Biophysics Quiz m

The absolute error in radioactive counting is measured over four times the original duration. Since the activity remains constant, the count will be four times higher. This means the absolute error, which is directly proportional to the count, will also be four times higher.

Speed is a derived quantity calculated by dividing distance by time. It is not a fundamental SI base unit.

Stochastic biological effects are random events that can happen in the body due to radiation exposure. These effects are not predictable and can occur even at low doses. The frequency of these effects increases with the dose.

The direction of light changes the most when it enters the cornea. The cornea has a significantly different refractive index compared to air, causing a sharp change in the light's direction.

The volumetric velocity of a viscous liquid is directly proportional to the pressure difference. This means that a higher pressure difference will result in a higher flow rate.

Osmotic pressure is the pressure needed to prevent the flow of solvent across a semipermeable membrane. It's not equal to the partial pressure of the solvent.

Ideal fluids are those that are incompressible and have no viscosity. Non-Newtonian fluids do not follow these properties, making them not ideal fluids.

Stokes' law states that the drag force on a spherical object moving in a viscous fluid is proportional to the velocity and the viscosity of the fluid. The diffusion constant is inversely proportional to the viscosity, meaning higher viscosity leads to slower diffusion.

The decay constant of a radioactive isotope is the probability of a nucleus decaying per unit time. It's related to the half-life by the equation: decay constant = ln(2) / half-life. So, for a half-life of 1 second, the decay constant is approximately 0.7/s.

A resting brain emits alpha waves. These waves are associated with a relaxed state of consciousness.

A biconcave lens is always a diverging lens. This is because the refractive index of the lens is greater than the refractive index of the surrounding medium, causing the light to bend away from the optical axis.

CT scans, due to the skull bone's absorption of X-rays, significantly reduce the resolution of acquired brain images.

Laplace's law determines the tension in the wall of a cylindrical pipe caused by the pressure in the pipe. This is relevant to understanding the forces present in blood vessels.

When a person suddenly stands up, blood pressure in the brain decreases temporarily. This happens because gravity pulls the blood down toward the feet.

The volumetric flow rate of blood through a vessel is proportional to the fourth power of the vessel's radius. A 19% increase in radius leads to a dramatic increase in flow rate, roughly doubling the blood flow.

Both CT and PET use ionizing radiation. CT uses X-rays, while PET uses gamma rays. Thermography uses infrared radiation, which is not ionizing.

The dark-adapted eye is the most sensitive to light. It takes a longer period for the eye to adapt from dark to light than it does from light to dark.

Two light waves interfere persistently when their phase difference is constant. This means that the waves are coherent.

The SI unit for the decay constant is 1/s, also known as the reciprocal of seconds. It represents the probability of an atom decaying per second.

Korotkov sounds are produced when the blood flow in the artery is turbulent. This happens when the pressure in the air sac falls below the systolic pressure, allowing blood to flow through the artery in bursts.

If a straight object is placed within the focal length of a diverging lens, the image produced will be virtual and upright. It will appear smaller than the object.

Alpha radiation has the highest biological effect for the same energy transferred. This is because alpha particles are large and heavy, causing significant damage to DNA.

Heavier particles settle faster than lighter ones during ultracentrifugation. This is because heavier particles experience a greater gravitational force. The sedimentation rate is also faster with a higher density of the settling medium, due to increased resistance. A particle with a higher density settles faster, and the lower the coefficient of friction, the faster the movement. Lastly, a smaller diffusion constant means slower movement, as the particles spread out more slowly.

Positron emission, usually part of beta decay, results in a decrease in the atomic number of the nucleus by one. This is because a proton is converted into a neutron, releasing a positron.

The effective half-life is a combination of the physical half-life and the biological half-life. It's calculated as the reciprocal sum of both half-lives, meaning it's shorter than both.

Alpha particles are not high-energy photons. They are helium nuclei consisting of two protons and two neutrons.

Beta waves have amplitudes in the range of 50-100µV. These waves are associated with a state of alertness and active thinking.

After twenty minutes, the isotope 13N will have gone through two half-lives (since it has a 10-minute half-life). This means 75% of the isotope will have decayed, leaving 25% remaining.

The refractive power of a lens system in contact is the sum of the refractive powers of the individual lenses.

The activity of a radioactive source is defined as the number of radioactive decays per second. It's measured in Becquerels (Bq).

Stokes' Law describes the force of resistance experienced by a spherical object moving in a viscous fluid. It's crucial for understanding the movement of particles in fluids like blood.

Radioactive tracing is a method of using radioactive isotopes to track the movement of substances in the body. It doesn't use electromagnetic radiation directly for imaging. Echoencephalography, thermography, and PET all use electromagnetic radiation for image creation.

The viscosity of a fluid is measured in kg/ms. It represents the resistance to flow, making thicker fluids have higher viscosities.

The degree of refraction at the boundary of two media depends on the relative refractive index of the second medium to the first medium. This means that the change in speed of light as it passes from one medium to another determines the amount of bending.

When two light waves meet, their amplitudes add up. Depending on the phase difference, this can lead to constructive interference (bigger amplitude) or destructive interference (smaller amplitude).

An object outside the focal length of a converging lens produces a real and inverted image. The image is smaller than the object if the object is further than twice the focal length, and larger if it's between the focal length and twice the focal length.

The frequency used for coil space diathermy is usually around 27.12 MHz. This frequency is within the radiofrequency spectrum and is used to heat tissues through electromagnetic radiation.

The ultrasound frequency band used in medical applications ranges from 2 to 18 MHz. These frequencies are high enough to create images but are still considered safe for medical use.

The pressure of an ideal fluid flowing in a pipe decreases when the diameter of the pipe increases. This is because the fluid has to spread out more, resulting in less pressure on the pipe walls.

The diffusion constant D depends on temperature, the size and shape of the diffusing particle, and the viscosity of the medium. It's not directly dependent on the density or the pH value of the medium.

MRI (Magnetic Resonance Imaging) provides the most accurate images of cancerous tumors. It uses magnetic fields and radio waves, allowing for detailed tissue visualization without ionizing radiation.

Braking radiation, also known as Bremsstrahlung, is generated when electrons are decelerated by an anode. Its minimum wavelength depends on the accelerating voltage, and its power is also affected by the accelerating voltage. The spectrum is continuous with no sharp peaks.

The patch-clamp technique isolates a small patch of cell membrane to study ion channels. It can measure the current through individual channels but not the speed of action potential propagation or the concentration of ions.

Teta waves have frequencies between 4 and 7 Hz. They are associated with drowsiness, sleep, and relaxation.

Hypotonic solutions cause haemolysis, which is the bursting of red blood cells. This happens because water moves into the cells due to the osmotic pressure gradient, and the cells swell until they burst.

The magnitude of the QRS complex peak in a two-lead ECG signal is typically around 1-2 mV. This peak represents the electrical activity associated with ventricular depolarization.

Lambert's Law describes the decrease in intensity of light as it passes through a material. It states that the intensity of the transmitted light decreases exponentially with the thickness of the material.

Blood pressure is highest in the heart, both during systole (contraction) and diastole (relaxation). This is because the heart is the source of the pressure that drives blood flow.

The volumetric flow rate of a viscous liquid is inversely proportional to viscosity. This means that a higher viscosity results in a slower flow rate. Think of trying to pour honey vs. water. Honey is more viscous and flows more slowly.

The concentration of Na in isotonic NaCl saline is 0.9%. This concentration is considered isotonic because it matches the salt concentration in human blood, preventing osmotic imbalance.

The amount of effective dose is measured in Sv (Sievert). It's a measure of the biological effect of radiation exposure, taking into account the type of radiation and its impact on different tissues.

The error of the mean decreases as the number of measurements increases. This is because the average becomes more reliable with more data points.

Weight is not a basic SI quantity; it's a force measured in Newtons (N). The SI base quantities include mass, length, time, temperature, electric current, luminous intensity, and amount of substance.

Fermi is not an official SI unit. It's a unit of length used in nuclear physics, equal to 1 femtometer (10^-15 meters). The official SI units for length are meter (m) and its multiples/submultiples.

While the dark-adapted eye is the most sensitive to light, it has poor visual acuity, meaning it cannot distinguish fine details. It's not true that the dark-adapted eye does not detect colors; it just has a lower sensitivity to colors than the light-adapted eye.

A kitten's mechanical energy is higher when it is running. This is because it has both kinetic energy (due to its motion) and potential energy (due to its height), while sitting on the wall it has only potential energy.

The energy of photoelectrons depends on the frequency of the light illuminating the metal surface, not its intensity. The ability of higher notes to pass through a medium is greater (not less) than lower notes. Thermography uses electromagnetic radiation (infrared) but is considered safe for fetuses. During mediated diffusion, particles move from a higher concentration to a lower concentration through the cell membrane, not the other way around.

After one hour (60 minutes), the isotope 11C will have gone through three half-lives (since it has a 20-minute half-life). This means 12.5% of the original isotope will remain.

The diffusion constant of globular proteins is usually higher than that of fibrillar proteins, not half as large. The diffusion constant is inversely proportional to the mass of the diffusing particle, not directly proportional. However, it's true that the diffusion constant increases when the temperature rises. If Stokes' law is applicable, the diffusion constant is inversely proportional to the viscosity of the medium, not directly proportional.

Rad (radiation absorbed dose) is not an official SI Unit. It's commonly used to measure absorbed dose: 1 rad = 0.01 Gy (Gray). The official SI unit for absorbed dose is Gy (Gray).

After forty minutes, the isotope 13N will have gone through four half-lives (since it has a 10-minute half-life). This means 6.25% of the original isotope will remain.

The wavelength of an electron accelerated by a 1.5V battery is about 0.3µm. This is calculated using the De Broglie wavelength formula, which relates the wavelength to the momentum of a particle.

Two light waves that meet cause persistent interference only if they are coherent, meaning they have a constant phase difference. Coherent light waves can be produced by lasers or special optical devices.

The SI unit for the period time is the second, the same as for the decay constant. The period time is the time it takes for one complete cycle of a wave, while the decay constant describes the rate of decay of a radioactive substance.

The normal activity of a 131I source used in thyroid tests is about 0.4 MBq (megabecquerel). This activity is low enough for safe use in medical imaging.

Beta particles are not hydrogen nuclei or high-energy photons. They are electrons or positrons emitted from radioactive decay. The distinction between electrons and positrons depends on whether the decay process is beta-minus or beta-plus.

The voltage-clamp technique holds the membrane potential of a cell constant while manipulating the ion concentrations across the membrane. It allows for the study of ion channel activity but doesnt directly measure the speed of action potential propagation.

Delta waves have amplitudes of less than 20 µV and are associated with deep sleep, often characterized by slow, deep breathing.

The absolute error of the difference of two quantities is the square root of the sum of the squares of both quantities' absolute errors. This is due to the error propagation rule, which states that errors add up in quadrature when quantities are combined through subtraction.

The radioactive decay constant is inversely proportional to the half-life. This means that a longer half-life has a smaller decay constant, implying a slower decay rate. The decay constant is independent of pressure and mass number.

Microwave slide thermocoagulation uses a frequency of approximately 2450MHz. This frequency falls within the microwave range and is used to heat tissues through electromagnetic radiation.

Hypertensive solutions cause plasmolysis, meaning that cell shrinkage occurs. This happens because water moves out of the cells due to the osmotic pressure gradient.

Beta particles are not hydrogen nuclei or high-energy photons; they are electrons or positrons.

The SI unit for irradiation dose is Gray (Gy). It measures the amount of energy absorbed per unit mass, usually expressed as Joules per kilogram (J/kg).

Capacitor field diathermy uses a frequency of 100 kHz to 1000 kHz (often around 400 kHz). This frequency is within the radiofrequency spectrum. These frequencies are used to heat tissues through electromagnetic radiation.

A real object placed within the focal length of a converging lens produces a virtual, upright, and enlarged image. This is how magnifying glasses work.

The diffusion constant D is independent of the density of the medium. It's influenced by temperature, size and shape of the particle, viscosity, and even the pH of the medium.

Alpha particles are not hydrogen nuclei or positrons. They are doubly ionized Helium atoms, containing two protons and two neutrons.

The statement that the light beam enters the medium with a higher refractive index into the medium with a lower refractive index, then the angle of refraction is less than the angle of incidence, is true. This is due to Snell's law of refraction. The penetrating power of higher notes is greater than that of low notes. Thermography does use electromagnetic radiation. Mediated diffusion is usually faster than simple diffusion because it uses membrane proteins to facilitate movement.

The degree of refraction at the border of two media is determined by the speed of light in the two media. Specifically, it depends on the difference in speed, which is directly related to the difference in refractive indices.

The electron wavelength in vacuum is approximately 0.3 µm when the electron is accelerated by a 1.5V battery. This is calculated using the De Broglie wavelength formula, which relates the wavelength to the momentum of a particle, and the energy gained by the electron from the battery.

It's false to say that the visual acuity of the light-adapted eye is poor. In fact, the light-adapted eye has better visual acuity than the dark-adapted eye, meaning it can distinguish finer details. The light-adapted eye is not necessarily the most sensitive to light; the dark-adapted eye is more sensitive.

The absolute error is directly proportional to the count, so if the count increases four times, the absolute error also increases four times. Therefore, the absolute error doubles in size.

Speed is a derived quantity, not a fundamental SI base unit. It is calculated from distance and time.

Stochastic biological effects are random events that occur due to radiation exposure. They can happen at low doses and their frequency increases with the radiation dose.

The cornea has a high refractive index compared to air. This causes the light to bend sharply as it enters the eye, changing its direction the most.

The volumetric velocity of a viscous liquid is directly proportional to the pressure difference. This means a higher pressure difference leads to a faster flow rate.

Osmotic pressure is the pressure needed to prevent solvent flow through a semipermeable membrane. It is not equal to the partial pressure of the solvent.

An ideal fluid is incompressible and has no viscosity. Non-Newtonian fluids do not fit this definition.

Stokes' Law relates the drag force on a spherical object in a viscous fluid to its velocity and the fluid's viscosity. The diffusion constant is inversely proportional to viscosity, meaning higher viscosity leads to slower diffusion.

The decay constant of a radioactive isotope is the probability of a nucleus decaying per unit time. It's related to the half-life: decay constant = ln(2) / half-life.

A resting brain emits alpha waves, which are associated with a relaxed state of consciousness.

A biconcave lens always causes light to diverge. This is because the refractive index of the lens is greater than that of the surrounding medium, causing the light to bend away from the optical axis.

CT imaging uses X-rays, which are significantly absorbed by the skull bone. This absorption reduces image resolution for brain structures.

Laplace's Law describes the tension in the wall of a circular pipe, specifically the tension caused by pressure inside the pipe. This helps understand the forces in blood vessels.

Blood pressure in the brain decreases temporarily when someone stands up because gravity pulls blood toward the feet, creating a temporary decrease in blood flow to the brain.

The volumetric flow rate of blood through a vessel is proportional to the fourth power of the vessel's radius. A 19% increase in radius leads to a significant (almost double) increase in the flow rate.

Both CT and PET use ionizing radiation. CT uses X-rays, and PET uses gamma rays.

The dark-adapted eye is the most sensitive to light because it has time to adjust to low-light conditions. The light-adapted eye has better visual acuity, but it's less sensitive to light.

Two light waves interfere persistently when they are coherent, meaning their phase difference is constant. Coherent light waves have a consistent relationship between their crests and troughs.

The SI unit of the decay constant is 1/s, also known as the reciprocal of seconds. It describes the probability of an atom decaying per second.

Korotkov sounds are caused by turbulent blood flow, which happens when the pressure in the air sac falls below the systolic pressure, making blood flow through the artery in bursts.

The image formed by a straight object placed within the focal length of a diverging lens will be virtual and upright. The image is always smaller than the object.

Alpha radiation, due to its large particles (helium nuclei), causes significant damage to DNA molecules, making it the most biologically effective for the same energy transferred.

Heavier particles settle faster during ultracentrifugation due to the stronger gravitational force they experience. Increased density of the medium also leads to faster sedimentation due to increased resistance. Additionally, a higher particle density and a lower friction coefficient both contribute to faster sedimentation.

Positron emission, typically a part of beta decay, decreases the atomic number of a nucleus by one as a proton is converted into a neutron, emitting a positron.

The effective half-life combines the physical and biological half-lives of a radioisotope. It's calculated using the reciprocal sum of both half-lives, resulting in a value shorter than either individual half-life.

Alpha particles are not high-energy photons. They are helium nuclei, containing two protons and two neutrons. They are essentially the nucleus of a helium atom.

Beta waves have amplitudes in the range of 50-100µV. These waves frequently occur during alertness and active thinking.

After twenty minutes, the isotope 13N will have gone through two half-lives, reducing it to 25% of its original amount.

Refractive power, a measure of how much a lens bends light, is additive for lenses in contact.

Stokes' Law relates the drag force on a spherical object in a viscous fluid to its velocity and the fluid's viscosity. The diffusion constant is inversely proportional to viscosity, meaning higher viscosity leads to slower diffusion.

A real object placed within the focal length of a converging lens produces a virtual, upright, and enlarged image. This is how magnifying glasses work.