Answer:
Index fossils
Explanation:
The index fossils are the fossils that come in very handy for the geologists when it comes to identifying or dating rock samples or other fossils. The reason for this is that the index fossils have already been dated. They are fossils that are very commonly found, wide dispersed, are easy to be identified, and are limited to only a certain geological period. These characteristics make them an excellent indicator for the dating of the rock layers in which they are found, or the fossils found in the same layers with them, without conducting further examinations.
The sclerenchyma is the tissue in which creates the plant firm and hard. The two kinds of sclerenchyma cells exist fibers and sclereids. Their cell walls be made up of cellulose, hemicellulose and lignin. The sclerenchyma cells are the principal associate cells in plant tissues that have come to a close elongation.
A dichotomous key is two paired sentences that have contrasting characteristics. That's all i know
Phosphorus is an essential nutrient for plants and animals. Phosphorus is a limiting nutrient for aquatic organisms. Phosphorus forms parts of important life-sustaining molecules that are very common in the biosphere.
