Soutěžící odevzdal odpovědní arch, aniž by uhodl bonusovou otázku.

By itself, soutěžící can be a bit ambiguous: it can be singular or plural, depending on context.

Here we know it is singular because of the verb odevzdal, which is 3rd person singular masculine.

So this sentence means one contestant, and specifically a male contestant. If it were a female contestant, you would get odevzdala.

In Czech, the past tense is built with an -l form of the verb.

For odevzdat meaning to hand in / submit, the masculine singular past form is odevzdal.

In the 3rd person, Czech does not add a separate auxiliary word like English has or did. So:

• odevzdal = he handed in
• odevzdala = she handed in
• odevzdali = they handed in

In contrast, 1st and 2nd person do use extra words:

• odevzdal jsem = I handed in
• odevzdal jsi = you handed in

Because odevzdal is perfective, and perfective verbs are typically used for completed actions.

Here the contestant finished handing in the answer sheet, so odevzdal is the natural choice.

Compare:

• odevzdal = he handed it in, completed
• odevzdával = he was handing it in / used to hand it in / was in the process of handing it in

The sentence is about a completed event, so odevzdal fits better.

Odpovědní arch means answer sheet.

The adjective odpovědní here means something like for answers / answer-related. It is part of a fixed expression.

This is different from odpovědný, which means responsible.

So:

• odpovědní arch = answer sheet
• odpovědný člověk = a responsible person

That difference is important, because learners often expect odpovědný arch, but that would be wrong.

It is in the accusative, because it is the direct object of odevzdal.

The dictionary form is:

• odpovědní arch = nominative singular

After odevzdal, we need the accusative:

• odevzdal odpovědní arch

But arch is a masculine inanimate noun, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So the form does not visibly change, even though the case does.

Aniž by is a common Czech way to say without doing something or without the fact that something happened.

So:

• aniž by uhodl bonusovou otázku = without guessing the bonus question correctly

This structure introduces a subordinate clause. In standard Czech, aniž is normally followed by by and then a verb form agreeing with the subject.

A very close alternative is:

• bez toho, aby... = without...

But aniž by is very common and compact.

After aniž by, Czech commonly uses by plus the -l form of the verb:

• aniž by uhodl
• aniž by přišel
• aniž by si všiml

So uhodl is the expected form here.

Also, uhodnout is perfective, and it usually means to guess correctly, to get right, or to figure out. It is not just the act of making a guess.

That means the sentence suggests he handed in the sheet without getting the bonus question right.

Because the subject is understood to be the same person as in the main clause.

So Czech does not need to repeat soutěžící:

• Soutěžící odevzdal odpovědní arch, aniž by uhodl bonusovou otázku.

This naturally means that the contestant both:

• handed in the answer sheet
• did not guess the bonus question correctly

If the subject were different, Czech could state it explicitly.

It is accusative singular, because it is the direct object of uhodl.

The nominative form is:

• bonusová otázka = a bonus question

In the accusative singular, feminine adjectives and nouns change:

• bonusová → bonusovou
• otázka → otázku

So:

• uhodl bonusovou otázku = guessed the bonus question correctly

Because aniž by uhodl bonusovou otázku is a subordinate clause, and Czech normally separates subordinate clauses with a comma.

So the comma here is required:

• Soutěžící odevzdal odpovědní arch, aniž by uhodl bonusovou otázku.

This is standard Czech punctuation.

Yes, Czech word order is fairly flexible.

For example, you could also say:

• Aniž by uhodl bonusovou otázku, soutěžící odevzdal odpovědní arch.

The basic meaning stays the same, but the emphasis changes a little.

The original order is very natural because it gives the main event first:

• the contestant handed in the answer sheet

and then adds the important accompanying circumstance:

• without having guessed the bonus question correctly

So the original version sounds smooth and neutral.