Answer:
Diffusion helps animals in respiration. The cells in an animal's body need glucose and oxygen for respiration. Both these are carried in the blood. When blood reaches the cells the molecules of glucose and oxygen diffuse out of the blood and into the cells. As cells use up the glucose and oxygen they produce waste chemicals and carbon dioxide.
Diffusion is a very important process for photosynthesis where carbon dioxide from the stomata diffuses into the leaves and finally into the cells. This helps the plants to photosynthesize and produce more food.
Example for animals: Animals using glucose and oxygen in diffusion.
Examples for plants: Plants using carbon dioxide to photosynthesize.
Answer:
AZT is a thymidine analog
Explanation:
Azidothymidine (AZT) is an antiviral drug used for the treatment of the Human immunodeficiency virus infection (HIV/AIDS) by preventing the transmission of HIV from infected cells. AZT is capable of suppressing the activity of the enzyme reverse transcriptase of the retroviral HIV genome, which enables it to copy RNA into DNA. In infected cells, this double-stranded DNA is integrated into the host genome which is then instructed to produce identical HIV copies. AZT is a thymidine analog that is incorporated into DNA and thus interferes with DNA synthesis, thereby inhibiting cell proliferation.
<span>The answer is nuclear imaging. A subject is asked to take in a radionuclide (radioactive
isotopes) and as the radioactive material passes though the body, it continually emits radiation that is detectable by an instrument such as a gamma camera. Examples of nuclear imaging
techniques are SPECT and PET.</span>
The method of virus transmission which results in a greater spread of disease is through airborne transmission
The KT boundary marks a mass extinction event. the KT boundary is the time between the Cretaceous and Tertiary periods. An asteroid hit the earth at the end of the Cretaceous and that caused the end of the Cretaceous period. Before the KT boundary, pollen from angiosperms and gymnosperms is high. After the meteor hits the earth, a mass extinction occurs and the amount of pollen from gymnosperms and angiosperms decreases dramatically, while the amount of spores from ferns increases. During the Cretaceous period there were many species of gymnosperms and angiosperms but they disappeared at the KT boundary, when the asteroid hit the earth.
