LET Elementary Natural Sciences Reviewer 2026

Answer: D. ban smoke-belchers on the roads

Banning smoke-belchers (vehicles that emit excessive smoke/pollution) directly removes the primary source of vehicular air pollution from roads. While other options like promoting bicycles or rail transit reduce overall vehicle usage, only option D addresses the immediate problem of vehicles already causing severe air pollution by preventing the most polluting vehicles from operating.

Answer: D. putting up plant nurseries

Plant nurseries are the primary physical locations where new plant varieties are propagated, grown, and distributed to farmers and agricultural centers. This hands-on cultivation and distribution method is how coconut varieties are discovered through selective breeding and then made available to the wider agricultural community.

Answer: C. unsanitary conditions

Unsanitary conditions during food preparation and processing introduce harmful bacteria, pathogens, and contaminants that cause food spoilage and foodborne illness. Miscalculation, bad weather, and mislabeling do not directly cause spoilage in the preparation process itself.

Answer: B. wash the vegetables well with clean water

Washing vegetables with clean water physically removes surface preservatives and chemical residues without damaging the vegetables or introducing harmful substances. Freezing preserves existing chemicals, soaking in detergent introduces toxic substances, and consuming immediately doesn't address the preservative concern.

Answer: D. stop malnutrition among schoolchildren

School feeding and milk rationing programs are nutritional interventions specifically designed to address malnutrition in schoolchildren. While these programs may provide food supplements and can be considered special programs by DepEd and DOH, their primary and ultimate goal is to prevent and reduce malnutrition, which directly impacts student health and academic performance.

Answer: A. these are biodegradable

Food, plants, and animal wastes are biodegradable materials that can be broken down naturally by microorganisms and decompose into organic matter. Segregating them allows for proper composting or organic waste treatment, preventing contamination of non-biodegradable waste streams and enabling resource recovery.

Answer: A. because the earth rotates on its own axis

Earth's rotation on its axis causes different parts of the planet to face toward and away from the sun in a continuous cycle. As Earth completes one full rotation every 24 hours, each location experiences a period of daylight (facing the sun) and darkness (facing away from the sun).

Answer: B. burning of fossil fuels

Burning of fossil fuels releases sulfur dioxide and nitrogen oxides into the atmosphere, which combine with water vapor to form sulfuric and nitric acids that fall as acid rain. Forest fires produce smoke but not the primary chemical precursors of acid rain, CFCs damage the ozone layer rather than cause acid rain, and while vehicles emit some pollutants, they are not the main source of acid rain formation.

Answer: C. parasitic

A parasitic relationship involves one organism (the parasite) benefiting while harming another organism (the host). The caterpillar benefits by obtaining food and nutrition from the leaf, while the plant is harmed by losing leaf tissue. This one-sided benefit makes it parasitism, not mutualism (mutual benefit), competition (both harmed), or predation (hunting and killing).

Answer: D. oxygen

Green plants use carbon dioxide, water, soil nutrients, and sunlight to produce food through photosynthesis. Oxygen is a byproduct of this process that plants release into the atmosphere, not a raw material used in food manufacture.

Answer: C. oxygen

During aerobic respiration, plants take in oxygen to break down glucose and release energy in the form of ATP. While plants also use carbon dioxide during photosynthesis, respiration specifically requires oxygen as the electron acceptor in the electron transport chain.

Answer: A. photosynthesis

Roots cannot perform photosynthesis because they lack chlorophyll and do not receive sunlight underground. Roots do perform the other functions: they anchor plants to soil, store nutrients and food reserves, and absorb water and minerals from the soil.