to be an additional force acting in the opposite direction of the normal force that will cause an increase of the magnitude of the normal force. It is also possible for the normal force to be equal to a directional component of the gravitational force, such as in the case where the object is elevated on an incline. An object can be in motion experiencing constant velocity. Therefore there is no requirement for the object to be at rest. When all the forces acting upon an object balance each other, the object will be at equilibrium, and will not accelerate. There is no requirement for the forces to be equal in magnitude in all of its sides. There is a requirement for the sum of forces on each side to balance the sum of forces on its opposite side.

Which of these events is caused by the stapes pushing against membrane covering the oval window? Choose 1 answer: Choose 1 answer: A The pressure change causes the organ of Corti to vibrate horizontally. B The pressure change causes the tectorial membrane to move horizontally. C The pressure change causes the organ of Corti to vibrate vertically. D The pressure change causes the tectorial membrane to vibrate vertically.

The pressure change does not cause the organ of Corti to vibrate horizontally. The pressure change causes the tectorial membrane to move laterally, not vertically. The pressure change causes the organ of Corti to vibrate vertically.

Given that nicotinamide adenine dinucleotide (NAD), in its reduced form as NADH, is a key electron-donating molecule in many metabolic reactions, which of the following is a good prediction for the standard reduction potential (E) of the reduction half-reaction of NAD? A Large and positive B Less than zero C Zero D Between zero and 1

The standard reduction potential is a measure of the tendency of a chemical species to be reduced. Electron accepting molecules like NAD have a strong tendency to be reduced under physiological conditions. The result is the electron-carrying molecule NADH A good prediction for the standard reduction potential of the reduction half-reaction of NAD is "less than zero."

Where does the repressor bind?

To the operator

Operon

Unit that is under the control of a promoter, expressed all together or not at all.

Topoisomerase

Unwinds DNA, temporarily breaks up portions of the backbone

Vector x Vector =?

Vector

Backside

Which of the following scenarios would produce a magnetic force?

Which of the following statements regarding DNA replication is true? Prokaryotic polymerases work at a faster rate than eukaryotic ones The timing of replication is tightly regulated in both eukaryotes and prokaryotes Both prokaryotic and eukaryotic DNA has multiple origins of replication Eukaryotes use DNA gyrase, while prokaryotic DNA is small enough to not need it

While eukaryotic DNA replication has many origins of replication, prokaryotic DNA is small and condensed enough that there is only one origin site. Both prokaryotes and eukaryotes have helicases and gyrases, which unzip and untwist, respectively. Though prokaryotic DNA is small, it is still a double-helix, and coiled enough that pressure needs to be relieved whenever it is accessed. Prokaryotic replication is likely to result in more mutations per base pair formed. Prokaryotic polymerases work faster than eukaryotic ones, adding about 2000bp per second while eukaryotic polymerases only add about 100.

Backside

Work is currently being done on the point charge The electric field is positive The net electrostatic force is 0 The net electric potential difference with respect to infinity is 0 The electric potential at a point charge is the sum of each individual source charge's contribution. Since both source charges are positive, they contribute a positive electric potential difference at point AAA. The electric field arrows of each source charge's contribution to the point charge is in the direction away from the source charge. Since the two source charges are in opposing directions, are equidistant from the point charge, and are equal in magnitude, the electric field vectors cancel out, thus electric field at position AAA is 0. If the electric field is 0, then there is no electrostatic force moving the point charge. If an object is not displaced, no work is being done. Since the point charge is equally repelled by both source charges, the net electrostatic force experienced by the charge at that point must be 0.

CAP, catabolite activator protein

activated transcription of the lac operon in ecoli. cAMP causes change in CAP so it can bind.

Microtubules

cell division, phagocytosis, flagella movement

Do you need a RNA primer for DNA replication?

yes