AP Biology : Cell Structures

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #21 : Cell Structures

Which of the following statements is true?

Possible Answers:

Plant cells lack ribosomes 

Both prokaryotic and eukaryotic cells have membrane-bound organelles 

Prokaryotic and eukaryotic cells have circular DNA 

Prokaryotic cells lack membrane-bound organelles 

Both prokaryotic and eukaryotic cells have DNA contained in a nucleus 

Correct answer:

Prokaryotic cells lack membrane-bound organelles 

Explanation:

The primary difference between prokaryotic and eukaryotic cells is that prokaryotic cells lack membrane-bound organelles and have circular DNA, while eukaryotic cells contain membrane-bound organelles and linear strands of DNA. Because prokaryotic cells lack membrane enclosed organelles, cells do not have nuclei. Rather, the cell’s DNA is located in the nucleoid, a nucleus-like region within the cell. Eukaryotic cells generally comprise more complex organisms, such as plants, humans, and animals. Prokaryotic cells generally comprise bacteria and smaller organisms. All cells have ribosomes.

Example Question #21 : Understanding Eukaryotic And Prokaryotic Differences

Prokaryotes reproduce via __________.

Possible Answers:

meiosis

sexual reproduction

mitosis

binary fission

Correct answer:

binary fission

Explanation:

Prokaryotes utilize binary fission for cellular division. Binary fission involves asexual reproduction of prokaryotes. First the cell grows and duplicates its genome, and any plasmids. The cell polarizes itself, then begins forming a cell wall to divide the cell into two slightly smaller cells. Eukaryotes use mitosis, and meiosis. Sexual reproduction occurs in some phyla of eukaryotes.

Example Question #22 : Cell Structures

Which of the following lacks a nucleus?

Possible Answers:

Eukaryotic cells

Animal cells

Prokaryotic cells

Plant cells

Correct answer:

Prokaryotic cells

Explanation:

Prokaryotic cells do not have a nucleus. The genetic material for prokaryotes is concentrated in a region called the nucleoid but there is no membrane separating this region from the rest of the cell unlike in eukaryotic cells, which do have membrane-bound nuclei. Animal cells and plant cells are eukaryotes.  

Example Question #22 : Cell Structures

Organelles are membrane-bound structures found only within the cells of eukaryotes. These structure provide different functions within the cell. 

Which of the following is not considered an organelle?

Possible Answers:

Mitochondria

Nucleus

Chloroplast

Ribosome

Peroxisome

Correct answer:

Ribosome

Explanation:

All of these structures are organelles except the ribosome. The ribosome is found in both prokaryotic and eukaryotic cells. It is the site of protein synthesis (translation). Ribosomes may be free-floating in the cytoplasm, or attached to the endoplasmic reticulum in eukaryotes. Since ribosomes are not membrane-bound, they do not fit the classical definition of an organelle.

Example Question #23 : Cell Structures

Cell walls can be found in all of the following groups of organisms except __________.

Possible Answers:

mammals

fungi

plants

bacteria

protists

Correct answer:

mammals

Explanation:

The only group organisms listed without cell walls are mammals. All of the other organisms may or may not have cell walls. For example, some fungi, but not all, have cell walls made of chitin. Bacteria, but not Archaea, have cell walls made of peptidoglycan, and plants have cell walls made of cellulose. A small subset of protists may also contain cell walls.

Example Question #22 : Cellular Biology

The DNA of prokaryotic cells can only be found in the __________.

Possible Answers:

histones

chromatin

nucleoid

nucleolus

nucleus

Correct answer:

nucleoid

Explanation:

Prokaryotic cells do not contain organelles (nucleus). They also lack chromosomes; therefore, histones and chromatin are not present. Finally, the nucleolus is a region of the nucleus where ribosomal subunits are assembled. This region is only present in eukaryotic cells. The nucleoid is a region in prokaryotic cells that contains the DNA.

Example Question #24 : Cell Structures

Which of the following can be found in a prokaryotic cell?

Possible Answers:

Endoplasmic reticulum

Mitochondria

Ribosomes

Nucleus

Centrioles

Correct answer:

Ribosomes

Explanation:

Prokaryotic cells do not have membrane-bound organelles or nuclei. However, they do have ribosomes. On the other hand, centrioles, the endoplasmic reticulum, the mitochondria, and the nucleus can all be found in eukaryotic cells, but not prokaryotic cells. 

Example Question #25 : Cell Structures

Which of these is not found in prokaryotic cells?

Possible Answers:

Cell membrane 

Membrane proteins

Cytosol 

Golgi apparatus

Ribosome

Correct answer:

Golgi apparatus

Explanation:

Prokaryotes do not contain membrane-bound organelles so they do not have a Golgi apparatus. Prokaryotic cells have cell membranes that include proteins and sugars that facilitate the passage and/or exclusion of certain substances into and out of the cell. Also, prokaryotic cells have ribosomes since they must also do translation, the act of translating RNA to protein in the cytoplasm. The cytosol is the area inside the cell membrane of the cell. The Golgi apparatus is membrane-bound and is thus only found in eukaryotic cells.

Example Question #23 : Cellular Biology

Which of the following is not a eukaryote?

Possible Answers:

Plants

Animals

Archaea

Fungi

Protists

Correct answer:

Archaea

Explanation:

Remember that even fungi have well-seen nuclei and that the presence of a nucleus is what makes a eukaryote a eukaryote. Archaea are their own domain and they are as small as bacteria and other prokaryotes but are quite different. They live in extreme environments and often we cannot study them due to that but we have studied some such as the halophiles (salt-loving archaea).

Example Question #22 : Cellular Biology

Which of the following cellular structures are common to both prokaryotes and eukaryotes?

Possible Answers:

mitochondria

ribosomes

chloroplasts

golgi bodies

nucleoli

Correct answer:

ribosomes

Explanation:

Ribosomes are components of prokaryotes and eukaryotes. Prokaryotes, although they came before eukaryotes, lack nucleoli, chloroplasts, mitochondria, and Golgi bodies. Ribosomes makes proteins and eukaryotes and prokaryotes both need proteins to function.

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