The following graphs represent age pyramids of a population. Identify the correct option representing the status of age pyramids labelled as A, B and C.
A - stable, B - declining, C - expanding
An age pyramid plots the pre-reproductive (base), reproductive (middle) and post-reproductive (top) age groups of a population. Its shape reflects the growth status: a triangular pyramid with a very broad base is expanding, a bell-shaped pyramid with nearly equal lower bars is stable, and an urn-shaped pyramid with a narrow base is declining.
Pyramid A: the lower bars are broad and close in width and the pyramid narrows gently upward — bell-shaped, so the population is stable.
Pyramid B: the base is narrower than the middle, so there are fewer young than reproductive individuals — urn-shaped, so the population is declining.
Pyramid C: the base is the widest bar and each higher bar is clearly shorter — triangular, so the population is expanding.
Any choice calling B expanding or stable ignores its narrow base, and any choice calling C declining ignores its broad base.
A - stable, B - declining, C - expanding option is correct.
Similar Questions
Given below are two statements.
Statement I: There is less species biodiversity in tropical latitudes than in temperate region
Statement II: Tropical environments unlike temperate ones are less seasonal, relatively more constant and predictable.
In the light of the above statements, choose the correct answer from the options given below.
The Annual Net Primary Productivity on land and ocean respectively are ________ and ________ billion tons.
Which one of the following options represents the steps of decomposition in sequence?
Which of the following is not correct with reference to exponential growth model?
Important Questions from Ecology
- Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : Abingdon tortoise in Galapagos islands became extinct within a decade after goats were introduced.
Reason R : Goats were more efficient at browsing than Abingdon tortoise.
In the light of the above statements, choose the most appropriate answer from the options given below : - Which of the following statements are correct ?
(a) Energy flow from producers to consumers is unidirectional
(b) Energy pyramid can never be inverted
(c) Transfer of energy follows the 1% law
Choose the correct answer from the options given below : - Arrange the following in descending order of number of species in the Amazonian rain forest.
(a) Plants
(b) Birds
(c) Fishes
(d) Invertebrates
(e) Mammals
Choose the correct answer from the options given below : - Match List-I with List-II.
List-I List-II A. Both species are harmed I. Predation B. One species is harmed and the other is benefited II. Mutualism C. Both species are benefited III. Competition D. One is benefited while the other has no effect IV. Commensalism
Choose the correct answer from the options given below : - Which of the following are primary consumers in a food chain ?
