Biology is the heaviest section of almost all the admission tests for medical and health degrees in Italy, and also the one where I see the biggest gap between “I studied a lot” and “I scored points”. The reason is almost always the same: biology looks like a subject to memorise, so people study by rereading. Then the test brings a question that asks what happens if a certain step is blocked, and memory is not enough.
For health-profession degrees (nursing, physiotherapy and the like), biology weighs 23 questions out of 60: the full picture of that test is in How to prepare for the Health Professions test.
Within biology, the part that weighs most and is studied worst is the cell-and-molecular block: cell structure, membranes and transport, energy metabolism, cell division, DNA and protein synthesis. These five chapters easily account for half of the biology questions across the TOLC-MED (the Italian medicine admission test) and the IMAT (the International Medical Admissions Test, the English-language medicine test). In this article I tell you what they really ask, what you can afford not to memorise, and the mistakes I see coming back every year.
How much this block weighs (and why it pays to start with it)
In the biology questions of admission tests, the bulk is concentrated in a few recurring cores: the cell and its organelles, molecular biology (DNA, RNA, proteins), Mendelian genetics, bioenergetics, then with less weight human anatomy and physiology, and a few questions on evolution and ecology.
The advantage of the cell-and-molecular block is that it is compact and closed: it is a finite body of knowledge, highly codified, which once understood will not slip away. Human anatomy, on the contrary, is a bottomless pit where you can pour 40 hours and still find questions you cannot answer. So if you are short of time, the rational order is: cell and molecular first, genetics straight after, anatomy last as a surface-level review.
If you are still deciding which test to aim for, I have written two dedicated guides to full preparation: one on the TOLC-MED and one on the IMAT for Medicine in English. If your goal is a three-year health degree (nursing, physiotherapy, midwifery), the test is a different one and biology weighs 23 questions out of 60 in it: the guide is Health professions test: structure, syllabus and how to prepare.
The cell: organelles as an assembly line
Mistake number one is to study organelles as a list of definitions: “mitochondrion: site of cellular respiration. Ribosome: site of protein synthesis. Golgi apparatus: modifies and sorts proteins”. If you learn them like that, the question that asks through which organelles a protein destined for secretion passes puts you in difficulty, because you have never seen the route.
Study them instead as a flow. The protein destined for the outside is born on a ribosome attached to the rough endoplasmic reticulum, enters the lumen of the RER, is glycosylated, travels in vesicles to the Golgi, is finished and addressed there, and ends up in a secretory vesicle that fuses with the plasma membrane. A cytosolic protein, on the other hand, is born on a free ribosome and stays where it is. With this single route in mind you answer a whole family of questions.
The two distinctions that come back in every session:
- Prokaryotes vs eukaryotes: no nucleus, no membrane-bound organelles, circular DNA, 70S ribosomes, a peptidoglycan wall in bacteria. Careful: prokaryotes do have ribosomes. It is a classic distractor.
- Animal vs plant cell: cellulose wall, chloroplasts and a large central vacuole in the plant cell; centrioles typically in the animal one. Both have mitochondria — plant cells respire too.
A detail the tests love: mitochondria and chloroplasts have their own DNA, a double membrane and their own ribosomes, and divide on their own. This is the endosymbiotic theory, and it is the explanation of maternal inheritance of mitochondria. Three different questions that come from the same idea.
Membrane and transport: the part with the most mistakes
The plasma membrane is a phospholipid bilayer with embedded proteins: the fluid mosaic model. So far, everyone knows it. Then the question on transport arrives and the disaster begins, because the categories get confused. Fix them like this, in a mental table with two questions: does it need ATP? and does it need a protein?
- Simple diffusion: no ATP, no protein. Down the gradient. Small, non-polar molecules pass — oxygen, carbon dioxide, lipophilic molecules.
- Facilitated diffusion: no ATP, yes protein (channel or carrier). Always down the gradient. Glucose, ions.
- Active transport: yes ATP, yes protein. Against the gradient. The model is the sodium-potassium pump: 3 Na⁺ out, 2 K⁺ in, for every ATP hydrolysed.
- Osmosis: diffusion of water across a semipermeable membrane, from the solution less concentrated in solutes towards the more concentrated one.
The mistake I see most often of all: saying that in osmosis “water goes where there is more water”. Put like that it is right, but then in the question the concentration is expressed in solute and the student reasons backwards, sending the water in the wrong direction. Get into the habit of always rewriting the data in terms of solute and asking yourself where the water will end up: in a hypertonic solution the cell loses water and shrivels, in a hypotonic one it absorbs water and may lyse. This single conversion saves you 2-3 points.
Metabolism: what to memorise and what not to
Here the temptation is to learn all the intermediates of the Krebs cycle by heart. You do not need to, and it is wasted time. What the questions really ask is the balance and the location.
Of cellular respiration you must know, with absolute certainty:
- Glycolysis: in the cytoplasm, does not require oxygen, from 1 glucose to 2 pyruvate, net yield 2 ATP + 2 NADH.
- Oxidative decarboxylation of pyruvate and the Krebs cycle: in the mitochondrial matrix, they require aerobic conditions. The Krebs cycle produces GTP/ATP by substrate-level phosphorylation, but its real output is the reduced coenzymes NADH and FADH₂.
- Electron transport chain and oxidative phosphorylation: on the inner mitochondrial membrane. Electrons run down the complexes, protons are pumped into the intermembrane space, and ATP synthase exploits the return flow of protons to produce ATP. Final electron acceptor: oxygen, which becomes water.
- Overall yield: about 30-32 ATP per glucose.
Then fermentation: in the absence of oxygen it serves only to regenerate NAD⁺ so that glycolysis can go on. It produces no additional ATP. In humans it is lactic, in yeasts alcoholic.
If you know these five lines with the exact location, you answer practically every bioenergetics question on the test. If instead you have memorised succinyl-CoA and oxaloacetate but are unsure where glycolysis takes place, you have studied backwards.
Mitosis and meiosis: one scheme, not two lists
The quickest way to never get a cell division question wrong again is to stop studying the phases in parallel and anchor everything to three comparisons:
- Purpose: mitosis makes two cells identical to the mother, for growth and repair. Meiosis makes four gametes with half the chromosomes, for sexual reproduction.
- Number of divisions: mitosis one, meiosis two (meiosis I reductional, meiosis II equational).
- What separates and when: in the anaphase of mitosis and in anaphase II the sister chromatids separate; in anaphase I the homologous chromosomes separate. This is the distinction that decides most questions.
Add the two events that generate variability and exist only in meiosis: crossing over in prophase I (exchange between paired homologues, the tetrads) and independent assortment in metaphase I. And keep in mind the classic trap on counting: a human cell in G2 has 46 chromosomes but 92 DNA molecules, because each chromosome is already duplicated into two chromatids. The number of chromosomes does not double with replication — it is the number of chromatids that doubles.
From DNA to protein: the route to keep in your head
The central dogma — DNA → RNA → protein — is the backbone of all molecular biology. But the questions do not ask “what is transcription”: they ask who does what, in which direction, and what happens if something breaks.
Replication: semiconservative, DNA polymerase synthesises only in the 5’→3’ direction, hence the continuous leading strand and the lagging strand in Okazaki fragments later sealed by ligase. An RNA primer made by primase is needed, and helicase opens the double helix.
Transcription: RNA polymerase produces the mRNA from the template strand. In eukaryotes it is followed by maturation: a cap at the 5’ end, polyadenylation at the 3’ end, and splicing, which removes the introns and joins the exons. Alternative splicing explains how one gene can give several proteins — a question that comes back often and that you can only solve if you have understood the mechanism, not if you have memorised the definition.
Translation: on the ribosome, tRNA brings the amino acid and pairs its anticodon with the mRNA codon. The genetic code is made of triplets, degenerate (several codons for the same amino acid) but unambiguous (one codon codes for only one amino acid). AUG is the start and codes for methionine; UAA, UAG, UGA are stop codons and code for nothing.
On degeneracy hangs the question on mutations, which is almost always the same reasoning: a substitution can be silent (the codon changes, the amino acid does not — precisely thanks to degeneracy), missense (the amino acid changes), nonsense (creates a premature stop, truncated protein). An insertion or deletion of a number of bases that is not a multiple of three causes a frameshift and scrambles the whole sequence downstream: it is the most damaging type of mutation, and the tests ask it in exactly this form.
The five mistakes that cost the most points
After a few years of preparing students, these come back with impressive regularity:
- Confusing prokaryotes with “without ribosomes”. Prokaryotes synthesise proteins like everyone else; what they lack is the nucleus and the membrane-bound organelles.
- Reversing the direction of osmosis because the data is given in solute and not in water.
- Attributing crossing over to mitosis. It exists only in prophase I of meiosis.
- Saying that fermentation produces ATP. It regenerates NAD⁺; the ATP comes from glycolysis.
- Counting chromosomes as if they doubled after the S phase. Chromatids double, not chromosomes.
If you recognise yourself in three of these five, you do not have a problem of study quantity: you have a problem of study type. You are memorising statements instead of rebuilding mechanisms.
How to study it without going mad
The method that works best with my students is brutally simple and rests on three rules.
First: for every process, draw it. Not “make a diagram” with the coloured arrows of the textbook — take a blank sheet and redraw the route from memory, then compare. If you cannot redraw the respiratory chain without looking, you do not know it, however many times you have reread it.
Second: study by questions, not by chapters. After each paragraph write yourself three exam-style questions (“what happens if I block ATP synthase?”, “which organelle is missing in a prokaryotic cell?”) and answer them the next day with the book closed. It is active testing, and it is the only thing that really moves the score.
Third: use the official questions from previous years as study material, not as a final check. A question got wrong in March is worth more than ten pages reread. It is the same principle I use for stoichiometry: you have to look for the mistake, not avoid it.
Realistic timelines
For the cell-and-molecular block, starting from a decent high school base:
- Targeted review (you know the material but it is confused): 3-4 lessons, with 40-50 questions between one lesson and the next. Two or three weeks.
- Rebuilding from scratch (biology done badly at high school or never done): 7-8 lessons on the cell-and-molecular block alone, within an overall plan of 15-20 lessons for the whole of biology.
- Pre-test polish in the last month: 2 lessons on the questions got wrong in practice tests, no new theory.
These are realistic timelines, not optimistic ones. Whoever arrives in June with all of biology still to do and expects to finish it in ten days typically memorises and forgets.
How we work in lessons
I always start with a diagnosis: I give you about twenty questions covering the five cores of this article and I look at where you go wrong, not how much. In most cases, within half an hour it becomes clear that the gap is concentrated in one or two points — almost always membrane and transport, or meiosis.
Then we work only on that, with the blank sheet: I ask you to explain the process to me aloud while you draw it. It is uncomfortable the first few times, and that is exactly why it works: it forces you to discover the steps you thought you knew. You review the theory yourself between lessons, on your own, using the material I leave you; the time together is spent on mechanisms and questions, not on rereading the book.
Lessons are online, single or in a 10-hour package — you will find up-to-date rates and packages on the pricing page. If you want to understand where you really stand, the first thing to do is a free introductory call: half an hour, a few questions, and I tell you honestly how many lessons are needed and on what.
You will find the full syllabus on the science tutoring page — general and inorganic chemistry, biology, earth sciences and astronomical geography — and the overview of the tests on the admission test preparation page, with the sections dedicated to TOLC-MED, IMAT and TOLC-B.
Cell division, at the level of a school test and with worked exercises, is in Mitosis and meiosis: differences, phases and exercises; the filter-semester approach (the semestre filtro, the first-semester exam route for Medicine), with timelines and fill-in questions, is in Biology in the Medicine filter semester. If your course is Biology or Biotechnology, the guide is the one for the TOLC-B. To train on the format there is the filter semester practice test.
