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Question 9381Question →

Complete the statement below regarding market demand relationships by identifying the correct classification of demand.

Fill in the blanks below

When an increase in the market demand for residential housing directly leads to a higher demand for construction materials such as cement, the demand for cement is classified as demand.

Show answer & explanation

Answer

derived

The correct answer is derived demand because the demand for raw materials like cement does not arise for direct personal satisfaction, but is derived from the consumer demand for the final output (residential housing).

Step-by-Step Solution

Analyze the relationship between the two commodities mentioned in the scenario

Residential housing is the final consumer commodity, whereas cement is an intermediate input used in construction.

Identifying whether a product is a final good or an input helps determine the origin of its demand.

Apply the economic definition of derived demand

The demand for cement exists because of the demand for the final product (housing).

When the demand for a factor or raw material depends on the demand for the ultimate good it produces, it is known as derived demand.

Key Concept

Derived Demand

Estimated Time:45s

Question 9382Question →

The table below shows the Total Utility ( $TU$ ) obtained by a consumer from consuming successive packs of plantain chips:

Packs Consumed ( $Q$ )	Total Utility ( $TU$ ) in utils
$1$	$10$
$2$	$22$
$3$	$30$
$4$	$34$
$5$	$34$
$6$	$30$

At which pack of plantain chips does the Law of Diminishing Marginal Utility FIRST set in for this consumer?

The

2^{\text{nd}}

pack

The

3^{\text{rd}}

pack

The

5^{\text{th}}

pack

The

6^{\text{th}}

pack

Show answer & explanation

Answer: The $3^{\text{rd}}$ pack

Answer

The Law of Diminishing Marginal Utility first sets in at the

3^{\text{rd}}

pack.

The Law of Diminishing Marginal Utility states that after a certain point, consuming additional units of a good yields progressively less extra satisfaction. Computing

MU = \Delta TU / \Delta Q

shows that

MU_1 = 10

MU_2 = 12

, and

MU_3 = 8

. Because marginal utility increases from the

1^{\text{st}}

to the

2^{\text{nd}}

pack and then drops for the

3^{\text{rd}}

pack, diminishing marginal utility first begins with the consumption of the

3^{\text{rd}}

pack.

Step-by-Step Solution

Calculate the Marginal Utility (

MU

) for each successive pack using the formula

MU_n = TU_n - TU_{n-1}

MU_1 = 10 - 0 = 10

utils;

MU_2 = 22 - 10 = 12

utils;

MU_3 = 30 - 22 = 8

utils;

MU_4 = 34 - 30 = 4

utils;

MU_5 = 34 - 34 = 0

utils;

MU_6 = 30 - 34 = -4

utils.

Marginal utility measures the extra utility derived from consuming one additional unit of a commodity.

Analyze the trend of Marginal Utility (

MU

) values to identify where

MU

begins to decrease.

From the

1^{\text{st}}

to the

2^{\text{nd}}

pack,

MU

increases from

10

12

utils. From the

2^{\text{nd}}

to the

3^{\text{rd}}

pack,

MU

falls from

12

8

utils.

The Law of Diminishing Marginal Utility states that as more units of a commodity are consumed, the additional satisfaction derived from consuming each additional unit eventually decreases.

Determine the exact unit at which the decline in

MU

first occurs.

The decline in

MU

starts upon consumption of the

3^{\text{rd}}

pack.

The

3^{\text{rd}}

pack is the first unit where marginal utility (

8

utils) is less than the marginal utility of the preceding unit (

12

utils).

Key Concept

Onset of the Law of Diminishing Marginal Utility

Estimated Time:1m 0s

Question 9383Question →

An economic study of consumer behavior in an urban market reveals that when household disposable income rises by $15\%$ , consumer purchases of local unpolished rice decrease by $8\%$ . Subsequently, the government grants a production subsidy to rice farmers, causing the retail market price of local unpolished rice to fall by $20\%$ . Based on economic principles governing demand determinants, which of the following correctly classifies local unpolished rice and describes the immediate effect of the price reduction on its demand curve?

Local unpolished rice is an inferior good, and the price reduction causes a downward movement along its existing demand curve.

Local unpolished rice is an inferior good, and the price reduction causes an outward (rightward) shift of its demand curve.

Local unpolished rice is a normal good, and the price reduction causes a downward movement along its existing demand curve.

Local unpolished rice is a complementary good, and the price reduction causes an inward (leftward) shift of its demand curve.

Show answer & explanation

Answer: Local unpolished rice is an inferior good, and the price reduction causes a downward movement along its existing demand curve.

Answer

Local unpolished rice is an inferior good, and the price reduction causes a downward movement along its existing demand curve.

The correct response accurately identifies that a commodity whose demand decreases when consumer income rises is an inferior good. Furthermore, it correctly distinguishes that a change in the retail price of the commodity itself—resulting from a production subsidy—causes a expansion in quantity demanded reflected by a downward movement along the existing demand curve rather than a shift in the curve.

Step-by-Step Solution

Analyze the relationship between income change and quantity demanded.

Income rose by

15\%

while demand for local unpolished rice fell by

8\%

. An inverse relationship between consumer income and demand defines an inferior good.

By definition, normal goods experience an increase in demand when income rises, whereas inferior goods experience a decrease in demand as consumers switch to higher-quality substitutes.

Analyze the effect of the price decrease resulting from the farmer subsidy.

The subsidy lowers the price of the commodity itself, leading to an increase in quantity demanded represented by a downward movement along the static demand curve.

Changes in non-price determinants (income, tastes, prices of related goods) shift the demand curve (change in demand), whereas a change in the good's own price causes movement along the curve (change in quantity demanded).

Key Concept

Distinction between non-price demand determinants (which shift the curve) and own-price changes (which cause movement along the curve), alongside good classification by income elasticity.

Estimated Time:1m 30s

Question 9384Question →

In a tropical savanna river valley, two bird species live within the same geographic locality. The Cattle Egret feeds primarily on terrestrial insects disturbed by grazing mammals, whereas the African Fish Eagle hunts aquatic fish from the river. Which of the following ecological terms best describes the distinct functional roles and resource utilization patterns of these two species?

Ecological niches

Primary ecological successions

Trophic levels of saprotrophs

Inverted energy pyramids

Show answer & explanation

Answer: Ecological niches

Answer

The distinct functional roles and resource utilization patterns of the two bird species represent ecological niches.

The correct answer emphasizes that an ecological niche encompasses an organism's role, dietary preferences, and interactions with biotic and abiotic resources in its environment. While both birds share the same physical habitat (the river valley), their different prey choices and feeding methods allow them to occupy separate ecological niches without competing directly.

Step-by-Step Solution

Identify the ecological concept being described in the scenario

The stem describes how two species in the same habitat exploit different food sources and behave differently.

Habitat defines where an organism lives, whereas ecological niche defines how it lives and functions, including its dietary habits.

Distinguish between habitat and ecological niche

Both birds share the same river valley habitat, but the Cattle Egret occupies an insectivorous terrestrial niche while the African Fish Eagle occupies a piscivorous aquatic niche.

Resource partitioning reduces direct competition between species coexisting in the same habitat.

Key Concept

Ecological Niche vs Habitat

Estimated Time:1m 0s

Question 9385Question →

A sole proprietor in Lagos receives a total Personal Income of $\text{₦680 million}$ during a given fiscal period. If direct personal income taxes paid to the government equal $\text{₦115 million}$ , what is the trader's disposable income in millions of Naira?

Show answer & explanation

Answer: 565

Answer

The disposable income is 565 million Naira.

Disposable Income is defined as Personal Income minus Personal Direct Taxes. Subtracting ₦115 million from ₦680 million leaves ₦565 million available for expenditure and savings.

Step-by-Step Solution

Extract Personal Income and Direct Personal Taxes from the prompt.

Personal Income = ₦680 million, Direct Tax = ₦115 million.

Disposable income is calculated from gross personal earnings minus direct tax obligations.

Deduct direct taxation from total personal income.

565 million Naira.

Disposable income measures the income remaining after direct tax deductions, available for personal consumption and savings.

Key Concept

Calculation of Disposable Income

Question 9386Question →

Match each market classification on the left with its defining economic function and traded instrument characteristic on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Money Market matches short-term debt instruments under one year; Capital Market matches long-term equity and bond funding; Commodity Spot Market matches immediate payment and physical goods delivery; Foreign Exchange Market matches currency conversion for international trade.

Markets are classified according to tenure (short-term money market vs long-term capital market), delivery timing (spot market for immediate delivery), and medium of exchange/asset traded (foreign exchange for national currencies).

Step-by-Step Solution

Classify financial markets by investment tenure

Money markets correspond to short-term instruments (Treasury Bills, Commercial Papers), whereas capital markets correspond to long-term instruments (stocks, corporate bonds).

Tenure of financial instruments is the primary legal and economic boundary separating money and capital markets.

Classify markets by transaction timing and physical delivery

Spot markets require immediate cash payment and physical delivery of agricultural/industrial goods.

Spot transaction timing contrasts directly with forward/futures markets where delivery occurs at a predetermined future date.

Identify the currency settlement mechanism

The foreign exchange market specifically handles cross-border currency conversion for international commerce.

National currency convertibility is essential for cross-border balance of payments settlement.

Key Concept

Classification of Markets by Tenure, Commodity Type, and Transaction Timing

Estimated Time:1m 30s

Question 9387Question →

In a socialist economic system, the central planning authority replaces the market price mechanism in deciding how land, capital, and labor resources are allocated across national industries.

True

False

Show answer & explanation

Answer: True

Answer

The statement is True. A central planning authority replaces the free market price mechanism to allocate productive resources in a command socialist economy.

State control and public ownership enable central planning authorities to directly command where labor, capital, and raw materials are directed, eliminating reliance on the private price mechanism.

Step-by-Step Solution

Examine the primary allocation mechanism of a socialist command economy.

Socialist economies rely on state ownership of key resources and direct state coordination.

Identifying the ownership and governance structure clarifies how fundamental economic decisions are made.

Compare administrative central planning against market price signals.

Central planners set quotas and allocate inputs directly, overriding the autonomous price mechanism seen in market economies.

Substituting administrative directives for supply-and-demand market forces is the core operational feature of command socialism.

Key Concept

Role of Central Planning versus the Price Mechanism in Command Socialism

Estimated Time:1m 0s

Question 9388Question →

Arrange the following poikilothermic vertebrate groups in increasing order of structural complexity and separation of oxygenated and deoxygenated blood in their cardiac chambers.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence from lowest to highest cardiac chamber complexity and separation of blood streams is: Pisces (two-chambered heart) → Amphibia (three-chambered heart with undivided ventricle) → Non-crocodilian Reptilia (three-chambered heart with partially divided ventricle) → Crocodilian Reptilia (four-chambered heart with completely divided ventricle).

The structural evolutionary sequence of heart chambers in poikilothermic vertebrates begins with Pisces, which possess a single-circuit, two-chambered heart (one atrium and one ventricle). Amphibians follow with a double-circuit, three-chambered heart (two atria and one undivided ventricle). Non-crocodilian reptiles feature a three-chambered heart with a partial inter-ventricular septum that reduces mixing of oxygenated and deoxygenated blood. Crocodilians represent the most structurally advanced poikilothermic heart with four distinct chambers (two atria and two completely separated ventricles).

Step-by-Step Solution

Determine the anatomical structure of the heart chambers for each poikilothermic group.

Pisces have 2 chambers; Amphibia have 3 chambers with an undivided ventricle; Non-crocodilian Reptilia have 3 chambers with a partial septum; Crocodilian Reptilia have 4 chambers with a complete septum.

Evolutionary adaptations in poikilothermic vertebrates progressively partition the cardiac chambers to optimize oxygen delivery during systemic circulation.

Order the groups sequentially based on increasing internal ventricular partitioning and blood separation efficiency.

Pisces < Amphibia < Non-crocodilian Reptilia < Crocodilian Reptilia.

Single-circuit circulation in fish is structurally simplest, followed by double circulation with a single ventricle in amphibians, partial ventricular division in lizards/snakes, and full ventricular division in crocodiles.

Key Concept

Evolutionary progression of heart chamber structures in poikilothermic vertebrates

Question 9389Question →

A genetics researcher classifies several human phenotypic observations recorded during a demographic study. Match each phenotypic observation on the left with its correct variation category and genetic basis on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Gradual variation in skin melanin density matches continuous polygenic morphological trait; PTC tasting perception matches discontinuous physiological trait governed by a single gene pair; Fingerprint pattern categories match discontinuous morphological trait uninfluenced by environment; ABO agglutinogen production matches discontinuous physiological trait determined by multiple alleles.

Each phenotype aligns precisely with its biological nature (morphological vs. physiological), distribution pattern (continuous vs. discontinuous), and underlying genetic mode of inheritance.

Step-by-Step Solution

Categorize each phenotypic trait as either morphological (structural/physical appearance) or physiological (functional/biochemical process).

Skin melanin density and fingerprint patterns are morphological traits; PTC tasting and erythrocyte agglutinogens are physiological traits.

Morphological traits involve anatomical features, while physiological traits relate to chemical functions and biological processes.

Determine whether each trait exhibits continuous variation (spectrum with intermediate phenotypes) or discontinuous variation (discrete non-overlapping categories).

Skin melanin density is continuous; PTC tasting, fingerprint patterns, and ABO blood groups are discontinuous.

Continuous variation displays quantitative grading across a spectrum, whereas discontinuous variation presents distinct qualitative groups.

Relate each categorized trait to its correct genetic control mechanism and environmental susceptibility.

Skin color is polygenic and environmental; PTC tasting is monogenic; fingerprints are genetically fixed structural types; ABO blood groups rely on multiple codominant/recessive alleles.

Matching structural, distributional, and genetic parameters confirms the exact paired classifications.

Key Concept

Human Morphological and Physiological Variations (Continuous vs. Discontinuous)

Question 9390Question →

A biologist dissects a homoiothermic vertebrate and identifies a muscular transverse partition that completely separates the thoracic cavity containing the heart and lungs from the abdominal cavity containing the digestive organs. Which class of homoiothermic vertebrates possesses this specific anatomical feature to assist in pulmonary ventilation?

Mammalia

Aves

Reptilia

Amphibia

Show answer & explanation

Answer: Mammalia

Answer

Mammalia is the correct class because mammals uniquely possess a muscular diaphragm separating the thoracic cavity from the abdominal cavity, which contracts to facilitate breathing.

Mammalia is the only vertebrate class possessing a muscular diaphragm that forms a complete partition between the thoracic and abdominal cavities. Contraction of the diaphragm increases thoracic cavity volume, lowering pressure to pull air into the lungs.

Step-by-Step Solution

Identify the homoiothermic (warm-blooded) vertebrate classes.

The two homoiothermic vertebrate classes are Aves (birds) and Mammalia (mammals). Reptilia and Amphibia are poikilothermic.

Eliminates non-homoiothermic classes based on the thermal regulation constraint in the stem.

Analyze the anatomical feature described in the stem.

A muscular transverse partition separating thoracic and abdominal cavities is a muscular diaphragm.

Determines the specific physiological structure described.

Compare respiratory anatomy between Aves and Mammalia.

Mammals possess a muscular diaphragm, whereas birds lack a diaphragm and rely on air sacs and sternal depression for lung ventilation.

Confirms Mammalia as the correct target class.

Key Concept

Anatomical distinctions between homoiothermic classes (Aves vs Mammalia)

Estimated Time:1m 0s

Question 9391Question →

A medical laboratory scientist performs a Gram stain on a bacterial culture isolated from a clinical sample. Microscopic analysis reveals that the organism possesses a thick, rigid cell wall that retains crystal violet dye. Which structural molecule forms the primary meshwork of this cell wall, distinguishing bacteria from eukaryotic plant cells?

Peptidoglycan

Cellulose

Chitin

Capsid protein

Show answer & explanation

Answer: Peptidoglycan

Answer

Peptidoglycan forms the primary structural constituent of the bacterial cell wall in Kingdom Monera, distinguishing it from the cellulose wall of plant cells.

Peptidoglycan is the defining macromolecule of bacterial cell walls in Kingdom Monera, consisting of repeating disaccharide units cross-linked by amino acid side chains.

Step-by-Step Solution

Identify the kingdom and cellular organization of the organism described in the question.

The organism is a bacterium, belonging to Kingdom Monera (prokaryotic).

Bacterial cell walls have a distinct biochemical composition compared to eukaryotic organisms.

Differentiate between prokaryotic and plant cell wall constituents.

Bacterial walls are made of peptidoglycan (murein), whereas plant walls are made of cellulose.

Peptidoglycan is a complex network of cross-linked polysaccharide chains and short peptide chains unique to prokaryotes.

Key Concept

Bacterial cell wall composition (Peptidoglycan vs. Cellulose)

Question 9392Question →

A consumer consumes successive cups of ice cream. The total utility ( $TU$ ) derived from the 1st, 2nd, 3rd, and 4th cups is $15$ utils, $25$ utils, $30$ utils, and $30$ utils respectively. What is the marginal utility ( $MU$ ) of the 4th cup of ice cream?

0

utils

30

utils

7.5

utils

5

utils

Show answer & explanation

Answer: $0$ utils

Answer

The marginal utility of the 4th cup of ice cream is

0

utils.

Marginal Utility (

MU

) measures the change in Total Utility (

TU

) resulting from consuming one additional unit of a good. Using

MU_4 = TU_4 - TU_3

, we subtract

30

utils (

TU_3

) from

30

utils (

TU_4

) to obtain

0

utils.

Step-by-Step Solution

Identify the Total Utility (

TU

) values for the 3rd and 4th units.

TU_3 = 30

utils and

TU_4 = 30

utils.

Calculating marginal utility requires comparing total utility before and after consuming the 4th unit.

Apply the Marginal Utility formula

MU_n = TU_n - TU_{n-1}

MU_4 = 30 - 30 = 0

utils.

The 4th cup adds zero extra utility, reaching the consumer's point of satiety.

Key Concept

Calculation of Marginal Utility from Total Utility

Question 9393Question →

A local government council has a fixed capital budget of ₦50 million and must choose between constructing a township road network and rebuilding a community healthcare center. If the council resolves to rebuild the healthcare center, what is the real cost of this economic decision?

The township road network that was foregone

The financial outlay of ₦50 million spent on the healthcare center

An outward shift of the local government's production possibility curve

The total satisfaction gained by community members from improved healthcare

Show answer & explanation

Answer: The township road network that was foregone

Answer

The township road network that was foregone

In economic analysis, real cost (or opportunity cost) refers to the real goods or services given up in order to obtain something else. By selecting the healthcare center, the local government sacrificed the opportunity to construct the township road network, making the foregone road network the real cost of the decision.

Step-by-Step Solution

Identify the scarce resource and competing alternatives

Resource is ₦50 million budget; alternatives are township road network vs community healthcare center.

Scarcity of resources necessitates making a choice between alternative uses.

Distinguish between money cost and real cost

Money cost is ₦50 million, while real cost is the sacrificed alternative (the township road network).

In economics, real cost is expressed in terms of the next best alternative foregone, not monetary expenditure.

Key Concept

Money Cost versus Real Cost

Question 9394Question →

Match each core characteristic or assumption of a perfectly competitive market on the left with its direct microeconomic implication on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches are: Large number of atomic buyers and sellers pairs with Renders each firm a strict price-taker facing a horizontal demand curve where

P = AR = MR

; Homogeneous product and perfect market knowledge pairs with Eliminates non-price competition and enforces the Law of One Price across all sellers; Perfect factor mobility and zero transport costs pairs with Prevents geographic price discrimination and equalizes factor prices across industry sectors; and Unrestricted entry and exit of firms in the long run pairs with Eradicates economic profits in long-run equilibrium, achieving optimal allocative and productive efficiency where

P = MC = \text{min } ATC

Each feature of perfect competition logically dictates a specific market mechanism: atomistic market agents eliminate market power (

P = AR = MR

); homogeneous goods and full knowledge enforce the Law of One Price; transport-free factor mobility equalizes geographic input pricing; and unrestricted long-run entry/exit drives economic profit to zero at minimum average total cost (

P = MC = \text{min } ATC

Step-by-Step Solution

Analyze the impact of atomistic market participants (large number of buyers and sellers).

Individual supply or demand shifts are too small to affect aggregate price, generating an infinitely elastic demand curve (

P = AR = MR

) for the individual price-taking firm.

Zero market power per firm requires accepting the price determined by aggregate industry demand and supply.

Evaluate the joint effect of product homogeneity and perfect information.

Consumers view products as identical substitutes and possess perfect price visibility, establishing the Law of One Price and eliminating non-price competition.

Branding and persuasive advertising are ineffective when goods are completely identical and buyers are fully informed.

Examine the role of factor mobility and zero transportation costs.

Resource inputs shift without friction to wherever returns are highest, eliminating spatial price wedges and equalizing input costs.

Absence of transport costs prevents sellers from establishing localized geographical monopolies.

Synthesize long-run adjustment dynamics from free entry and exit.

Market entry drives down supernormal profits while market exit eliminates economic losses until

P = MC = \text{min } ATC

in long-run equilibrium.

Frictionless movement of resources into and out of the industry enforces zero economic profit in the long run.

Key Concept

Characteristics and Microeconomic Implications of Perfect Competition

Question 9395Question →

Commercial bank customers in an economy decide to shift a substantial portion of their funds from checking accounts (demand deposits) into long-term fixed deposit accounts. What is the immediate effect of this transaction on narrow money supply ( $M_1$ ) and broad money supply ( $M_2$ )?

M_1

decreases while

M_2

remains constant

Both

M_1

and

M_2

decrease simultaneously

M_1

remains constant while

M_2

increases

Both

M_1

and

M_2

increase simultaneously

Show answer & explanation

Answer: $M_1$ decreases while $M_2$ remains constant

Answer

Narrow money supply (

M_1

) decreases while broad money supply (

M_2

) remains unchanged.

Narrow money (

M_1

) consists of currency outside banks and demand deposits. When depositors transfer funds from checking accounts to fixed time deposit accounts, demand deposits fall, causing

M_1

to decrease. However, broad money (

M_2

) is defined as

M_1

plus quasi-money (savings and time deposits). Because the drop in

M_1

is exactly matched by an equal increase in quasi-money, the total value of

M_2

remains constant.

Step-by-Step Solution

Define narrow money (

M_1

) components

M_1 = \text{Currency in Circulation} + \text{Demand Deposits}

Identify which monetary aggregate is affected by withdrawing funds from checking accounts.

Define broad money (

M_2

) components

M_2 = M_1 + \text{Quasi-Money (Savings and Time Deposits)}

Understand how time deposits fit into broader monetary measures.

Analyze the net effect of the deposit transfer

Demand deposits fall, so

M_1

falls. Time deposits rise by the identical amount, so quasi-money increases. The net change in

M_2

(- \Delta M_1) + (+ \Delta \text{Time Deposits}) = 0

Evaluate the immediate impact on both aggregates.

Key Concept

Monetary Aggregates (

M_1

M_2

) and Money Supply Structure

Question 9396Question →

A manufacturing enterprise operates under a strict budget constraint of $\text{\mathbb{N}}20\text{ million}$ and must choose among three mutually exclusive capital projects: Project X yields an expected net profit of $\text{\mathbb{N}}35\text{ million}$ , Project Y yields an expected net profit of $\text{\mathbb{N}}28\text{ million}$ , and Project Z yields an expected net profit of $\text{\mathbb{N}}22\text{ million}$ . If the firm decides to execute Project X, which statement accurately articulates the fundamental economic relationship between scarcity, choice, and opportunity cost in this scenario?

Scarcity of capital forces the firm to make a choice, resulting in an opportunity cost equal to the

\text{\mathbb{N}}28\text{ million}

net profit foregone from Project Y.

Scarcity of capital forces the firm to make a choice, resulting in an opportunity cost equal to the

\text{\mathbb{N}}20\text{ million}

financial outlay required to execute Project X.

Scarcity of capital forces the firm to make a choice, giving rise to an opportunity cost of

\text{\mathbb{N}}50\text{ million}

, which represents the combined net profit of Projects Y and Z.

Selecting Project X shifts the firm's production possibility curve outward, eliminating the opportunity cost associated with unselected projects.

Show answer & explanation

Answer: Scarcity of capital forces the firm to make a choice, resulting in an opportunity cost equal to the $\text{\mathbb{N}}28\text{ million}$ net profit foregone from Project Y.

Answer

Scarcity of capital forces the firm to make a choice, resulting in an opportunity cost equal to the

\text{\mathbb{N}}28\text{ million}

net profit foregone from Project Y.

Because human wants exceed limited resources (scarcity), economic agents are compelled to make a choice based on a scale of preference. When Project X is chosen, the firm sacrifices the benefits of all other options. In economics, opportunity cost is defined specifically as the value of the next best alternative sacrificed—in this case, Project Y, which yields

\text{\mathbb{N}}28\text{ million}

Step-by-Step Solution

Identify the resource constraint and available options

The firm faces capital scarcity (limited to

\text{\mathbb{N}}20\text{ million}

) and must rank mutually exclusive options: Project X (

\text{\mathbb{N}}35\text{ million}

), Project Y (

\text{\mathbb{N}}28\text{ million}

), and Project Z (

\text{\mathbb{N}}22\text{ million}

Scarcity mandates that not all desired projects can be funded simultaneously, necessitating a scale of preference.

Determine the choice made and identify all foregone alternatives

The firm chooses Project X. The unselected alternatives are Project Y and Project Z.

Economic choice involves selecting the option that maximizes net benefit according to the scale of preference.

Calculate the opportunity cost by locating the next best alternative

The next best alternative sacrificed is Project Y, valued at

\text{\mathbb{N}}28\text{ million}

Opportunity cost is defined strictly as the value of the single highest-ranked alternative foregone when a choice is made under scarcity.

Key Concept

Relationship between Scarcity, Choice, Scale of Preference, and Opportunity Cost

Question 9397Question →

Match each blood vessel involved in mammalian circulation on the left with its corresponding physiological transport pathway or function on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Hepatic portal vein matches with transport of nutrient-rich blood from the digestive tract to the liver; Pulmonary artery matches with carrying deoxygenated blood from the right ventricle to the lungs; Renal artery matches with delivering oxygenated blood to the kidneys; Coronary artery matches with supplying oxygenated blood to the cardiac muscle tissue.

Each vessel is correctly paired with its target organ and blood state: the hepatic portal vein connects the gut capillaries to the liver, the pulmonary artery transports deoxygenated blood to the lungs, the renal artery supplies the kidneys under high pressure, and the coronary arteries feed the myocardium.

Step-by-Step Solution

Identify the destination and function of the hepatic portal vein.

It connects the capillary beds of the stomach/intestines directly to the sinusoids of the liver, transporting absorbed products of digestion.

Portal systems begin and end in capillaries without returning directly to the heart first.

Determine the role of the pulmonary artery.

It originates at the right ventricle and carries deoxygenated blood to the pulmonary capillaries in the lungs.

Arteries carry blood away from the heart; pulmonary arteries specifically supply the pulmonary circuit.

Examine the vessel supplying the kidneys.

The renal artery branches from the aorta to deliver oxygenated blood to the renal glomeruli.

Kidneys require high arterial pressure for effective ultrafiltration.

Identify the blood supply to the heart itself.

The coronary arteries branch from the base of the ascending aorta to feed the heart muscle.

Heart tissue cannot exchange nutrients directly from the blood inside its heart chambers due to thick muscular walls.

Key Concept

Mammalian Blood Vessels and Circulatory Pathways

Estimated Time:1m 30s

Question 9398Question →

During a clinical assessment of involuntary motor responses, a patient exhibits a rapid auditory startle reflex in response to an unexpected loud sound. Which of the following sequences correctly represents the pathway of the nerve impulse from initial reception to muscular response?

Auditory receptor

\rightarrow

Sensory neuron

\rightarrow

Relay neuron

\rightarrow

Motor neuron

\rightarrow

Effector muscle

Auditory receptor

\rightarrow

Motor neuron

\rightarrow

Relay neuron

\rightarrow

Sensory neuron

\rightarrow

Effector muscle

Auditory receptor

\rightarrow

Sensory neuron

\rightarrow

Motor neuron

\rightarrow

Relay neuron

\rightarrow

Effector muscle

Auditory receptor

\rightarrow

Relay neuron

\rightarrow

Sensory neuron

\rightarrow

Motor neuron

\rightarrow

Effector muscle

Show answer & explanation

Answer: Auditory receptor $\rightarrow$ Sensory neuron $\rightarrow$ Relay neuron $\rightarrow$ Motor neuron $\rightarrow$ Effector muscle

Answer

Auditory receptor

\rightarrow

Sensory neuron

\rightarrow

Relay neuron

\rightarrow

Motor neuron

\rightarrow

Effector muscle

A functional reflex arc always follows a strict unidirectional pathway: Receptor

\rightarrow

Sensory (afferent) neuron

\rightarrow

Central nervous system / Relay neuron

\rightarrow

Motor (efferent) neuron

\rightarrow

Effector (muscle or gland). In an auditory reflex, sound is detected by receptors in the ear, passed along sensory neurons to interneurons in the brainstem, which transmit the signal via motor neurons to neck or skeletal muscles to elicit the involuntary contraction.

Step-by-Step Solution

Identify the primary stimulus receptor

The sensory hair cells in the cochlea (auditory receptors) convert sound vibrations into electrical nerve impulses.

Receptors are the starting point of any reflex pathway.

Trace afferent signal transmission

The sensory neuron carries afferent impulses from the sensory organ into the central nervous system.

Afferent (sensory) neurons transmit impulses toward the brainstem or spinal cord.

Identify central processing within the synapse

The relay neuron (interneuron) within the CNS receives signal from sensory neuron and passes it to motor neuron.

Interneurons integrate sensory inputs and route them directly to motor pathways.

Trace efferent signal transmission to target organ

The motor neuron carries efferent impulses from CNS to the effector muscle, causing contraction.

Efferent (motor) neurons conduct signals away from CNS to executive tissues (effectors).

Key Concept

Reflex Arc Impulse Transmission Pathway

Estimated Time:1m 0s

Question 9399Question →

Marsupials are naturally restricted to Australia and South America, yet comparative biochemical analysis reveals near-identical amino acid sequences in their cytochrome c proteins. Which of the following best explains this observation?

The organisms share a common ancestor that inhabited the unified landmass prior to continental separation

The organisms independently evolved identical amino acid sequences as an adaptive response to similar climatic environments

The organisms acquired identical protein alterations during their lifespan due to environmental stress from continental movement

The organisms represent extreme ends of continuous variation within a single geographically continuous population

Show answer & explanation

Answer: The organisms share a common ancestor that inhabited the unified landmass prior to continental separation

Answer

The organisms share a common ancestor that inhabited the unified landmass prior to continental separation.

High sequence homology in essential proteins such as cytochrome c demonstrates close genetic relationship. When combined with biogeographical evidence showing Australia and South America were once joined as part of Gondwana, it indicates that marsupial ancestors lived on the shared landmass before continental drift isolated them.

Step-by-Step Solution

Analyze the biogeographical evidence presented in the stem.

The presence of related marsupial lineages in South America and Australia reflects a disjunct distribution resulting from tectonic continental drift (breakup of Gondwana).

Geographical isolation on separate continents accounts for spatial distribution patterns of related organisms.

Analyze the comparative biochemical evidence.

High amino acid sequence similarity in cytochrome c indicates genetic homology and close evolutionary ancestry.

Conserved proteins accumulate mutations over geological time; minimal sequence divergence points to a shared evolutionary past.

Integrate biogeographical and biochemical findings to reach the accurate evolutionary conclusion.

The ancestors of these marsupials inherited the conserved protein structure on a continuous supercontinent before plate tectonics separated the populations.

Combining molecular homology with vicariance models provides robust evidence for macroevolution.

Key Concept

Biogeographical disjunct distribution combined with molecular protein homology provides evidence of common ancestry prior to continental drift.

Question 9400Question →

A cotton farmer sells raw cotton to a textile mill for ₦50,000. The textile mill processes the cotton into fabric and sells it to a garment factory for ₦120,000. The garment factory turns the fabric into shirts and sells them to final consumers for ₦200,000. What is the total contribution of this production process to National Income using the output (value-added) method?

₦200,000

₦370,000

₦150,000

₦170,000

Show answer & explanation

Answer: ₦200,000

Answer

The total contribution to National Income is ₦200,000.

The output method avoids double counting by summing only the incremental net value created at each production stage (₦50,000 + ₦70,000 + ₦80,000 = ₦200,000), which also equals the final market value of the consumer goods.

Step-by-Step Solution

Calculate the value added by the cotton farmer

₦50,000 - ₦0 = ₦50,000

The raw cotton has no specified intermediate cost.

Calculate the value added by the textile mill

₦120,000 - ₦50,000 = ₦70,000

Subtract the cost of intermediate raw cotton from the fabric sales value.

Calculate the value added by the garment factory

₦200,000 - ₦120,000 = ₦80,000

Subtract the cost of intermediate fabric from the final shirt sales value.

Sum the net value added at each stage

₦50,000 + ₦70,000 + ₦80,000 = ₦200,000

The output method measures National Income by summing the net value added at every stage of production.

Key Concept

Output (Value Added) Method of Measurement

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