According to Boyle's law, as volume decreases, pressure , and as volume increases, pressure . Air always moves from an area of high pressure to an area of pressure. During , the pressure in the alveoli is less than the atmospheric pressure. During , the atmospheric pressure is less than the alveolar pressure. When the diaphragm muscle contracts, the pressure in the alveoli . As the intercostal muscles relax and the thoracic cavity becomes smaller, the pressure in the alveoli .

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.

answer >   yes we do, women; have three holes, urethral opening(pee hole, vagina, and the women pee/girls pee out of the urethra like the men do; only they have a single opening to pee/ejaculate.   (sorry if i'm too forward with this, but this is for a biology class, isn't it? )

hope that !         : )

here is the answer

water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. weathering is the breaking down or dissolving of rocks and minerals on earths surface. once a rock has been broken down, a process called erosion transports the bits of rock and minerals away.