help with assignment on Communication (1 Viewer)


New Member
May 8, 2004
(This is straight from a dotpoint): Construct a table to compare and describe the nature and functioning of photoreceptor cells in mammals insects and one other named animal.

I'm not sure what this is looking for. I have a textbook that suggests for me to use a table with the titles:

Feather of Comparison
Structure(s) that refract light
Number and type of photoreceptors
Ability to focus
Visual acuity
Sensitivity to light
Detection of movement

Aren't photoreceptor cells just rods and cones? If it is don't I describe and compare the nature and functioning of these rather than the titles that they suggested? It seems to me that the only titles relevent are "number and type of photoreceptors", "visual acuity" and "sensitivity to light", and that there should also be "detection of colour".

Describe two examples of technology that can be used to prevent blindness from cataracts.

Do two different types of surgery count as one or two technologies?

Explain the importance of being able to focus on both near and far objects

I just said things off the top of my head about needing to be aware of the surroundings in order to respond to danger and to navigate. Do you think this is what it's looking for?

I'd really appreciate any help you can offer, especially in regard to the first one.


Feb 20, 2003
With the first one, in my summary I didn't have it in table form, but basically this is what I had:

Mammals (just all the rods and cones stuff)
Insects- have compound eyes made up of a large number of separate structures called ommatidia. Each ommatidium has its own cornea and a crystalline cone that acts as a lens. The light travels through these and strikes the light sensitive receptor cells. The receptor cells transmit the stimulus to the brain. There are often many thousands of ommatidia, giving the insect a large field of view and this is put together to form a mosaic image.
Planarian (flat worm) - have the simplest type of photoreceptors called ocelli. Light falls on the photoreceptor cells and stimulate an impulse so that the animal is aware of light in the environment and the direction it is coming from. There is no lens or image formed.

I think you could put this info in to a table quite simply. E.g. for "ability to focus", mammals have a high ability to focus, while insects and planarian cannot focus. I think the categories you have there would be good to work off to construct your table and you wouldn't need any other additional information than those categories that I can think of.

With the second question, I think the different types of surgery would count because I can't think of any other way besides surgery to cure cateracts.

With the third question, you need to make sure that you mention that the inability to focus on near and far objects results in blurred vision which hampers visual communication. The things you have mentioned are forms of visual communication, so you could then go on to use the things you mentioned as examples.

I hope this helps. Are these directly from the dot points? Because they are different to the dot points I have, or maybe I'm just not finding the right points.


New Member
Mar 28, 2004

We are doing a similar assignment except for we have to find diagrams showing photoreceptor cells belonging to a mammal other than a human, an insect and any other animal of your choice. I can not find any diagrams any where! Does any one know where I might find some? Any help would be appreciated. :D


Apr 24, 2006
i think it took him 3 years to read the comment made in 04...either way ....BIO IS TOO SCHOOL FOR COOL!

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