AP Biology : Understanding Other Cell Structures

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #1 : Understanding Other Cell Structures

Skin can be stretched and pulled with great force without breaking or tearing. Which cellular junction is most responsible for keeping skin resilient and intact?

Possible Answers:

Tight junctions

Gap junctions

Intercalated discs

Desmosomes

Correct answer:

Desmosomes

Explanation:

Desmosomes are the primary junction that helps keep tissues that are under a lot of stress, like skin, intact. Although tight junctions typically accompany desmosomes, their primary function is to prevent substances from passing between cells. Gap junctions are used for communication between cells, and intercalated discs are only found in cardiac muscle tissue.

Example Question #2 : Understanding Other Cell Structures

Which cellular structure is least likely to bear a membrane protein that moves hydrogen ions out of the organelle?

Possible Answers:

Golgi body

Nucleus

Mitochondria

Lysosome

Chloroplast

Correct answer:

Lysosome

Explanation:

The lysosome is an organelle that is used to digest broken cellular machinery or foreign particles. It maintains an acidic environment inside by pumping hydrogen ions in, not out. This environment helps denature the things it needs to digest, and is the most effective pH for the digestive enzymes that are inside.

The other structures do not maintain acidic environments, and would need the capability of removing protons.

Example Question #3 : Understanding Other Cell Structures

Where would you be least likely to find a transmembrane protein?

Possible Answers:

Cell membrane

Chloroplasts

Nucleus

Mitochondria

Ribosomes

Correct answer:

Ribosomes

Explanation:

The simple answer here is that all of these organelles have a membrane, except for ribosomes. Nuclei, mitochondria, chloroplasts, and cells as a whole have transmembrane proteins spanning the lipid bilayer, which can be used for transport or other purposes. Ribosomes are mostly comprised of rRNA and do not have membranes; thus, they will not bear transmembrane proteins.

Example Question #4 : Understanding Other Cell Structures

The Golgi apparatus is responsible for which function of the cell?

Possible Answers:

Protein packaging

Protein degradation

Protein synthesis

Protein storage

Correct answer:

Protein packaging

Explanation:

The Golgi apparatus is a series of flattened membrane sacs found in the cell. It receives vesicles filled with proteins from the rough endoplasmic reticulum. The Golgi apparatus is responsible for recognizing proteins based on their signal sequences and sending concentrations of similar proteins to various parts of the cell. It can also deliver proteins out of the cell using secretory vesicles. The membrane sacs of the Golgi apparatus are constantly used and regenerated to create vesicles of packaged proteins.

Example Question #5 : Understanding Other Cell Structures

Which of the following structures/functions is not created using microtubules?

Possible Answers:

Eukaryotic flagella

Cilia

Mitotic spindles

Muscle contraction

Correct answer:

Muscle contraction

Explanation:

Muscle contraction is accomplished using the function of microfilaments, namely actin and myosin. Microtubules are not a key player in muscle contraction, but are used to create the mitotic spindles, flagella, and cilia. Microtubules are a key element of the cytoskeleton, and are generally involved in structural aspects of the cell.

Example Question #6 : Understanding Other Cell Structures

Ribosomes are the site of protein synthesis in both eukaryotes and prokaryotes. In eukaryotes, ribosomes can either be "free" or "bound." To which larger organelle are bound ribosomes attached?

Possible Answers:

Lysosomes

Golgi apparatus

Rough endoplasmic reticulum

Mitochondria

Smooth endoplasmic reticulum

Correct answer:

Rough endoplasmic reticulum

Explanation:

While free ribosomes are present independently in the cytosol, bound ribosomes are attached to the rough endoplasmic reticulum. Their presence gives this organelle its "rough" appearance and distinguishes it from the smooth endoplasmic reticulum, which does not contain ribosomes. The nuclear envelope, which surrounds and protects the eukaryotic nucleus, is also the site of some bound ribosomes and is connect to the rough endoplasmic reticulum. The Golgi apparatus, lysosomes, and mitochondria have no ribosomes bound to their membranes.

Example Question #7 : Understanding Other Cell Structures

Which of the following organelles directly requires oxygen to maintain optimal function?

Possible Answers:

Mitochondria

Smooth endoplasmic reticulum

Plasmids

Nucleolus

Ribosomes

Correct answer:

Mitochondria

Explanation:

The mitochondria are membrane-bound organelles involved in the process of cellular respiration. Specifically, the Krebs cycle takes place in the matrix of the mitochondria and the electron transport chain takes place along the inner mitochondrial membrane. During aerobic respiration, oxygen is used as the final electron receptor of the electron transport chain and generates water as a byproduct. Without oxygen, the mitochondria cannot perform oxidative phosphorylation, and the cell must rely on glycolysis for energy.

Example Question #8 : Understanding Other Cell Structures

Of the following organelles, which contains hydrolytic enzymes that can break down cellular debris?

Possible Answers:

Peroxisome

Nucleus

Lysosome

Plasma membrane

Endoplasmic reticulum

Correct answer:

Lysosome

Explanation:

Lysosomes contain hydrolytic enzymes that can digest macromolecules from phagocytosis, endocytosis, and autophagy. When damage occurs to the membrane of the lysosome, these enzymes can be released and cause damage to the cell, leading to apoptosis.

Peroxisomes contain peroxidases, which help to eliminate hydrogen peroxide from the cell and prevent the creation of free radicals. The nucleus houses DNA and would be severely damaged by the introduction of hydrolytic enzymes. The plasma membrane is used to contain the cytoplasm and organelles and the endoplasmic reticulum is used to modify and package proteins.

Example Question #9 : Understanding Other Cell Structures

A centriole is a cylindrical structure that is primarily involved in which process?

Possible Answers:

Lipid storage

Glycolysis

Cell division

Cellular respiration

Gluconeogenesis

Correct answer:

Cell division

Explanation:

Centrioles are cell structures that are mainly composed of tubulin and are involved in the organization of the mitotic spindle and cytokinesis during cell division.

Cellular respiration primarily occurs on the inner mitochondrial membrane with the aid of membrane proteins. Glycolysis and gluconeogenesis occur in the cytoplasm and are facilitated by proteins. Lipids are mostly stored in bones and adipose tissue. These processes do not require intervention from the cytoskeleton or microtubules that compose the centrioles.

Example Question #114 : Cellular Biology

What cellular structure is composed of a protein skeleton that is made up of lamins?

Possible Answers:

Nucleus

Mitochondrion

Peroxisome

Chloroplast

Lysosome

Correct answer:

Nucleus

Explanation:

Nuclear lamins are fibrous proteins (intermediate filaments) that provide the structural function and the transcriptional regulation in the nucleus of a cell. Note that lamins differ from laminins, which are a protein component of basement membranes.

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