A alga cresce quando o nitrato está alto.

to be

Breakdown of A alga cresce quando o nitrato está alto.

• quando: when
• alto: high
• crescer: to grow

Questions & Answers about A alga cresce quando o nitrato está alto.

Why does the sentence use a alga and o nitrato? In English, we often say algae or nitrate without the.

Portuguese often uses the definite article with nouns when talking about things in a general or class-wide sense.

So:

• A alga cresce = Algae grow / The algae grows
• O nitrato está alto = Nitrate is high / The nitrate level is high

This is very natural in Portuguese, even where English would often leave the article out.

A few similar examples:

• O açúcar faz mal em excesso. = Sugar is bad in excess.
• A água está fria. = The water is cold / Water is cold.

So the articles here do not necessarily mean one specific alga and one specific nitrate sample. They can also express a general statement.

Why is it a alga? Is alga feminine?

Yes. Alga is a feminine singular noun, so it takes the feminine singular article a.

• a alga = the algae / the alga
• as algas = the algae (plural)

Even though many words ending in -a are feminine, that is not always true in Portuguese. But in this case, alga really is feminine.

Why is it o nitrato? Is nitrato masculine?