Biology homework help..?

Question

Which of the following best describes prokaryotes and eukaryotes?

 Prokaryotes have a nucleus and eukaryotes do not. 

Prokaryotes do not have a nucleus; eukaryotes have a nucleus. 

Both have membrane-bound structures. 

Prokaryotes have membrane-bound structures and eukaryotes have free floating organelles.

Answer 1

Prokaryotes do not have a nucleus; eukaryotes have a nucleus.

Answer 2

The answer which best describes prokaryotes and eukaryotes is: "Prokaryotes do not have a nucleus; eukaryotes have a nucleus."

This answer choice and the following explanations for each option below are based on the following definition: eukaryotic cells and prokaryotic cells differ in that eukaryotic cells contain a membrane bound nucleus and other membrane bound organelles, while prokaryotic cells do not contain a nucleus nor other membrane bound organelles. Instead, the genetic material in a prokaryotic cell floats within the cell's cytoplasm (liquid that fills the cell).

Let's go through each answer choice:

1) "Prokaryotes have a nucleus and eukaryotes do not." -- This is the opposite of the correct answer and incorrect because prokaryotes are known for not having a nucleus while eukaryotes have a nucleus. This is one of the key distinctions between the 2 organism types.

2) "Prokaryotes do not have a nucleus; eukaryotes have a nucleus." -- This is consistent with the definitions of prokaryotes and eukaryotes and thus accurately describes each of them.

3) "Both have membrane-bound structures." -- The phrase "membrane-bound structures" in this answer refers to membrane-bound organelles within each of the organisms' cells. Eukaryotes are known to have many of these, such as the mitochondria, endoplasmic reticulum, vacuole, etc. Although this is true for eukaryotes, prokaryotes have no such membrane-bound organelles. "Membrane-bound" is biologists' way of saying that there is a membrane surrounding the organelle like an orange being surrounded by its peel.

4) "Prokaryotes have membrane-bound structures and eukaryotes have free floating organelles." -- Similar to how answer choice #1 contradicts the definitions of prokaryotes and eukaryotes, so does this answer choice. The answer choice #4 says that prokaryotes have membrane-bound structures/organelles, but we know that it is eukaryotes which have these structures in their cells, not prokaryotes. In addition, the answer choice #4 says that eukaryotes have free floating organelles, meaning that the organelles are not bound by a membrane. This is not true because we know that eukaryotes' organelles are membrane-bound.