单选题 1 The human ear contains the organ for hearing and the organ for balance. Both organs involve fluid-filled channels containing hair cells that produce electrochemical impulses when the hairs are stimulated by moving fluid.
2 The ear can be divided into three regions: outer, middle, and inner. The outer ear collects sound waves and directs them to the eardrum separating the outer ear from the middle ear. The middle ear conducts sound vibrations through three small bones to the inner ear. The inner ear is a network of channels containing fluid that moves in response to sound or movement.
3 To perform the function of hearing, the ear converts the energy of pressure waves moving through the air into nerve impulses that the brain perceives as sound. Vibrating objects, such as the vocal cords of a speaking person, create waves in the surrounding air. These waves cause the eardrum to vibrate with the same frequency. The three bones of the middle ear amplify and transmit the vibrations to the oval window, a membrane on the surface of the cochlea, the organ of hearing. Vibrations of the oval window produce pressure waves in the fluid inside the cochlea. Hair cells in the cochlea convert the energy of the vibrating fluid into impulses that travel along the auditory nerve to the brain.
4 The organ for balance is also located in the inner ear. Sensations related to body position are generated much like sensations of sound. Hair cells in the inner ear respond to changes in head position with respect to gravity and movement. Gravity is always pulling down on the hairs, sending a constant series of impulses to the brain. When the position of the head changes--as when the head bends forward--the force on the hair cells changes its output of nerve impulses. The brain then interprets these changes to determine the head's new position.

单选题 What can be inferred about the organs for hearing and balance?
【正确答案】 B
【答案解析】You can infer that the organs for hearing and balance both send nerve impulses to the brain. Clues: Both organs involve fluid-filled channels containing hair cells that produce electrochemical impulses...; To perform the function of hearing, the ear converts the energy of pressure waves moving through the air into nerve impulses that the brain perceives as sound," When the position of the head changes.., the force on the hair cells changes its output of nerve impulses. The brain then interprets these changes
单选题 Hearing involves all of the following EXCEPT
【正确答案】 A
【答案解析】Hearing does not involve motion of the vocal cords so that they vibrate; this is an aspect of speaking, not hearing. All the other answers are given as part of hearing: ...fluid-filled channels containing hair cells that produce electrochemical impulses when the hairs are stimulated...; ...bones of the middle ear amplify and transmit the vibrations...; ...the ear converts the energy of pressure waves moving through the air into nerve impulses
单选题 It can be inferred from paragraphs 2 and 3 that the cochlea is a part of
【正确答案】 D
【答案解析】You can infer that the cochlea is a part of the inner ear. Clues: The inner ear is a network of channels containing fluid...; ... the cochlea, the organ of hearing; ...the fluid inside the cochlea. Hair cells in the cochlea convert the energy of the vibrating fluid....
单选题 What can be inferred from paragraph 4 about gravity?
【正确答案】 A
【答案解析】You can infer that gravity has an essential role in the sense of balance. Clues: Hair cells in the inner ear respond to changes in head position with respect to gravity and movement. Gravity is always pulling down on the hairs, sending a constant series of impulses to the brain.