The theme of Macbeth is the relationship between gender and power.

You don't ask a question in your question, you just give a
topic, so I don't really know if you're supposed to agree or disagree, explain, or use
the prompt as a thesis statement.  Also, the 150 words are up to you.  It's your
assignment.  You have to take the information given and write your own assignment
answer. 

Gender and power certainly do not constitute
the theme of Shakespeare's Macbeth.  They
constitute one theme--one idea or issue raised--in the
play. 

Males possess the power.  Lady Macbeth would like
to.  She would alter her gender if she could.  She wants to be an aggressive, powerful
warrior and ruler, but she is limited by her gender to using her husband to achieve
power. 

Lady Macbeth is supposed to be a good wife, be a
good hostess, and be a good mother.  She relishes the role of wife (possibly only
because her husband is her path to power, we don't know), but plays hostess only to set
a trap for Duncan, and rejects the love a mother should have for a child in favor of her
ambition for power. 

Lady Macbeth is intelligent, a planner
and organizer.  Born a female, she longs to reverse roles and be a male.  When she comes
as close as she can by manipulating her husband into murdering
Duncan--her only means of power--it backfires.  Macbeth shuts her
out of his decision-making process and causes his own downfall, as well as
hers.

She, figuratively, is a man trapped in a woman's
body.  She, literally, is a woman trapped in a man's world.