i need help! (1 Viewer)

[Buiboi]

I have so many questions about this topic, any help will do...cheeeeers!

1)waht are pheromones? how do they work and when are they used?

2)wavelengths human eye can detect? is it 390 nanometres to 780? im getting different wavelengths in nearly all textbooks!?!?!

3)distinguish between light sensitive pigments and photoreceptors? confused!

4)this dot point: compare the change in refractive power of the lens from rest ot maximum accomodation? btw what is the maximum accomodation?

5) what needs to be said for this dot point :"identify photoreceptor cells as those containing light sensitive pigments and explain that these cells convert light images to electrochemical signals that the bain can interpret"----

photosensitive pigments absorb light that strikes the retina, rods and cones are triggered and convert the light image to an alectrochemical impulse due to photochemical changes (sodium and potassium ion transfers) which is then sent to the brain via optic nerve for interpretation? ---is this valid or sufficient?

6) explain the distribution of the rods and cones? all i have is that rods are concentrated mostly aroudn the retina and mainly at the periphery of the reatina and the cones are absent except forh te fovea? is this enough?

7) ummm the structure of the rods and cones?

8)"identy that there are 3 types of cones each containing separte pigment sensitive to either red blue or green....hwat must be written for this dotpoint?!? what mroe cna be said?

9)"explain that colour blindness in humans results from the lack of one or more of the oclour sensitive pigments in teh cones"...what more c na be said!?!? for this dot point?

10) for the secondary souce one ..describe the nature and functioning of photoreceptor cellsin mammals insects and in antoher....for the insect (fly/bee)ar ethe ommatidium the actual photoreceptor?? ummm im not sure on what info i neeed to find for this dotpoint? so far i have headings comparing each organism; type of photoreceptor, tyep of image produced, similarities, difference in photreceptors.....it doesnt seem enough what am i missing?

11)"prcess and analyse info to describe and alnalyse the use of colour for communication in animals and relate this to the occurrence of colour vision in animals??- i know the 5 different ways colour is used for communication but 'occurence..???"

12) "outline and compares some of the sturcutres used by animals to produce sound"--- i have the frog and grasshopper, howver im unsure for what i have written for the frog...how do they produce sound"

13){outline the structure of the human larynx and the associated structures that assist the production fo sound"....sources ive referred to had different structures associated...for my answer i referred only to the larynx, vocal cords, tongue, soft and hard palate and lips...am i missing any other important ones?

14)is the role of the shadow cast, to allow us to identify and distinguish the location and source of sound as am eans of interpretting the difference in loudness and time of arrival at each ear, which is to then be analysed by the brain?!?

 

[yoakim]

Ok...this is all from the top of my head, apologies if there are slight inconsistencies.

1. (Wikipedia ): pheromones are chemicals emitted by living organisms to send messages to individuals of the same species. (I don't think we need to know these in depth, but just a general idea). Instead, I think we need to know about neurotransmitters.

2. the human eye can detect wavelengths in the range of about 360-760nm.

3. Photoreceptors are the 2 cells: Rods and Cones. Photoreceptors CONTAIN light sensitive pigments which are: Rhodopsin (composed of retinal and opsin) in rod cells, and iodopsin/photopsin light sensitive pigments in cone cells.

4. Maximum accomodation is when the lens changes shape to become as FAT/THICK as possible. Thicker the lens = higher refractive power to bend light. At rest, the lens is stretched (becomes flat), becomes the ciliary muscles are relaxed, hence the suspensory ligaments are tight, which in turn stretches the lens to be flat = low refractive power. Maximum accommodation = not at rest.

5) As stated above in 3), photoreceptor cells are rods and cones. Rods contain rhodopsin which is its only light senstive pigment, composed of retinal and opsin (Protein and a Vitamin A derivative). When light hits this, it undergoes chemical decomposition where the 2 components split from each other temporarily. This causes an electrochem. signal to form, which is sent from the rod cells to the bipolar cells --> ganglion cells--> optic nerve --> brain --> interpretation --> image

Your statement is quite valid, but if it was worth 4 marks, you would most likely receive only 2/3. You need to be specific (altough hypocritically my example response does not reflect ).

6) You need more than that I'm afraid. That's only worth 2/3 marks. You need to give numbers: 125mil rods, 6-7 mil cones. Cones are more concentrated in the macula region of the fovea, hence is used for daytime/colour vision, rods mainly in the peripheral and none at the fovea, hence is useful for nightvision. You could also mention how they're grouped together, eg: rods are linked in groups to single neurones.

7) Rods are rod-shaped: long, flat, thin/narrow, . Cones are cone-shaped (no way!): they're rounder, shorter (I think?). Rods are connected to ONE biopolar cell (neurone), unlike cone cells which are connected to many (hence more visual acuity with cones - colour vision).

8) There are actually specific names for them, but i can't remember them. You should know the peak sensitivities of each colour, eg: blue is something like 430, green = 530, red = 560nm

9) Colour blindness occurs because one or more of the three types of photopigments (3 colours) in cones is either absent or does not function properly.
The most common form of colour blindness is the failure to discriminate between brown, red and green. There are different types such as mono/dichromatic and trichromatic (complete colourblindness - only rely on rod cones) colour blindness.
These can be caused due to stuff like mutation (too much exposure to radiation), congenital (you were born with it), trauma, taking drugs, injury, age, etc.

10). Yes, ommatidia are photoreceptor cells in insect eyes, (compound eyes). They are hundreds of optical units (photoreceptor cells). What you have there is fine, it's only a 'describe' question, which includes THREE organisms. You will be sweet if it's even a '12 mark' question hahaha.

So basically: insects have three colour vision but can see ultra-violet light and not red light. Their images are blurred, and lack detail compared to humans. Humans have HIGH visual acuity because of their highly complex/advanced three colour vision system. Planarians or flat worms have photoreceptor cells located in 'cup eyes'. These are very poor in visual acuity (sharpness) and cannot detect colour, used only for directional information only. Because of their poor detail, they are instead VERY sensitive to movement to compensate it.

11) Yes, occurrence basically means that you need to describe WHAT the organisms sees. Eg: use of colour for communication in bees is for the detection of pollen in flowers. The occurence of colour vision is that they cannot see red, but instead sees it as white (or is it the other way around??!?!??!!). They also see UV light on flowers, which is another occurrence. Also, birds that feed in the daylight see colours very clearly, eg:hummingbirds, the occurence of colour is that they see red light/flowers from over 1 km away.

12) Male frogs vocalise by squeezing their lungs while shutting their nostrils and mouth, air flows over their vocal cords and into their vocal sacs. This is important especially for the 'compare' verb in this syllabus dot point, because you can compare this use of air/vocal cords with the human's vocal cord/lungs etc.
You can also mention about the fish: some fish vibrate their swim bladders to create sound which sounds similar to an aerator in a fish tank haha.

13) You could name some cartilages such as the thyroid and arytenoid. Yes so the two main components are: upper/false vocal cord (vestibular fold), and the lower/true vocal cord (vocal fold). It's only an 'outline' question, so I would imagine that there wouldn't be a 4+ marker in the HSC.

14) YES! Distinguish/determine/judge the location/distance/direction/loudness of speed - because each ear is situated at diff. sides of the head. Animals wiggle their ears instead to locate the sound, just like how a cat does, but too bad my cat is deaf.


You certainly had A LOT of questions, but hopefully I cleared things up for you. They were also good revision for me too!

 

[Buiboi]

ahhahah...AWESOME!! Thanks heaps!