C. 5 1/2 because <span>A sleep cycle lasts about 90 minutes and during that time we move through five stages of sleep </span>
The answer is C. nitrogen.
Plants are main producers in ecosystems so, primary productivity of ecosystems depends on them. Carbon is necessary for plants, but it is widely present in plants. On the other hand, calcium and sodium are not as essential. However, nitrogen is important for plants because it is necessary to make proteins. Proteins take part in many different processes such as photosynthesis (this is actually primary productivity). But, nitrogen is not available to plants, they cannot absorb it simply from the air but rely on some symbiotic bacteria which are able to.
Answer:
Ovulation, ejaculation, implantation, fertillisation, development, birth
Explanation:
Answer:
Sistemas orgánicos
Explanation:
Aunque cada órgano del cuerpo realiza sus funciones específicas, los órganos también funcionan juntos por grupos, a los que se denomina sistemas orgánicos (ver Principales sistemas orgánicos). Los médicos clasifican las enfermedades y sus propias especialidades médicas de acuerdo a los diferentes sistemas orgánicos.
