With Respect to X-Chromosome Inactivation, Which, If Any, of the Following

question 21

Multiple Choice

With respect to X-chromosome inactivation, which, if any, of the following statements are not correct ?

• A) X-chromosome inactivation in mammals begins in the pre-implantation embryo
• B) In humans all diploid cells that carry two normal X-chromosomes are subject to a random pattern of X-inactivation.
• C) Once a decision has been made to inactivate an X chromosome (either the paternal or maternal X), all descendant cells show the same pattern of X-inactivation.
• D) The inactivated X chromosome becomes a highly condensed Barr body in which genes are silenced across the length of the chromosome.

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Definitions:

Trade Deficit

The amount by which the value of a nation’s imports exceed the value of its exports.

International Payments

Transactions between countries involving the transfer of money and payments for goods and services across borders.

Merchandise Exports

Goods produced domestically and sold to buyers in another country.

Freely Floating Exchange Rates

A system where the value of currencies is determined by supply and demand in the foreign exchange market without direct intervention by central banks.