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Question 4841Question →

In a socialist command economy, state planners reallocate productive resources to consumer goods and fix official retail prices below their market-clearing levels. If state enterprise managers are evaluated strictly on meeting physical output targets rather than profitability, what is the direct impact on resource allocation and consumer satisfaction?

The price mechanism automatically adjusts production quotas until consumer demand equals supply.

Consumer preferences remain secondary, resulting in persistent product shortages and non-price rationing.

Artificially low retail prices generate a market surplus by encouraging factories to overproduce consumer goods.

Private entrepreneurs intervene to allocate private capital into under-supplied consumer sectors.

Show answer & explanation

Answer: Consumer preferences remain secondary, resulting in persistent product shortages and non-price rationing.

Answer

Consumer preferences remain secondary, resulting in persistent product shortages and non-price rationing.

In a command (socialist) economy, central planning authorities determine resource allocation, production targets, and price levels. When retail prices are artificially fixed below market-clearing equilibrium and managers are rewarded for volume rather than profitability, the economy lacks dynamic price signals to adjust output. Consequently, consumer sovereignty is ignored, resulting in chronic market shortages and non-price rationing such as queues.

Step-by-Step Solution

Identify the primary mechanism for resource allocation in a command economy.

Production decisions and prices are set by central government planners rather than through market forces.

Public ownership of the means of production eliminates the profit motive and free market price signals.

Analyze the effect of administrative price fixing below market-clearing levels.

Prices cannot fluctuate to clear the market, leading to excess demand (shortages) and rationing mechanisms like queuing.

Enterprise managers focus on fulfillment of state-mandated physical units rather than responding to consumer sovereignty.

Key Concept

Central Planning and Resource Allocation in Command Economies

Question 4842Question →

An animal specimen collected during a field study is triploblastic, unsegmented, possesses a pseudocoelom, and has a complete digestive tract with both a mouth and an anus. To which phylum does this organism belong?

Nematoda

Platyhelminthes

Coelenterata

Porifera

Show answer & explanation

Answer: Nematoda

Answer

Nematoda

The correct answer identifies Nematoda because roundworms are characteristically triploblastic, unsegmented, possess a pseudocoelom derived from the blastocoel, and have a complete digestive tract featuring both a mouth and an anus.

Step-by-Step Solution

Analyze the structural characteristics described in the question stem.

The organism is triploblastic (three germ layers), unsegmented, has a pseudocoelom (false body cavity), and features a complete digestive system (mouth and anus).

Identifying diagnostic anatomical features allows precise classification into the correct lower invertebrate phylum.

Compare the features against the characteristics of lower invertebrate phyla.

Porifera lack true tissues. Coelenterata are diploblastic with an incomplete gut. Platyhelminthes are triploblastic but acoelomate with an incomplete gut. Nematoda possess three germ layers, a pseudocoelom, and a complete gut.

The presence of a pseudocoelom combined with a alimentary canal having separate oral and anal openings is unique to Nematoda among the listed lower invertebrate groups.

Key Concept

Body plan and structural characteristics distinguishing lower invertebrate phyla (Porifera, Coelenterata, Platyhelminthes, and Nematoda)

Estimated Time:1m 0s

Question 4843Question →

In national income accounting, non-monetized activities such as unpaid housework performed by family members are included in official Gross Domestic Product (GDP) calculations.

True

False

Show answer & explanation

Answer: False

Answer

The statement is False. Unpaid household services and non-monetized activities are excluded from Gross Domestic Product (GDP) estimations because no money changes hands, creating a major practical difficulty in measuring total national output.

Unpaid domestic work does not enter the market mechanism, so no prices or transactional data exist to measure its value. Consequently, statistical agencies omit these non-monetized activities, which remains a primary conceptual and practical problem in national income measurement.

Step-by-Step Solution

Examine the role of non-monetized household activities in economic accounting.

Unpaid housework generates utility and productive output but lacks a market price.

National income accounting depends primarily on recorded monetary transactions in organized markets.

Determine if non-market domestic activities are included in official GDP statistics.

They are omitted from official national income figures.

The absence of transaction receipts makes calculating an accurate monetary valuation extremely difficult.

Key Concept

Exclusion of Non-Monetized Transactions

Estimated Time:45s

Question 4844Question →

In Nigeria's agricultural sector, cattle rearing simultaneously yields beef and hides, whereas raw cassava tubers can be processed into either garri or industrial starch. If an expansion in livestock farming occurs alongside a major shift by processors toward industrial starch production, what will be the effect on the market supply of hides and garri?

The supply of hides will increase, while the supply of garri will decrease.

The supply of hides will decrease, while the supply of garri will increase.

The supply of both hides and garri will increase.

The supply of hides will remain unchanged, while garri experiences a movement along its existing supply curve.

Show answer & explanation

Answer: The supply of hides will increase, while the supply of garri will decrease.

Answer

The supply of hides will increase, while the supply of garri will decrease.

Beef and hides are by-products of cattle rearing, meaning they are in joint (complementary) supply; expanding livestock production inherently increases hide availability. On the other hand, garri and industrial starch rely on cassava as a shared input, placing them in competitive supply; diverting cassava toward starch manufacturing reduces the raw materials available for garri, shifting the supply curve of garri to the left (decrease in supply).

Step-by-Step Solution

Identify the type of supply relationship between beef and hides.

Beef and hides are produced together from cattle rearing, making them joint (complementary) supply goods.

An increase in cattle production automatically leads to an increase in the output of both beef and hides.

Identify the type of supply relationship between garri and industrial starch.

Garri and industrial starch compete for the same raw material (cassava), making them competitive supply goods.

Because the supply of raw cassava is finite, increasing the quantity allocated to industrial starch leaves less cassava available for garri processing.

Synthesize the simultaneous market effects.

Increased cattle farming shifts the supply curve of hides to the right (increase in supply), while reallocation of cassava to starch shifts the supply curve of garri to the left (decrease in supply).

Joint supply leads to parallel movement with primary production, whereas competitive supply creates an inverse production relationship between competing final uses.

Key Concept

Distinguishing between Joint (Complementary) Supply and Competitive Supply

Estimated Time:2m 0s

Question 4845Question →

In a population of moths inhabiting an industrial region, dark-colored individuals became significantly more common over several generations as pollution darkened the tree trunks. According to Charles Darwin's theory of natural selection, which mechanism best accounts for this change in the population?

Pre-existing dark genetic variations provided a camouflage advantage against predators, resulting in higher survival and reproduction rates for dark moths.

Individual light-colored moths actively developed darker wing pigments during their lifetime to adapt to the soot and passed these acquired traits to their offspring.

Environmental soot directly induced beneficial genetic mutations in all light moths to prevent the species from going extinct.

Light-colored moths stopped using their light wing pigments, causing the light coloration to deteriorate and disappear over generations.

Show answer & explanation

Answer: Pre-existing dark genetic variations provided a camouflage advantage against predators, resulting in higher survival and reproduction rates for dark moths.

Answer

Pre-existing dark genetic variations provided a camouflage advantage against predators, resulting in higher survival and reproduction rates for dark moths.

According to Darwin's theory of natural selection, populations contain natural genetic variations. When the environment changed due to industrial pollution, dark moths gained a camouflage advantage. They were preyed upon less frequently by birds, allowing them to survive and pass their dark-pigment genes to the next generation at higher rates.

Step-by-Step Solution

Identify the foundation of Darwinian evolution.

Natural selection requires inherited genetic variation to already exist within a population prior to environmental change.

Organisms do not generate intentional phenotypic changes within their lifetime to suit new environments.

Analyze the environmental selective pressure.

Soot-covered trees made dark moths less visible to predators compared to light-colored moths.

Selective pressures determine which existing phenotypes offer a survival advantage.

Determine the population-level outcome.

Darker moths survived longer and produced more offspring, increasing the proportion of dark moths in future generations.

Differential survival and reproduction cause advantageous alleles to accumulate in the population over time.

Key Concept

Natural Selection and Differential Reproduction

Estimated Time:1m 0s

Question 4846Question →

Match each short-run cost concept on the left with its correct definition or property on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Total Fixed Cost (TFC) matches with 'Cost that remains constant regardless of the quantity of output produced'; Marginal Cost (MC) matches with 'The addition to total cost resulting from producing one extra unit of output'; Average Variable Cost (AVC) matches with 'Total variable cost divided by the total quantity of output produced'; Average Fixed Cost (AFC) matches with 'Total fixed cost divided by quantity, which continuously declines as output increases'.

Total Fixed Cost represents expenses that remain constant regardless of output. Marginal Cost measures the additional cost incurred when producing one extra unit. Average Variable Cost is total variable cost per unit of output. Average Fixed Cost is total fixed cost per unit of output, which declines continuously as output expands.

Step-by-Step Solution

Identify the definition of Total Fixed Cost (TFC)

TFC is independent of output volume

By definition, fixed costs remain unchanged regardless of how much output is produced in the short run.

Identify the definition of Marginal Cost (MC)

MC is the addition to total cost from producing one more unit

Marginal refers to incremental change, calculated as

MC = \frac{\Delta TC}{\Delta Q}

Identify the definition of Average Variable Cost (AVC)

AVC is variable cost per unit of output

Average variable cost is calculated by dividing total variable cost by total output (

AVC = \frac{TVC}{Q}

Identify the definition of Average Fixed Cost (AFC)

AFC is fixed cost per unit, which declines continuously as output rises

Since TFC is constant, dividing it by an increasing output

Q

causes AFC to continuously diminish.

Key Concept

Definitions and properties of short-run cost concepts

Question 4847Question →

A manufacturing enterprise operating in a developing economy is determining whether to utilize fully automated assembly lines or hire additional manual laborers to manufacture agricultural tools. Which basic economic problem of society is this enterprise primarily addressing?

How to produce

What goods and services to produce

For whom to produce

How to minimize explicit financial outlay

Show answer & explanation

Answer: How to produce

Answer

How to produce

The correct answer identifies the problem of 'How to produce', which deals with determining the specific combination of resources (labor vs. capital) and technological methods used in the production process.

Step-by-Step Solution

Analyze the decision facing the enterprise in the scenario.

The firm is choosing between two production techniques: capital-intensive machinery versus labor-intensive manual work.

Identifying the nature of the economic choice is necessary to categorize the underlying fundamental economic problem.

Relate the input combination choice to the fundamental economic questions.

The choice of input proportions and technical methods of production corresponds directly to the problem of technique selection.

Economic theory defines 'How to produce' as the decision regarding which combination of factors of production (capital vs. labor) to employ.

Select the option representing factor combination.

The firm is resolving 'How to produce'.

This directly matches the technical decision highlighted in the scenario.

Key Concept

Basic Economic Problems of Society - How to produce

Estimated Time:1m 0s

Question 4848Question →

Match each digestive secretion or enzyme of the mammalian alimentary canal with its primary physiological function or mode of action in animal nutrition.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Bile salts pair with lipid emulsification; Enterokinase pairs with trypsinogen activation; Ptyalin pairs with starch hydrolysis to maltose; Rennin pairs with caseinogen coagulation.

Each secretion or enzyme fulfills a distinct biochemical function: bile salts physically emulsify fats to assist lipase, enterokinase converts inactive trypsinogen into active trypsin in the small intestine, ptyalin hydrolyzes starch to maltose in the buccal cavity, and rennin precipitates milk protein in juvenile stomachs.

Step-by-Step Solution

Identify the non-enzymatic role of liver secretions in fat digestion.

Bile salts reduce lipid surface tension without chemical cleavage, performing emulsification.

Increasing the lipid surface area enhances subsequent chemical digestion by lipase.

Determine the activation cascade of pancreatic proteolytic enzymes.

Enterokinase, secreted by the succus entericus, activates trypsinogen to trypsin.

Proteolytic enzymes are produced as inactive zymogens to prevent autolysis of gland tissues.

Analyze carbohydrate hydrolysis in the anterior alimentary canal.

Ptyalin (salivary amylase) breaks down cooked starch to maltose.

Amylase acts specifically on alpha-1,4 glycosidic bonds in cooked carbohydrates.

Examine specialized gastric protein digestion in young mammals.

Rennin converts soluble caseinogen to insoluble casein in the presence of calcium ions.

Precipitating milk protein slows gut transit time so pepsin can effectively digest it.

Key Concept

Digestive Secretions, Enzymes, and Functional Specificity

Question 4849Question →

A monopolist faces a market demand curve given by $P = 70 - 2Q$ and operates with a short-run total cost function $TC = 50 + 10Q + Q^2$ , where $P$ is the price in Naira ( $\mathbb{N}$ ) and $Q$ is the output level in units. What is the firm's profit-maximizing output level and its resulting short-run economic profit?

10

units of output and a profit of

\mathbb{N}250

15

units of output and a profit of

\mathbb{N}175

10

units of output and a profit of

\mathbb{N}200

10

units of output and a profit of

\mathbb{N}50

Show answer & explanation

Answer: $10$ units of output and a profit of $\mathbb{N}250$

Answer

The profit-maximizing output is

10

units and the short-run economic profit is

\mathbb{N}250

To find the equilibrium output for a monopolist, set Marginal Revenue equal to Marginal Cost (

MR = MC

). From the demand equation

P = 70 - 2Q

, Total Revenue is

TR = 70Q - 2Q^2

, yielding

MR = 70 - 4Q

. The derivative of Total Cost

TC = 50 + 10Q + Q^2

gives

MC = 10 + 2Q

. Equating

70 - 4Q = 10 + 2Q

yields

6Q = 60

, so

Q = 10

units. Substituting

Q = 10

into the demand curve yields

P = 70 - 2(10) = \mathbb{N}50

. Total Revenue is

10 \times 50 = \mathbb{N}500

and Total Cost is

50 + 10(10) + 10^2 = \mathbb{N}250

. Subtracting Total Cost from Total Revenue gives an economic profit of

\mathbb{N}250

Step-by-Step Solution

Derive Total Revenue (

TR

) and Marginal Revenue (

MR

) functions from the demand curve.

TR = P \times Q = (70 - 2Q)Q = 70Q - 2Q^2

, so

MR = \frac{dTR}{dQ} = 70 - 4Q

Monopoly pricing power implies

MR

declines at twice the rate of the linear demand curve.

Derive the Marginal Cost (

MC

) function from Total Cost (

TC

MC = \frac{dTC}{dQ} = 10 + 2Q

Marginal cost is the first derivative of the total cost function with respect to output.

Equate

MR

and

MC

to find the profit-maximizing equilibrium output (

Q

70 - 4Q = 10 + 2Q \implies 60 = 6Q \implies Q = 10

units.

All profit-maximizing firms produce where marginal revenue equals marginal cost.

Substitute equilibrium output into the demand function to find the selling price (

P

P = 70 - 2(10) = 50

Naira.

The price a monopolist can charge is determined by consumer demand at the profit-maximizing output level.

Calculate Total Revenue (

TR

), Total Cost (

TC

), and Economic Profit (

\pi

TR = 50 \times 10 = 500

Naira;

TC = 50 + 10(10) + (10)^2 = 250

Naira;

\pi = TR - TC = 500 - 250 = 250

Naira.

Economic profit equals total revenue minus total cost.

Key Concept

Monopoly Short-Run Price and Output Determination

Estimated Time:2m 0s

Question 4850Question →

Match each type or characteristic of oligopoly on the left with its corresponding market description on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Collusive Oligopoly matches with firms agreeing on price and output to restrict competition; Non-Collusive Oligopoly matches with independent strategic behavior; Pure Oligopoly matches with producing identical/homogeneous goods; Differentiated Oligopoly matches with producing distinct, branded products.

Collusive oligopoly is defined by firm cooperation and collusion; Non-collusive oligopoly features independent strategic action; Pure oligopoly is characterized by homogeneous products; Differentiated oligopoly features distinct, branded products.

Step-by-Step Solution

Analyze oligopoly categories based on market conduct and cooperation.

Collusive oligopolies feature cooperation and price agreement, while non-collusive oligopolies feature independent strategic rivalry.

Firm behavior regarding mutual agreements determines the collusive or non-collusive nature of the market.

Analyze oligopoly categories based on product differentiation.

Pure oligopolies involve homogeneous products like cement, while differentiated oligopolies feature distinct branded goods like motor vehicles.

Product nature distinguishes pure (standardized) from differentiated (heterogeneous) oligopoly structures.

Key Concept

Classification and types of oligopoly market structures

Question 4851Question →

In a non-collusive oligopolistic market for wireless telecommunication services, a major network provider operating at an equilibrium price of $P_0$ observes that raising its subscription rates leads to a sharp decline in total revenue, while lowering rates below $P_0$ yields negligible changes in sales volume. Based on the kinked demand curve model, which of the following explains this asymmetric revenue outcome?

Rival firms ignore price increases, making demand relatively elastic above

P_0

, but match price cuts, making demand relatively inelastic below

P_0

Rival firms match price increases to protect profit margins, making demand inelastic above

P_0

, but ignore price cuts, making demand elastic below

P_0

The firm operates on a perfectly elastic demand curve both above and below

P_0

due to formal collusion among market leaders.

Rival firms ignore both price cuts and price increases, causing a horizontal shift in the firm's marginal revenue curve.

Show answer & explanation

Answer: Rival firms ignore price increases, making demand relatively elastic above $P_0$ , but match price cuts, making demand relatively inelastic below $P_0$ .

Answer

Rival firms ignore price increases, making demand relatively elastic above the prevailing price, but match price cuts, making demand relatively inelastic below the prevailing price.

Under non-collusive oligopoly, Paul Sweezy's kinked demand curve model assumes asymmetrical rival behavior: competitors ignore price increases (making the demand curve elastic above the prevailing price

P_0

) and match price cuts (making the demand curve inelastic below

P_0

). This causes total revenue to fall when prices are raised and fail to increase when prices are lowered, reinforcing price rigidity at

P_0

Step-by-Step Solution

Analyze the price increase scenario above the prevailing price

P_0

If the firm raises price above

P_0

, competitors do not follow because they can capture switching customers. Consequently, quantity demanded falls drastically, demonstrating that demand is relatively price elastic (

E_d > 1

). Total revenue falls.

Competitors seek to gain market share at the expense of the price-raising firm.

Analyze the price cut scenario below the prevailing price

P_0

If the firm lowers price below

P_0

, competitors immediately match the price cut to prevent losing their customers. The initiating firm gains very little additional quantity, demonstrating that demand is relatively price inelastic (

E_d < 1

). Total revenue does not rise significantly.

Competitors protect their existing customer base from price undercutting.

Combine the two behavioral responses to explain the asymmetric revenue outcome.

The asymmetry in rival behavior creates a 'kink' in the demand curve at price

P_0

, resulting in price rigidity, as any price movement away from

P_0

decreases or fails to meaningfully improve total revenue.

Paul Sweezy's kinked demand model accounts for mutual interdependence under non-collusive oligopoly.

Key Concept

Price Interdependence and Sweezy's Kinked Demand Curve Model

Estimated Time:1m 30s

Question 4852Question →

An increase in the price of yam leads to a rise in the demand for cassava as consumers switch to an alternative staple food. What type of demand is demonstrated by cassava in this market scenario?

Competitive demand

Joint demand

Derived demand

Composite demand

Show answer & explanation

Answer: Competitive demand

Answer

Competitive demand

Cassava and yam serve as alternative staple foods. When the price of yam increases, consumers substitute away from yam toward cassava, which demonstrates competitive demand.

Step-by-Step Solution

Analyze the relationship between yam and cassava in the scenario

The two goods serve as alternative options to satisfy the same consumer want (staple food).

When the price of yam rises, consumers switch to purchasing cassava instead.

Identify the classification of demand for substitute goods

The demand for cassava is classified as competitive demand.

Competitive demand exists between commodities that are substitutes for one another.

Key Concept

Types of Demand (Competitive / Substitute Demand)

Estimated Time:45s

Question 4853Question →

Which of the following chemical changes occurs during the industrial conversion of a liquid vegetable oil into solid margarine via catalytic hydrogenation?

The ester linkages are hydrolyzed to yield glycerol and free fatty acids

The degree of unsaturation decreases as carbon-carbon double bonds are converted to single bonds

The alkanoic acid chains undergo dehydration to produce gaseous alkynes

The triacylglycerol molecules are oxidized to form short-chain dicarboxylic acids

Show answer & explanation

Answer: The degree of unsaturation decreases as carbon-carbon double bonds are converted to single bonds

Answer

The degree of unsaturation decreases as carbon-carbon double bonds are converted to single bonds.

Vegetable oils are naturally liquid at room temperature due to their high degree of unsaturation (presence of multiple

C=C

double bonds in the fatty acid tails). During industrial hydrogenation, hydrogen gas (

H_2

) is reacted with the oil using a nickel catalyst at elevated temperatures. This addition reaction converts unsaturated

C=C

bonds into saturated

C-C

single bonds, thereby decreasing the degree of unsaturation, increasing the packing efficiency of the molecules, and raising the melting point to produce solid margarine.

Step-by-Step Solution

Identify the chemical structure of vegetable oils

Vegetable oils are liquid triacylglycerols (esters of glycerol and long-chain fatty acids) containing a high proportion of unsaturated carbon-carbon double bonds (

C=C

Liquid fats have lower melting points due to kinks created by double bonds in the hydrocarbon chains.

Determine the reaction mechanism of catalytic hydrogenation

Addition of hydrogen gas (

H_2

) in the presence of a finely divided nickel catalyst converts

C=C

double bonds into

C-C

single bonds.

Adding hydrogen saturates the hydrocarbon chains, causing them to pack more tightly and raising their melting point to solidify the oil into margarine.

Key Concept

Hardening of Oils and Hydrogenation of Unsaturated Lipids

Estimated Time:1m 0s

Question 4854Question →

During a period of persistent demand-pull inflation, an economy experiences rapid increases in the general price level driven by excess aggregate demand. Which of the following fiscal policy measures should the government adopt to stabilize the economy?

Increase personal income tax rates and cut spending on public projects

Reduce income tax rates and expand government expenditure on infrastructure

Sell government treasury bills in the open market and raise commercial bank reserve requirements

Increase government transfer payments to households while maintaining budget deficits

Show answer & explanation

Answer: Increase personal income tax rates and cut spending on public projects

Answer

The government should implement contractionary fiscal policy by raising direct tax rates and cutting public spending to reduce aggregate demand and cool down inflation.

The correct action is to raise personal income taxes and reduce government spending. Higher tax rates lower disposable income for consumers, which decreases private consumption expenditure. Simultaneously, reduced government spending cuts public sector demand. Together, these contractionary fiscal measures lower aggregate demand and bring inflation under control.

Step-by-Step Solution

Identify the macroeconomic problem

The economy is experiencing demand-pull inflation caused by excessive aggregate demand.

Economic stabilization requires dampening total expenditure to align demand with supply.

Distinguish fiscal policy instruments from monetary policy instruments

Fiscal policy involves government taxation and spending, whereas monetary policy involves central bank reserve ratios, interest rates, and open market operations.

The question specifically asks for a fiscal policy solution.

Select the appropriate fiscal direction

Contractionary fiscal policy (higher taxes and reduced public spending) contracts disposable income and aggregate demand.

Reducing total demand lowers pressure on overall price levels.

Key Concept

Contractionary Fiscal Policy for Inflation Control

Question 4855Question →

Consider the reversible gas-phase reaction represented by the equation below:

N_2O_4(g) \rightleftharpoons 2NO_2(g) \quad \Delta H = +57.2\text{ kJ mol}^{-1}

Which of the following conditions will shift the position of equilibrium to favor the yield of nitrogen dioxide ( $NO_2$ )?

Increasing the temperature of the reaction vessel

Adding a platinum catalyst to the equilibrium mixture

Increasing the total pressure on the equilibrium system

Decreasing the volume of the reaction container at constant temperature

Show answer & explanation

Answer: Increasing the temperature of the reaction vessel

Answer

Increasing the temperature of the reaction vessel

Because the forward reaction absorbs heat (endothermic,

\Delta H > 0

), an increase in temperature shifts the position of dynamic equilibrium toward the right (forward direction) to absorb the excess thermal energy, thereby increasing the equilibrium yield of nitrogen dioxide (

NO_2

Step-by-Step Solution

Analyze the enthalpy change (

\Delta H

) of the forward reaction

The forward reaction

N_2O_4(g) \rightarrow 2NO_2(g)

has

\Delta H = +57.2\text{ kJ mol}^{-1}

, indicating an endothermic process.

Temperature perturbations affect equilibrium based on whether heat is absorbed or released.

Apply Le Chatelier's principle for a temperature increase

Increasing temperature adds heat energy to the system, causing the system to absorb heat by shifting in the endothermic (forward) direction.

The system opposes the stress of added heat by favoring the reaction direction that consumes heat.

Determine the effect on product yield

Shifting to the right increases the equilibrium concentration and yield of

NO_2(g)

The forward reaction produces

NO_2(g)

Key Concept

Le Chatelier's Principle and Temperature Perturbation

Question 4856Question →

A freshwater unicellular protist such as Amoeba continuously absorbs water from its hypotonic environment while producing metabolic nitrogenous waste. Which of the following correctly identifies the organelle responsible for maintaining osmotic balance and the primary mechanism by which its nitrogenous waste is eliminated?

Contractile vacuole for osmoregulation, and diffusion across the cell surface membrane for nitrogenous waste excretion

Flame cells for osmoregulation, and nephridia for nitrogenous waste excretion

Contractile vacuole for nitrogenous waste excretion, and diffusion across the cell surface membrane for osmoregulation

Malpighian tubules for osmoregulation, and contractile vacuole for nitrogenous waste excretion

Show answer & explanation

Answer: Contractile vacuole for osmoregulation, and diffusion across the cell surface membrane for nitrogenous waste excretion

Answer

The contractile vacuole functions in osmoregulation, while nitrogenous wastes are excreted via diffusion across the general cell surface membrane.

In freshwater protozoans like Amoeba, the contractile vacuole serves specifically for osmoregulation by collecting and pumping out excess water that constantly diffuses into the hypertonic cytoplasm. Nitrogenous waste, mainly ammonia, is small, soluble, and removed primarily by simple diffusion across the cell surface membrane into the aquatic environment.

Step-by-Step Solution

Identify the osmoregulatory challenge of freshwater single-celled organisms

Because the interior cytoplasm of Amoeba is hypertonic to freshwater, water constantly enters the cell via osmosis.

To prevent bursting (osmotic lysis), excess water must be continuously gathered and discharged.

Determine the organelle responsible for water balance

The contractile vacuole collects excess intracellular fluid, migrates to the plasma membrane, and fuses with it to expel water externally.

This establishes the contractile vacuole as the dedicated osmoregulatory organelle.

Identify how metabolic waste products are discharged

Ammonia (

NH_3

) is highly soluble and diffuses readily down its concentration gradient across the thin cell surface membrane.

Unicellular organisms lack specialized organ systems, relying on a high surface area-to-volume ratio for waste removal via simple diffusion.

Key Concept

Excretory mechanisms and osmoregulation in single-celled organisms

Estimated Time:1m 0s

Question 4857Question →

A monopolist faces a market demand function given by $P = 140 - 2Q$ , where $P$ is the price in Naira and $Q$ is the output level. The total cost function of the firm is $TC = 20Q + Q^2 + 200$ . What is the maximum economic profit, in Naira, earned by the monopolist at equilibrium?

Show answer & explanation

Answer: 1000

Answer

The maximum economic profit earned by the monopolist at profit-maximizing equilibrium is 1000 Naira.

To maximize economic profit, a monopolist sets marginal revenue equal to marginal cost (

MR = MC

). From

P = 140 - 2Q

TR = 140Q - 2Q^2

, giving

MR = 140 - 4Q

. Differentiating

TC = 20Q + Q^2 + 200

gives

MC = 20 + 2Q

. Equating

MR = MC

yields

140 - 4Q = 20 + 2Q \implies Q = 20

units. Substituting

Q = 20

into the demand equation gives price

P = 100

Naira. Total revenue is

2000

Naira (

100 \times 20

) and total cost is

1000

Naira (

20(20) + 20^2 + 200

). The resulting maximum economic profit is

2000 - 1000 = 1000

Naira.

Step-by-Step Solution

Derive Total Revenue (TR) and Marginal Revenue (MR) functions

TR = 140Q - 2Q^2

and

MR = 140 - 4Q

Marginal revenue is the first derivative of total revenue with respect to quantity.

Derive Marginal Cost (MC) function

MC = 20 + 2Q

Marginal cost is the first derivative of total cost with respect to quantity.

Equate MR to MC to solve for the profit-maximizing output level (Q)

140 - 4Q = 20 + 2Q \implies 6Q = 120 \implies Q = 20

units

The necessary condition for profit maximization in all market structures is

MR = MC

Determine the equilibrium price (P) from the demand curve

P = 140 - 2(20) = 100

Naira

Monopolists set price based on consumer willingness to pay at the profit-maximizing output level.

Calculate Total Revenue (TR), Total Cost (TC), and Economic Profit (\pi)

TR = 100 \times 20 = 2000

TC = 20(20) + (20)^2 + 200 = 1000

, Profit

= 2000 - 1000 = 1000

Naira

Economic profit is the difference between total revenue and total cost at equilibrium output.

Key Concept

Monopoly Profit Maximization Condition (MR = MC)

Estimated Time:2m 30s

Question 4858Question →

Which system of taxation takes a higher percentage of income from higher-income earners than from lower-income earners?

Progressive tax system

Regressive tax system

Proportional tax system

Specific tax system

Show answer & explanation

Answer: Progressive tax system

Answer

Progressive tax system

In a progressive tax system, the rate of tax increases as the taxable income increases. Consequently, individuals with higher incomes pay a larger percentage of their total income in tax compared to those with lower incomes.

Step-by-Step Solution

Define the relationship between tax rate and income level.

Identify the system where the tax rate increases as income increases.

Tax systems are classified by how the tax rate changes relative to the taxpayer's income base.

Evaluate the definition against standard tax system types.

A system where high earners pay a higher proportion of income is defined as progressive taxation.

Progressive taxation is designed to reduce income inequality by scaling tax rates according to ability to pay.

Key Concept

Progressive Taxation

Question 4859Question →

Match each type of economic system listed on the left with its corresponding primary mechanism of resource allocation on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Free Market Economy matches with resource allocation guided by consumer sovereignty, private ownership, and the price mechanism; Command Economy matches with resource allocation controlled entirely by a central planning authority and public ownership; Mixed Economy matches with resource allocation featuring the co-existence of private market forces and state intervention; Traditional Economy matches with resource allocation determined primarily by customs, habits, and ancestral traditions.

Each economic system is characterized by how it addresses the fundamental economic problems of what, how, and for whom to produce. Capitalist market systems rely on decentralized price signals, command economies use state planning directives, mixed economies integrate both market and government actions, and traditional economies depend on inherited social customs.

Step-by-Step Solution

Identify the defining allocation mechanism for Free Market Economy.

Free market systems rely on private property and price signals resulting from market forces.

Consumer sovereignty and price mechanisms drive market decisions in capitalism.

Identify the defining allocation mechanism for Command Economy.

Command systems are centrally planned by state directives rather than price indicators.

Socialism places resource control under government authority.

Identify the defining allocation mechanism for Mixed Economy.

Mixed economies balance market operations with government regulatory and public service roles.

It combines aspects of both private enterprise and state intervention.

Identify the defining allocation mechanism for Traditional Economy.

Traditional economies answer production questions through historical custom and social roles.

Heritage and non-market customs govern economic activity in traditional systems.

Key Concept

Types of Economic Systems and their Resource Allocation Mechanisms

Question 4860Question →

In Paul Sweezy's kinked demand curve model for a non-collusive oligopoly, a firm observes that its price elasticity of demand is $|E_d| = 2.5$ for price increases above the prevailing market price $P_0$ , but $|E_d| = 0.4$ for price cuts below $P_0$ . Which of the following best explains the underlying behavioral assumption of rival firms and the resulting structure of the firm's marginal revenue curve?

Rival firms ignore price increases but match price cuts, creating a sharp change in demand elasticity at

P_0

that results in a vertical discontinuity (gap) in the marginal revenue curve at the prevailing output level.

Rival firms match price increases to protect profit margins but ignore price reductions, making demand relatively inelastic above

P_0

and highly elastic below

P_0

Rival firms collude to fix prices at

P_0

, ensuring that the firm's marginal revenue remains equal to average revenue across all output levels despite changes in marginal cost.

Rival firms ignore both price increases and price cuts, causing the demand curve to remain smooth and linear with a continuous marginal revenue curve passing through

P_0

Show answer & explanation

Answer: Rival firms ignore price increases but match price cuts, creating a sharp change in demand elasticity at $P_0$ that results in a vertical discontinuity (gap) in the marginal revenue curve at the prevailing output level.

Answer

Rival firms ignore price increases but match price cuts, creating a sharp change in demand elasticity at the prevailing price that results in a vertical discontinuity (gap) in the marginal revenue curve at the prevailing output level.

The correct option accurately captures the fundamental premise of Sweezy's kinked demand model: an oligopolist expects competitors to ignore price increases (making demand price-elastic above

P_0

) but match price reductions (making demand price-inelastic below

P_0

). This change in elasticity at

P_0

creates a kink in the demand curve, which mathematically generates a discontinuous vertical gap in the marginal revenue curve at the existing output level.

Step-by-Step Solution

Analyze rival firm reactions under non-collusive oligopoly according to Sweezy's hypothesis.

If a firm raises its price above

P_0

, rival firms will not follow, causing the price-raising firm to lose a significant market share (

|E_d| = 2.5 > 1

, elastic segment). Conversely, if the firm lowers its price below

P_0

, rival firms immediately match the price cut to prevent losing customers, resulting in minimal extra market share gained by the firm (

|E_d| = 0.4 < 1

, inelastic segment).

Establishing rival reaction patterns defines the shape of the firm's average revenue (demand) curve.

Examine the geometric relationship between the kinked demand curve and the marginal revenue (MR) curve.

Because the slope of the demand curve changes abruptly (kinks) at the prevailing output level corresponding to price

P_0

, the derived MR curve exhibits a vertical break or gap directly below the point of the kink.

Each linear or curved segment of demand produces its own MR line; the transition between the elastic upper portion and inelastic lower portion creates a vertical discontinuity.

Evaluate the economic implication of the vertical MR gap for price rigidity.

As long as the firm's marginal cost (MC) curve shifts within this vertical gap in the MR curve, the profit-maximizing condition

MC = MR

continues to occur at the same output level and prevailing price

P_0

, explaining price stability (rigidity) in oligopolistic markets.

Synthesizes the behavioral assumptions with the structural characteristics of the kinked demand framework.

Key Concept

Kinked Demand Curve and Price Rigidity in Non-Collusive Oligopoly

Estimated Time:2m 0s

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