The answer is that the criteria of classification change with the improved understanding of organisms around us. During the time of Aristotle, not much was known about the living organisms. So, he classified them as he observed. Plants were classified into herbs, shrubs and trees; very much like what’s taught to a second grade student. Animals as Enaima and Anaima based on the presence or absence of RBCs. After him, Carolus Linnaeus tried his hand over classification. He came up with the 2 kingdom classification: Plants and Animals. He considered only a set of morphological and physiological criteria to decide the kingdom to which an organism belongs. It includes presence of cell wall, mode of nutrition, contractile vacuole, locomotion and others. Based on these criteria, he included widely differing organisms into a single kingdom, for example, fungi, bacteria, algae, and higher plants were included into plant kingdom just because they have cell wall as a common aspect. Then came, Ernst Haeckel, who came with a third kingdom of Protista to include unicellular organisms. Copeland gave a 4 kingdom classification segregating unicellular organisms into 2 separate kingdoms based on their nuclear structure. R.H. Whittaker came next introducing the most accepted 5 kingdom classification system. You should understand one thing that man’s knowledge of classifying organisms improved with the improving technologies available to him, which he exploited to very effective extent. Carl Woese gave the 6 kingdom classification and 3 domain system based on the 16S rRNA sequence.
Our understanding of organisms around us is improving day by day and the system of classification will also change further in pace with the improvement in technology.
I hope this helps! :D]
~ Kana ^^
DNA<span> and </span>RNA<span> are both comprised of nucleotides that bind to a sugar backbone. The </span>DNA<span> nucleotide </span>bases<span> include adenine, cytosine, guanine and thymine. The </span>RNA <span>nucleotide </span>bases<span> include adenine, uracil, guanine and cytosine.</span>
The sister chromatids are then pulled apart by the mitotic spindle which pulls one chromatid to one pole and the other chromatid to the opposite pole.
The chromosomes line up neatly end-to-end along the centre (equator) of the cell.
The centrioles are now at opposite poles of the cell with the mitotic spindle fibres extending from them.
The mitotic spindle fibres attach to each of the sister chromatids.
The DNA in the cell is copied in preparation for cell division, this results in two identical full sets of chromosomes?.
Outside of the nucleus? are two centrosomes, each containing a pair of centrioles, these structures are critical for the process of cell division.
Answer:
Inertia
Explanation:
Inertia is the resistance of any physical object to any change in its velocity. This includes changes to the object's speed, or direction of motion.
Answer:
Medulla.
By analyzing the DNA extracted from the hair follicle, the medullary index and the pattern of medulla in the hair samples obtained from a crime scene, an investigator can identify the owner.
Explanation:
The hair consists of follicle and shaft. The follicle is the part of the skin, where the hair grows and the hair shaft has three layers: an inner medulla, a cortex, and an outer cuticle.
The morphology (physical characteristics) of hair provides a broad detail on the racial background of an individual and an investigator can identify a group of people who share similar traits. But the hair without follicle cells attached to it, cannot be used to identify a specific individual. If the follicle of a hair is present, then it can lead to individual identification by DNA analysis. Also the medulla of animals is larger than that in the humans. By comparing the medullary index (the ratio of the diameter of the medulla to the diameter of the entire hair), it can be determined if the hair obtained from crime scene belongs to animals or humans. The macroscopic (length, color, and curliness) and microscopic characteristics ( pattern of the medulla, pigmentation of the cortex, and types of scales on the cuticle) of the hair samples are studied during a crime investigation. If the entire hair follicle (follicular tag) is present in the hair samples found at the crime scene, the blood and tissue attached to the follicle is extracted and analyzed using DNA profiling. DNA analysis of the hair follicle provides an identification with greater accuracy than the hair shaft.
