Which kingdom would this organism belong to?

Characteristics
Has nucleus
Has mitochondria
Is multicellular
Cells grow in columns
Cell wall present
Decomposer

Ah, sounds like we have a curious organism on our hands! If we're looking at its characteristics, we can narrow down the choices. Given that this organism has a nucleus, mitochondria, is multicellular, and has cells that grow in columns, it belongs to the Kingdom Fungi! And as a bonus, since it's a decomposer, we can call it nature's little recycling clown.

Based on the given characteristics, this organism would belong to the Kingdom Fungi. Fungi are characterized by having a nucleus, mitochondria, being multicellular (except yeasts), growing in vertical columns (hyphae), and having a cell wall made of chitin. Fungi are also known as decomposers, as they obtain nutrients by breaking down organic matter.

To determine the kingdom to which an organism belongs, we can focus on its characteristics and compare them to the five main kingdoms: Animalia, Plantae, Fungi, Protista, and Monera.

Based on the given characteristics of the organism: having a nucleus, having mitochondria, being multicellular, cells growing in columns, having a cell wall, and being a decomposer, we can eliminate Plantae (plants) as they generally do not have a cell wall composed of chitin and they are not decomposers.

Next, we can eliminate Animalia (animals) as they lack a cell wall and do not typically grow in columnar fashion.

This leaves us with three remaining kingdoms: Fungi, Protista, and Monera.

Protista is a diverse kingdom consisting of eukaryotic organisms, but it includes both unicellular and multicellular organisms. Since the given organism is described as multicellular, we can eliminate Protista.

Now, let's compare the characteristics of the organism with those of Fungi and Monera.

Fungi are eukaryotic organisms, have a nucleus, and possess mitochondria. They are typically multicellular, and most fungi have a cell wall that contains chitin. Fungi also include decomposers within their kingdom.

On the other hand, Monera consists of prokaryotic organisms (bacteria and archaea), which lack a nucleus and mitochondria. Monera typically do not possess a cell wall made of chitin and do not display columnar cell growth.

Considering the presence of a nucleus, mitochondria, multicellularity, columnar cell growth, cell wall presence, and being a decomposer, the given organism is most likely part of the Fungi kingdom.