AP Biology : Cellular Biology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Understand Endosymbiotic Theory

Mitochondria and chloroplasts have their own DNA, which is similar to the DNA of

Possible Answers:

fungi

bacteria

humans

protozoa

Correct answer:

bacteria

Explanation:

Bacteria, a prokaryote, has circular DNA, as do mitochondria and chloroplasts. This provides support for the Endosymbiotic Theory, which states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote).

Example Question #2 : Understand Endosymbiotic Theory

Reproduction of chloroplasts and mitochondria occurs via

Possible Answers:

Meiosis

Fission-like process, similar to the reproduction process of eukaryotes

Mitosis

Fission-like process, similar to the reproduction process of bacteria

Correct answer:

Fission-like process, similar to the reproduction process of bacteria

Explanation:

Chloroplasts and mitochondria reproduce through fission, the same process through which bacteria reproduce. Eukaryotes reproduce through mitosis or meiosis, depending upon the type of cell.

Example Question #3 : Understand Endosymbiotic Theory

Supporting the Endosymbiotic Theory, mitochondria and chloroplasts have a _________ membrane.

Possible Answers:

thick

double

single

thin

Correct answer:

double

Explanation:

The Endosymbiotic Theory states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote). Mitochondria and chloroplasts have a double membrane (the inner membrane would have initially been the ingested prokaryote’s single membrane).

Example Question #4 : Understand Endosymbiotic Theory

Mitochondria and chloroplasts have ribosomes that are ___, similar to __ cells.

Possible Answers:

70 S, prokaryotic

80S, eukaryotic

70S, eukaryotic

80S, prokaryotic

Correct answer:

70 S, prokaryotic

Explanation:

Prokaryotic cells, mitochondria, and chloroplasts have 70S ribosomes, whereas eukaryotic cells have 80S ribosomes. This provides support for the Endosymbiotic Theory, which states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote).

Example Question #5 : Understand Endosymbiotic Theory

The Endosymbiotic Theory posits that, before being engulfed by a eukaryotic cell, they were

Possible Answers:

Viruses

Free-living eukaryotes

Free-living prokaryotes

Organelles

Correct answer:

Free-living prokaryotes

Explanation:

The Endosymbiotic Theory states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote). The aerobic bacteria were initially free-living prokaryotes, before being ingested by anaerobic bacteria.

Example Question #6 : Understand Endosymbiotic Theory

Which of the following is NOT evidence for the Endosymbiotic Theory?

Possible Answers:

Mitochondria and chloroplasts have 70S ribosomes

Mitochondria and chloroplasts have circular DNA

Mitochondria and chloroplasts have a single membrane

Mitochondria and chloroplasts have a double membrane

Correct answer:

Mitochondria and chloroplasts have a single membrane

Explanation:

The Endosymbiotic Theory states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote). This theory explains the origin of eukaryotic cells. Numerous lines of evidence exist, including that mitochondria and chloroplasts have their own circular DNA (prokaryotes also have circular DNA), mitochondria and chloroplasts have a double membrane (the inner membrane would have initially been the ingested prokaryote’s single membrane, and the outer membrane initially would have come from the cell that engulfed it), mitochondria and chloroplasts have 70S ribosomes (prokaryotes 70S have ribosomes, whereas eukaryotes have 80S ribosomes).

Example Question #41 : Cellular Communications And Junctions

Which is false regarding cell signaling?

Possible Answers:

Paracrine signals are used to communicate the nearby cells

Paracrine signals are long-lasting

Autocrine signals bind to receptors on the same cell that released the ligand

Endocrine signals move via the bloodstream

Correct answer:

Paracrine signals are long-lasting

Explanation:

Endocrine signals are signals from distance cells that move using the bloodstream, paracrine signals are signals used to communicate between cells in close proximity, and autocrine signals are signals that are received by the same cell in which the signal originated. Paracrine signals are signal are short-lasting, whereas endocrine signals are long-lasting.

Example Question #42 : Cellular Communications And Junctions

What type of signaling uses the bloodstream to transport ligands to targets?

Possible Answers:

Direct

Paracrine

Endocrine

Autocrine

Correct answer:

Endocrine

Explanation:

Endocrine signals are signals from distance cells that move using the bloodstream, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions).

Example Question #43 : Cellular Communications And Junctions

Which type of cell-surface receptor, when bound by a ligand, begins a cycle where GDP is exchanged for GTP, causing the alpha subunit to separate from the beta and gamma subunits, and causing a cellular response?

Possible Answers:

Ion channel- linked receptor

Enzyme-linked receptor

GTP hydrolyzation receptor

 

G-protein linked receptor

Correct answer:

G-protein linked receptor

Explanation:

G-protein linked receptors are a type of cell-surface receptor that, when unbound by a ligand, consists of an alphaGDP subunit and a beta gamma subunit. When a ligand binds, GDP is exchanged for GTP, which causes the alphaGTP subunit to dissociate from the receptor and the beta gamma subunit. Then, the alphaGTP and beta gamma subunits can activate other molecules in the cell.

Example Question #44 : Cellular Communications And Junctions

A cell releases a ligand that binds to receptors on its own surface. Which type of signaling is this?

Possible Answers:

Paracrine

Endocrine

Direct

Autocrine

Correct answer:

Autocrine

Explanation:

Endocrine signals are signals from cells that move using the bloodstream and signal to distant cells, paracrine signals are signals used to communicate between cells in close proximity, autocrine signals are signals that are received by the same cell in which the signal originated, and direct signaling occurs across gap junctions through the movement of small molecules (such as Calcium ions).

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