Intro Biology

What this covers

• Predicting osmotic water movement and solute flux across membranes, and distinguishing simple diffusion, facilitated diffusion, primary and secondary active transport
• Tracking chromosome and chromatid number through mitosis and meiosis I and II, including what nondisjunction at each stage produces
• Solving monohybrid, dihybrid, sex-linked, and pedigree problems, and applying chi-square goodness-of-fit to observed ratios
• Working from DNA sequence to mRNA to polypeptide, including template versus coding strand, reading frame, and the effect of point, frameshift, and nonsense mutations
• Interpreting gene regulation models such as the lac and trp operons, and explaining how eukaryotic regulation differs
• Applying Hardy-Weinberg to calculate allele and genotype frequencies, and identifying which evolutionary force explains a given change
• Reading phylogenetic trees for shared derived characters, sister taxa, and monophyletic groups

Where learners get stuck

Calling a solution hypertonic or hypotonic without saying what it is relative to, then reasoning backwards about which way water moves

Textbook diagrams usually show a cell in a beaker, so students memorise the picture instead of the comparison. Once the problem describes two compartments with no cell, or gives solute concentrations in different units, the memorised image stops working.

Confusing homologous chromosomes with sister chromatids, which makes anaphase I and anaphase II look identical

After S phase both structures appear as paired rods in diagrams. Students who learned mitosis first import the rule 'anaphase splits the pair at the centromere' into meiosis I, where the pair separating is a homologous pair and centromeres stay intact. This single error then breaks ploidy counting, crossing-over questions, and nondisjunction problems.

Describing evolution as organisms developing traits because they need them, or as a population 'trying' to adapt

Everyday language about adaptation is goal-directed, and lecture shorthand like 'the beak evolved to crack seeds' reinforces it. The fix is to insist that variation exists before selection acts and that selection sorts existing variants, which is also what makes Hardy-Weinberg and genetic drift problems make sense.

What a session looks like

A session usually opens with a short diagnostic question on the assigned reading or lecture, then moves into problems you talk through — sketching a meiosis stage in words, setting up a Punnett square or chi-square table, or translating a short sequence. Evelyn asks you to state the prediction before the reasoning, then probes the step where the answer went wrong. Vocabulary is checked in passing rather than drilled, and sessions often end with you explaining one process back in your own words as if teaching it.

Helpful to know first

• High school biology, or comfort with the idea of cells, DNA, and inheritance
• Basic algebra for allele frequency and dilution calculations, plus the ability to work with square roots and percentages
• Familiarity with ratios and simple probability for genetics crosses
• No chemistry beyond knowing what an atom, ion, and covalent bond are; anything deeper is covered in the General Chemistry topic

Questions

Is this for biology majors or for the non-majors survey course?

Sessions can run at either level. The majors sequence goes deeper into genetics problem sets, Hardy-Weinberg calculations, and molecular detail; the non-majors course puts more weight on concepts and examples. Say which course you are in at the start and the depth adjusts.

Can it help with lab reports and data analysis?

It can help you interpret results, choose between a t-test and chi-square for a given dataset, structure a discussion section, and explain what a control actually controls for. It does not write reports for you or supply data you did not collect.

I keep failing the genetics section specifically. Can we just work on that?

Yes. A common plan is several sessions on crosses and pedigrees alone, starting with single-gene problems and adding sex linkage, linkage and recombination frequency, and chi-square testing once the setup is reliable.

How is this different from the Biochemistry topic?

Intro Biology treats cellular respiration and photosynthesis as pathways with inputs, outputs, and locations, and spends most of its time on cells, inheritance, evolution, and ecology. Biochemistry works through enzyme kinetics, reaction mechanisms, and molecular structure in detail.