2 - Interaction with External Environment Flashcards
What factors influence light climate
Intensity (irradiance/insolation)
Atmospheric attenuation, proximity to the equator (seasonality)
Wavelength
Polarisation
What is light polarisation and how is it used
It’s the angle at which light vibrates and scatters; used for navigation, foraging, and migration (affected by cloud cover and surface reflection)
How do animals use light
Vision
Communication
Behaviour
Body heat
Vitamin D synthesis
Phototaxis
Regulating cyclic changes
How do plants use light
To produce metabolic energy and gather environmental information
What is the simplest form of an eye in metazoans
A structure with two cells: one photosensitive and one with shading pigment
What types of eyes exist in animals
Simple eyes, compound eyes, and complex eyes (clusters of cells connected to nerves)
What is photoreception
The detection of light based on wavelength, intensity, or other qualities — often results in phototaxis
What is vision
Using reflected light to form an image of the external environment
How do light-sensitive cells detect light
Via opsin proteins and chromophores that react to light, converting it into nerve impulses
What determines spectral sensitivity
Variations in amino acids in opsins; under genetic control
Do plants have sound sensors
There’s no clear evidence, but they may respond through calcium ion permeability in cell membranes
What is an example of acoustic response in plants
Bat-pollinated plants shape their leaves to reflect echolocation signals, helping bats locate them
What is mechanosensing in plants
A sensitivity to touch and pressure, used for directional growth and defence
What is thigmotropism
A slow, irreversible growth movement in response to physical contact
What is thigmonasty
A rapid, reversible response to mechanical stimulation (e.g. leaf folding)
What is photonasty in plants
Movement caused by changes in light levels, such as flower or leaf closure in low light
What do mechanoreceptors do
They convert mechanical stimuli into electrical signals.
What are baroreceptors
Receptors that detect changes in internal pressure
What are Pacinian corpuscles
Receptors that respond to vibration
What are Merkel discs sensitive to
Light touch and pressure
What mechanoreceptors do invertebrates have
Hair-like sensors that respond to displacement, and proprioceptors for detecting body position
What do statocysts do
Help invertebrates sense gravity and maintain balance (equilibrium)
Birds - What are Meissner’s corpuscles
Receptors for light touch, texture, and pattern.
Birds - What are Grandry corpuscles
Detect the speed of mechanical stimuli, especially in feathered skin
