Q.1 What is the study of the interactions between organisms and their environment called?
Zoology
Botany
Ecology
Genetics
Explanation - Ecology is the branch of biology that studies how organisms interact with each other and with their environment.
Correct answer is: Ecology
Q.2 Which of the following is a biotic factor in an ecosystem?
Sunlight
Temperature
Plants
Water
Explanation - Biotic factors are living components of an ecosystem, such as plants and animals.
Correct answer is: Plants
Q.3 Which level of ecological organization includes all the organisms of the same species in an area?
Community
Population
Ecosystem
Biosphere
Explanation - A population consists of all individuals of the same species living in a particular area.
Correct answer is: Population
Q.4 The largest level of ecological organization is:
Community
Biosphere
Ecosystem
Population
Explanation - The biosphere is the global ecological system that integrates all living beings and their relationships.
Correct answer is: Biosphere
Q.5 Which organisms are considered primary producers in most ecosystems?
Carnivores
Herbivores
Green plants
Decomposers
Explanation - Green plants use photosynthesis to convert sunlight into energy, forming the base of the food chain.
Correct answer is: Green plants
Q.6 Which of the following is an example of mutualism?
Lion hunting deer
Bee pollinating flowers
Fungus feeding on tree
Tick on dog
Explanation - In mutualism, both species benefit. Bees get nectar, and flowers are pollinated.
Correct answer is: Bee pollinating flowers
Q.7 What term describes the role an organism plays in its ecosystem?
Habitat
Community
Niche
Biome
Explanation - A niche is the role or 'job' an organism has in its ecosystem, including how it gets energy and interacts with others.
Correct answer is: Niche
Q.8 Which process returns carbon dioxide to the atmosphere?
Photosynthesis
Respiration
Pollination
Nitrification
Explanation - Respiration releases carbon dioxide as organisms break down glucose for energy.
Correct answer is: Respiration
Q.9 Which cycle involves processes such as evaporation, condensation, and precipitation?
Carbon cycle
Nitrogen cycle
Water cycle
Oxygen cycle
Explanation - The water cycle describes how water moves between the Earth's surface and atmosphere through processes like evaporation and rainfall.
Correct answer is: Water cycle
Q.10 What do decomposers do in an ecosystem?
Produce food
Recycle nutrients
Consume producers
Control population
Explanation - Decomposers like fungi and bacteria break down dead matter, recycling nutrients back into the soil.
Correct answer is: Recycle nutrients
Q.11 Which biome is characterized by very low rainfall and extreme temperatures?
Tundra
Rainforest
Desert
Savanna
Explanation - Deserts receive very little rainfall and have extreme temperature fluctuations between day and night.
Correct answer is: Desert
Q.12 Which of the following is an example of a density-dependent limiting factor?
Earthquake
Flood
Predation
Volcanic eruption
Explanation - Density-dependent factors like predation increase in effect as population density rises.
Correct answer is: Predation
Q.13 What type of succession occurs after a volcanic eruption?
Secondary succession
Primary succession
Climax succession
Retrogression
Explanation - Primary succession starts on bare rock where no soil exists, like after a volcanic eruption.
Correct answer is: Primary succession
Q.14 Which gas is the most abundant greenhouse gas?
Carbon dioxide
Methane
Nitrous oxide
Water vapor
Explanation - Water vapor is the most abundant greenhouse gas, though carbon dioxide is the main human-contributed one.
Correct answer is: Water vapor
Q.15 What is the main source of energy for life on Earth?
The Moon
The Sun
The Wind
The Oceans
Explanation - The Sun provides the energy that drives photosynthesis, weather systems, and most life processes.
Correct answer is: The Sun
Q.16 What is biomagnification?
Increase of population size
Increase of toxin concentration up the food chain
Recycling of nutrients
Energy loss at each trophic level
Explanation - Biomagnification is when toxins like pesticides become more concentrated in organisms at higher trophic levels.
Correct answer is: Increase of toxin concentration up the food chain
Q.17 Which of the following is an abiotic factor?
Birds
Fish
Sunlight
Trees
Explanation - Abiotic factors are non-living components of ecosystems such as light, water, and temperature.
Correct answer is: Sunlight
Q.18 Which biome has the highest biodiversity?
Desert
Temperate forest
Tropical rainforest
Tundra
Explanation - Tropical rainforests have the greatest variety of species due to warm climate and abundant rainfall.
Correct answer is: Tropical rainforest
Q.19 What does the term 'carrying capacity' refer to?
Maximum number of species globally
Maximum number of individuals an environment can support
Number of predators in a system
Total biomass in a community
Explanation - Carrying capacity is the maximum population size that an environment can sustain indefinitely.
Correct answer is: Maximum number of individuals an environment can support
Q.20 Which organisms are at the top of the food chain?
Producers
Herbivores
Carnivores
Decomposers
Explanation - Carnivores, especially apex predators, are at the top of the food chain with no natural predators.
Correct answer is: Carnivores
Q.21 What term describes the gradual recovery of ecosystems after disturbance?
Evolution
Succession
Migration
Competition
Explanation - Ecological succession is the gradual process by which ecosystems change and recover over time.
Correct answer is: Succession
Q.22 What percentage of energy is typically transferred from one trophic level to the next?
100%
50%
10%
1%
Explanation - On average, only about 10% of energy is passed to the next trophic level, with the rest lost as heat.
Correct answer is: 10%
Q.23 Which of the following is a keystone species example?
Sharks
Sea otters
Ants
Pigeons
Explanation - Sea otters are a keystone species because they control sea urchin populations, maintaining kelp forest ecosystems.
Correct answer is: Sea otters
Q.24 What is the main cause of eutrophication in lakes and rivers?
Increased oxygen
Nutrient pollution from fertilizers
Decreased sunlight
Acid rain
Explanation - Excess nutrients, especially nitrogen and phosphorus, cause algal blooms leading to oxygen depletion in water bodies.
Correct answer is: Nutrient pollution from fertilizers
Q.25 Which cycle involves bacteria converting nitrogen into usable forms for plants?
Carbon cycle
Nitrogen cycle
Phosphorus cycle
Water cycle
Explanation - The nitrogen cycle involves processes like nitrogen fixation, nitrification, and denitrification, mostly mediated by bacteria.
Correct answer is: Nitrogen cycle