Each sieve tube element is normally associated with one or more nucleated companion cells, to which they are connected by plasnodesmata (channels between the cells). Each companion cell is derived from the same mother cell as its associated sieve tube member. Sieve tube members have no cell nucleus, ribosomes, or vacues. Thus, they depend on companion cells to provide proteins, ATP, and signalling molecules
Amblyopia, optic neuritis is a dimness of vision or the partial loss of sight without detectable disease of the eye.
Partial blindness means you have very limited vision. Complete blindness means you cannot see anything and do not see light. Decreased vision in one or both eyes without detectable anatomic damage in the eye or your vision.
Temporary vision loss (total or partial) can also be the result of migraine headaches, sickle cell anemia, also referred to as sickle cell disease (inherited blood condition) acute angle-closure glaucoma (sudden rise in eye pressure).Types of vision loss include central vision loss or difficulty seeing things in the center of vision. Peripheral vision loss, or difficulty seeing things out of the corner of the eyes.
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Living things respond to their enviroment.
It's just what they do and how they grew up!
Hope that helped:)
Hey There!
The "Complementary base pair rule" <span>is used to join the free nucleotides to the exposed bases of the DNA.
Have a good day! :)</span>