Answer:A good index fossil is one with four characteristics: it is distinctive, widespread, abundant, and limited in geologic time. Because most fossil-bearing rocks formed in the ocean, the major index fossils are marine organisms. That being said, certain land organisms are useful in young rocks and specific regions.
Explanation:
A
CO₂ is the waste product of respiration of cells. Oxygen, on the other hand, is required in cellular respiration. Therefore at the alveolar in the lungs of an organism, CO₂ will be expelled while O₂ will be taken in.
Explanation:
This occurs passively due to the diffusion gradient, CO₂ usually has a higher concentration in the blood and lower concentration in alveoli hence this gas diffuses from the bloodstream into the lungs. On the other hand, oxygen is higher in concentration in the alveoli than in the blood capillaries hence difuses into the blood and taken to the cell for respiration. The CO₂ in the lungs is then expelled through exhalation of the lungs.
Learn More:
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Denitrification is the major process involved in converting nitrogen components present in the nitrogen gas and it is released into the atmosphere.
<u>EXPLANATION: </u>
With the help of the nitrogen cycle, the nitrogen that enters living things by nitrogen fixation is converted back into nitrogen and is released in the atmosphere by microbes.
The nitrogen-fixing bacteria converts the nitrogen contents into ammonia by the process called ammonification. Then it oxidizes ammonia to nitrite by the process called nitrification and these nitrates are absorbed by plants.
Then, the bacteria present in the soil convert nitrate back to nitrogen gas which is released back to the atmosphere.
Answer:
B. secrete granzymes and perforin.
Explanation:
Perforins are the proteins that perforate the plasma membrane of the target cell and lead to bursting of cells due to holes formed in its membrane. Granzymes are the proteolytic enzymes. They serve to stimulate the target cells to kill themselves by the process of apoptosis.
Binding of natural killer cells to their target cells stimulate the release of granules that are filled with perforins or granzymes to kill the target cells.
Likewise, cytotoxic T cells bind to the infected body cells and release the granules filled with perforins or granzymes to kill those infected cells.
^^ what she said I think is true
