________________________ is an age-related decline in the ability of the lens to accommodate to different distance of visual stimuli.

The hypothalamus controls the ________________________. 

Sleep research supports three helpful hints to avoid insomnia.  Which of the following statements is one of them?

A person can have ________________________ taste buds in their mouth.

Freud believed that dreams ________________________. 

The four stages of sexual activity include excitement, plateau, orgasm and ____________________________. 

Sex organs and traits that develop at puberty and are only indirectly involved in human reproduction are called ____________________________ sex characteristics. 

The nervous system is defined as ________________________. 

The brain and spinal cord are two components of the ________________________. 

A biological cycle, or rhythm, that is approximately 24 hours long is called a(n) ________________________ cycle.