Ans.
Cell-to-cell communication allows signalling of essential substances between the plant cells, which are surrounded by cell walls. The molecules used by plants for long-distance signalling are known as hormones, such as auxin, ethylene, and gibberelin.
These hormones are secreted by one plant cell and received by another plant cell, where it exerts it affect. Thus, the correct answer to be fill in the blank is 'option A). hormones.'
<span>Compare: both RNA and DNA have 3 nitrogenous bases: Adenine Cytosine and Guanine. Also b</span>oth have a phosphate groups in their nucleotides<span>
Contrast: </span>RNA is a polymer with a ribose AND a phosphate backbone. It has four different nitrogenous bases: adenine, guanine, cytosine, and uracil.
DNA<span> is a long polymer with deoxyriboses AND phosphate backbone. It also has four </span>different<span> nitrogenous bases: adenine, guanine, cytosine and thymine.
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Hope this helps
DNA is a negatively-charged molecule. Also cell membranes are negatively charged. The problem would be how to push this charges together? I<span>f you put some CaCl2 into the mixture, the CaCl2 will "split" giving 2Cl- and Ca2+. This last ion will be attracted by the negatively charged DNA and will "cover" it, hiding its negative charge. Hope this answers the question.</span>
Quite sure C is correct ;) remember that humans are also placental mammals.
