Final exam preview

What this reading is about

MCAS is done. Now we have the course final exam. The final covers the same biology as MCAS, but it tests some things differently. This reading walks you through the three biggest differences so you know exactly what to practice.

Difference 1: Codon chart from memory

On MCAS, you get a codon chart. On the final, you do not. That means you need to know the key codons without looking them up.

What you must memorize:

• AUG = methionine (Met) = START. Every protein begins with AUG.
• UAA, UAG, UGA = STOP. They do not code for any amino acid.
• The process: DNA → transcriptionThe first step of protein synthesis: a DNA gene is copied into a strand of mRNA. → mRNA → translationThe second step of protein synthesis: mRNA is read at the ribosome and used to build a protein. → protein.
• codonA group of three mRNA bases that codes for one amino acid. math still applies: count the mRNA bases, divide by 3 = number of codons.

On the final, you may be given a short mRNA strand and asked to identify where translationThe second step of protein synthesis: mRNA is read at the ribosome and used to build a protein. starts (find the AUG) and where it stops (find UAA, UAG, or UGA). You will NOT have the full chart to look up every amino acid — but you will usually only need to recognize start and stop.

Difference 2: Mitosis phase identification from pictures

MCAS tests mitosisCell division — one cell becomes two identical cells. vs meiosisCell division that makes 4 sex cells (eggs or sperm) with half the DNA. at a conceptual level — "which makes 2 identical cells?" The final goes deeper: you see a picture and must name the phase.

The four phases in order: P-M-A-T

1. prophaseFirst stage of mitosis. Chromosomes condense and become visible. — chromosomes condense into visible X-shapes, scattered around the cell.
2. metaphaseSecond stage of mitosis. Chromosomes line up in the middle. — chromosomes line up in the Middle.
3. anaphaseThird stage of mitosis. Chromosomes pull apart toward opposite ends. — chromosomes pull Apart toward opposite ends.
4. telophaseFourth stage of mitosis. Two new nuclei form and the cell divides. — Two new nuclei form; the cell pinches in half.

Strategy: Find metaphase first — it's the easiest to spot (everything lined up neatly in the middle). Once you find metaphase, prophase is before it and anaphase is after it. Telophase is last.

Difference 3: Food web analysis without a reference

MCAS gives you a food web diagram and asks straightforward questions. The final may ask you to predict what happens when you remove or add an organism — and you need to trace the effect through the web.

Key rules for food web analysis:

• Arrows point from the eaten to the eater (from producerAn organism that makes its own food from sunlight (like a plant). → consumerAn organism that gets energy by eating other organisms.).
• If a producerAn organism that makes its own food from sunlight (like a plant). disappears, everything above it in the food web is affected.
• If a predator disappears, its prey increases (nothing eating it).
• Energy decreases at each level (~90% lost as heat). Matter is recycled.
• decomposerAn organism that breaks down dead things and recycles nutrients.s recycle nutrients back to the soil — they connect to every level.

What stays the same

Most of the final is the same material as MCAS. If you studied for MCAS, you have already done most of the work. The final still tests:

• Cell structure (prokaryote vs eukaryote, organelle functions)
• Macromolecules (carbon backbone, -ose = carb, -ase = enzyme)
• Transport (diffusion vs active transport vs osmosis)
• Photosynthesis and cellular respiration (opposites, chloroplast vs mitochondria)
• DNA structure and base pairing (A-T, C-G)
• Inheritance patterns (codominance, incomplete dominance, sex-linked)
• Evolution (four conditions for natural selection, best evidence = DNA)
• Ecology and populations (carrying capacity, feedback loops)

The difference is that the final tests a few things without a reference that MCAS gave you. Practice those three areas — codon starts/stops, PMAT phase pictures, and food web predictions — and you'll be ready.

Your study plan for the next 2 weeks

1. Block 12 drills codon chart translation in detail.
2. Block 13 drills mitosis phase identification from pictures.
3. Blocks 14–15 are practice finals (closed-book, full format).
4. Block 16 is targeted review of whatever you missed on the practice finals.

Use the study guide pages for Blocks 12 and 13 to review. Then take the practice finals without looking. Whatever you miss on those — that's what Block 16 is for.