Q: What are the newest, outer layers of secondary xylem called? Choices: - bark - fibrous - vascular - sapwood A:
sapwood

Q: What atmosphere do gills help exchange gas in? Choices: - stratosphere - ecosystem - air - water A:
water

Q: What law explains why some objects float and some sink. Choices: - newton's law - montenegrins ' law - flanges ' law - archimedes' law A:
archimedes' law