A relação entre raiz e caule é clara.

In Portuguese, it is very common to use the definite article where English might leave it out.

So A relação means the relationship. In this sentence, it refers to a specific relationship already understood from the context: the one between raiz and caule.

You could sometimes omit the article in other contexts, but here A relação sounds natural and standard.

Because relação is a feminine noun.

In Portuguese, nouns have grammatical gender, so:

• a relação = the relationship
• o caule = the stem
• a raiz = the root

A very useful pattern is that many nouns ending in -ção are feminine:

• a relação
• a informação
• a explicação

So once you see -ção, feminine is often a good guess.

Entre means between.

So:

• entre raiz e caule = between root and stem

It is used much like English between. In Portuguese, entre can be used with two items and also with more than two, unlike the stricter English distinction between between and among.

Examples:

• entre mãe e filha = between mother and daughter
• entre os alunos = among / between the students

This is a very natural question.

The sentence says:

• entre raiz e caule

not

• entre a raiz e o caule

Both can be possible, but they are not used in exactly the same way.

In this sentence, the nouns are being used in a more general, scientific, or conceptual way. It is like talking about root and stem as categories, not about one specific root and one specific stem.

So:

• entre raiz e caule = between root and stem, in a general sense
• entre a raiz e o caule = between the root and the stem, more specific

The version without articles is common in definitions, biology, technical writing, and general statements.

Yes.

• a raiz = the root
• o caule = the stem

This is something you simply need to learn with the noun, because the endings do not always make gender obvious.

For example:

• raiz ends in -z, but it is feminine
• caule ends in -e, but it is masculine

So it is best to memorize them with the article:

• a raiz
• o caule

This is about the difference between ser and estar.

• é comes from ser
• está comes from estar

In this sentence, é clara means is clear in the sense of being clearly understandable or inherently clear as a statement or relationship.

So:

• A relação entre raiz e caule é clara.
  = The relationship between root and stem is clear.

Using ser here sounds more natural because you are describing the relationship itself.

If you said está clara, it would suggest something more temporary or context-based, like it has now become clear.

Compare:

• A explicação é clara. = The explanation is clear.
• Agora está claro. = Now it is clear.

Because adjectives usually agree with the noun they describe in gender and number.

Here, clara refers to relação, which is feminine singular.

So:

• a relação → clara
• o problema → claro
• as relações → claras
• os problemas → claros

That is why the sentence has:

• A relação ... é clara

and not é claro.

Because here clara is a predicate adjective, not directly attached before the noun.

The structure is:

• A relação = subject
• é = verb
• clara = adjective describing the subject

So it works like:

• The relationship is clear

not

• the clear relationship

If you put the adjective before the noun, you get a different structure:

• A clara relação entre raiz e caule...

This is possible, but it sounds more literary, emphatic, or less neutral. The original sentence is the normal, straightforward way to say it.

É means is. It is the third-person singular form of ser:

• eu sou = I am
• tu és = you are
• ele/ela é = he/she is

The accent is important because:

• é = is
• e = and

So the accent distinguishes two completely different words.

Compare:

• A relação é clara. = The relationship is clear.
• raiz e caule = root and stem

The accent marks the stressed syllable.

relação is pronounced with the stress on the final syllable:

• re-la-ÇÃO

Without the accent, the pronunciation rules would suggest a different stress pattern.

For learners, the important point is:

• relação → stress on -ção

This is very common in Portuguese words ending in -ção.

A rough European Portuguese pronunciation is:

A relação entre raiz e caule é clara.
≈ uh r'luh-SOWN en-truh rysh ee KAW-luh eh KLAR-uh

A few notes:

• relação: the final -ção sounds roughly like sown with a nasal quality
• raiz in European Portuguese often sounds close to rysh
• e before a consonant is often a reduced sound, like a very weak uh
• clara has a clear a sound: KLAR-uh
• é is pronounced like eh

This is only an approximation, but it can help an English speaker get started.

Yes, you can.

That version is also correct:

• A relação entre a raiz e o caule é clara.

The difference is mainly one of reference and style:

• entre raiz e caule = more general, conceptual, technical
• entre a raiz e o caule = more specific, as if referring to a particular root and stem

In biology or explanatory writing, the version without the articles often sounds very natural.

Yes, that is also possible.

• A relação da raiz com o caule é clara.

This literally means something like The relationship of the root with the stem is clear.

It is grammatical and natural, but it is structured a bit differently from:

• A relação entre raiz e caule é clara.

The original version with entre is often more neutral and direct when talking about the relationship between two things.

Yes, you could say:

• É clara a relação entre raiz e caule.

That is grammatical, but it sounds more formal, literary, or emphatic. It puts focus on clara.

The most neutral and common order is:

• A relação entre raiz e caule é clara.

So both are correct, but the original is the safest choice for everyday standard Portuguese.

You could say:

• As relações entre raiz e caule são claras.

Changes:

• A → As
• relação → relações
• é → são
• clara → claras

Notice that the adjective and the verb both change to agree with the plural noun.

No. Entre can be used for both physical and abstract relationships.

Examples:

• entre raiz e caule = between root and stem
• entre amigos = among friends
• entre duas ideias = between two ideas
• entre o passado e o presente = between the past and the present

So in this sentence, it works perfectly for the conceptual relationship being discussed.