CatalystEnvironmental
Science Exam
Prep Engine
For college juniors grinding APES at 1 a.m., grad applicants chasing GRE scores, and professionals who haven't touched biogeochemical cycles since undergrad.
Avg. Score Improvement
across all active users
Questions in Bank
across 9 exam domains
Pass Rate
among users completing Stage 5
Your environmental science exam, reverse-engineered.
Diagnose
Know exactly where you stand before you study a single page.
A 20-question adaptive placement test maps your knowledge across all nine APES/GRE domains. Low-stakes, high-signal. The engine identifies your ceiling and your floor — so you never waste time reviewing material you already own.
Field Data
87% of students who complete the diagnostic
report "finally knowing what to study" within the first session.
What's included at this stage ↓
Learn
Concepts explained like a field scientist, not a textbook committee.
Each of the nine domains has a dense, annotated concept guide — the kind of notes a grad student would tape to their wall. Diagrams, worked examples, and system maps. No filler paragraphs. Every sentence earns its place.
Field Data
Students who complete Stage 2 concept guides
score 28% higher on conceptual application questions than rote-recall formats.
What's included at this stage ↓
Drill
Repetition without boredom. The engine knows which questions you need.
The question bank has 14,200+ items tagged by domain, difficulty, question type, and concept cluster. Spaced repetition surfaces the exact questions you got wrong two sessions ago, right when you're about to forget them. Free plan gives you 40 questions per day. Pro removes all limits.
Field Data
Students who complete Stage 3 drill sequences
score 31% higher on water quality and toxicology modules — the two most commonly failed APES domains.
What's included at this stage ↓
Simulate
The real test is a timed experience. Train accordingly.
Full-length mock exams with identical timing, question distribution, and scoring rubrics as the actual APES, GRE Subject, or certification exam. The interface mirrors the real thing. The countdown clock is real. The pressure is real. Pro users get 8 full-length exams. Free users get one.
Field Data
Students completing 3+ full mock exams
report 40% lower test-day anxiety and score an average of 19 points higher than those who skip simulation.
What's included at this stage ↓
Pass
Walk in knowing you've seen every question type the exam can throw.
The night before your exam, the engine delivers a 25-question final calibration set — your historically weakest questions, curated for that specific exam. No new material. Just reinforcement of the things most likely to appear. Plus a pre-exam checklist and a reminder that you've done the work.
Field Data
94.6% of Pro users who complete all five stages
pass their target exam on the first attempt. Average score improvement: +23 percentage points.
What's included at this stage ↓
Know your gaps before you guess at them.
Five questions. Five domains. Instant results. Your personalized drill sequence, built in two minutes.
No account required · Results in under 3 minutes
Five questions.
Five domains.
Atmosphere · Hydrosphere · Biodiversity · Policy · Data Analysis
Instant scoring. No account needed. Your personalized study plan preview appears after the final question — not before. Value first, gate second.
< 3 min
To complete
5
Domains tested
Instant
Results
Free
No card required
The primary driver of photochemical smog formation in urban areas is the reaction between NOₓ and volatile organic compounds in the presence of:
"I'd been staring at the nitrogen cycle for three semesters and never understood it as a system. Catalyst's concept guide showed me how the reservoirs connect. I finally stopped memorizing and started reasoning."
Maya Okonkwo
College Junior · APES Review
Start free. Go deep when you're ready.
The diagnostic is always free. Upgrade when the free plan shows you exactly what you're missing.
Free
Start diagnosing. No card required.
- Adaptive placement test (20 questions)
- 3-domain strength map
- 40 practice questions per day
- Detailed answer explanations
- 1 full-length mock exam (APES)
- Atmospheric chemistry concept guide (partial)
- All 9 domain concept guides
- Spaced repetition scheduling
- Unlimited practice questions
- Score projection & pass probability
- Pre-exam calibration set
Pro
Everything the engine has. No limits.
- Adaptive placement test (20 questions)
- All 9-domain strength map
- Unlimited practice questions
- Detailed answer explanations
- 8 full-length mock exams (APES / GRE / CEEM)
- All 9 domain concept guides + PDFs
- Spaced repetition scheduling (SM-2)
- Custom drill sets by domain
- Score projection & pass probability
- Pre-exam calibration set
- Retake protocol (if needed)Free if you don't pass
Team
For instructors and study cohorts.
- Everything in Pro
- Up to 30 student seats
- Instructor analytics dashboard
- Cohort performance comparison
- Custom question sets (instructor-authored)
- LMS integration (Canvas, Blackboard)
- Priority support & onboarding
- Bulk exam scheduling
- Branded certificate templates
- API access for grade passbackComing Q3 2026
- Dedicated success manager
No credit card required for Free plan · Pro trial cancels anytime · Team pricing scales at 30+ seats
94.6% pass rate · 14,200+ questions · No stock photos of smiling students
The exam doesn't care how hard you tried.
Catalyst cares that you pass.
No credit card · Results in under 3 minutes · Personalized plan included