Water means it is the mixture of hydrogen and oxygen. As we know that
hydrogen is colourless as well as oxygen is also colourless gas.
So at last when hydrogen and oxygen reacts with one another and they
form H2O means water. If both are colourless so their product will also
be colourless. So water is seen colourless.
Cross over is the first way genes are shuffled to give rise to genetic diversity. Cross over takes place in sexual reproduction. The normal way that cross over occurs is chromosomes line up side by side and break off pieces of themselves, then trade those pieces with each other.
If they break the pieces at the same locus in the sequence of base pairs, the result is an exchange of genes called genetic recombination and it ensures that the daughter cells produced have a different genetic makeup from the parent cell and thus diversity occurs.
X: Ozone layer destruction
Y: Mass extinction
Cell walls are supporting structures that help the plant to have a fixed shape and protect it from injury. Other than that, it helps to keep the plant turgid so that it can stay firm and upright. Because when it enters a high water potential solution, as water moves in, the water exerts turgor pressure on the cell wall and the cell wall thus exerts an opposing pressure to keep water out. Hence cell wall is needed for the plant.
On the other hand, animal cells do not need to keep the structures, as they have the skeletal system to protect the organs and cushion them against any
external injuries.
I hope that helped
