Scan and solve
From a photo to an explanation
Point the camera at the question. The answer comes back as steps, with the reasoning for each one, not just a letter.
Biology AI tutor for iPhone
Biology, explained until it makes sense.
Photograph a question and Cyllo shows the reasoning step by step. Ask about any step, then drill the topic with quizzes and flashcards until you can do it on your own.
Free to download. Cells to ecosystems, high school through intro college.
Worked example
Two pea plants, both RrYy, are crossed. What fraction of the offspring are round and yellow?
- 9 Round, yellow
- 3 Round, green
- 3 Wrinkled, yellow
- 1 Wrinkled, green
= 9 of 16 are round and yellow. The full ratio is 9 : 3 : 3 : 1.
Concept guides
The pairs everyone mixes up, set side by side
Each guide puts the two things next to each other, works an example where there is one to work, and names the mistakes that cost the marks.
Cells
Membranes and transport
Cellular energetics
Heredity and genetics
DNA, RNA and gene expression
How it works
From a photo of the question to knowing the answer
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Photograph the question, or type it
A textbook problem, a worksheet, a diagram you cannot label. Cyllo reads it and explains the answer one step at a time, so you can see where your own reasoning stopped.
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Quiz the topic until it sticks
Ten-question quizzes in cell biology, genetics and DNA, human body systems, and ecology and evolution. Wrong answers are the useful ones.
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Look it up without leaving the app
A built-in reference from action potential onward, in one plain sentence each. Biology is a vocabulary subject before it is anything else.
What is in the app
A tutor, a quiz deck and a glossary
Three ways at the same material, because understanding, recall and vocabulary are different jobs.
Ask Cyllo
Follow-ups until it makes sense
Why does crossing over happen in meiosis but not mitosis? Ask. Then ask the question underneath that one.
Quizzes
Four areas, ten questions at a time
Short enough to do between classes, and built to show you what you do not know yet.
Flashcards
The vocabulary biology runs on
Terms and definitions by topic, for the part of the subject that is simply knowing the words.
Chat history
Every explanation, kept
Past questions stay in your history, so revision starts from what you actually struggled with.
Reference
A glossary in your pocket
Key definitions one tap from the home screen, written to be read in ten seconds.
Questions
Before you download
Is Cyllo free?
Free to download, with the quizzes, flashcards and reference included. Photo solving and the chat tutor need a subscription, which the app offers inside.
Is this for AP Biology?
It is built around AP Biology topics, and it works for any high school or intro college course that covers cells, genetics, energy, body systems, ecology and evolution.
Will it just give me the answer?
It gives the answer with every step and the reason for it, which is the point. The habit that pays off is covering the steps, trying the next one yourself, and then checking.
What if an explanation is wrong?
Explanations are AI-generated and can contain a mistake, which is exactly why each step is shown. Ask in chat about the step you doubt. The concept pages on this site are checked against open textbooks and list their sources.
The next question is the one you finally get.
Free to download on iPhone. Quizzes and flashcards are included; photo solving and chat are the subscription.
Free to download