Can modern phylogeny-based taxonomic systems ever produce a satisfactory phylogenetic tree based on DNA

Phylogenetic (evolutionary) Tree

showing the evolutionary relationships among various biological species or other entities that are believed to have a common ancestor.

• Each node is called a taxonomic unit.

• Internal nodes are generally called hypothetical

taxonomic units

• In a phylogenetic tree, each node with

descendants represents the most recent

common ancestor of the descendants, and the

• edge lengths (if present) correspond to time

estimates.

Explanation:

Phylogenetic trees are usually based on morphological or genetic homology. A comparison of anatomical traits can reveal an evolutionary relationship among species. Taxonomy, the science of classifying organisms, is based on phylogeny. Early taxonomic systems had no theoretical basis; organisms were grouped according to apparent similarity.

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."

the food storage products of chrysophytes are oils or the polysaccharide laminarin.   formerly classified as plants, the chrysophytes contain the photosynthetic pigments chlorophyll a and c all but the yellow-green algae also contain the carotenoid pigment fucoxanthin.