Question

the nitrogen cycle
forms of nitrogen
directions: read the sentences and fill (in) in the blanks with the appropriate word from the list below.
(1)________in the (2)______is in a (3)______form. however, it is the (4)______kind of form for most (5)______. they need nitrogen that has been (6)______or (7)______with other (8)______ into (9)______useful (10)________.

nitrogen biologically atmosphere combined compounds
fixed gas organisms wrong elements

Explanation:

This passage describes the nitrogen cycle, focusing on atmospheric nitrogen and its usability for organisms. Each blank is filled using the provided word list, aligned with biological nitrogen cycle concepts:

1. The main nitrogen source in air is nitrogen.
2. Nitrogen's primary large reservoir is the atmosphere.
3. Atmospheric nitrogen exists as a gas.
4. This gaseous form is biologically wrong (unusable) for most life.
5. Living things that need nitrogen are organisms.
6. Nitrogen must be fixed to become usable.
7. It can also be combined with other substances.
8. Nitrogen bonds with other elements to form usable materials.
9. These processes create biologically useful substances.
10. The end products are nitrogen-containing compounds.

Answer:

1. nitrogen
2. atmosphere
3. gas
4. wrong
5. organisms
6. fixed
7. combined
8. elements
9. biologically
10. compounds