Bio FC Paper 2

Question 1

Describe a reflex arc

Answer 1

*sensory neurone, interneurone, motor neurone
*provide pathway
*along which AP transmitted
*from a receptor to a effector
*without involving conscious regions of the brain

Question 2

Reflex arc advantages

Answer 2

Enables organisms to make reflexes that are:

*rapid and automatic adjustments to the environment
*protect against damage to body tissue
*don’t have to be learnt
*help escape from predators
*enable homeoatatic control
*posture and balance
*finding food/mate/suitable living conditions

Question 3

How organisms adapted to see in dark

Answer 3

*high density of rods away from the fovea in the retina
*contains rhodopsin pigment, making rod cells very sensitive to all wavelength of light so helps to see in the dark
*light breaks down rhodopsin, leading to a ge erator potential
* several rods connected to a single bipolar neurone
*meaning if enough light detected by any of the rod cells spatial summation gives enough NT to reach and pass threshold
*to send a single nerve impulse to optic nerve/brain via bipolar neurone
*giving high visual se sensitivity