This Science Ecology section of the LET General Education exam covers 5 expert-reviewed practice questions. Each question has a plain-English explanation and notes on why the wrong answers are wrong.
Sample 1
The Philippines belong to the type of biome called _____.
- A deciduous forest
- B taiga
- C tropical rainforest✓
- D grassland
Answer: C
The Philippines has a tropical climate with heavy rainfall, placing it in the tropical rainforest biome. This biome is characterized by dense vegetation, high biodiversity, warm temperatures year-round, and abundant rainfall.
Why the other choices are wrong
- A. Deciduous forests have trees that shed leaves seasonally — found in temperate regions like eastern US, not tropical Philippines.
- B. Taiga (boreal forest) is a cold-climate biome with coniferous trees — found in Russia, Canada, Scandinavia.
- D. Grasslands have mostly grasses with few trees — the Philippines is too wet and forested for this.
Sample 2
Tropical rainforests have many trees and other plants that photosynthesize. What happens when huge areas of tropical rain forests are destroyed?
- A Oxygen level increases and carbon dioxide level decreases.
- B Oxygen level increases and carbon dioxide level increases.
- C Oxygen level decreases and carbon dioxide level decreases.
- D Oxygen level decreases and carbon dioxide level increases.✓
Answer: D
Trees do photosynthesis: they ABSORB carbon dioxide (CO2) and RELEASE oxygen (O2). If you destroy huge areas of rainforest, you remove the trees doing this work. Result: less O2 produced (oxygen level DECREASES) and less CO2 absorbed (CO2 level INCREASES). Both effects worsen at the same time — that's why deforestation drives climate change.
Tip: Trees = O2 makers + CO2 absorbers. No trees = less O2, more CO2. Always opposite directions.
Why the other choices are wrong
- A. Backwards on both — destroying trees doesn't increase O2 or decrease CO2.
- B. Half right (CO2 increases) but O2 wouldn't increase without trees.
- C. Half right (O2 decreases) but CO2 wouldn't decrease — without trees, less CO2 gets absorbed, so it builds up.
Sample 3
A hypothetical ecosystem contains lettuce (the producer), a caterpillar (the primary consumer), a small passerine bird (the secondary consumer) and a lion (the tertiary consumer). A gardener arrives and sprays pesticide, killing all the caterpillars. What can happen to the ecosystem?
- A The passerine birds will thrive.
- B The lions will eventually die.✓
- C the passerine birds will convert to herbivores.
- D the lettuce will wilt and die.
Answer: B
Think of a food chain like a tower of blocks. Lettuce is the bottom block, caterpillars are the next, then birds, then lions. If you pull out the caterpillar block (pesticide), the birds starve. If the birds starve, the lions starve. The whole tower falls down.
Tip: When a food-chain link is removed, the levels ABOVE it starve, and the levels BELOW it thrive (no one eats them).
Why the other choices are wrong
- A. Birds will starve without caterpillars, not thrive — caterpillars were their food.
- C. Birds can't suddenly switch to eating plants — their bodies are built to eat insects.
- D. Lettuce will actually GROW MORE without caterpillars eating it, not wilt.
