Explain why globalization is increasing the gap in income, wealth and economic growth that already exists between developed and developing countries.

This is a questionable premise.  After all, it is
globalization that has allowed for the rise of China, which was very much a "developing
country" a decade or two ago and is now an economic power.  Globalization really has
helped many developing nations catch up to the more developed nations.  Globalization
does seem to contribute to increasing inequality within
nations, but it does not seem to contribute as much to increasing
inequality between
nations.

However, if you have to argue that it does, you
can argue that globalization allows developed countries to treat developing countries
like colonies.  The developed countries, you can argue, let the poorer countries do the
low-paid, low-skilled jobs that do not create much wealth.  The developed countries can
also buy raw materials from the poorer countries without really helping those countries
to develop.  You can say that globalization lets the rich countries exploit the poor
ones by buying cheap things from the poor countries without really helping those
countries progress to the point where they can compete against the developed countries
in producing things that are more profitable.