Practise 23 real Federal Board questions on Ecology from 2023 to 2026. See the answer and explanation as soon as you answer.
Ecology is one of the 15 main chapters in our Federal Board FSC Biology question bank (11th and 12th class), and about 5% of its real questions come from it. Tayyari Karo has 23 real questions on this chapter from 2023 to 2026; 6 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 20 medium, 3 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Which organisms are most affected by ocean acidification?
Answer: D. Shell-forming organisms
Ocean acidification lowers carbonate ion availability, impairing shell/skeleton formation in shell-forming organisms such as corals and molluscs.
The compound(s) mainly responsible for depletion of the ozone layer is/are:
Answer: B. Chlorofluorocarbons (CFCs)
CFCs release chlorine radicals in the stratosphere that catalytically destroy ozone molecules, making them the principal cause of ozone depletion.
Rapid melting of ice caps and glacier is due to:
Answer: A. Greenhouse effect
Rising global temperatures from the enhanced greenhouse effect are the main driver of accelerated melting of polar ice caps and glaciers.
The cause of acid rain is:
Answer: C. Oxides of nitrogen and sulphur
Acid rain forms mainly when oxides of sulphur (SOₓ) and nitrogen (NOₓ) released by burning fossil fuels combine with atmospheric water to form sulphuric and nitric acids.
Water within the basin is called:
Answer: D. Aquifer
An aquifer is an underground layer of water-bearing rock/sediment that stores and transmits groundwater within a drainage basin.
Explain kinds and general stages of succession.
Kinds of succession: (1) Primary succession — occurs on a completely new, lifeless substrate that has never supported life before (e.g. bare rock, new volcanic land), starting with pioneer species like lichens. (2) Secondary succession — occurs on a substrate that previously supported life but has been disturbed/destroyed (e.g. after fire, flood, farmland abandonment), starting from existing soil, so it proceeds faster.
General stages: (1) Nudation — the exposure of a bare area. (2) Invasion — arrival and establishment of pioneer species (e.g. lichens, mosses on bare rock). (3) Competition/coaction — as populations grow, organisms compete for space, light and nutrients. …
The full model answer is in the app.
Explain briefly the concept of climax community and its significance.
A climax community is the final, relatively stable and self-perpetuating stage of ecological succession, in equilibrium with the prevailing climate and environment of an area, which persists unless disturbed by an external factor (fire, disease, human activity). Its significance: it represents the community with the greatest species diversity and biomass that a habitat can support, shows efficient nutrient cycling and energy flow, and serves as a reference/benchmark for assessing environmental disturbance and guiding conservation and restoration efforts.
Differentiate between: (A) Ammonification and denitrification (B) Xerarch and hydrarch succession.
(A) Ammonification is the breakdown of nitrogenous organic matter (dead organisms, waste) by decomposer bacteria/fungi, releasing ammonia/ammonium into the soil. Denitrification is the conversion of soil nitrates back into atmospheric nitrogen gas (N₂) by denitrifying bacteria, removing usable nitrogen from the soil.
(B) Xerarch succession begins on a dry, bare substrate (e.g. bare rock) with pioneer species like lichens tolerant of low water availability. Hydrarch succession begins in a body of water (e.g. a pond) with aquatic pioneer species, gradually filling in with sediment and vegetation until it becomes dry land — both eventually converge toward a similar climax community.
| Session | Questions |
|---|---|
| 2026 Annual | 4 |
| 2025 1st Annual | 5 |
| 2025 2nd Annual | 5 |
| 2024 Annual | 6 |
| 2023 Annual | 3 |
23 real Federal Board (FBISE) Biology questions on Ecology from 2023 to 2026, for 11th and 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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