Which of the following is NOT a characteristic of prokaryotic cells?

Question

BlackTom AI · Accepted Answer

Prokaryotic cells lack a membrane-bound nucleus, so "Presence of a nucleus" is not a characteristic of prokaryotes.

1. Relevant knowledge points and concepts
- Prokaryotes (bacteria and archaea) are defined by the absence of membrane-bound organelles, including a true nucleus. Their genetic material is located in a nucleoid region, not enclosed by a nuclear membrane.
- Typical prokaryotic features: a single circular chromosome (often), 70S ribosomes, small cell size (commonly 0.1–5 µm), and absence of membrane-bound organelles.
- Eukaryotes have a membrane-bound nucleus and larger 80S ribosomes.

2. Step-by-step reasoning
- Evaluate each option against known prokaryotic characteristics.
  a) Single circular chromosome — Prokaryotes commonly have one circular chromosome; this matches prokaryotes.
  b) Lack of membrane-bound organelles — By definition, prokaryotes lack these; this matches.
  c) Presence of ribosomes — Prokaryotes possess ribosomes (70S) for protein synthesis; this matches.
  d) Small size — Prokaryotic cells are generally much smaller than eukaryotic cells; this matches.
  e) Presence of a nucleus — Prokaryotes do not have a membrane-enclosed nucleus; this does not match.

3. Intermediate facts/steps shown
- Chromosome type: bacterial chromosomes are typically circular; plasmids may be present but are separate.
- Ribosome type: prokaryotic ribosomes are 70S (composed of 50S and 30S subunits), distinct from eukaryotic 80S ribosomes.
- Size comparison: prokaryotes ~0.1–5 µm; eukaryotes ~10–100 µm.
- Cellular organization: genetic material in a nucleoid (not a nucleus).

4. Why the correct answer is correct
- "Presence of a nucleus" contradicts the defining trait of prokaryotes. A true nucleus enclosed by a nuclear membrane is a hallmark of eukaryotic cells, not prokaryotic ones.

5. Why the other options are incorrect choices for "NOT characteristic"
- Each of the other options (single circular chromosome, lack of membrane-bound organelles, presence of ribosomes, small size) accurately describes typical prokaryotic features and thus are characteristics of prokaryotic cells.

6. Conclusion
- The correct response is "Presence of a nucleus," which matches the provided answer.

Which of the following is NOT a characteristic of prokaryotic cells?单项选择题

类似问题

Question at position 17 All prokaryotes containmitochondria and DNA.chloroplasts and vacuoles.DNA and a cell wall.a nucleus and DNA.Clear my selection

Which of the following is NOT a characteristic of prokaryotic cells?

Bacteria are:

What are the main characteristics of prokaryotic microorganisms?

Which of the following IS CHARACTERISTIC of prokaryotic organisms?

Which of the following is NOT a characteristic of prokaryotic cells?

Which of these phrases apply to prokaryotes? originated ~3.8 billion years ago originated ~1.6 billion years ago have plasmids have circular chromosomes have chloroplasts have mitochondria have DNA inside a nucleus

Which of the following BEST describes a bacterium?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单