Darwin's proposed mechanism for evolution is natural selection. Natural selection allows species to respond to their surroundings through time, or to become progressively excellently-suited. Natural selection is environmentally based and involves established heritable variation within a population.
They lead to changes in species over time:
- Darwin suggested species will evolve over time, new species originate from pre-existing species, and all species share a common ancestor with each other.
- In this framework each organism has its own special set of heritable i.e genetic variations from the common ancestor that have slowly developed over very longer periods of time.
- Parroted branching activities that isolate new species from a common ancestor create a multi-level tree that connects all living organisms.
Answer:
a. The maternal copy of UBE3A is expressed and the paternal copy is silenced.
Explanation:
When UBE3A chromosome is in neurons, paternal allele is silent and maternal allele is expressed in process of genomic imprinting. In some cases UBE3A is expressed from both paternal and maternal chromosomes. The paternal chromosome is blue whereas maternal chromosome is magenta.
The tissue you are referring to here is the xylem, a <u>vascular tissue</u>, whose basic function is to transport water and nutrients from the roots to the rest of the plant.