Some fantastic jelly-fish answers

Do you think that the polyp form or the medusa form was the common stage in the cnidarian ancestor? Explain your answer.

-Ancestors must have come up with a plan where conditions were tough to avoid extinction- produce medusa
-Polyps come up with a very clever plan
-Scientifically it is more ethical to say the polyp stage is common to the ancestor cnidaria.

Compare and contrast the feeding behaviour of Hydra and Planaria.

-Hydra-hostile, Planaria-gracile
-Planaria are autotrophic
-Planaria embark on a journey for food.
-Planaria have a blood circulatory system.
-They have a blood transport system so that you can live on land.
-In conclusion the feeding behaviour has been compared and contrasted and a summary (in table form) has been made for convenience.
-The planarians outer layer is very choosy in allowing diffusion of gases.

Instead of having pluripotent cells, would it have been better for these phyla to have specialised cells or a blood transport system? Justify your answer (5 marks)

-Pluripotent cells might forget about producing sex cells
-The cells will able to focus in their function if they are for protection and wont have to sense as pluripotent cells would to know what’s wrong they just perform the function immediately after realising the problem,.

Talking rubbish...?

Line from an essay on modes of excretion in worms:

‘…and when you can’t taste anything, there is nothing entirely wrong with excreting waste through your mouth.’

Who knew so much was at stake...

When asked to explain the activation of a protein-digesting enzyme, the student wrote the following. What they were supposed to write was something along the lines of, the enzyme is only activated in the duodenum as the pancreas doens't have any mechanisms in place to prevent self-digestion, and thus it produces the enzymes in an inactive form. This is what they actually wrote...

"…This is to ensure that it does not react with the other substance that it should not react with as prevention of self destruction."

Stating the blatantly obvious...

Q: Explain the activation of chymotrypsinogen [an enzyme].

A: There is a process in which chymotypsinogen is activated...