A mango seed is planted in a pot with soil. It is watered regularly but kept in a dark cupboard. After 2 weeks, the seed sprouts but has yellow leaves.
(a) Refraction. (b) Light bends when it passes from water to air (different densities).
Two identical bar magnets are placed on a table. When the north pole of magnet X is brought near magnet Y, magnet Y moves away.
A cheek cell and an onion cell are observed. psle 2012 science questions and answers
Note: Due to copyright restrictions, the exact 2012 exam paper cannot be reproduced verbatim. Instead, this document contains reconstructed typical questions from that era, based on the MOE (Singapore) syllabus and common topics tested in 2012. Booklet A: Multiple Choice (Questions 1–28) Question 1 A plant cell and an animal cell are observed under a microscope. Which part is present in the plant cell but absent in the animal cell? A) Nucleus B) Cytoplasm C) Cell wall D) Cell membrane
(a) Complete metamorphosis. (b) Larva lives in water, breathes through siphon tube; adult flies, breathes through spiracles. (Or: Larva does not have wings; adult has wings.)
(a) Producer. (b) Grasshopper population will increase initially because there are no frogs to eat them. A mango seed is planted in a pot with soil
(a) What process do the plants carry out during the day that benefits the fish? (b) What gas do the fish release that is used by the plants?
(a) Stores water. (b) Reduces water loss (less surface area for transpiration) and protects from herbivores.
(a) What has happened to the steel rod? (b) What is this process called? (a) Refraction
A pupil wants to test if light is needed for photosynthesis. She uses two potted plants, one in sunlight and one in a dark cupboard. After 48 hours, she tests both leaves for starch.
(a) Algal bloom. (b) Algae block sunlight → plants die → less oxygen → fish die.
(a) Cell wall (or large vacuole or chloroplasts – but onion cells have no chloroplasts; cell wall is best). (b) Controls cell activities / contains genetic material.
A student builds two circuits. Circuit A has one bulb and one battery. Circuit B has the same bulb but two batteries connected in series.
C) Cell wall Explanation: Plant cells have a rigid cell wall outside the cell membrane for support; animal cells do not.