Important Information Can Be Learned by Studying the Immune System

question 29

Multiple Choice

Important information can be learned by studying the immune system of female carriers of the XLA disease gene. These individuals, identified as mothers of boys with XLA, show non-random X chromosome inactivation in their B cells, but random X chromosome inactivation in all of their other cells, including their T cells and macrophages. This finding indicates that:

• A) The BTK protein is expressed by bone marrow stromal cells that support B cell development.
• B) The BTK protein is required in hematopoietic stem cells.
• C) The BTK protein is required for mature B cells to enter lymphoid follicles.
• D) B cells and T cells do not share a common progenitor.
• E) B cells require the BTK protein for normal development.

---

Definitions:

Income

Regular revenue generated through employment or by making investments.

Goods and Services

Refers to the physical products and intangible benefits that fulfill the needs or wants of consumers.

Surplus

The condition when supply exceeds demand, leading to excess goods or services being available.

White Water Rafting

A recreational outdoor activity which uses an inflatable raft to navigate a river or other body of water with varying degrees of rough water.