On the rainforest floor you discover a small multicellular organism. You’ve never seen anything like it, and are not sure if it is an animal or plant. Which of the following characteristics can help you distinguish an animal from a plant? Select all that apply.

embryo eukaryotic gap junctions heterotrophic
motile multicellular muscles neurons
lack of cell walls sexual reproduction

The correct answers are "embryo, gap junctions, heterotrophic, motile, muscles, neurons and lack of cell walls".

Explanation:

In order to select which characteristics can help to distinguish an animal from a plant it is important to know which characteristics are unique for animals. These characteristics include:

- Embryo. Plants do not reproduce as animals where an organism gets pregnant and develops an embryo. Plants reproduce by diverse sexual and asexual approaches, where embryos are only produced inside a seed.

- Gap junctions. These structures are only present within intercellular connections in animal cells. Plant cells have other structure called plasmodesmata that perform this process.

- Heterotrophic. Animals cannot produce their own energy, therefore they are heterotrophs that feed from other organisms. On the other hand, plants are autotrophs.

- Motile. Most animals are motile, while only a few plants have limited motility and it only occurs in the presence of a stimuli like the presence of a prey or sunlight.

- Muscles. Plants do not have muscles, they have other structures to allow a limited movement and growth.

- Neurons. Plants do not have a nerve system based on the presence of neurons.

- Lack of cell walls. Plants have cell walls to provide rigidity to their structures. Animal cells do not have these structures.