AP Biology : Cell Structures

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #3 : Understand Functions Of Organelles In The Cell

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

Possible Answers:

Cell division

Glycolysis

Gluconeogenesis

Lipid storage

Cellular respiration

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 #121 : Cell Structures

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

Possible Answers:

Chloroplast

Nucleus

Mitochondrion

Peroxisome

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.

Example Question #122 : Cell Structures

What term describes the tendency of an organism to maintain a relatively stable equilibrium between interdependent elements in its internal environment?

Possible Answers:

Mitosis

Synthesis

Respiration

Reproduction

Homeostasis

Correct answer:

Homeostasis

Explanation:

Homeostasis is the mechanism that allows for organisms to maintain equilibrium of their internal environments. Certain variables of the internal environments are regulated such that the conditions of the organism remain stable and relatively constant. This is often accomplished via negative feedback loops and hormone regulation.

Reproduction refers to an organism's ability to generate offspring. Respiration refers to the method of gas exchange in the lungs. Synthesis refers to the generation of certain molecules. Mitosis refers to cellular division. While any of these processes could be used to affect the equilibrium state of an organism, they are all mediated by homeostatic mechanisms in order to maintain biological stability.

Example Question #123 : Cell Structures

Which of the following is true of mitochondria?

Possible Answers:

All of these are true statements

Mitochondria are involved in energy metabolism

Mitochondria have more than one membrane

Mitochondria are independent of the endomembrane system

Mitochondria contain DNA and ribosomes

Correct answer:

All of these are true statements

Explanation:

Each of these answers correctly describes characteristics of mitochondria. Mitochondria are semi-autonomous: they are capable of synthesizing some of their own proteins with DNA and ribosomes. The proteins are then embedded in the inner mitochondrial membrane, and function in the electron transport chain. Mitochondria have two membranes, an inner membrane and an outer membrane. Mitochondria are the sites of cellular respiration and ATP production, often called the "powerhouse" of the cell. After glycolysis, pyruvate is transported to the mitochondrial matrix for the Krebs cycle and electron transport chain. Mitochondria are not involved in the endomembrane system; they are separate organelles.

Example Question #124 : Cell Structures

What is euchromatin?

Possible Answers:

DNA unavailable for transcription

DNA that is being translated

DNA available for transcription

DNA that is not being translated

Correct answer:

DNA available for transcription

Explanation:

Euchromatin is “light” chromatin that represents DNA that is currently active for transcription. The fact that it is “light” implies that it is relatively decondensed and accessible by polymerases. Euchromatin is generally present during interphase, when most transcription and replication takes place, and is converted to heterochromatin during mitosis.

Translation occurs outside of the nucleus and uses mRNA as a template, not DNA.

Example Question #125 : Cell Structures

The smooth endoplasmic reticulum in hepatocytes can expand as a response to which of the following?

Possible Answers:

A diet that is high in fats

An increase in aerobic exercise

Recovery from a physical injury

Consumption of prescribed drugs to treat a health condition

Correct answer:

Consumption of prescribed drugs to treat a health condition

Explanation:

The smooth endoplasmic reticulum contains enzymes responsible for the metabolism of small chemical molecules such as alcohol, pharmaceutical drugs, and environmental contaminants. Expansion of the smooth endoplasmic reticulum can occur under conditions of new and continued exposure to a given chemical or stimulus as an adaptation to metabolize and eliminate the drug or chemical.

Smooth endoplasmic reticulum is particularly abundant in hepatocytes, or liver cells. Blood absorbs nutrients and ingested toxins from the small intestine and immediately travels to the liver through the portal vein. Hepatocytes then filter and metabolize the absorbed toxins before they can circulate through the body.

Example Question #126 : Cell Structures

In what ways are chloroplasts and mitochondria alike?

Possible Answers:

They function to provide energy to the cell

All of these statements give similarities between chloroplasts and mitochondria

They each contain their own DNA and ribosomes

They can change shape and move around the cell

Correct answer:

All of these statements give similarities between chloroplasts and mitochondria

Explanation:

Mitochondria and chloroplasts are organelles within eukaryotic and plant cells, respectively. All eukaryotic organisms contain mitochondria, but only photoautotrophs will contain chloroplasts. The function of these organelles is to produce energy for the cell to survive and function. Mitochondria produce energy through respiration and chloroplasts produce energy through photosynthesis. These organelles have their own DNA to express their own set of genes and have ribosomes to make the proteins necessary to make energy for the cell. The proteins for the electron transport chain, for example, are transcribed and translated within the mitochondrial matrix before being implanted in the inner mitochondrial membrane.

Example Question #127 : Cell Structures

Which of the following is not true of the Golgi apparatus? 

Possible Answers:

It is a derivative of the endoplasmic reticulum

It accounts for the difference between the rough and smooth endoplasmic reticulum

It sends proteins to the cell surface within vesicles

It functions in exocytosis

Correct answer:

It accounts for the difference between the rough and smooth endoplasmic reticulum

Explanation:

The Golgi apparatus is derived from the endoplasmic reticulum and consists of a series of flattened sacs. The function of the Golgi apparatus is to package and transport proteins to the cell surface within vesicles, which pinch off from the Golgi. These vesicles then interface with the cell membrane, releasing their contents into the extracellular space or integrating membrane proteins into the cell membrane.

The Golgi apparatus is not involved in differentiation between the smooth and rough endoplasmic reticulum. This difference comes from the presence of ribosomes, which are embedded in the surface of the rough endoplasmic reticulum, but absent from the smooth endoplasmic reticulum. The rough endoplasmic reticulum is responsible for synthesizing and modifying proteins that are destined for the Golgi apparatus for packaging. The smooth endoplasmic reticulum helps eliminate toxins from the cell.

Example Question #614 : Cellular Biology

A microscopic view of a cell shows a dense, rigid exterior. Which of the following types of cells is least likely being observed?

Possible Answers:

A bacterial cell

A liver cell

A mushroom cell

A fern cell

Correct answer:

A liver cell

Explanation:

The dense, rigid exterior is most likely describing a cell wall. Cell walls are used to protect cells and help them maintain their shape. Plant cells, fungal cells, and most prokaryotic cells have a cell wall structure, though the composition of the cell walls varies between cell types. Plants, such as ferns, use cellulose in their cell walls. Fungi, such as mushrooms, generally use chitin. Prokaryotic cell walls vary in composition, but bacteria generally use peptidoglycan, which can help in identifying bacteria via Gram staining.

Animal cells, such as those found in the liver, do not have cell walls.

Example Question #128 : Cell Structures

Which of the following organelles is known as the transport and processing center?

Possible Answers:

Smooth endoplasmic reticulum

Lysosomes

Golgi apparatus

Ribosomes

Rough endoplasmic reticulum

Correct answer:

Golgi apparatus

Explanation:

The Golgi apparatus is where transport vesicles are developed and is known as the transport and processing center. Proteins and other compounds are taken to the Golgi apparatus. The Golgi has several membrane-bound sacs that allow proteins to become engulfed in vesicles or integrated into the membranes of vesicles. Complete vesicles are then transported within the cell or to the cell membrane, where they fuse and release their contents into the extracellular space. The membrane of the vesicles is incorporated into the cell membrane, along with any integrated proteins.

Lysosomes are processed in the Golgi apparatus and contain enzymes that are activated by low pH to get rid of waste and damaged organelles. The smooth endoplasmic reticulum is responsible for absorbing and removing drugs and poisons. The rough endoplasmic reticulum manufactures and modifies proteins before they are packaged in the Golgi apparatus. Ribosomes function in translation, producing proteins from mRNA.

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