1. The final stable community in ecological succession is called:
Correct Answer: c) Climax community
Explanation: The climax community represents the endpoint of ecological succession - a stable, self-perpetuating community that remains relatively unchanged until disrupted by major environmental changes. It's in equilibrium with the local climate and soil conditions.
2. Primary succession occurs on:
Correct Answer: b) Bare rock
Explanation: Primary succession begins on completely new, lifeless substrates like bare rock, lava flows, or sand dunes where no soil exists initially. Pioneer species like lichens and mosses colonize these areas and begin the slow process of soil formation.
3. Dominant producers in a forest ecosystem are:
Correct Answer: b) Trees
Explanation: Trees are the dominant primary producers in forest ecosystems, forming the canopy that captures most sunlight. They account for the majority of biomass production through photosynthesis and create the physical structure that supports diverse forest life.
4. Example of a decomposer in forests:
Correct Answer: b) Earthworm
Explanation: Earthworms are crucial decomposers in forest ecosystems. They break down dead organic matter, enhance soil fertility through their castings, and improve soil structure by creating burrows that allow air and water to penetrate.
5. Grasslands are characterized by:
Correct Answer: b) Seasonal droughts
Explanation: Grasslands typically experience distinct wet and dry seasons, with periodic droughts that prevent tree growth but allow drought-resistant grasses to thrive. This intermediate precipitation (25-75 cm annually) creates the ideal conditions for grassland ecosystems.
6. Key herbivore in grasslands:
Correct Answer: b) Zebra
Explanation: Zebras are iconic grassland herbivores, perfectly adapted to graze on tough grasses with their specialized teeth and digestive systems. They play a crucial role in nutrient cycling and serve as prey for large carnivores in African savanna ecosystems.
7. Plants in deserts adapt by:
Correct Answer: b) Deep roots
Explanation: Desert plants like mesquite develop extensive root systems that may reach 20-30 meters deep to access groundwater. Other adaptations include reduced leaves (spines in cacti), waxy coatings, and CAM photosynthesis to minimize water loss.
8. Nocturnal animals in deserts are active at night to:
Correct Answer: d) All of the above
Explanation: Nocturnality in deserts provides multiple advantages: (1) Cooler nighttime temperatures (often 30°C+ cooler than daytime), (2) Reduced predation risk as many predators are diurnal, and (3) Increased prey availability as many desert species are also nocturnal.
9. Phytoplankton are found in:
Correct Answer: b) Pelagic zone
Explanation: Phytoplankton inhabit the photic zone (upper 200m) of the pelagic (open water) region where sunlight penetrates for photosynthesis. They form the base of aquatic food webs, producing about 50% of Earth's oxygen through photosynthesis.
10. Coral reefs are part of:
Correct Answer: b) Marine ecosystems
Explanation: Coral reefs are marine ecosystems found in shallow, tropical waters (between 30°N and 30°S latitudes). They're built by colonies of coral polyps and host incredible biodiversity, often called the "rainforests of the sea."
11. The 10% energy transfer rule implies:
Correct Answer: a) 90% energy is lost as heat
Explanation: Lindeman's 10% law states that only about 10% of energy is transferred between trophic levels. The remaining 90% is lost primarily as metabolic heat during respiration, movement, and other life processes, following the Second Law of Thermodynamics.
12. Which human activity disrupts ecological succession?
Correct Answer: b) Urbanization
Explanation: Urbanization dramatically alters landscapes through habitat destruction, pollution, and introduction of non-native species, preventing natural succession processes. It creates artificial ecosystems (cities) that require constant energy inputs to maintain.
13. If a grassland has 10,000 kcal energy at the producer level, how much reaches a tertiary consumer?
Correct Answer: c) 10 kcal
Explanation: Applying the 10% energy transfer rule: Producers (10,000 kcal) → Primary consumers (1,000 kcal) → Secondary consumers (100 kcal) → Tertiary consumers (10 kcal). This explains why food chains rarely exceed 4-5 trophic levels.
14. In a pyramid of numbers for a tree ecosystem, the largest number is for:
Correct Answer: b) Insects
Explanation: In tree-dominated ecosystems, the pyramid of numbers is often inverted because a single tree can support thousands of insects (herbivores, parasites). This demonstrates that pyramids of numbers don't always match the typical pyramid shape.