biology

GPT-4.5

GPT-4.5 is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand GPT-4.5 rather than just read about it. In short: GPT-4.5 (codenamed "Orion") is a large language model developed by OpenAI as part of the GPT series. Officially released on February 27, 2025, GPT-4.5 is available to users subscribed to the ChatGPT Plus and Pro plans across web, mobile, and desktop platforms.

Key takeaways

GPT-4.5 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect GPT-4.5 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GPT-4.5 from memory before moving on to harder problems.

Reference excerpt

GPT-4.5 (codenamed "Orion") is a large language model developed by OpenAI as part of the GPT series. Officially released on February 27, 2025, GPT-4.5 is available to users subscribed to the ChatGPT Plus and Pro plans across web, mobile, and desktop platforms. Access was also provided through the OpenAI API and Developer Playground until July 14, 2025. On August 7, 2025, with the release of GPT-5, GPT-4.5 was removed from both the API and ChatGPT users with the Plus and Teams tier, while Pro users are still able to access to GPT-4.5 model under the "Legacy Models" tab. On May 28th, 2026, It was announced that GPT-4.5 would be sunset completely from ChatGPT on June 27th, 2026.

Overview GPT-4.5 was primarily trained using unsupervised learning, which improves its ability to recognize patterns, draw connections, and generate creative insights without reasoning. This method was combined with supervised fine-tuning and reinforcement learning from human feedback. The computational resources needed for training were provided by Microsoft Azure. Sam Altman described GPT-4.5 as a "giant, expensive model". As of February 2025, through OpenAI's API it costs $75 per million input tokens and $150 per million output tokens, whereas GPT-4o only costs $2.50 per million input tokens and $10 per million output tokens. The model was tested on the MMLU test set, which tested 15 different languages, namely Arabic, Bengali, Chinese, English, French, German, Hindi, Indonesian, Italian, Japanese, Korean, Portuguese, Spanish, Swahili, and Yoruba, with the model outperforming GPT-4o on all of them. In April 2025, OpenAI announced that it was phasing out GPT-4.5 from API access in favor of GPT-4.1, set to take effect on July 14.

Reception GPT-4.5 was mostly seen by reviewers as an incremental upgrade over GPT-4o. Cade Metz, writing for The New York Times, stated that the model "signifies the end of an era" as it is their last chatbot to not do chain of thought reasoning. The Times also said it was "unlikely to generate as much excitement as GPT-4". Eric Schwartz from TechRadar praised its ability to understand subtext and respond to questions in a more humanlike manner compared to GPT-4o, but concluded that "it doesn't feel like an enormous leap" from the prior model. Aaron Levie, the CEO of cloud services company Box, told Axios that GPT-4.5 is "about 20% better" than GPT-4o on specific tasks, such as information extraction in large datasets.

Illustrations

Worked examples

Example 1 — a first encounter with GPT-4.5

Start with the simplest possible case. Write down what GPT-4.5 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to GPT-4.5 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about GPT-4.5 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of GPT-4.5

In research: GPT-4.5 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses GPT-4.5 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: GPT-4.5 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2025 in artificial intelligence, 2025 software, ChatGPT, so understanding it makes those chapters shorter.
In everyday life: Look for GPT-4.5 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “GPT-4.5” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study GPT-4.5 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GPT-4.5 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain GPT-4.5 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GPT-4.5 in simple terms?

Why does GPT-4.5 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study GPT-4.5?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on GPT-4.5.