12 Biology Gas Exchange

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logy12 Biology Demonstrate understanding of adaptation of animals to their way of life Gas exchange – Process in which gas is oxygen exchanged for carbon dioxide
THE WORM

The worm lives underneath the ground in moist rich humus soil. The worm is Terrestrial- which means it is related to earths or its inhabitants, and is not restricted to moist environments as the worms internal lungs keep it moist. As worms are nocturnal they only are active at night Which gives them less chance to be eaten by birds as birds hunt in the day time. This is an advantage as they will not dry out in the day time. In hot days in summer the worm burrows deeper to avoid drying out and dying. In wet days it is possible that the worm will be brought to the surface this gives the worm a higher death rate as in winter if worms stay in the wet soil they will drown.

The worm is an herbivore, this is important as birds feed on worms for nutrition and worms feed on nutrients from the soil and leaf litter in the fertile part of the soil called the humus. The worm increases the soil fertility by excreting the leaf litter.

The worm has an external gas exchange system which is their skin, as they have no internal organs. The worm breathes through its skin as you can see in fig3 in the annotated diagram. The worm’s supply of gas is diffusion through the worms skin and the worm also has an open circulatory system which contains haemoglobin, haemoglobin carries oxygen around the body. Red haemoglobin present in worms which is used to transport oxygen and white blood cells to fight infections. The Worm has mucus glands underneath its skin which keeps it moist and so gases can be diffused across membranes to have efficient gas exchange in the body. It receives oxygen from the environment as the oxygen in the air dissolves in the worm’s skin and then travels into the worm’s skin into the blood capillaries below the skin so the cO2 diffuses in the opposite direction.

The worm has a...
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