Which of these statements is true about tracheids? 1-They lose their end walls at maturity.

2-They open at each end with bar-like strips across the opening.

3-They are cells with pitted ends.

4-They have sieve plates.

The carbon cycle is best defined as a process in which a. carbon changes from inorganic forms to organic forms and back b. carbon is changed into other elements such as oxygen or nitrogen c. carbon is continually created from the sun’s energy by plants d. carbon is consumed and regenerated from other elements such as oxygen and nitrogen