Cambodia Health Entrance Exam common mistakes
Cambodia Health Entrance Exam · Understand the traps and how to avoid them.
On osmosis and diffusion items, treating water as if it moves toward the higher solute concentration only when the membrane is described as fully permeable, then choosing the wrong direction when the stem says 'semi-permeable'.
Candidates memorise 'water follows salt' as a slogan but never link it to the membrane property, so they apply the rule indiscriminately and invert the answer on selective-permeability items.
What to do instead
Before answering any transport question, underline the membrane description and the two solute concentrations, then write the arrow for water (low solute to high solute) and for solute (high to low, only if the membrane allows it). Practise ten stems that vary membrane type and confirm the arrow each time.
Confusing mitosis and meiosis outcomes, stating that meiosis produces two identical diploid cells or that crossing over occurs in mitosis.
The two processes are taught together and the numbers 2n and n get swapped under time pressure; candidates also recall 'division' without attaching it to a specific phase or product.
What to do instead
Build a two-column table from memory listing starting cell, number of divisions, products, ploidy, and where crossing over happens, then redraw it weekly until it is automatic. Answer every genetics item by first naming which process the stem describes.
Balancing chemical equations by changing subscripts in a formula (writing H2O2 as H2O to make it balance) instead of adjusting coefficients.
Candidates focus on making atom counts equal and take the shortest visual route, forgetting that changing a subscript creates a different substance.
What to do instead
Adopt a fixed routine: list each element, count atoms on both sides, and only ever write or erase numbers in front of formulas. When stuck, balance oxygen and hydrogen last and check one polyatomic ion as a single unit.
Mixing up oxidation and reduction, labelling the species that gains electrons as oxidised, or misidentifying the oxidising agent as the one that is oxidised.
The mnemonic 'OIL RIG' is remembered as a phrase without being attached to electron transfer, and the term 'oxidising agent' sounds like the thing being oxidised.
What to do instead
Write 'loss of electrons = oxidation at the anode; gain = reduction at the cathode' at the top of rough work, then for each species record electron change before naming the agent. The oxidising agent is the species that is reduced.
Using g = 10 m/s² in one line and 9.8 m/s² in the next within the same problem, or dropping the direction sign when adding vectors.
Candidates copy values from different memorised examples and treat signs as decoration rather than as information about direction.
What to do instead
State the value of g and the positive direction once at the start of each solution and never change them mid-problem. For vectors, draw a small arrow diagram and assign + and − before substituting numbers.
Substituting into a formula without converting units, for example putting 20 cm into a formula that requires metres, or mixing minutes and seconds in a rate problem.
Exam stems deliberately mix cm, m, g, kg, minutes and hours; candidates pattern-match the numbers and skip conversion because it feels like extra work.
What to do instead
Convert every quantity to SI units in a dedicated first line before any formula appears, and write the unit next to each substituted number. Do a final dimensional check: if the answer's unit is wrong, the arithmetic is wrong.
Solving word problems by grabbing numbers and applying the first operation that comes to mind, without defining the unknown or checking the answer against the question.
Time pressure rewards speed over structure, and candidates have practised bare equations far more than translation from text to algebra.
What to do instead
Use a three-line template for every word problem: let x = ..., write the equation, solve and substitute back. Reserve the last 30 seconds of each item to re-read the question and confirm the answer matches what was asked (rate, total, or difference).
Losing marks on multi-step arithmetic through sign errors in negative numbers, incorrect fraction addition, or misapplying order of operations in expressions such as 3 + 2 × 5².
These operations are assumed to be already mastered, so candidates never drill them and rush the intermediate steps.
What to do instead
Do a daily ten-item mental arithmetic set covering fractions, negatives, and order of operations, and write intermediate lines rather than combining steps. In the exam, bracket substituted negative values before squaring or multiplying.
Answering logical reasoning items from intuition or personal belief instead of from the premises given, or assuming a statement's converse is true ('all A are B' therefore 'all B are A').
Everyday reasoning rewards plausibility, and candidates have rarely been trained to treat premises as the only permitted evidence.
What to do instead
For each item, write the premises in symbols (A → B) and test only what follows necessarily; reject options that reverse the arrow or add information. Practise syllogisms and 'must be true' sets where the content is deliberately unfamiliar so intuition cannot help.
Misreading Khmer literary or general-knowledge items by skimming the question and choosing an answer that matches a familiar name or title rather than the specific detail asked (author, period, or work).
Recognition memory feels like knowledge, so a familiar option attracts the choice before the stem's actual requirement is processed.
What to do instead
Read the stem twice and circle the interrogative word (who, which period, which work) before looking at options. Keep a one-page revision sheet pairing each major author with period, genre, and one representative work, and self-test by covering the answer column.