Mistake Master
Student view — seeing the site as a student does
Mistake Master · AP Biology · Unit 3 · Step-Through Animation

Selection Is Keeping the Books

You'll learnhow an organism's leftover energy surplus becomes offspring, which is what fitness counts.

Every organism runs on a closed budget: energy comes in at some finite rate, and everything it does is an expense drawn against it. What is left after the bills is the only thing that can become offspring. Eleven short steps; press Next for each one.

AP BIOLOGY · 11 STEPS · 6 QUICK CHECKS · FITNESS = SURVIVING OFFSPRING · NET, NOT GROSS · THE BUDGET IS CLOSED · v5

a closed budget · what the leftovers buy · who leaves more young
Before you start
What you're looking at
One bird’s whole day of energy, drawn as a single bar that everything it does is paid out of.
The question
After every bill is paid, what is left over — and what can that surplus be turned into?
Step 1 / 11