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

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

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 are the two key factors to be able to exchange enough oxygen and carbon dioxide to keep an organism alive?Large surface area and wet membranesLarge surface area and dry membranesLarge volume and dry membranes

6.What do larger organisms need to transport substances around their body?

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.