Viruses don't make their own proteins because they are not cells. A virus is a nucleic acid enclosed in a protein coat, and does not contain organelles. Bacteriophages, viruses that target bacteria as a host, inject their genetic material into the host bacterial cell. Therefore, cells don't even need proteins, (not including their protein coat) so they do not make them.
*Keep in mind that since there are no organelles, there are no ribosomes for the RNA (ribonucleic-acid) to deliver the coded message and amino acids to.
Answer:
Because viruses do not have their own cellular mechinary. They lack enzymes for replication of DNA and to produce their protein.
Explanation:
(Points : 1)
(a)increased earthquakes
(b) changing ocean circulation
(c) extinction of animals
(d) changing earth's position on its axis
The correct answer is - (b) changing ocean circulation.
The ocean currents are very important when it comes to the climate. The movement of the tectonic plates though, over time, is changing their patters. The changes appear because of the movement of the land masses, so there can be situations where the ocean currents are interrupted by a moving land mass, or more space to be opened up for an already existing ocean current with the moving away of a land mass of its path. Those movements and spaces in the water bodies are affecting the direction and the temperature of the ocean currents, and those changes will reflect on the climate on the regions that they are influencing.
The correct macthing of the organs with their organ systems is as follows.
1. Digestive system - intestines.
2. Central nervous system - brain.
3. Respiratory system - tracheal system.
4. Excretory system - bladder.
Digestive system is made up of the alimentary canal consisting of the digestive organs and the glands. Among the digestive organs, the intestines play a major role in the process of digestion. The small intestine is the site of complete digestion which is associated with the pancreas and liver. The large intestine is involved the absorption of water from the digested food and remaining waste material is stored and thrown out of the body during defecation.
The central nervous system is made up of the brain and the spinal cord. The brain makes the largest part and the functional of the central nervous system. It controls most of the activities of the body. It is made up of three parts called the cerebrum, cerebellum and medualla oblongata and is protected by the skull.
The respiratory system is divided into the upper respiratory tract consisting of the nasal cavity, pharynx and larynx, and the lower respiratory tract consisting of the trachea, bronchi, bronchioles and the alveoli. The trachea or the wind pipe is a cylindrical tube infront of the oesophagus, supported by 16-20 C-shaped hyaline cartilage. It serves as a passage for air to move in and out of the lungs.
The excretory system is made up of a pair of kidneys, a pair of ureters, an urinary bladder and an urethra. The urine produced by the kidney flows through the ureters and is collected in the urinary bladder. A spinchter (a ring of muscle) guards the opening of the bladder into the urethra and relaxes only at the time of urination under the impulse from the brain.
Arteries carry blood______the heart.
YOUR ANSWER==> AWAY FROM
B. There are now better diagnostic tests available for autism, which causes more cases to be identified.
C. The increase in autism is due to the decline of public education.
D. The increase in immunizations is the only possible cause for autism