Oxygen must diffuse to the cells of a cockroach…

Contributed by StemPy Lab

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Oxygen must diffuse to the cells of a cockroach. Use $t = \dfrac{x^2}{2D}$ , with $D = 0.00002\ \text{cm}^2/\text{s}$ for tissue and $D = 0.2\ \text{cm}^2/\text{s}$ for air.

How long does oxygen take to diffuse $0.4\ \text{cm}$ through tissue, in seconds?

How long does it take to diffuse the same distance in air, in seconds?

How many times longer is the time in tissue than the time in air?

What distance can oxygen diffuse through tissue in $1\ \text{s}$ , in centimetres? Give the answer to four decimal places.

Need a reminder? The key ideaShow

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

← All Problems

← A cockroach has ten pairs of spiracles: two pairs in the thorax and eight pairs in the abdomen…What is the brain of a cockroach called, and where is it? … →

More onTissues and Organs › Structural Organisation in Animals

Discussion (0)

Loading…

The blood vascular system of the cockroach is open. The blood, called haemolymph, bathes the organs in the body space. A tubular heart with funnel shaped chambers and ostia pumps it forwards. The respiratory system is a network of tracheae that open through ten pairs of spiracles, two pairs in the thorax and eight in the abdomen. The tracheae branch into tracheoles that carry air to the cells. Malpighian tubules remove nitrogenous waste. The nervous system has a brain in the head and a ventral nerve cord with nine ganglia, three in the thorax and six in the abdomen. The sense organs are the antennae, the compound eyes, the palps and the anal cerci. The time for diffusion over a distance x is x squared divided by two times the diffusion constant.