Phototaxios

Question 1

What is Phototaxis?

Answer 1

It’s the orientation on movement in respect that it can be either positive or negative or be away or towards light

Question 2

How do larval swim?

Answer 2

They swim in a helical fashion
Rotation means that their dorsal side is directed to the axis of the helix it keeps the body in the right orientation

Question 3

What is the tropism theory?

Answer 3

Larvae compare the sense of light intensity through two eyes - if one eye gets more light it will travel in that direction

Question 4

What is photo positive?

Answer 4

They will go towards the light

Question 5

What is photo negative

Answer 5

Travels away from light

Question 6

What is the platynerisdumerlli? The worm?

Answer 6

It has a simple visual system
It is a polychete worm
Their cilia beats in rhythm to eachother to generate currents to drive animal through water

Question 7

What are eyespots in the worm?

Answer 7

They have a shaded cell that block lights from reaching the photo receptor in certain direction
The eye spot is a single photoreceptor which are shaded by the pigmented cell
Eye spots work independently

Question 8

What is broad spectral sensitivity?

Answer 8

Photo receptor have a broad sensitivity - it is useful in the aquatic and natural environment

Question 9

What is significant about rhabdomeric receptors?

Answer 9

They have folded apocal membranes and conduct light activations through the IP signalling pathway

Question 10

What other photo receptors are there?

Answer 10

Ciliary type receptors which have foldedcilliaand conduct via the cGMP signalling pathway

Question 11

Hope do opsins work?

Answer 11

The opsin photoreceptive protein will respond to a particular wavelength
They opsin then trigger an IP3or cGMP pathway intracellularly

Question 12

What are the role of cilliated cells in platyneris?

Answer 12

12 ciliated cells
They go around the eyespots which sensitive nerves that are situated for the eyespots

Question 13

How does swimming work in platynereis

Answer 13

Photicstimulatin of the photo receptor -sensory motor nueron
Directly influences cilarly beating by synpasing with cilarly cells
As eye spot is activated the ACh modulates beat frequency on the ipsilateral side
Water flow is reduced and animal turns

Question 14

What happens when you shine light on one side of the platyneris

Answer 14

Its body wil flex its trunk according to the eye that has been illuminate. The bending motion drives the animal in the direction of light

Question 15

What happens when you apply ACh antagonists

Answer 15

They are unable to perform phototaxis

Question 16

What happens to older larvae in platyneris

Answer 16

They develop 4 visual eyes
They have 2-7 ohototreceptors
They still have non-visual eyes

Question 17

What happens when you use eye ablation to platyneris?

Answer 17

Use a laser to take out the eyes/one eye or both
Stimulation of one side- it will cause a direction change towards the light
Ablation of a non-visual eye = no effect on Phototaxis
A ablation of all 4 visual eyes = effect on Phototaxis

Question 18

Are fruit larvae photo positive or negative

Answer 18

They are photonegative they want to avoid light- this is to avoid prey

Question 19

What behaviours do fruit fly larvae exhibit when light is present

Answer 19

They crawl forward and turn to the light and wave their head to scan the environment.they either accept or reject the light regime (move with or against light)
Turns can be accepted if light conditions are suitable

Question 20

What happens if you put fruit fly larvae on a lit up checkerboard

Answer 20

The fruit fly will sweep its head
The head sweeps increased at dark:light
The head sweeps decrease light:dark

Question 21

Why do fruit fly larvae sweep their head

Answer 21

To detect luminosity in the environment

Question 22

What is the fruit fly larvae’s bolwig organ

Answer 22

The bolwig organ has photoreceptors in it to make up part of the flies visual system

Question 23

Does the bolwigs organ have an opaque cup?

Answer 23

Yes,it contains photoreceptive cells inside the cup

Question 24

How does the opaque cup work in the bolwigs organ?

Answer 24

When the larvae sweep its head the light will either hit or not hit the photoreceptors
Which will allow the larvae to change direction