Certain alleles may cause serious diseases in a given environment but they may also be beneficial in different environmental conditions. It is a principle of natural selection.
<h3>Natural selection and alleles</h3>
Natural selection refers to the differential survival and reproduction of an organism in a given environment.
Certain alleles such as the allele of sickle cell disease show an evolutionary advantage in specific environmental conditions.
This allele is lethal in homo-zygous individuals, thereby tending to be eliminated from the population.
However, in regions where malaria is endemic, the presence of carriers individual having the sickle cell allele is advantageous to prevent this disease.
Learn more about natural selection here:
brainly.com/question/1657375
According to your diagram A comes first. It’s true because if it doesn’t evaporate everything else can’t happen.
<h2>CNS </h2>
Explanation:
An example of a myelin producing cell in the CNS is oligodendrocyte
- The major function of oligodendrocytes is the formation of myelin
- Myelin acts as an insulator of axonal segments and is a prerequisite for the high velocity of nerve conduction
- Larger axons form thicker myelin
- During development, oligodendrocytes arise from precursors located in the sub-ventricular zone such as the sub-ventricular zone of the lateral ventricles for the cerebrum or the fourth ventricle for the cerebellum
- In the spinal cord, oligodendrocytes originate from the ventral regions of the neural tube and in the optic nerve they migrate into the nerve from the third ventricle
- It is the oligodendrocyte precursor cells which migrate to their destination where they then differentiate into the more mature oligodendrocytes
- The proliferation of the oligodendrocyte progenitor cells is controlled by a number of growth factors released predominantly from neurons but also from astrocytes such as platelet derived growth factor (PDGF) or fibroblast growth factor (FGF)
Answer:
Mutualism
Explanation:
In biology, the term <em>symbiosis </em>refers to close and often long-term interactions between organisms that belong to different species. There are three main types of symbiotic relationships:
- mutualism - both organisms benefit from their relationship
- commensalism - one organism benefits, while the other doesn't benefit or suffer any harm
- parasitism - one organism causes harm to the other
In the given scenario, both the bird and plant benefit from their relationship. The bird gets food, while the plant reproduces more easily. This is why their relationship is an example of mutualism.
