he Piranha is one of the most efficient predators on the face of the earth. Granted it is not a large animal, with most only reaching about 5 1/2 to 10 inches (14 – 26 cm), but it is known world wide for its ferocious nature. They have razor sharp teeth and are opportunistic carnivores.
A frenzied attack by a group of Piranha will set the water churning. They will attack and eat all sorts of aquatic animals, insects, lizards and amphibians. They will also devour rodents, carrion (dead meat), and sickly or weakened land animals that venture into the water.
The teeth of the Piranha are triangular in shape with an exact fit in their jaw, comparable to a bear-trap. They are designed to puncture and slice the flesh from their prey. They can strip their prey to the bone in a matter of minutes.
These fish are a great source of fascination. Their natural behaviors have become fodder for the scripts of moviemakers looking for a sensational twist to excite and entice an audience. What could be more intriguing than creating a 'fear factor' from the behaviors of these provocative fish found in the "wild". Yet just like the Great White Shark and the Anaconda constrictor, also popular subjects of thriller movies, the Piranha’s behaviors are over-fantasized.
The Piranha does engage in a feeding frenzy that will "make the water boil" if only because a hungry school of fish are trying to reach the same limited food source. All that activity is bound to create water turbulence. A Piranha school generally only consists of about 20 or so fish, but in a feeding frenzy it can reach up to several hundred..
Piranhas are not always that deadly. Many species live solitary lives once they reach maturity and only four or five species pose any significant danger. Piranhas rarely attack people. Many experts believe they are actually timid fish, and shoal for protection. Even the most aggressive are thought to be not really dangerous until they are trapped and confined, and then attack in self defense. As a pet they are fascinating and beautiful fish, yet you can't hold or pet them. They are not affectionate and owners must be extremely careful, especially when handling them. They do have sharp teeth and an aggressive/defensive nature. Most Piranha bites are sustained when the fish are being handled, though that's not to say a hungry fish is never dangerous.
Answer:
Eukaryotes:
-Organisms with a well defined nucleus are known as eukaryotes. such cells are called as eukaryotic cells.
- Their nucleus is enclosed within the nuclear membrane.
- They do not posses a mitochondria.
- The cell wall is the outer most layer of a eukaryotic cell (only plant cells have a cell wall)
- The cells are divided by a process called mitosis.
Eg: Plants, Animals.
Prokaryotes:
- Organisms without a well defined nucleus are known as prokaryotes. Such cells are called as Prokaryotic cells.
- They lack nuclear membrane.
- Mitochondria, Golgi bodies, chloroplast and lysosomes are absent.
- The genetic material (DNA) is present on the chromosome.
Eg: Every organism coming under the kingdom monera.
Explanation:
Answer:
False
Explanation:
Populations cannot grow exponentially indefinitely.
Explanation:
Almost all eukaryotic proteins are subject to post-translational modifications during mitosis and cell cycle, and in particular, reversible phosphorylation being a key event. The recent use of high-throughput experimental analyses has revealed that more than 70% of all eukaryotic proteins are regulated by phosphorylation; however, the mechanism of dephosphorylation, counteracting phosphorylation, is relatively unknown. Recent discoveries have shown that many of the protein phosphatases are involved in the temporal and spatial control of mitotic events, such as mitotic entry, mitotic spindle assembly, chromosome architecture changes and cohesion, and mitotic exit. This implies that certain phosphatases are tightly regulated for timely dephosphorylation of key mitotic phosphoproteins and are essential for the control of various mitotic processes. This review describes the physiological and pathological roles of mitotic phosphatases, as well as the versatile role of various protein phosphatases in several mitotic events.
