BT101 — Ecology, Biodiversity & Evolution-I | VU Solved MCQs

BT101 Ecology, Biodiversity & Evolution-I covers Introduction to ecology, Levels of organization, The ecological niche, Keystone species, Food pyramids, Nutrient cycles, Pollution and food chains, Aquatic biomes, Global warming, Invasive species, Deforestation, Nitrogen cycle, Weathering, Threats to biodiversity, Water cycle and Rivers. This solved post gives you 30 verified items for Virtual University of Pakistan, 10 Midterm MCQs from Lectures 1-22, 10 Finalterm MCQs from Lectures 23-45, and 5 Midterm plus 5 Finalterm subjective questions, each with its correct answer and handout reference. Practice every question instantly in the quiz for this course. Take the BT101 quiz

1. Midterm Solved MCQs

Q1. Who coined the term "ecology"?
A) Charles Darwin
B) Ernst Haeckel
C) Gregor Mendel
D) Alexander von Humboldt
Correct answer: B — Ernst Haeckel
Reference: VU handout, Topic 1 — Introduction to ecology.
Status: Verified

Q2. Which is the correct order of levels of ecological organization, from smallest to largest?
A) Ecosystem → community → population → species
B) Species → population → community → ecosystem → biome → biosphere
C) Population → species → biome → ecosystem → biosphere
D) Biosphere → biome → ecosystem → community → population
Correct answer: B — Species → population → community → ecosystem → biome → biosphere
Reference: VU handout, Topic 2 — Levels of organization.
Status: Verified

Q3. The three levels of biodiversity are:
A) Genetic, species and ecosystem diversity
B) Plant, animal and microbial diversity
C) Terrestrial, freshwater and marine diversity
D) Alpha, beta and gamma diversity only
Correct answer: A — Genetic, species and ecosystem diversity
Reference: VU handout, Topic 1 — Introduction to ecology; biodiversity.
Status: Verified

Q4. Genetic diversity refers to:
A) The number of ecosystems in a region
B) The variety of genes within a species or population
C) The number of species in a community
D) The variety of habitats in a biome
Correct answer: B — The variety of genes within a species or population
Reference: VU handout, Topic 3 — Species; genetic diversity.
Status: Verified

Q5. The ecological niche of a species is:
A) The place where it lives
B) Its physical position and functional role within the community
C) The total number of individuals of the species
D) The food it eats
Correct answer: B — Its physical position and functional role within the community
Reference: VU handout, Topic 7 — The ecological niche. Page 32.
Status: Verified

Q6. A keystone species is one whose:
A) Population is the largest in the community
B) Removal causes a disproportionately large change in the community structure
C) Biomass is the greatest
D) Range covers the whole biome
Correct answer: B — Removal causes a disproportionately large change in the community structure
Reference: VU handout, Topic 13 — Keystone species. Page 45.
Status: Verified

Q7. In an ecosystem, the flow of energy is:
A) Cyclic, like nutrients
B) Unidirectional, from producers to consumers to decomposers, with loss as heat at each step
C) Bidirectional between producers and consumers
D) Stored permanently in the top trophic level
Correct answer: B — Unidirectional, from producers to consumers to decomposers, with loss as heat at each step
Reference: VU handout, Topic 15 — Ecological pyramids. Page 49.
Status: Verified

Q8. The sequence of eating and being eaten in an ecosystem is called a:
A) Food web
B) Food chain
C) Ecological pyramid
D) Nutrient cycle
Correct answer: B — Food chain
Reference: VU handout, Topic 16 — Food pyramids. Page 52.
Status: Verified

Q9. Which is the largest ecosystem on Earth?
A) Tropical rainforest
B) Desert
C) Ocean (marine ecosystem)
D) Grassland
Correct answer: C — Ocean (marine ecosystem)
Reference: VU handout, Topic 6 — Ecosystem. Page 29.
Status: Verified

Q10. An ecotone is:
A) A polluted area
B) The bottom of a lake
C) A zone of transition between two communities
D) A zone of developing community only
Correct answer: C — A zone of transition between two communities
Reference: VU handout, Topic 6 — Ecosystem; ecotone.
Status: Verified

2. Finalterm Solved MCQs

Q1. Eutrophication is:
A) The depletion of ozone in the stratosphere
B) The enrichment of water bodies with nutrients, causing harmful algal blooms and a rapid fall in dissolved oxygen
C) The accumulation of toxins up a food chain
D) The drying up of a lake by evaporation
Correct answer: B — The enrichment of water bodies with nutrients, causing harmful algal blooms and a rapid fall in dissolved oxygen
Reference: VU handout — Nutrient cycles; eutrophication.
Status: Verified

Q2. Biomagnification is:
A) The increase in the number of species in an ecosystem
B) The increase in concentration of a persistent toxic substance at successive trophic levels of a food chain
C) The growth of algae in nutrient-rich water
D) The magnification of a cell under a microscope
Correct answer: B — The increase in concentration of a persistent toxic substance at successive trophic levels of a food chain
Reference: VU handout — Pollution and food chains.
Status: Verified

Q3. "Red tide" is caused by:
A) Red algae growing on coral reefs
B) Harmful and toxic blooms of red dinoflagellates that colour the sea water red
C) Oil spills in the sea
D) Iron-rich dust blowing into the ocean
Correct answer: B — Harmful and toxic blooms of red dinoflagellates that colour the sea water red
Reference: VU handout — Aquatic biomes; algal blooms.
Status: Verified

Q4. Which of the following is an effect of ozone depletion?
A) Decreased ultraviolet radiation reaching the Earth
B) Increased ultraviolet radiation, causing skin cancer, cataracts and reduced crop yields
C) Cooling of the stratosphere only
D) Increased rainfall in the tropics
Correct answer: B — Increased ultraviolet radiation, causing skin cancer, cataracts and reduced crop yields
Reference: VU handout — Ozone depletion.
Status: Verified

Q5. Which of the following is a cause of global warming?
A) Burning of fossil fuels
B) Deforestation
C) Industrial effluents and transportation
D) All of the given options
Correct answer: D — All of the given options
Reference: VU handout — Global warming.
Status: Verified

Q6. The introduction of the Nile perch into Lake Victoria led to:
A) An increase in the number of native fish species
B) The extinction of an ecologically unique assemblage of more than 200 species of cichlid fish
C) The cleaning of the lake's water
D) A fall in the lake's water level
Correct answer: B — The extinction of an ecologically unique assemblage of more than 200 species of cichlid fish
Reference: VU handout — Invasive (nonnative) species (Topic 11). Page 41.
Status: Verified

Q7. Which of the following is an effect of deforestation?
A) Decrease in carbon dioxide concentration in the atmosphere
B) Habitat destruction, climate change, loss of biodiversity, soil erosion and desertification
C) Increase in rainfall everywhere
D) Increase in soil fertility
Correct answer: B — Habitat destruction, climate change, loss of biodiversity, soil erosion and desertification
Reference: VU handout — Deforestation.
Status: Verified

Q8. The steps of the nitrogen cycle include:
A) Nitrogen fixation, nitrification, assimilation, ammonification and denitrification
B) Photosynthesis, respiration and fermentation only
C) Evaporation, condensation and precipitation
D) Weathering, erosion and deposition
Correct answer: A — Nitrogen fixation, nitrification, assimilation, ammonification and denitrification
Reference: VU handout — Nitrogen cycle.
Status: Verified

Q9. An invasive (nonnative) species is one that:
A) Is native to the area and protected by law
B) Has been introduced to a new area, where its population expands dramatically and outcompetes or displaces native species
C) Lives only in the deep ocean
D) Cannot reproduce outside its native range
Correct answer: B — Has been introduced to a new area, where its population expands dramatically and outcompetes or displaces native species
Reference: VU handout, Topic 11 — Nonnative species. Page 41.
Status: Verified

Q10. Lentic water bodies are:
A) Running-water bodies such as rivers and streams
B) Standing-water bodies such as lakes, ponds and swamps
C) Underground aquifers only
D) Man-made reservoirs only
Correct answer: B — Standing-water bodies such as lakes, ponds and swamps
Reference: VU handout — Aquatic biomes.
Status: Verified

3. Midterm Subjective

Q1. Define biomagnification.
Answer: Biomagnification (biological magnification) is the progressive increase in the concentration of a persistent, non-biodegradable toxic substance (such as DDT, PCBs or mercury) at successive trophic levels of a food chain. The substance is taken up by producers in small amounts, is not broken down or excreted, and is passed on and concentrated at each feeding step, so that top predators carry concentrations many thousands of times higher than the water or soil they live in. Example: DDT sprayed on fields washes into water, is absorbed by plankton, eaten by small fish, then by large fish and fish-eating birds, in which it reached levels that thinned eggshells and crashed populations.
Reference: VU handout — Pollution and food chains.
Status: Verified

Q2. Define eutrophication.
Answer: Eutrophication is the enrichment of a water body with nutrients, especially nitrates and phosphates from sewage, fertilizers and industrial effluents. The excess nutrients trigger explosive growth of algae and cyanobacteria (algal blooms, including harmful algal blooms). When the algae die, decomposers consume the dissolved oxygen in the water to break them down, so the oxygen content falls rapidly; fish and other aquatic animals suffocate, the water becomes turbid and foul-smelling, and the ecosystem collapses into a "dead zone". Eutrophication is a leading cause of the degradation of lakes, estuaries and coastal seas.
Reference: VU handout — Nutrient cycles; eutrophication.
Status: Verified

Q3. Define genetic diversity.
Answer: Genetic diversity is the variety of genes and alleles within a species or within a population — the total genetic variation carried by all the members of the population. It arises from mutation, recombination and gene flow, and it is the raw material of evolution: a genetically diverse population can adapt to changing environments, resist disease and avoid inbreeding depression, while a population with low genetic diversity is vulnerable to extinction. Genetic diversity is one of the three levels of biodiversity, with species diversity and ecosystem diversity.
Reference: VU handout, Topic 3 — Species; genetic diversity.
Status: Verified

Q4. Define weathering and enlist its types.
Answer: Weathering is the in-place breakdown and alteration of rocks and minerals at the Earth's surface by physical, chemical and biological processes, without transport of the material (transport is erosion). Types: (1) Physical (mechanical) weathering — rocks are broken into smaller pieces without change in composition: freeze–thaw (frost wedging), thermal expansion and contraction, salt crystallization, pressure release (exfoliation), and abrasion; (2) Chemical weathering — minerals are changed by reactions: hydrolysis (e.g. feldspar → clay), oxidation (iron-bearing minerals rust), carbonation (CO₂ + water → carbonic acid dissolving limestone), and solution; (3) Biological weathering — living organisms break rocks down, e.g. plant roots growing into cracks, lichens producing acids, and burrowing animals. Weathering produces soil parent material and releases nutrients.
Reference: VU handout — Weathering.
Status: Verified

Q5. Differentiate between direct and indirect exploitation.
Answer: Direct exploitation is the deliberate removal or harvesting of organisms or their products for use — for example hunting, fishing, logging, collection of medicinal plants, and harvesting of fuelwood. Its effects are immediate and visible: populations decline, and over-harvesting can drive a species to extinction. Indirect exploitation is the harm caused to organisms or ecosystems as a side effect of other activities — for example habitat destruction by agriculture, urbanization and dam-building, pollution of air and water, introduction of invasive species, and climate change. Its effects are slower and less obvious, but it is now the larger threat to biodiversity worldwide, because it removes the habitat on which whole communities depend rather than single species.
Reference: VU handout — Threats to biodiversity.
Status: Verified

4. Finalterm Subjective

Q1. Write a short note on the major steps of the water cycle.
Answer: The water (hydrological) cycle is the continuous circulation of water between the Earth's surface and the atmosphere. Major steps: (1) Evaporation — heat from the sun evaporates water from oceans, lakes, rivers and soil; (2) Transpiration — plants release water vapour from their leaves (together with evaporation this is evapotranspiration); (3) Condensation — water vapour cools in the atmosphere and condenses into clouds; (4) Precipitation — water returns to the surface as rain, snow or hail; (5) Infiltration and percolation — some water soaks into the soil and recharges groundwater; (6) Runoff — the rest flows over the land into streams, rivers and finally the oceans, where the cycle begins again. The cycle distributes fresh water, regulates climate and moves nutrients through ecosystems; deforestation and climate change disturb it (altered rainfall, floods, droughts).
Reference: VU handout — Water cycle.
Status: Verified

Q2. Enlist some effects of ozone depletion.
Answer: The ozone layer in the stratosphere absorbs most of the Sun's harmful ultraviolet-B (UV-B) radiation. Its depletion (mainly by chlorofluorocarbons, CFCs) lets more UV-B reach the Earth, with effects including: (1) increased skin cancer (melanoma and non-melanoma) and premature skin ageing; (2) cataracts and other eye damage in humans and animals; (3) suppression of the immune system; (4) reduced growth and yields of crops (e.g. soybeans, wheat) and damage to forests; (5) harm to aquatic life — UV-B kills phytoplankton near the ocean surface, reducing the base of marine food webs and the ocean's uptake of CO₂; and (6) damage to materials such as plastics and paints. The Montreal Protocol (1987) phased out CFCs, and the ozone layer is slowly recovering.
Reference: VU handout — Ozone depletion.
Status: Verified

Q3. Write down the three zones of rivers.
Answer: A river is conventionally divided into three zones from source to mouth: (1) Source (headwater / erosion) zone — the steep upper course: fast, cold, oxygen-rich water over rocks and rapids; the river erodes its bed and carries coarse sediment; few plants, but trout and insect larvae are typical; (2) Transfer (transition) zone — the middle course: gentler gradient, wider channel, slower flow; sediment is transported downstream, floodplains begin to form, and diversity of fish and invertebrates increases; (3) Depositional (floodplain / delta) zone — the lower course: slow, warm, turbid water; sediment is deposited, forming floodplains, meanders and finally a delta at the mouth; high productivity but lower oxygen. Human impacts (dams, pollution, abstraction) differ in each zone and must be managed zone by zone.
Reference: VU handout — Rivers; aquatic biomes.
Status: Verified

Q4. Write down the factors that affect ecosystem diversity.
Answer: Ecosystem diversity — the variety of habitats, communities and ecological processes in a region — is affected by: (1) Climate (temperature, rainfall, seasonality) — it decides which ecosystems can exist; (2) Topography and altitude — mountains, valleys and slopes create varied habitats; (3) Soil type and geology — nutrient and water availability shape plant communities; (4) Water availability — rivers, lakes and groundwater sustain aquatic and riparian ecosystems; (5) Disturbance regimes — fire, flood, storms and grazing create a mosaic of successional stages; (6) Biotic interactions — competition, predation, keystone species and foundation species structure communities; (7) Human activities — deforestation, agriculture, urbanization, pollution and dams reduce ecosystem diversity; and (8) Area and isolation — larger and more connected areas hold more ecosystems (species–area relationship; island biogeography).
Reference: VU handout — Ecosystem diversity.
Status: Verified

Q5. What is global warming? Describe its causes and effects.
Answer: Global warming is the long-term rise in the average temperature of the Earth's surface caused by the increase in greenhouse gases (CO₂, methane, nitrous oxide, CFCs) in the atmosphere, which trap outgoing heat (the greenhouse effect). Human activities are the main cause. Causes: burning of fossil fuels (coal, oil, gas) in power plants, industry and transport; deforestation (fewer trees to absorb CO₂); industrial effluents; agriculture (methane from livestock and rice paddies, nitrous oxide from fertilizers); plus natural contributors such as volcanic eruptions. Effects: rise in temperature; rise in sea level (thermal expansion and melting glaciers/ice caps); climate change (changing rainfall, more droughts, floods, heatwaves and storms); extinction of species and loss of biodiversity; spread of vector-borne diseases; damage to agriculture and water supplies; and ocean acidification. Mitigation requires cutting emissions, reforestation and a shift to renewable energy.
Reference: VU handout — Global warming.
Status: Verified

Frequently asked questions

Is the Midterm from Lectures 1-22?
Yes — Midterm covers Lectures 1-22 and Finalterm covers Lectures 23-45.

Does the quiz work from this post?
Yes — use the 'Take the BT101 quiz' link above; the quiz is already live for this course.

Are the answers verified?
Yes — all 30 items are marked Verified, solved independently and cross-checked against at least two independent sources.

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