By creating a water current that continuously replenishes water over the respiratory surfaces, many invertebrates that lack specialized respiratory organs increase the diffusion of oxygen byMultiple choice question.maximizing the surface area for diffusion.maximizing Δp in Fick's law.decreasing the distance over which gases travel.reducing the Δp in Fick's law.

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans ?

By having the blood flow in the opposite direction as the water, gills maximized the diffusion of oxygen. This process is calledosmoregulationgastrulationcounter-current exchangehomeothermy

Why have most multicellular organisms evolved structural adaptations which maximize gas diffusion from the environment?Multiple choice question.Because direct diffusion of oxygen into each cell normally takes over 0.5 minutes.Because direct diffusion of oxygen into each cell can provide enough oxygen only if the diffusion distance is more than 0.5 mmBecause direct diffusion of oxygen into each cell can provide enough oxygen only over distances under 0.5 mm.

What limits the size of organisms that rely entirely on oxygen diffusion from the environment (and not on a transportation/exchange system of any kind)?Multiple choice question.The fact that those organisms don't have hemoglobinThe rate of oxygen diffusionThe fact that for every molecule of oxygen that comes in hundreds of CO2 molecules are producedThe thickness of the plasma membrane

What is diffusion?The passive movement of particles from a high concentration to a low concentrationThe passive movement of particles from a low concentration to a high concentrationThe active movement of particles using energy from respirationThe passive movement of water though a semi-permeable membrane from an area of high concentration to an area of low concentration2Which of the following factors do not speed up diffusion?Small surface area to volume ratioIncrease in temperatureIncrease in concentration gradientLarge surface area to volume ratio3During ventilation, in which order does air enter the following structures to reach the lungs?Bronchi, bronchiole, trachea, alveoliTrachea, alveoli, bronchi, bronchioleTrachea, bronchi, bronchiole, alveoliBronchi, trachea, bronchiole, alveoli4Which one of the following characteristics would you expect to find in alveoli to make them efficient at gas exchange?Small surface areaRich supply of blood capillariesLong diffusion distanceThick walls5Which two mechanisms are important for maintaining the steep concentration gradients of oxygen and carbon dioxide that are necessary for gas exchange?Respiration and ventilationVentilation and circulationVentilation and excretionRespiration and circulation6During gas exchange:Oxygen moves down a concentration gradient from the air in the alveoli to the bloodOxygen moves down a concentration gradient from the blood to the air in the alveoliOxygen moves up a concentration gradient from the blood to the air in the alveoliOxygen moves up a concentration gradient from the air in the alveoli to the blood