Which organelle is primarily responsible for protein synthesis in eukaryotic cells?
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Reference & Solution
Correct Answer:B
Your Attempt:No input ✗
Mark Scheme Analysis:
Ribosomes are the cellular machines responsible for translating mRNA transcripts into polypeptide chains (protein synthesis). Mitochondria synthesize ATP via oxidative phosphorylation, the nucleus stores genetic material, and the Golgi apparatus modifies, sorts, and packages proteins for secretion.
What is the stoichiometric balanced equation for the complete combustion of methane ()?
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Reference & Solution
Correct Answer:B
Your Attempt:No input ✗
Mark Scheme Analysis:
Complete combustion of methane requires sufficient oxygen to produce carbon dioxide and water: . Balancing: 1 Carbon on both sides; 4 Hydrogens produce ; right side has Oxygens, requiring on the reactant side. Option A is unbalanced, and Option C represents incomplete combustion.
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MathsQuadratic Equations & RootsPending
Solve the quadratic equation algebraically:
简答作答区 (支持 LaTeX $...$)
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Reference & Solution
Correct Answer:x = 3 or x = -1/2
Your Attempt:No input
Mark Scheme Analysis:
Factoring by grouping: find two numbers that multiply to and sum to . These are and . Rewrite: . Setting each factor to zero gives or . Common mistake: Omitting the fractional negative root.
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PhysicsForces & Newton's Laws✓ Mastered
What is the SI derived unit of force, and what is its equivalent in base SI units?
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Reference & Solution
Correct Answer:C
Your Attempt:No input ✗
Mark Scheme Analysis:
From Newton's second law (), force has the derived unit Newton (N), which in SI base units is . Joule () is the unit of work/energy, Watt is power, and Pascal is pressure ().
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EconomicsMacroeconomic Objectives & PolicyPending
Which of the following is widely recognized as a fundamental macroeconomic objective of national governments?
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Reference & Solution
Correct Answer:B
Your Attempt:No input ✗
Mark Scheme Analysis:
The core macroeconomic objectives comprise: low and stable inflation, low unemployment (high employment), sustainable long-term economic growth, and balance of payments equilibrium. Options A, C, and D are microeconomic corporate objectives.
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BiologyCell Membranes & Active TransportPending
Describe the primary mechanism and stoichiometry of the sodium-potassium pump ( ATPase).
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Reference & Solution
Correct Answer:B
Your Attempt:No input ✗
Mark Scheme Analysis:
The sodium-potassium pump is an electrogenic transmembrane protein that hydrolyzes 1 molecule of ATP to actively export 3 ions and import 2 ions against their respective electrochemical gradients, maintaining the negative resting membrane potential and cellular osmotic balance.
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MathsDifferentiation & Calculus✓ Mastered
Find the first derivative of the polynomial .
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Reference & Solution
Correct Answer:12x³ - 4x + 5
Your Attempt:No input
Mark Scheme Analysis:
Applying the power rule term by term:
Therefore, . Common pitfall: forgetting that the derivative of a linear term is its constant coefficient .
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ChemistryEnergetics & Enthalpy CyclesPending
Define standard enthalpy change of formation ().
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Reference & Solution
Correct Answer:Enthalpy change when 1 mole of a compound is formed from its constituent elements in standard states under standard conditions (298 K, 100 kPa)
Your Attempt:No input
Mark Scheme Analysis:
Standard enthalpy change of formation () is precisely defined as the enthalpy change when ONE mole of a compound is formed from its constituent elements in their standard states under standard conditions (298 K, 100 kPa). Essential key points required by examiners: "1 mole of compound", "from constituent elements", and "standard states/conditions".
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PhysicsDirect Current Circuits & Ohm's LawPending
State Ohm's Law and state the condition under which it strictly holds true.
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Reference & Solution
Correct Answer:B
Your Attempt:No input ✗
Mark Scheme Analysis:
Ohm's Law states that the electric current passing through an ohmic conductor between two points is directly proportional to the potential difference across the two points, provided all physical conditions such as temperature remain constant ().