A dichotomous key is two paired sentences that have contrasting characteristics. That's all i know
Answer:
In human vision, the cone visual opsins are grouped into four photoreceptor protein families LWS, SWS1, SWS2, RH2
.
- SWS1: produce pigments sensitive to very short wavelengths, UV-violet, 360-450 nm.
- SWS2: produce pigments sensitive to short wavelengths, blue, 450-495 nm
- RH2: produce pigments sensitive to medium wavelengths, green, 495-560 nm
- LWS: produce pigments sensitive to long wavelengths, yellow-red, 560-770nm.
Explanation:
Photoreceptor proteins are light-sensitive proteins that mediate light-induced signal transduction, thus they are involved in the sensing and response to light in a variety of organisms.
The photoreceptor proteins are classified based on the chemical structure of the chromophores involved, the light absorption and on the protein sequence.
This photoreceptor proteins are located at the cone photoreceptor cells and are responsible of photopic vision.
For scotopic vision, rhodopsin is responsible. Rhodopsins are the visual pigments (visual purple) of the rod photoreceptor cell in the retina. They are responsible of human vision in dim light, as it contains a sensory protein that converts light into an electric signal.
Answer:
Hydrophilic heads facing exterior
Hydrophobic tails facing interior
Explanation:
In 1972, the fluid mosaic model was proposed to describe the structure of the plasma membrane. This model describes the plasma membrane to possess components including phospholipids, cholesterol and proteins. The phospholipid component is composed of glycerol, two fatty acids and a phosphate-containing head, which are arranged in two adjacent layers forming the phospholipid bilayer in the membrane of biological organisms.
Phospholipids have both the hydrophilic and hydrophobic region. Hence they are said to be AMPHIPATHIC.
The head of the phospholipid is negatively charged due to its phosphate content, making it polar and hydrophilic i.e. water-loving. This hydrophilic head faces the exterior of the cell in order to interact with fluids.
The tails of the phospholipid are long fatty acids that keep away from water i.e. hydrophobic. Due to their water-fearing nature, they avoid water and face the interior of the cell, where each tail face each other.
Having a high surface area helps so yes in the human body villi is an example of a structure that increases surface area to increase absorption rates.
