A free question is useful when you can see the whole teaching, not only the stem and a letter. That means the vignette, all five options, an explanation of the correct answer, a reason each other option fails, and one educational objective. A screenshot of a stem with the answer cropped, or a file that says “B” and nothing else, is not practice. It is a spoiler with no lesson.
What to require from any free set
Before you spend an evening on a free PDF, a forum thread, or an app preview, check five things. If one is missing, close it.
- The story is in time order, and it does not hand you a buzzword that makes the lead-in pointless.
- There are five options, A through E, and you can read them before you are told the answer.
- The lead-in asks a second-order or third-order question: a mechanism, a structure, a nerve, a lab change, or the best next action.
- The correct answer is explained in sentences, not as a bare letter.
- Each distractor has its own reason, tied to this patient. A list of fun facts that never mentions the stem does not count.
The four items on this page meet that bar. They are original StepLobe questions, already expanded in the HTML. You do not need an account to read them. Use them as the standard when you judge any other free source. If that source cannot explain the wrong letters, it cannot teach you to stop picking them.
Why most free sets fail students
The usual failure is volume without a review rule. Twenty unexplained items feel like work because the evening disappeared. The next morning you remember a funny stem and not a single objective. Another failure is recycled wording from a commercial deck or a video series, copied into a document with the pictures stripped out. You cannot learn a mechanism from a caption that assumed you had just watched someone else’s lesson. StepLobe’s questions are written for this bank. They are not copied from a third-party deck.
A third failure is doing free questions you will never see again, then buying a bank and starting at zero. The point of a free set is to practice the review habit you will use on the paid bank: choose a letter, then harvest one sentence. If you will not do that for four items, you will not do it for forty.
What StepLobe gives you without a card
Create a free account and you can open 10 questions from the NBME-style bank and 10 from the USMLE-style bank, with the same full explanations the paid bank uses. You also get 50 flashcards, 2 visual study packs, and the first week of a study plan. Separately, you can take one 50-question sample exam in USMLE-style (a Prometric-like screen) or NBME-style (a self-assessment screen with a score report and a performance profile). No card is required for any of that. The score is an estimate for study. It is not an official result.
The rest of the banks are paid. There are 3,494 NBME-style questions and 2,984 USMLE-style questions in the current StepLobe set, and 33,914 flashcards. Founding price is $14.99 a month or $139 a year, which is $11.58 a month. The yearly plan starts with 3 days free and does ask for a card. Monthly bills from day one. Details and the pass guarantee’s eligible plans are on the pricing section and the guarantee page.
How to spend one free evening
Do this once, on the samples below, before you touch the 50-question exam. It takes less than an hour and it shows you whether you will actually review.
- Set a 6-minute timer per item. Read the lead-in, then the story in order, then the five letters. Commit to one letter on paper.
- Open the explanation. If you were right for a vague reason, treat it as a miss.
- For each wrong letter, write the finding in the stem that kills it. One clause. Skip any letter you already understand.
- Write the educational objective in your own words. If you need the vignette’s names to say it, you do not have it yet.
- Make at most one flashcard for the whole evening: the objective you most want to see again in three days.
Only after that, take the free 50-question exam. Pick the style you want to feel: the USMLE-style screen if you care about the block interface, or the NBME-style screen if you want the score report layout. Do not pause to read explanations in the middle if you are timing yourself. The report at the end is the study list. The next day, redo only the misses, using the same five steps. A second full exam on the same night adds fatigue and almost no new objectives.
How to read the score report
A percent on 50 items is a noisy number. Use the report to pick systems, not to predict a pass. If one system is a cluster of misses, that system gets the next tutor block and the next deck session. If the misses are scattered and the timing was fine, your next job is mixed review, not a new textbook. If you ran out of time, the next session is a 20-question block at 30 minutes, not another 50.
Write three lines under the report: the system you will tutor next, the kind of miss you made most (misread the lead-in, right fact at the wrong time, or changed a good answer), and the date you will look at those misses again. The USMLE Step 1 questions guide turns those three lines into a week. The NBME-style questions guide is the close read of a single stem when the miss was structural.
When free is no longer the right tool
Stay on the free set while you are proving the habit: you can finish a block, you can write objectives, and you know which system is weakest. Move to the full bank when the 10-question preview in a system is no longer new and you are ready to mix. Buying access and then doing untimed, unreviewed questions is an expensive way to repeat the free-PDF problem. The study plan is there so the larger bank has a daily size instead of an infinite queue.
If you like learning from a spoken case before you answer items, the Learn page has short cases and longer episodes by subject. Use a case, then one question on the same objective. Watching without a question afterward is optional entertainment, not a study block.
StepLobe is not affiliated with or endorsed by NBME, FSMB, or USMLE. “USMLE-style” and “NBME-style” describe our original questions. For study only. Not medical advice. The samples below are safe to use as a drill because every option is explained. They are not a protocol for a real patient.
Four free questions, fully explained
These items are original StepLobe questions, printed in full. Nothing is hidden behind a login or a click. Read the vignette in time order, answer the lead-in, then use the explanation, every option, and the educational objective.
Free sample 1 · Pharmacology
Original pharmacology vignette
A 47-year-old woman comes to the office for follow-up 2 months after completing treatment for cancer of both ovaries. She underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, and omentectomy. Pathologic examination showed high-grade serous carcinoma with peritoneal implants. Six cycles of carboplatin and paclitaxel led to a complete radiologic response. Her mother was diagnosed with breast cancer at age 39 years, and her maternal aunt died of ovarian cancer at age 52 years. Germline genetic testing shows a heterozygous frameshift variant, predicted to truncate the encoded protein, in a tumor suppressor gene at chromosome 17q21. Sequencing of her tumor shows the same variant and loss of the wild-type allele. Maintenance therapy with olaparib is begun.
Which of the following best explains why this drug is more lethal to her tumor cells than to her nonneoplastic cells?
- A.Double-strand breaks form from unrepaired single-strand breaks, and tumor cells cannot repair them by homologous recombination
- B.Mismatch repair is inhibited, and tumor cells accumulate replication errors that cause lethal microsatellite instability
- C.Nonhomologous end joining is inhibited, and tumor cells are left without a pathway to rejoin double-strand breaks
- D.Nucleotide excision repair is inhibited, and tumor cells cannot remove bulky DNA adducts left by prior platinum
- E.Topoisomerase I is trapped on DNA, and tumor cells cannot relieve supercoiling ahead of replication forks
Correct answer: A
Olaparib inhibits and traps PARP, so single-strand breaks persist and collapse replication forks into double-strand breaks. Her tumor has lost both BRCA1 alleles and cannot repair these breaks by homologous recombination. Her heterozygous normal cells can.
PARP1 and PARP2 detect single-strand breaks and synthesize poly(ADP-ribose) chains that recruit base excision repair proteins such as XRCC1. Olaparib blocks this catalytic activity and traps PARP on DNA. During S phase, unrepaired breaks and trapped PARP collapse replication forks into double-strand breaks. Homologous recombination normally repairs these breaks accurately: BRCA1 promotes end resection, and BRCA2 loads RAD51 for strand invasion of the sister chromatid. Her nonneoplastic cells keep one functional BRCA1 allele and repair the damage. Her tumor cells have lost the second allele. They fall back on error-prone end joining, accumulate chromosomal rearrangements, and die. Either defect alone is survivable; together they are lethal.
Why each option is right or wrong
- A. Correct. PARP inhibition converts single-strand breaks into replication-associated double-strand breaks. BRCA1-null tumor cells cannot use homologous recombination to repair them; heterozygous normal cells can.
- B. Olaparib does not affect mismatch repair. Mismatch repair loss (MLH1, MSH2) defines Lynch syndrome, not a BRCA1 defect.
- C. PARP inhibitors do not block nonhomologous end joining. HR-deficient cells actually rely on error-prone end joining, which generates the lethal chromosomal rearrangements.
- D. Olaparib does not inhibit nucleotide excision repair. Her platinum response reflects HR deficiency, and olaparib's toxicity does not depend on residual platinum adducts.
- E. This describes camptothecins, not olaparib. Olaparib traps PARP, not topoisomerase I, on DNA.
Educational objective. PARP inhibition converts single-strand breaks into double-strand breaks that are lethal only in homologous recombination–deficient (BRCA1-null) tumor cells.
Free sample 2 · Gastrointestinal
Original gastrointestinal vignette
A male newborn is examined in the delivery room immediately after spontaneous vaginal delivery at 38 weeks' gestation. His mother is 19 years old, gravida 1, para 1, and received no prenatal care. She smoked one-half pack of cigarettes daily throughout the pregnancy. Physical examination shows loops of small and large intestine outside the abdomen. They protrude through a 3-cm full-thickness defect in the anterior abdominal wall immediately to the right of the umbilical cord. The umbilical cord is intact and inserts normally into the abdominal wall at the umbilicus, and no bowel is present within the cord. The exposed bowel is edematous and matted together by a thick fibrinous coating. No membrane covers the bowel. The tongue is normal in size, and there are no dysmorphic facial features. The remainder of the examination shows no abnormalities.
Which of the following is the most likely embryologic cause of this newborn's condition?
- A.Failed fusion of the caudal body wall fold
- B.Failed fusion of the lateral body wall folds
- C.Failed return of the physiologically herniated midgut
- D.Incomplete closure of the umbilical ring
- E.Incomplete rotation of the midgut loop
Correct answer: B
The bowel protrudes uncovered through a full-thickness defect beside a normal cord. This is gastroschisis. The lateral body wall folds failed to fuse during week 4, so the intestine herniated into the amniotic cavity rather than into the cord.
During week 4, the embryonic disc folds both craniocaudally and laterally. The lateral body wall folds meet in the ventral midline and fuse, closing the anterior abdominal wall around the umbilical ring. If fusion is incomplete, typically just right of the cord, a full-thickness gap remains. Bowel extrudes through it directly into the amniotic cavity. Because the bowel lacks a peritoneum-amnion covering, prolonged exposure to amniotic fluid produces this patient's edematous, matted, fibrin-coated loops. The cord is unaffected because the umbilical ring forms normally. The extruded midgut never re-enters the abdomen in sequence, so nonrotation is a consequence of the defect, not its cause.
Why each option is right or wrong
- A. Failed caudal fold closure produces infraumbilical and pelvic defects such as bladder exstrophy. Bowel would not protrude beside a normal cord.
- B. Correct. Incomplete fusion of the lateral folds leaves a paraumbilical, full-thickness defect. Uncovered bowel herniates through it while the cord inserts normally.
- C. This causes omphalocele: a midline mass covered by amnion and peritoneum, with the cord inserting on the sac. Here there is no sac and the cord is normal.
- D. A patent umbilical ring causes an umbilical hernia: a skin-covered, reducible bulge at the umbilicus. Bowel is never exposed.
- E. Nonrotation does accompany gastroschisis, but it follows the extrusion. It does not create a body wall defect.
Educational objective. Gastroschisis results from failed fusion of the lateral body wall folds, unlike omphalocele, which results from failed return of physiologically herniated midgut.
Free sample 3 · Hematology/Oncology
Original hematology/oncology vignette
A 20-month-old boy is brought to the office by his mother because of decreased activity and loss of recently acquired words over the past 6 weeks. The family immigrated 1 year ago and lives in an apartment built in 1925; paint is peeling from several windowsills, and the mother reports that the boy frequently puts paint chips and dirt in his mouth. His diet consists mostly of cow's milk and crackers, and he eats little meat or vegetables. He was born at term and met early milestones. He is at the 25th percentile for weight and the 50th percentile for height. Physical examination shows conjunctival pallor and no hepatosplenomegaly. Laboratory studies show:
| Test | Value |
|---|---|
| Hemoglobin | 8.1 g/dL |
| Mean corpuscular volume | 68 fL |
| Red cell distribution width | 17% |
| Serum ferritin | 6 ng/mL |
| Serum iron | 22 μg/dL |
| Serum lead | 48 μg/dL (N<3.5) |
A peripheral blood smear shows hypochromic, microcytic red cells with coarse basophilic stippling.
Which of the following best explains why this patient's low iron stores increased his absorption of the ingested toxin?
- A.Iron deficiency decreases hepatic hepcidin, increasing basolateral ferroportin export of absorbed lead
- B.Iron deficiency increases heme oxygenase activity, liberating lead bound within dietary heme
- C.Iron deficiency raises transferrin saturation, enhancing receptor-mediated endocytosis of lead in the duodenum
- D.Iron deficiency reduces gastric acid secretion, converting ingested lead to a more soluble, absorbable form
- E.Iron deficiency upregulates the divalent metal transporter DMT1 on duodenal enterocytes, which also transports lead
Correct answer: E
Low iron stores upregulate duodenal DMT1 (SLC11A2), the apical divalent-cation importer. DMT1 is nonselective and also carries Pb2+, so iron-deficient children absorb much more ingested lead—coupling a poor diet and old paint to lead toxicity.
DMT1 (SLC11A2) is the proton-coupled apical transporter that imports ferrous iron into duodenal enterocytes. Its expression is controlled by cellular iron status through iron-responsive elements: when stores fall, iron regulatory proteins stabilize DMT1 mRNA and transcription rises. DMT1 is not iron-specific and transports other divalent cations, including Pb2+. An iron-poor, milk-heavy diet therefore raises DMT1 abundance and dramatically increases intestinal lead absorption. This is why dietary iron repletion and reducing exposure are central to managing childhood lead poisoning, and why iron-deficient toddlers are most vulnerable.
Why each option is right or wrong
- A. Hepcidin/ferroportin control basolateral iron export, not luminal uptake; lead absorption is governed by apical DMT1, not ferroportin.
- B. Heme oxygenase degrades heme to release iron and biliverdin intracellularly; it does not liberate or transport lead, which is not carried in heme.
- C. Iron deficiency lowers, not raises, transferrin saturation; transferrin-receptor endocytosis moves iron into cells from plasma, not lead across the gut lumen.
- D. Iron deficiency does not reduce gastric acid; low pH actually increases metal solubility. Mechanism of enhanced lead uptake is DMT1 upregulation.
- E. Correct. Iron deficiency upregulates apical DMT1, a nonselective divalent-metal importer that also carries Pb2+, increasing lead absorption.
Educational objective. Iron deficiency upregulates duodenal DMT1, a nonselective divalent-metal transporter that also carries lead, increasing gastrointestinal lead absorption.
Free sample 4 · Pulmonary
Original pulmonary vignette
A 64-year-old man comes to the office because of a 5-week history of shortness of breath with exertion and when lying flat. Six weeks ago, he underwent coronary artery bypass grafting through a median sternotomy, with harvest of the left internal thoracic (mammary) artery; the postoperative course was uncomplicated. He has hypertension and type 2 diabetes mellitus. Current medications include aspirin, atorvastatin, metoprolol, and metformin. He has never smoked. His temperature is 37°C (98.6°F), pulse is 72/min, respirations are 20/min, and blood pressure is 126/78 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 95%. His voice is normal. The sternotomy incision is well healed. There is dullness to percussion and decreased breath sounds at the left lung base. Cardiac examination shows no abnormalities. There is no jugular venous distention or peripheral edema. No winging of either scapula is seen when he pushes against a wall. Sensation over the chest and abdominal wall is normal. A chest x-ray shows the left hemidiaphragm 4 cm higher than the right, with no pleural effusion. During fluoroscopy, the right hemidiaphragm moves downward and the left hemidiaphragm moves upward with each rapid sniff.
Injury to which of the following nerves is the most likely cause of these findings?
- A.Left intercostal nerves
- B.Left long thoracic nerve
- C.Left phrenic nerve
- D.Left recurrent laryngeal nerve
- E.Left vagus nerve
Correct answer: C
Left phrenic nerve (C3–C5). It is the only motor nerve to the left hemidiaphragm. Once denervated, the dome becomes flaccid and is pulled upward when the right side contracts and intrathoracic pressure falls during a sniff.
The phrenic nerve arises from C3–C5 and descends through the thorax anterior to the lung root. It runs between the fibrous pericardium and the mediastinal pleura, with the pericardiophrenic vessels. It carries all motor fibers to its hemidiaphragm. During cardiac surgery it can be stretched, cauterized during internal thoracic artery harvest, or cooled by topical cardioplegic slush. A denervated hemidiaphragm is passive. During a sniff, the intact right side and the accessory muscles make intrathoracic pressure more negative, and the flaccid left dome is sucked upward. Lying supine lets the abdominal contents push the dome higher, which compresses the left lower lobe and causes orthopnea.
Why each option is right or wrong
- A. Lower intercostal nerves give sensory fibers to the peripheral diaphragm but no motor fibers. Injury causes chest-wall numbness or neuralgia; his sensation is normal.
- B. It supplies serratus anterior. Injury causes medial scapular winging, which is absent, and does not affect the diaphragm.
- C. Correct. It is the sole motor supply to the left hemidiaphragm, lies in the operative field of cardiac surgery, and its injury explains the elevation and paradoxical sniff motion.
- D. It hooks under the aortic arch and is also at risk in cardiac surgery, but it supplies laryngeal muscles. Injury causes hoarseness; his voice is normal.
- E. It passes posterior to the lung root and supplies the larynx and thoracic viscera, not diaphragm muscle. Injury above its recurrent branch causes hoarseness.
Educational objective. Paradoxical upward sniff-test motion of an elevated hemidiaphragm after cardiac surgery indicates injury to the ipsilateral phrenic nerve, the diaphragm's sole motor supply.
For study only. Not medical advice. StepLobe is not affiliated with or endorsed by NBME, FSMB or USMLE.
Use these four as the evening drill
The pharmacology item is a third-order question: why a drug is lethal in one genome and tolerable in another. The abdominal-wall item is an embryology question decided by whether a membrane covers the bowel and where the cord inserts. The lead item is about a transporter that is not specific for iron. The diaphragm item is a nerve question, and the normal voice and the absent scapular winging are there to retire the neighboring nerves. If you can say those four objectives without looking, you have done more with free material than most people do with a hundred unexplained stems. Next step, when you want a clock and a report: the free 50-question exam.
The sample exam needs a free account and no card. Founding price is $14.99/month or $139/year ($11.58/month). Yearly starts with 3 days free, card required.
Keep going
- Free 50-question examUSMLE-style or NBME-style, timed, with a score report. No card.
- NBME-style questionsHow the vignette and the lead-in are built, with four more explained items.
- USMLE Step 1 practice questionsA week of tutor blocks, mixed blocks, and a late test-day rehearsal.
- Question guidesThe map of both banks and which guide to open next.
- Free case videosShort cases and longer episodes, then a question on the same idea.
- Mnemonics bookOriginal mnemonics, schematics, and an A–Z index. Buy now on the book page, founding price $29.
- PricingWhat the full banks cost after the free preview.
Questions students ask
Can I practice USMLE Step 1 questions for free?
Yes. This page shows four original questions with every option explained, and you can read them with no account. A free StepLobe account, still with no card, adds 10 questions from each bank, 50 flashcards, 2 study packs, week 1 of a plan, and a 50-question sample exam with a score report.
What should a free question include?
A chronological vignette, a second-order or third-order lead-in, five options, an explanation of the correct answer, a reason for each distractor, and one educational objective. A bare answer letter is not a usable free question.
Does the free sample exam need a credit card?
No. The 50-question sample and the small preview need a free account only. The yearly plan is $139 at the founding price and starts with 3 days free, and that trial does require a card. Monthly founding price is $14.99, billed from day one.
How do I get something out of a 50-question sample?
Take it timed, without reading explanations in the middle. The next day, review only the misses: why the right option fits, why each chosen distractor does not, and one objective in your own words. Use the report to pick a system, not to predict a pass. Scores are estimates.
Are these official USMLE questions?
No. They are original StepLobe questions for study. StepLobe is not affiliated with or endorsed by NBME, FSMB, or USMLE. Nothing here is medical advice.
StepLobe is not affiliated with or endorsed by NBME, FSMB or USMLE. “NBME-style” and “USMLE-style” describe the format of original StepLobe questions. For study only. Not medical advice.