Class prep · TJ IBET Biology

Understand biology,from experimental design to the human body.

A full honors biology course taught with worked examples and original practice, from experimental design and research skills through cells, energy, genetics, microbes, evolution, ecology and the human body. It is pitched for strong students, with the quantitative and experimental depth of the front half of AP Biology, and covers the biology content only. Every problem has a full worked solution. Built by Neil Kothari, a TJ alumnus.

Try the free lesson Enroll

$395 covers the full school year. The first lesson is free.

Try one. This is a test-level problem from the course.

Problem 1

Test level
Multiple choice
No calculator
4 pts

A student tests whether a soil extract slows an enzyme that turns a colorless dye blue. In each tube, the average of 3 replicate tubes, the blue color appears at these rates: buffer only (negative control) $42\ \text{units/min}$ ; soil extract $41\ \text{units/min}$ ; a compound known to cut this enzyme's rate by about $80\%$ in working assays (positive control) $40\ \text{units/min}$ . The student concludes: 'The soil extract has no effect on the enzyme.' Which statement is the best evaluation?

original problems, each with a full worked solution: 416; original problems, each with a full worked solution
at test level or beyond: 288; at test level or beyond
short lessons, one for every idea: 32; short lessons, one for every idea
units, all available now: 6; units, all available now

Free lesson

Lesson 1.1: Designing Fair Experiments: Variables, Controls and Replication

How to turn a question into a fair test, spot what is wrong with a shaky design, and design an experiment that separates two explanations.

This lesson starts from zero. No biology background is needed.

Problem 2

Core
True or false
No calculator
2 pts

True or False: Suppose you hypothesize that a pigment in a pond alga protects it from bright light, and from that you predict that algae with the pigment removed will bleach faster under a strong lamp. If the pigment-free algae do not bleach faster, the hypothesis is automatically proven false. Justify your answer.

Answer

False. The prediction came from the hypothesis plus extra assumptions about the setup (for example, that the lamp was bright enough and that the removal method did not change anything else). A failed prediction means at least one of them is wrong, so you must check the assumptions before rejecting the hypothesis.

Full solution

Separate the two ideas. The hypothesis is the proposed explanation: the pigment protects the alga from bright light. The prediction is a specific, testable result that should follow if the hypothesis is true: pigment-free algae bleach faster under a strong lamp.
A prediction never follows from the hypothesis alone. It follows from the hypothesis together with assumptions about the experiment: the lamp is strong enough to cause bleaching, the removal treatment takes out only the pigment, bleaching is measured accurately, and so on. Write it as: hypothesis AND assumptions leads to prediction.
Now use logic. If the prediction fails, the combined statement (hypothesis AND assumptions) must have a false part. That could be the hypothesis, but it could just as well be an assumption. For example, if the lamp was too dim to bleach any alga, the pigment-free algae would not bleach faster even if the hypothesis were correct.
So the right response to an unexpected result is to ask which part broke. Check the assumptions (was there a positive control showing the lamp can bleach algae? did the removal method damage something else?) and only then decide whether the hypothesis should be revised or rejected.
Sanity check from the other direction: a prediction that comes true does not prove the hypothesis either, because some other explanation might give the same result. Evidence supports or weakens a hypothesis; it rarely proves or disproves it by a single run.

Where students lose points

Treating one failed prediction as an instant verdict on the hypothesis. A good scientist asks 'what else had to be true for this prediction to work?' before rejecting the idea.

Problem 3

Core
Multiple choice
No calculator
4 pts

A teacher has 24 identical bean seedlings and two growth-room shelves. The top shelf is slightly warmer and closer to the lamp than the bottom shelf. She wants to test whether a plant-food powder increases stem growth. Which plan best prevents the shelf position from being confused with the effect of the powder?

Open the rest of this lesson, free

The full lesson and all 13 of its problems, with every solution.

How it works

Class prep that works alongside class

A full honors biology course for grades 9 to 12. It works well alongside a school biology class and also stands on its own. Students who already know the material get faster and more careful. Students who feel behind rebuild a topic with the lesson before they try the problems.

Every problem is original and pitched for strong students: true or false, multiple choice, multi-part and free response.
Each one is marked core, test level or beyond, and calculator or no calculator.
Solutions show every step and end with the mistake that most often costs points.
Worked examples in every lesson, and diagrams wherever a picture makes the idea clear.

What is inside

1Doing Biology: Experiments, Data and Research Skills6 lessons · 78 problems
2Molecules and Cells5 lessons · 65 problems
3Energy in Living Systems4 lessons · 52 problems
4Genetics and DNA Science6 lessons · 78 problems
5Microbes, Evolution and Diversity6 lessons · 78 problems
6Ecology and the Human Body5 lessons · 65 problems

The front entrance of Thomas Jefferson High School for Science and Technology

Who built it

Neil Kothari

TJHSST alumnus · Co-founder, EduAvenues · 10+ years in TJ preparation

Neil is a TJ alumnus and has spent more than a decade working with TJ students and their families. He built this course so students can practice the experimental reasoning and the quantitative work together. Every problem is written for the course and every answer is checked before it goes in.

Tuition

$395for the full school year

One tuition covers every unit of the course. All 6 units are available now. The Designing Fair Experiments: Variables, Controls and Replication lesson stays free for everyone.

All 6 units: 32 lessons and 416 original problems
A full worked solution for every problem
Access through the end of the school year

Enroll