Grade 11 · University
SBI3U Grade 11 Biology, worked through with a live AI tutor
SBI3U is the first course where biology stops being descriptive and starts asking you to reason: predict a cross, explain why a trait spreads, argue where an organism belongs on a cladogram. The vocabulary load is real, but the marks are lost on the reasoning questions. The tutor can quiz you on terms and, more usefully, walk a dihybrid cross or a natural-selection scenario until the logic holds.
Prerequisite: SNC2D (Grade 10 Science, academic)
What SBI3U covers
The strands of SBI3U Biology, in our words rather than the Ministry’s. Your teacher’s course outline decides the order and the weight.
Diversity of living things
How organisms are classified and why the system keeps changing, the major groups from viruses and bacteria to animals, and reading a phylogenetic tree.
Evolution
Variation, natural selection and adaptation, the evidence for evolution, speciation, and how the theory developed and was tested.
Genetic processes
Meiosis, Mendel's laws, mono- and dihybrid crosses, incomplete dominance and codominance, sex-linked traits, and the uses and ethics of genetic technology.
Animals: structure and function
The digestive, respiratory and circulatory systems, how they interact, and what happens to the organism when one of them is disrupted.
Plants: anatomy, growth and function
Plant tissues and structures, how water and nutrients move, reproduction and growth, and why plants matter to ecosystems and to people.
Curriculum reference: Ontario Ministry course page, checked .
Where students get stuck
Dihybrid crosses and the sixteen-box grid
Write each parent's gametes first, and there are four for a double heterozygote: every combination of one allele from each gene. Put those four across the top and four down the side, fill the grid, and the phenotype ratio falls out as nine to three to three to one. Students who skip the gamete step and copy the parents' genotypes into the grid get a grid that is wrong before they fill a single box.
Sex-linked traits and why sons are affected more
A gene on the X chromosome has two copies in a female and one in a male. A recessive allele needs both copies to show in a female, but only one in a male because there is no second X to mask it. Write the X and Y explicitly with the allele as a superscript on the X, and the Punnett square explains the pattern without memorising it.
Natural selection acts on individuals, populations evolve
An individual does not adapt in its lifetime; it survives or does not with the traits it was born with. The population changes because the survivors reproduce more, so the allele frequency shifts over generations. Any answer that says an organism developed a trait because it needed it will lose the mark, and the correction is to rewrite it in terms of who survived.
Meiosis versus mitosis in one sentence each
Mitosis makes two identical cells with the full chromosome number for growth and repair. Meiosis makes four different cells with half the chromosome number for reproduction, and the difference comes from crossing over and from homologous pairs separating in the first division. If a question mentions gametes, variation, or halving, it is meiosis.
How a session on SBI3U works
- 1
Bring the actual problem
Share your screen, upload the page, or hold it up to the camera. The tutor reads the SBI3U question itself instead of your retyped version of it.
- 2
Talk it through on the whiteboard
You explain where you got to, out loud. The tutor writes the next step on a shared board while it talks, and asks you to take the one after that.
- 3
Try the next one yourself
Generate a practice set on the same topic, with full worked solutions that show the method rather than only the answer.
It starts in Learn mode: concepts first, the answer as a last resort. The tutor is not a Ministry resource and does not replace your teacher’s course outline.
SBI3U questions
Does the tutor follow the Ontario SBI3U curriculum?
It works from your textbook, your notes and your assignment, and from the five SBI3U strands: diversity, evolution, genetic processes, animal structure and function, and plant anatomy. It is not an official Ministry resource.
Can the tutor help me memorise the classification terms?
Yes, through flashcards and practice quizzes built from your own notes. For the reasoning questions, the cross, the cladogram, the selection scenario, a live session where you talk the logic through is the better use of the time.
Do I need SBI3U for SBI4U?
Yes. SBI4U's prerequisite is SBI3U, and the Grade 12 course assumes the genetics and cell biology from this one.
Stuck on SBI3U tonight
Bring the question from your own textbook or assignment. Talk it through out loud and watch it worked out step by step on a whiteboard.
Free Trial