Cell Structure and Function

42 questions

Question 1Question →

The smooth endoplasmic reticulum is studded with ribosomes that synthesize polypeptides, whereas the rough endoplasmic reticulum lacks ribosomes and specializes in lipid synthesis and detoxification.

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Answer: False

Answer

False. The statement reverses the structural characteristics and primary functions of the rough and smooth endoplasmic reticulum.
The statement is false because it swaps the structural definitions and cellular functions of the two types of endoplasmic reticulum. In eukaryotic cells, the rough endoplasmic reticulum is named for the ribosomes attached to its cytoplasmic surface, which synthesize proteins destined for membranes or secretion. In contrast, the smooth endoplasmic reticulum is tubular, lacks ribosomes, and primarily synthesizes lipids, phospholipids, and steroid hormones while detoxifying metabolic byproducts and drugs.

Step-by-Step Solution

1
Analyze the structural characteristics described for the rough and smooth endoplasmic reticulum.
The statement asserts that the smooth endoplasmic reticulum possesses ribosomes and the rough endoplasmic reticulum lacks them.
Identifying the physical markers of each organelle confirms whether the structural definitions are accurate.
2
Evaluate the cellular functions attributed to each organelle against established biological principles.
Ribosomes are attached to the rough endoplasmic reticulum to synthesize proteins, whereas the smooth endoplasmic reticulum synthesizes lipids and handles detoxification.
Matching each organelle to its correct metabolic role determines the overall truth value of the assertion.
3
Formulate the final evaluation.
The statement is false because it inverts both the presence of ribosomes and the functional duties between the rough and smooth endoplasmic reticulum.
A direct comparison proves the statement is factually incorrect.

Key Concept

Endoplasmic Reticulum Structure and Function (Rough vs. Smooth ER)
Question 2Question →

During a laboratory investigation, a plant cell and an animal cell are both placed into a hypotonic solution. While the animal cell swells and lyses (bursts), the plant cell remains structurally intact and builds internal turgor pressure. Which cellular structure prevents the plant cell from bursting, and which organelle maintains the internal hydrostatic pressure that pushes against it?

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Answer: The cell wall prevents bursting, while the large central vacuole maintains turgor pressure.

Answer

The cell wall prevents the plant cell from bursting, while the large central vacuole maintains turgor pressure.
Plant cells contain a rigid outer cell wall composed of cellulose that prevents the cell from bursting when water rushes in during exposure to a hypotonic environment. Inside the cell, the large central vacuole fills with water and exerts outward hydrostatic pressure (turgor pressure) against the cell wall, keeping the plant upright and firm.

Step-by-Step Solution

1
Analyze the behavior of cells in a hypotonic environment
Water enters both plant and animal cells via osmosis due to the solute gradient.
Hypotonic external solutions cause a net influx of water into the cytoplasm.
2
Identify the structural adaptation preventing lysis in plant cells
The rigid cell wall composed of cellulose withstands internal osmotic pressure.
Animal cells possess only a flexible plasma membrane and burst under excessive influx.
3
Identify the organelle responsible for storing water and generating turgor pressure
The large central vacuole accumulates water, pushing cytoplasm outward against the cell wall.
This hydrostatic interaction maintains plant rigidity and structural uprightness.

Key Concept

Plant versus animal cellular structural adaptations under osmotic pressure
Estimated Time:1m 30s
Question 3Question →

Which organelle is found in plant cells and functions as the primary site of photosynthesis?

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Answer: Chloroplast

Answer

Chloroplast
Chloroplasts are double-membrane organelles found in plants and algae that contain the green pigment chlorophyll. They absorb solar energy to convert carbon dioxide and water into glucose through the process of photosynthesis.

Step-by-Step Solution

1
Identify the cellular process and target cell type in the question
The question asks for the organelle responsible for photosynthesis in plant cells.
Pinpointing the specific biochemical process helps narrow down the organelle's specialized function.
2
Match the organelle to photosynthesis
Chloroplasts contain chlorophyll pigments that absorb sunlight to synthesize glucose from water and carbon dioxide.
Chloroplasts are uniquely adapted for photosynthesis and are characteristic of plant cells rather than animal cells.

Key Concept

Plant Cell Organelles and Photosynthesis
Estimated Time:30s
Question 4Question →

Proteins synthesized by free cytosolic ribosomes are packaged into transport vesicles and routed through the Golgi apparatus for extracellular secretion.

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Answer: False

Answer

False. Free cytosolic ribosomes synthesize intracellular proteins, whereas secreted proteins are synthesized exclusively by ribosomes bound to the rough endoplasmic reticulum before moving to the Golgi apparatus.
Evaluating the statement as false is correct because the Golgi apparatus processes proteins delivered specifically from the rough endoplasmic reticulum. Free ribosomes translate proteins that remain in the cytoplasm or enter organelles like the nucleus and mitochondria directly without vesicular packaging.

Step-by-Step Solution

1
Identify the cellular sites of protein synthesis and their functional specialization.
Ribosomes exist either freely suspended in the cytosol or bound to the membrane of the rough endoplasmic reticulum.
The destination of a newly synthesized protein depends directly on where it is translated.
2
Trace the pathway required for extracellular secretion (the endomembrane secretory pathway).
Secretory proteins possess a signal peptide directing them to dock at the rough endoplasmic reticulum, from which they bud in vesicles to the cis-Golgi, undergo processing, and are targeted to the plasma membrane for exocytosis.
Vesicular trafficking requires luminal entry into the endoplasmic reticulum network.
3
Evaluate the role of free cytosolic ribosomes against the statement.
Free cytosolic ribosomes release their products directly into the cytosol, bypassing the endoplasmic reticulum and Golgi apparatus entirely.
Free ribosomes do not feed into the lumen of the endomembrane system, making the statement false.

Key Concept

Compartmentalization and the endomembrane secretory pathway versus cytosolic translation.
Estimated Time:1m 0s
Question 5Question →

An unidentified eukaryotic cell maintains high metabolic activity through aerobic respiration, yet it does not release oxygen when exposed to sunlight and carbon dioxide. Additionally, when the cell is placed in a hypotonic solution (pure water), it swells but structurally remains intact without bursting. Based on these findings, which specific organelle is definitively ABSENT from this cell, and what structure provides its osmotic protection?

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Answer: Chloroplast; cell wall

Answer

Chloroplast; cell wall
The correct answer identifies that the inability to produce oxygen from sunlight and carbon dioxide means the cell lacks chloroplasts. Furthermore, the cell's ability to survive in a hypotonic solution (pure water) without bursting indicates the presence of a rigid cell wall, which provides structural support against osmotic pressure.

Step-by-Step Solution

1
Analyze the metabolic clue regarding oxygen and sunlight.
The cell does not produce oxygen in sunlight, meaning it does not perform photosynthesis. Therefore, chloroplasts are absent.
Chloroplasts are responsible for converting light energy and carbon dioxide into glucose and oxygen.
2
Analyze the metabolic clue regarding respiration.
The cell uses aerobic respiration, which confirms the presence of mitochondria.
Mitochondria are the site of aerobic cellular respiration in eukaryotes.
3
Analyze the structural clue regarding the hypotonic solution.
The cell swells but does not burst in pure water, indicating the presence of a rigid outer boundary.
Animal cells (which only have a cell membrane) will swell and burst (lyse) in hypotonic solutions. Cells with a cell wall (like plant or fungal cells) will become turgid but remain intact.
4
Synthesize the findings to select the correct pair.
The absent organelle is the chloroplast, and the structure providing osmotic protection is the cell wall.
Combining the deductions from steps 1 and 3 directly matches one of the provided options.

Key Concept

The functional differentiation of cellular organelles and structural boundaries (cell wall vs. cell membrane) under varying environmental and metabolic conditions.
Question 6Question →

Newly synthesized proteins must be chemically modified, sorted, and packaged into membrane-bound vesicles before being routed to their final intracellular or extracellular destinations. Which cellular organelle is responsible for this packaging and distribution process?

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Answer: Golgi apparatus

Answer

The Golgi apparatus is the organelle responsible for modifying, sorting, and packaging proteins into vesicles for distribution.
The Golgi apparatus functions as the post office of the cell. It receives newly synthesized proteins from the rough endoplasmic reticulum, adds chemical tags such as carbohydrates, sorts them, and pinches off membrane-bound vesicles to deliver them to specific locations inside the cell or outside via exocytosis.

Step-by-Step Solution

1
Identify the cellular function described in the question stem.
The process involves modifying, sorting, and packaging synthesized proteins into transport vesicles.
Matching the specific metabolic task to the correct organelle determines the correct structure.
2
Evaluate the primary functions of each listed organelle.
Mitochondria produce ATP, chloroplasts conduct photosynthesis, central vacuoles store water and waste, and the Golgi apparatus modifies and packages proteins.
Each organelle possesses a distinct physiological role in eukaryotic cells.
3
Select the organelle corresponding to protein modification and vesicle packaging.
The Golgi apparatus is confirmed as the cellular packaging center.
It receives raw proteins from the endoplasmic reticulum and tags them for their target destinations.

Key Concept

Cellular organelle specialization and protein trafficking
Estimated Time:45s
Question 7Question →

Ribosomes are the cellular structures responsible for synthesizing proteins in both plant and animal cells.

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Answer: True

Answer

True. Ribosomes serve as the primary sites of protein synthesis across all eukaryotic organisms, including plants and animals.
The statement is true because ribosomes are universally responsible for manufacturing proteins from amino acids in both plant and animal cells.

Step-by-Step Solution

1
Identify the biological role of ribosomes.
Ribosomes bind messenger RNA and transfer RNA to synthesize polypeptide chains (proteins).
Understanding organelle specialization verifies whether the stated function matches the organelle.
2
Verify the presence and role of ribosomes in plant and animal cells.
Both plant and animal cells require proteins for structural and enzymatic functions and contain ribosomes in their cytoplasm and on the rough endoplasmic reticulum.
Confirming cellular distribution ensures the scope of the statement is accurate.

Key Concept

Ribosome function in cellular protein synthesis
Estimated Time:30s
Question 8Question →

A biomedical researcher observes that a cell line fails to attach carbohydrate tags to newly synthesized digestive enzymes, causing the enzymes to be misdirected and secreted outside the cell rather than delivered to lysosomes. Which organelle has malfunctioned?

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Answer: Golgi apparatus

Answer

The Golgi apparatus is the malfunctioning organelle responsible for post-translational modification, carbohydrate tagging, and routing of proteins.
The Golgi apparatus functions as the primary sorting and distribution center of the cell. It receives nascent proteins from the rough endoplasmic reticulum, adds post-translational carbohydrate modifications (such as mannose-6-phosphate tags for lysosomal enzymes), and packages them into specific transport vesicles.

Step-by-Step Solution

1
Analyze the specific cellular dysfunction described in the stem.
The defect involves failing to attach carbohydrate recognition tags (glycosylation) and improperly routing enzymes to their target vesicles (lysosomes).
Identifying the biochemical role isolates the organelle responsible for post-translational processing.
2
Map the identified function to the corresponding cellular organelle.
The Golgi apparatus receives newly synthesized proteins from the rough endoplasmic reticulum, modifies them with carbohydrate markers, and sorts them for appropriate cellular destinations.
The Golgi apparatus serves as the central sorting and packaging hub within the endomembrane system.
3
Evaluate and eliminate the alternative structures.
Mitochondria produce ATP, chloroplasts conduct photosynthesis, and the cell wall provides structural protection; none perform protein glycosylation or vesicle routing.
Eliminating distinct functional systems confirms the correct organelle assignment.

Key Concept

The Golgi apparatus functions as the molecular packaging and sorting center of the eukaryotic cell, modifying proteins and directing them to specific intracellular or extracellular destinations.
Estimated Time:1m 0s
Question 9Question →

Which cellular component forms a selectively permeable boundary that regulates the passage of materials into and out of the cell?

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Answer: Cell membrane

Answer

The cell membrane
The cell membrane (also called the plasma membrane) consists of a phospholipid bilayer with embedded proteins. It encloses the cell contents and is selectively permeable, allowing essential nutrients to enter while keeping harmful substances out and expelling waste.

Step-by-Step Solution

1
Identify the primary cellular structure that acts as a selectively permeable barrier.
The plasma membrane (cell membrane) is composed of a phospholipid bilayer that regulates transport into and out of the cytoplasm.
Every living cell requires a flexible, selective barrier to maintain homeostasis by controlling nutrient uptake and waste removal.

Key Concept

Cell membrane structure and selective permeability
Estimated Time:35s
Question 10Question →

Match each cellular organelle with its primary function in a eukaryotic cell.

Click a left item, then click its matching right item

Items

Nucleus
Mitochondrion
Lysosome
Vacuole

Matches

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Answer

Nucleus pairs with housing genetic material and directing cellular activities; Mitochondrion pairs with producing cellular energy in the form of ATP; Lysosome pairs with containing digestive enzymes to break down waste; Vacuole pairs with storing water, nutrients, and maintaining internal pressure.
Each organelle performs a distinct role necessary for cell survival: the nucleus contains DNA and controls cell processes, the mitochondrion produces usable chemical energy (ATP), the lysosome digests cellular waste with specialized enzymes, and the vacuole stores water and essential substances.

Step-by-Step Solution

1
Identify the function of the cell's command center.
The nucleus stores the cell's genetic code (DNA) and directs vital life processes.
Establishing the central control organelle provides a clear foundation for categorizing the remaining structures.
2
Identify the energy-converting organelle.
The mitochondrion synthesizes ATP via cellular respiration.
Mitochondria are specifically dedicated to metabolic energy production.
3
Differentiate between waste degradation and storage organelles.
Lysosomes use digestive enzymes for cellular breakdown, whereas vacuoles serve as storage compartments for fluids and nutrients.
Distinguishing enzymatic catabolism from fluid storage ensures accurate matching of specialized organelles.

Key Concept

Eukaryotic Organelle Functions
Estimated Time:45s
Question 11Question →

Specialized eukaryotic organelles perform distinct biochemical and structural tasks essential for cellular homeostasis. Match each cellular structure listed on the left with its precise physiological role or enzymatic process on the right. How should these cellular structures and functions be correctly paired?

Click a left item, then click its matching right item

Items

Lysosome
Peroxisome
Nucleolus
Centrosome

Matches

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Answer

Lysosome matches with the containment of acid hydrolases for digesting macromolecules and debris; Peroxisome matches with utilizing oxidases and catalase to break down fatty acids and hydrogen peroxide; Nucleolus matches with synthesizing ribosomal RNA and assembling ribosomal subunits; Centrosome matches with organizing the microtubule spindle apparatus for cell division.
Each structure is paired according to its defining biochemical and physical role: lysosomes house hydrolytic enzymes for intracellular digestion, peroxisomes carry out oxidative reactions involving catalase to neutralize peroxides, the nucleolus synthesizes rRNA and assembles ribosome subunits, and the centrosome nucleates microtubule spindle fibers during cell division.

Step-by-Step Solution

1
Differentiate the digestive and oxidative vesicles based on their specific enzymes
Identify that acid hydrolases are specific to lysosomes, whereas catalase and oxidative lipid breakdown are specific to peroxisomes.
Both lysosomes and peroxisomes are membrane-bound spheres, but lysosomes maintain an acidic lumen for macromolecular degradation, while peroxisomes manage redox reactions involving hydrogen peroxide (H2O2H_2O_2).
2
Identify the distinct nuclear subcompartment dedicated to ribosome manufacturing
Match the nucleolus to ribosomal RNA transcription and ribosomal subunit assembly.
The nucleolus is specialized within the nucleus specifically for generating and packaging rRNA before subunits migrate to the cytoplasm.
3
Determine the structural component responsible for mitotic organization
Match the centrosome to organizing microtubules and the mitotic spindle.
The centrosome contains centriole pairs in animal cells and directs the structural tubulin fibers that pull chromosomes apart.

Key Concept

Distinct metabolic, genetic, and structural specializations of eukaryotic cellular organelles
Estimated Time:1m 30s
Question 12Question →

Match each eukaryotic cellular structure with its primary physiological function.

Click a left item, then click its matching right item

Items

Lysosome
Nucleolus
Cytoskeleton
Peroxisome

Matches

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Answer

Lysosome correctly matches hydrolytic waste breakdown; Nucleolus correctly matches ribosomal RNA transcription and subunit synthesis; Cytoskeleton correctly matches structural scaffolding and internal transit; Peroxisome correctly matches fatty acid oxidation and peroxide detoxification.
Each structure performs a distinct function: lysosomes digest cellular waste via hydrolytic enzymes, the nucleolus synthesizes ribosomal RNA and subunits, the cytoskeleton provides structural shape and transport networks, and peroxisomes decompose hydrogen peroxide and metabolize fatty acids.

Step-by-Step Solution

1
Determine the unique metabolic or structural role of each organelle in the eukaryotic cell.
Lysosomes handle waste degradation; the nucleolus builds ribosomal subunits; the cytoskeleton maintains mechanical integrity; peroxisomes neutralize oxidative threats and process lipids.
Eukaryotic cells rely on distinct compartmentalized organelles to carry out specialized, non-overlapping cellular functions.
2
Match each organelle name to the corresponding descriptive function on the right.
Each pair is uniquely and correctly matched without ambiguity.
Differentiating between catabolic vesicles (lysosomes vs. peroxisomes) and structural versus genetic components ensures precise biological categorization.

Key Concept

Eukaryotic Organelle Roles and Functional Specialization
Estimated Time:1m 0s
Question 13Question →

In plant cells, which organelle stores water and nutrients while creating internal turgor pressure to help the plant stay upright?

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Answer: Central vacuole

Answer

Central vacuole
The central vacuole is a prominent, membrane-bound organelle taking up a large portion of a mature plant cell's volume. By filling with water and dissolved substances, it exerts hydrostatic pressure (turgor pressure) outward against the rigid cell wall, keeping plant tissues crisp and upright.

Step-by-Step Solution

1
Identify the cellular functions described in the question: fluid storage and maintenance of internal pressure in plant cells.
The target organelle is large, membrane-bound, and responsible for hydrostatic turgor pressure.
Plant cells rely on internal fluid pressure pressing against their cell walls to maintain structure and prevent wilting.
2
Evaluate the candidate organelles based on their primary functions.
The central vacuole serves as the main water-storage reservoir and provides turgor pressure, whereas ribosomes make proteins, lysosomes digest waste, and the nucleolus makes ribosome subunits.
Matching organelle structure to its specific physiological role identifies the correct answer.

Key Concept

Plant cell specialization and the role of the central vacuole in maintaining turgor pressure and fluid balance.
Estimated Time:45s
Question 14Question →

Animal cells are surrounded by a rigid cell wall composed of cellulose that maintains their fixed shape.

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Answer: False

Answer

False
The statement is false because animal cells do not have a cell wall. A rigid cell wall made of cellulose is an outer structural feature found in plant cells, whereas animal cells are enclosed only by a flexible cell membrane.

Step-by-Step Solution

1
Identify the structural boundaries characteristic of animal cells versus plant cells.
Animal cells possess a flexible outer plasma membrane but do not have a rigid cellulose cell wall.
Cellulose cell walls are specialized structures found in plant cells to provide structural rigidity, whereas animal cells require flexibility for diverse functions and mobility.

Key Concept

Distinction between plant and animal cell boundaries regarding the cell wall
Estimated Time:30s
Question 15Question →

A student examines an unknown biological specimen under a compound light microscope and identifies a rigid cellulose cell wall surrounding the plasma membrane, along with a prominent central vacuole. Based on these observed structures, which of the following conclusions about the specimen is correct?

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Answer: The specimen is a plant cell capable of maintaining internal turgor pressure.

Answer

The specimen is a plant cell capable of maintaining internal turgor pressure.
Plant cells are uniquely characterized by the presence of a rigid outer cell wall composed of cellulose and a large central vacuole. Together, these structures enable the plant cell to absorb water and build internal hydrostatic pressure (turgor pressure) against the cell wall, providing essential structural support.

Step-by-Step Solution

1
Identify the diagnostic cellular structures described in the stem.
The specimen possesses a rigid cellulose cell wall and a large central vacuole.
Cellulose walls and large central vacuoles are defining structural features of plant cells rather than animal cells.
2
Correlate these structures with their primary physiological role.
The central vacuole stores water and exerts outward pressure against the rigid cell wall, creating turgor pressure.
Turgor pressure provides mechanical support and structural rigidity to plant tissues.

Key Concept

Distinction between plant and animal cell structures, specifically the presence and role of the cellulose cell wall and central vacuole in maintaining turgor pressure.
Estimated Time:1m 0s
Question 16Question →

A specialized cell is placed in an experimental chamber containing a solution of radioactive glucose and high concentrations of oxygen. After several hours in complete darkness, a researcher observes that the cell has rapidly consumed the radioactive glucose, producing significant amounts of radioactive carbon dioxide and ATP. Upon microscopic examination, the cell is found to have a rigid outer layer composed of cellulose and a large central sac containing water. Based on these observations, which of the following conclusions about this cell is most accurate?

Show answer & explanation

Answer: It is a plant cell utilizing its mitochondria to perform cellular respiration.

Answer

It is a plant cell utilizing its mitochondria to perform cellular respiration.
The correct answer accurately synthesizes the structural and functional clues. The presence of a rigid cellulose cell wall and a large central vacuole definitively identifies the specimen as a plant cell. Furthermore, the metabolic process described—consuming glucose and oxygen to yield carbon dioxide and ATP in total darkness—is cellular respiration. In eukaryotic cells, including plant cells, this process is carried out by mitochondria.

Step-by-Step Solution

1
Analyze the structural characteristics provided in the prompt.
The cell has a rigid cellulose cell wall and a large central water sac (vacuole).
Identifying these structural features is necessary to determine if the cell is a plant or animal cell.
2
Determine the cell type based on the structural characteristics.
The cell is a plant cell.
Cellulose cell walls and large central vacuoles are defining characteristics of plant cells, distinguishing them from animal cells.
3
Analyze the metabolic activity occurring in the dark chamber.
The cell is consuming glucose and oxygen to produce carbon dioxide and ATP in the absence of light.
Identifying the inputs (glucose, oxygen) and outputs (carbon dioxide, ATP) is required to determine the cellular process.
4
Identify the cellular process and the organelle responsible.
The process is cellular respiration, which takes place in the mitochondria.
Photosynthesis requires light and produces glucose, whereas cellular respiration breaks down glucose to produce ATP and can occur in the dark. Plant cells possess mitochondria and perform cellular respiration to meet their energy needs.

Key Concept

Plant cells possess both chloroplasts for photosynthesis and mitochondria for cellular respiration, and can be distinguished from animal cells by the presence of a cell wall and a large central vacuole.
Question 17Question →

Plant cells synthesize carbohydrates in chloroplasts through photosynthesis and therefore do not contain mitochondria to carry out cellular respiration.

Show answer & explanation

Answer: False

Answer

False. Plant cells possess both chloroplasts and mitochondria.
The statement is false because plant cells contain both chloroplasts and mitochondria. Chloroplasts synthesize organic molecules via photosynthesis, but mitochondria are essential to oxidize those carbohydrates to produce ATP.

Step-by-Step Solution

1
Identify the primary functions of chloroplasts and mitochondria in eukaryotic cells.
Chloroplasts perform photosynthesis to produce organic sugars, whereas mitochondria perform cellular respiration to convert biochemical energy from sugars into ATP.
Distinguishing the energy-converting roles of both organelles is necessary to determine cellular requirements.
2
Evaluate whether plant cells possess mitochondria in addition to chloroplasts.
Plant cells require continuous ATP for metabolic processes, active transport, and growth, which is generated by mitochondria through aerobic respiration.
Directly tests whether chloroplast presence excludes mitochondria in plant biology.

Key Concept

Plant Cell Energy Organelles (Dual Presence of Chloroplasts and Mitochondria)
Estimated Time:45s
Question 18Question →

Which plant cell organelle absorbs sunlight to synthesize glucose from carbon dioxide and water during photosynthesis?

Show answer & explanation

Answer: Chloroplast

Answer

Chloroplast
Chloroplasts are the primary sites of photosynthesis in green plants and algae. They contain chlorophyll pigments that capture light energy and convert it into chemical energy in the form of glucose.

Step-by-Step Solution

1
Identify the cellular process described in the question.
The process described is photosynthesis, which uses solar energy, carbon dioxide, and water to produce glucose.
Recognizing the chemical reaction indicates which specialized organelle performs it.
2
Match the identified function to the corresponding plant organelle.
Chloroplasts contain chlorophyll to trap light energy and conduct photosynthesis.
Other organelles perform distinct functions such as cellular respiration, structural support, or protein synthesis.

Key Concept

Chloroplasts are specialized plastids found in plant cells that carry out photosynthesis.
Estimated Time:40s
Question 19Question →

During a laboratory investigation, a researcher introduces a compound that selectively prevents messenger RNA (mRNA) from being translated into polypeptide chains. Which cellular organelle is directly targeted and inhibited by this compound?

Show answer & explanation

Answer: Ribosomes

Answer

Ribosomes are the cellular organelles directly responsible for translating messenger RNA (mRNA) into polypeptide chains during protein synthesis.
Ribosomes are the cellular complexes responsible for protein synthesis. They bind to messenger RNA (mRNA) strands and assemble amino acids into polypeptide chains according to the genetic code. Inhibiting mRNA translation directly impairs ribosomal function.

Step-by-Step Solution

1
Identify the cellular process disrupted in the scenario.
The compound specifically halts the translation of mRNA into polypeptide chains (proteins).
Determining the exact metabolic pathway affected pinpoints which organelle is malfunctioning.
2
Match the biological process of translation to its corresponding organelle.
Ribosomes read mRNA codons and bind matching transfer RNA (tRNA) molecules to link amino acids together.
Ribosomes serve as the enzymatic machinery for protein synthesis in all living cells.

Key Concept

Ribosomal translation and protein synthesis in cell biology
Estimated Time:45s
Question 20Question →

Which cellular structure provides a rigid outer layer of support and protection in plant cells, but is absent in animal cells?

Show answer & explanation

Answer: Cell wall

Answer

Cell wall
Plant cells possess a rigid outer cell wall made mostly of cellulose that surrounds the cell membrane to maintain structural integrity, withstand turgor pressure, and protect the cell. Animal cells lack a cell wall and have only a flexible cell membrane.

Step-by-Step Solution

1
Identify the structural requirements stated in the question.
The target component must provide rigid outer support and exist in plant cells while being absent in animal cells.
Plant and animal cells share several core organelles but differ in external structural boundaries.
2
Evaluate the candidate cellular structures against the requirements.
The cell wall is a tough external layer made of cellulose found in plant cells but absent in animal cells.
Animal cells are surrounded solely by a flexible cell membrane, whereas plant cells have an outer cell wall outside their membrane.

Key Concept

Distinguishing plant and animal cell structures
Estimated Time:35s
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