To kill a foreign object, the white blood cells need to recognize the object by looking at their cell receptor. If the virus changes its receptor, it won't be recognized by the white blood cells. The immune system cant fight the infection if they don't learn to recognize the new form of the virus. This makes the virus hard to fight
Answer: the control group was grown at a pH of 2
Explanation:
Seeds comprise a radicle, which descends and becomes the root system; the endosperm, containing stored food; an epicotyl, which develops into the stem and the seed coat that protects the seed. which are small food storage organs and plant embryos encased in a seed coat. These embryos require specific conditions in order to break their dormancy; seed dormancy is a temporary state in which plant development and growth are halted, until specific conditions required for germination to occur. Conditions required for seed germination:
- Light- some seeds require light to break their dormancy
- Oxygen- for respiration
- Water- protein hydration and enzyme activation; should be near to neutral pH
- Temperature- a specific range 20-30 °C which activates specific enzymes needed for growth
During the germination process, plants emerge from the seed and start growing. However, the delicate tissue structures can be damaged by low pH; this can occur due to acid rain, where the pH of the rainwater is lowered by the presence of pollutants.
Due to the presence of atmospheric carbon dioxide, normal rain’s pH is typically around 5.6, and in heavily polluted areas with other gases as pollutants, acid rain’s pH can range from 3-4. A highly acidic pH of 2 can denature enzymes required for germination and seed growth; apart from causing damage to the entire seed, there’s no expected growth at this pH range making it a suitable control.
Experimental controls give valuable information about the experiment’s conditions and validity; they are usually carried out in the same conditions as the other experiments, but the independent variable (pH) is usually changed.
