No. It's a construct state ("סמיכות") – two nouns joined together to create one term.
In a way, it's like saying "a soup of tomatoes". The "of" is implied.
The word we originally learned for tomato looks like the plural. What is the singular form?
The same word exists in Arabic written with the same three letters: مرق but it means "sauce". I love languages ___
So, is this the genitive case in hebrew? What should the pronunciation of מרק be if the correct nikkud were there?
I get that, I'm just not sure that there is an acoustic difference (= if the vocal muscles are doing different movements; if the consonant /y/, in Hebrew or in English, is anything more than a transition between /i/ and another vowel). If I try to pronounce the two, even slowly and carefully, I'm quite sure they come out indistinguishable. The real test is to say it to another person, sometimes trying to pronounce one and sometimes the other, and see if they distinguish correctly without knowing which you intended.
That niqqud in the מ is called שווא נע. Probably at the time the niqqud was invented it was pronounced as a very short /e/ sound. I believe that very formal speakers (e.g. some news narrators in the radio) actually reproduce that sound, and that sounds very formal but correct. Pronouncing it without vowel at all (as implied by /mrak/) or a full blown /e/ sounds very strange and wrong to me. As said above, Hebrew speakers just say /marak/.