For the answer to the question above, the answer is "Systemic Acquired Resistance''.
<span>it is a whole-plant resistance response and it occurs by following an earlier localized exposure to a pathogen. It is analogous to the innate immune system that can be found in the animals, and there is also an evidence that SAR in plants and innate immunity in the animals may be evolutionarily conserved.</span>
Compared to arteries, valves have no pulse, have thin walls and have valves that prevent backflow of the blood. The pressure in the veins is less than that of the arteries, hence, there is no pulse. They are nearer to the surface of the skin. It also connects arteries and capillaries which transport blood all throughout the circulatory system.
A 'red' apple does not emit red light. Rather, it simply absorbs all the frequencies of visible light shining on it EXCEPT for a group of frequencies that is perceived as red, which are REFLECTED. An apple looks red to us because it REFLECTS infrared waves.
