Gender is important in determining life expectancy.

Where a person lives can affect the type of life insurance that is available.  The life insurance industry is actually regulated on a state level.  Each state has its very own set of regulations so the state in which a person lives is very important.  Not every insurance company offers the same policies in every state.  Some states have extra fees and others have requirements or even limitations.  Also, not every life insurance company is licensed to provide insurance in all of the states.  When buyers answer questions about the state in which they life, they will get life insurance quotes that are competitive in that particular state.
Gender
Gender is important in determining life expectancy.  Overall, women life longer than men and therefore have lower premiums.
Height and Weight
Questions about height and weight may seem unimportant, but they can actually tell a  company quite a bit about a person.  The ratio of a person's height and rate can help determine which rate class that person will fall under.  Height and weight can help describe a person's physical build and the build plays a large role in the state of a person's health.  The larger a person is, the more likely he or she is to have high blood pressure, diabetes, or other diseases that affect health.  A person can also pay higher premiums if he or she is too small for his or her height.
The birthday question seems standard, but many term life insurance companies base their rates largely on age.  A person's birthday will show the company how likely that person is to pass away in the next set period of time.  The company can determine an estimated life expectancy and therefore know what premium rate to charge the buyer.
Life Insurance & Tobacco Use
Some life insurance companies have policies that are very competitive for non-smokers.  There are lots of benefits for people who do not use tobacco.  There are so many health risks with smoking that insurance companies tend to charge tobacco users much higher rates.
Health Considerations when Applying for Life Insurance
Some companies will even require the buyer to undergo a physical health exam.  Even if this is not required, the company will want to know what health rate the buyer falls under.  To get the best rates, a person will want to be in the preferred best health class.  That will be determined by the health history of the person as well as his or her family history and many other factors.  The better the health class, the lower the premium.