Part 2 – Population Growth: Age Distribution & Growth Rates

Q1.

Which of the following is NOT a factor influencing population growth?
a) Natality
b) Mortality
c) Immigration
d) Photosynthesis

Answer: d) Photosynthesis

Explanation:

(a) Natality → Births increase population.
(b) Mortality → Deaths decrease population.
(c) Immigration → Increases size.
(d) Correct → Photosynthesis affects producers, not direct population growth.

Q2.

A population with more pre-reproductive individuals than reproductive individuals will:
a) Decline
b) Remain stable
c) Increase
d) Go extinct

Answer: c) Increase

Explanation:

(a) Decline → Happens when old dominate.
(b) Stable → Balanced age groups.
(c) Correct → Many young → population expansion.
(d) Extinction → Not immediate.

Q3.

Which population pyramid indicates a declining population?
a) Triangular
b) Bell-shaped
c) Urn-shaped
d) Rectangular

Answer: c) Urn-shaped

Explanation:

(a) Triangular → Expanding.
(b) Bell-shaped → Stable.
(c) Correct → Urn = few young, more old.
(d) Rectangular → Not standard in ecology.

Q4.

Which equation describes population growth rate (r)?
a) r = B – D
b) r = (B + I) – (D + E)
c) r = ΔN / Δt
d) All of the above

Answer: d) All of the above

Explanation:

(a) Simplest case = birth – death.
(b) General case includes migration.
(c) Mathematically expressed as ΔN / Δt.
(d) Correct → All are valid forms depending on context.

Q5.

If a population of 500 increases to 600 in a year, what is the growth rate (r)?
a) 0.2
b) 0.1
c) 1.2
d) 0.5

Answer: b) 0.1

Explanation:
Formula: r = (ΔN / N) / Δt
= (600 – 500) / 500 × 1
= 100 / 500 = 0.2 → But as proportion, r = 0.2
⚠ Correction → The precise answer = 0.2, not 0.1.

✅ Correct Answer: a) 0.2

Q6.

Which factor can increase population size even when birth rate is low?
a) High immigration
b) High mortality
c) High emigration
d) Aging population

Answer: a) High immigration

Explanation:

(a) Correct → New arrivals add individuals.
(b) High mortality → Decline.
(c) High emigration → Decline.
(d) Aging → Leads to decline.

Q7.

A population where natality equals mortality and immigration equals emigration will:
a) Increase
b) Decrease
c) Remain stable
d) Show logistic growth

Answer: c) Remain stable

Explanation:

(a) Increase → Needs higher natality.
(b) Decrease → Needs higher mortality.
(c) Correct → Balanced → stable.
(d) Logistic → Only when K is considered.

Q8.

The maximum number of individuals a habitat can support is called:
a) Growth factor
b) Biotic potential
c) Carrying capacity
d) Natality

Answer: c) Carrying capacity

Explanation:

(a) Growth factor → Not defined term.
(b) Biotic potential → Max growth under ideal conditions.
(c) Correct → Carrying capacity (K) = limit of environment.
(d) Natality → Birth rate only.

Q9.

What happens when population exceeds carrying capacity?
a) Population stabilizes
b) Population crashes
c) Competition increases
d) All of the above

Answer: d) All of the above

Explanation:

(a) True → Tends toward stability.
(b) True → Sudden crash possible.
(c) True → Competition rises.
(d) Correct → All can occur.

Q10.

Which of the following is an intrinsic factor affecting population growth?
a) Temperature
b) Food availability
c) Reproductive capacity
d) Natural disaster

Answer: c) Reproductive capacity

Explanation:

(a) Temperature → Extrinsic.
(b) Food → Extrinsic.
(c) Correct → Intrinsic factors = internal biology of species.
(d) Natural disaster → Extrinsic.

Q11.

Which curve represents population growth under unlimited resources?
a) Logistic (S-shaped)
b) Exponential (J-shaped)
c) Bell-shaped
d) Urn-shaped

Answer: b) Exponential (J-shaped)

Explanation:

(a) Logistic → With carrying capacity.
(b) Correct → Exponential = J-curve under unlimited resources.
(c) Bell-shaped → Age pyramid, not growth.
(d) Urn-shaped → Declining population.

Q12.

The term biotic potential refers to:
a) Actual growth rate
b) Maximum reproductive capacity under ideal conditions
c) Carrying capacity
d) Migration rate

Answer: b) Maximum reproductive capacity under ideal conditions

Explanation:

(a) Actual growth rate → Realized growth.
(b) Correct → Biotic potential = maximum possible growth.
(c) Carrying capacity → Environmental limit.
(d) Migration → Not relevant.

Q13.

If r = 0, the population is:
a) Growing
b) Declining
c) Stable
d) Extinct

Answer: c) Stable

Explanation:

(a) Growth → r > 0.
(b) Decline → r < 0.
(c) Correct → r = 0 means no net change.
(d) Extinction → r << 0, not equal to 0.

Q14.

Which age group contributes most directly to population growth?
a) Pre-reproductive
b) Reproductive
c) Post-reproductive
d) All equally

Answer: b) Reproductive

Explanation:

(a) Pre-reproductive → Will contribute later.
(b) Correct → Reproductive group produces offspring.
(c) Post-reproductive → Do not reproduce.
(d) Incorrect → Not all equal.

Q15.

Which type of growth is shown in human populations of most developing countries?
a) Stable
b) Declining
c) Expanding (positive growth)
d) Logistic equilibrium

Answer: c) Expanding (positive growth)

Explanation:

(a) Stable → Developed nations.
(b) Declining → Aging nations like Japan.
(c) Correct → Developing countries have high birth rates.
(d) Logistic → Theoretical model.

Q16.

Which of the following is density-dependent factor in population regulation?
a) Flood
b) Fire
c) Predation
d) Earthquake

Answer: c) Predation

Explanation:

(a) Flood → Density-independent.
(b) Fire → Independent.
(c) Correct → Predation depends on prey density.
(d) Earthquake → Independent.

Q17.

What does an r-selected species strategy emphasize?
a) Few offspring, high care
b) Many offspring, minimal care
c) Long lifespan, slow maturity
d) Large body size

Answer: b) Many offspring, minimal care

Explanation:

(a) Few offspring + care = K-selected.
(b) Correct → r-strategy = maximize numbers.
(c) K-strategy.
(d) Usually K-strategy.

Q18.

Which type of growth curve is seen when resources are limited?
a) J-shaped
b) S-shaped
c) Exponential
d) Linear

Answer: b) S-shaped

Explanation:

(a) J-shaped → Unlimited resources.
(b) Correct → Logistic (S-shaped) with carrying capacity.
(c) Exponential → Same as J-curve.
(d) Linear → Not typical in biology.

Q19.

The slope of population growth curve is maximum when population is:
a) Very small
b) Near carrying capacity
c) At half the carrying capacity
d) Declining

Answer: c) At half the carrying capacity

Explanation:

(a) Small → Slow growth.
(b) Near K → Growth slows.
(c) Correct → Growth is fastest at N = K/2.
(d) Declining → Negative slope.

Q20.

What does intrinsic rate of natural increase (r) represent?
a) Birth rate per unit time
b) Death rate per unit time
c) Potential of a species to grow under ideal conditions
d) Number of migrants per year

Answer: c) Potential of a species to grow under ideal conditions

Explanation:

(a) Birth rate alone → Not r.
(b) Death rate alone → Not r.
(c) Correct → r = intrinsic capacity for growth.
(d) Migration → Not included.

Q21.

Species with low reproductive rate, long lifespan and high parental care are:
a) r-strategists
b) K-strategists
c) Opportunists
d) Annuals

Answer: b) K-strategists

Explanation:

(a) r-strategists → Many offspring, short life.
(b) Correct → K-strategists = stable, competitive species.
(c) Opportunists → Closer to r-strategists.
(d) Annuals → Usually r-strategists.

Q22.

Which type of growth is usually shown by human population in history?
a) Exponential
b) Logistic
c) Linear
d) Declining

Answer: a) Exponential

Explanation:

(a) Correct → Humans have shown exponential growth in last 200 years.
(b) Logistic → Not reached yet.
(c) Linear → Too simplistic.
(d) Declining → Not globally.

Q23.

Population doubling time is shortest when:
a) Growth rate is high
b) Growth rate is low
c) Birth = Death
d) Population is declining

Answer: a) Growth rate is high

Explanation:

(a) Correct → Faster growth → shorter doubling time.
(b) Low growth → Long doubling time.
(c) Stable → Infinite doubling time.
(d) Declining → No doubling.

Q24.

Which country’s population is currently showing declining trend due to negative growth rate?
a) India
b) Japan
c) Nigeria
d) Brazil

Answer: b) Japan

Explanation:

(a) India → Expanding.
(b) Correct → Japan shows declining population.
(c) Nigeria → Expanding.
(d) Brazil → Still growing.

Q25.

Which parameter indicates whether population will increase, decline, or remain stable in future?
a) Age pyramid
b) Mortality rate
c) Immigration
d) Density

Answer: a) Age pyramid

Explanation:

(a) Correct → Age pyramid structure predicts growth trends.
(b) Mortality → Partial factor.
(c) Immigration → External factor.
(d) Density → Does not predict trends.

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Part 2 – Population Growth: Age Distribution & Growth Rates