Learn Hardcore Indonesian: Dalam eksperimen itu, kami mengumpulkan data sederhana untuk memahami pengaruh cahaya pada tanaman. - In that experiment, we collect simple data to understand the effect of light on plants.

Dalam eksperimen itu ≈ In that experiment / During that experiment (as a context)
Di eksperimen itu is usually avoided; di is more for physical locations (di rumah, di sekolah).
Pada eksperimen itu is possible, but sounds more formal and less natural in everyday speech. Pada often corresponds to "on / at" in more formal or written contexts.

So dalam eksperimen itu is the most natural way to say "in that experiment" in this sentence.

What is the role of itu in eksperimen itu?

Itu is a demonstrative meaning that or the (referring to something known/previously mentioned).

eksperimen itu = that experiment / the experiment (already known to both speaker and listener)
Without itu (dalam eksperimen, kami…) it would sound like you are talking about experiments in general, not a specific one.

So itu specifies that it’s a particular experiment that both people know about.

Why is kami used instead of kita?

Indonesian distinguishes two kinds of we:

kami = we (not including the person being spoken to)
kita = we (including the person being spoken to)

Here, kami suggests the speaker’s group did the experiment, but the listener was not part of that group.

If the listener was one of the experimenters, you’d use kita:

Dalam eksperimen itu, kita mengumpulkan data… = In that experiment, we (you and I) collected data…

What is the base form of mengumpulkan, and what does the me- prefix do?

The base form is kumpul (to gather, to get together).

mengumpulkan = meN- prefix + kumpul
- -kan suffix
Literally: to make gather / to collect (something)

Function of the affixes:

meN- (here meng-) → turns the root into an active verb, often transitive (takes an object).
-kan → often adds a causative or object-focus nuance (doing the action to/for something).

So:

kumpul = to gather (intransitive: people gather)
mengumpulkan data = to collect data (you actively gather something: data)

Why is it data sederhana and not sederhana data?

In Indonesian, adjectives usually come after the noun they describe.

data sederhana = simple data
sederhana data is ungrammatical.

Other examples:

buku baru = new book
mobil merah = red car

So the pattern is: noun + adjective, not the other way around.

Does data here mean singular or plural? How do Indonesians show plural for words like this?

Indonesian usually does not mark plural explicitly; context tells you whether it’s singular or plural.

data can mean data (in general), data points, pieces of data, a dataset, etc.

If you really want to emphasize plurality, you can use:

banyak data = many data (much data)
data-data = data (plural, emphasized, but often sounds unnecessary or childish for abstract nouns)

In most natural Indonesian, data alone is enough; you don’t need a special plural form.

What does untuk do in untuk memahami pengaruh…? Is it like “to” in English?

Yes. Untuk here functions like “in order to / to” expressing purpose.

untuk memahami pengaruh cahaya pada tanaman
= in order to understand the effect of light on plants

Structure:

untuk + verb = to (do something) for a purpose
- untuk belajar = to study / in order to study
- untuk memahami = to understand / in order to understand

You could often translate untuk as “for” or “to” when it introduces a purpose clause.

What is memahami formed from, and how is it different from paham?

The base word is paham (to understand, to be aware/knowledgeable).

memahami = meN- (here mem-) + paham
It means to understand (something), used as an active verb taking an object.

Difference:

paham:
- As a verb/adjective-like: Saya paham. = I understand / I get it.
memahami:
- Always a verb needing an object: Saya memahami konsep ini. = I understand this concept.

In the sentence:

untuk memahami pengaruh cahaya… = to understand the effect of light…

What does pengaruh mean exactly, and how does it relate to mempengaruhi?

Pengaruh is a noun meaning influence / effect / impact.

pengaruh cahaya = the effect/influence of light

It’s related to the verb mempengaruhi:

mempengaruhi = to influence / to affect (something)
Example: Cahaya mempengaruhi pertumbuhan tanaman.
= Light affects the growth of plants.

So:

pengaruh = influence/effect (noun)
mempengaruhi = to influence/affect (verb)

Why is pada used in pengaruh cahaya pada tanaman? Can we use di or kepada instead?

Here, pada is a preposition that roughly means on / upon / to / in relation to and is common in more formal or abstract expressions.

pengaruh cahaya pada tanaman = the effect of light on plants

Alternatives:

pengaruh cahaya terhadap tanaman
- Also very common and means essentially the same thing. Terhadap is often used for "toward / on / against" in an abstract sense.
pengaruh cahaya di tanaman
- Sounds wrong/unnatural here; di is more for physical location.
pengaruh cahaya kepada tanaman
- Grammatically possible but less natural; kepada is more often to (a person/recipient), e.g. memberi hadiah kepada ibu.

So the most natural choices here are pada or terhadap.

What does tanaman mean, and how is it different from tumbuhan?

Both relate to plants, but there is a nuance:

tumbuhan = plants in general, living organisms in the plant kingdom.
tanaman comes from tanam (to plant), and often means cultivated plants / crops / plants that are planted by people.

In this sentence, tanaman fits well because it suggests plants being grown or studied (like in a pot or field) rather than plants in the wild in general.

Why is the word order kami mengumpulkan data sederhana, not kami sederhana mengumpulkan data?

Basic Indonesian sentence order is:

Subject – Verb – Object – (Adjective)

So:

kami (subject)
mengumpulkan (verb)
data (object)
sederhana (adjective describing the noun data)

Kami sederhana mengumpulkan data would sound wrong, because sederhana is an adjective modifying data, not the verb mengumpulkan.

Where is the past tense in this sentence? How do we know it means “we collected” and not “we collect”?

Indonesian verbs do not change form for tense. There is no conjugation like collect / collected / will collect.

Mengumpulkan can mean:

collect (present)
collected (past)
will collect (future)

Context gives the time:

Dalam eksperimen itu suggests a specific, completed experiment in the past, so we understand it as “we collected”.

If you need to be explicit, you can add time words:

Kemarin, dalam eksperimen itu, kami mengumpulkan data…
= Yesterday, in that experiment, we collected data…
Besok, dalam eksperimen itu, kami akan mengumpulkan data…
= Tomorrow, in that experiment, we will collect data…

But the verb form mengumpulkan stays the same.