Florida Biology 1 EOC Reporting Category 1 (Molecular and Cellular Biology): a complete overview of cells, organelles, transport, the cell cycle, and microscopy

What the cellular half of Reporting Category 1 demands

Molecular and Cellular Biology is the largest reporting category on the Florida Biology 1 EOC at about 35 percent of the test. This guide covers its cellular half: what a cell is, the parts inside it, how things cross the membrane, how cells divide, and how we observe them. (The biochemistry and energy half, with macromolecules, enzymes, photosynthesis, and respiration, is in the biochemistry and energy guide.) The recurring theme throughout is structure and function: nearly every item rewards connecting the shape or contents of a structure to the job it does.

This guide ties together the matching topic pages, each with its own practice questions: cell theory and the discovery of cells, comparing prokaryotic and eukaryotic cells, cell structure and organelles, the cell membrane and transport, the cell cycle, mitosis, and cancer, and microscopes and studying cells.

Cell theory and how we know it

Cell theory has three parts: all living things are made of one or more cells; the cell is the basic unit of structure and function; and all cells come from pre-existing cells. It was built over more than 150 years (Hooke named cells, Leeuwenhoek saw living single-celled organisms, Schleiden and Schwann generalized to plants and animals, Virchow added that cells come from cells) as the microscope improved. The EOC uses this history to teach the nature of science: a theory is a well-supported explanation that gets refined as new evidence and tools appear, not a guess.

Two kinds of cell

All cells share a membrane, cytoplasm, ribosomes, and DNA. The split is between prokaryotes (bacteria, archaea), which have no nucleus and no membrane-bound organelles, and eukaryotes (plants, animals, fungi, protists), which have a true nucleus and organelles and are larger. The advantage of the eukaryotic design is compartmentalization: membranes wall off reactions so the cell can run many at once. Among eukaryotes, plant cells add a cell wall, chloroplasts, and a large central vacuole that animal cells lack.

The organelles

Each organelle is a worked example of structure fitting function. The nucleus stores DNA and directs the cell; ribosomes build proteins; the rough ER makes and folds proteins while the smooth ER makes lipids; the Golgi apparatus modifies and packages them into vesicles; mitochondria release energy by respiration; chloroplasts (plants) carry out photosynthesis; lysosomes digest waste; and the cell membrane controls transport. When an item shows a striking feature (many mitochondria, abundant rough ER), the answer connects that structure to a function.

The cell membrane and transport

The selectively permeable membrane, a phospholipid bilayer with embedded proteins, controls what crosses. Passive transport needs no energy and moves substances down a gradient: diffusion spreads particles, osmosis is the diffusion of water, and facilitated diffusion uses a protein channel. Active transport uses energy (ATP) to move substances against a gradient through membrane proteins. In osmosis, water moves toward the side with more solute, so a cell swells in a hypotonic solution and shrinks in a hypertonic one.

The cell cycle and cancer

The cell cycle is the orderly sequence a cell follows to grow and divide: interphase (growth and DNA copying) then mitosis (PMAT: prophase, metaphase, anaphase, telophase) and cytokinesis. Mitosis produces two genetically identical cells with the full chromosome number, used for growth and repair. The cycle is regulated by genes at checkpoints. A mutation in those genes can remove the controls, so the cell divides without stopping, forming a tumor and possibly cancer.

Microscopy

A light microscope uses visible light, views living color, and reaches about 1000x; an electron microscope uses electrons for far higher resolution but needs a dead specimen. Total magnification for a light microscope is the eyepiece times the objective (for example, $10 \times 40 = 400$). Magnification is how big the image looks; resolution is how much detail you can distinguish.

Check your knowledge

A mix of recall and reasoning questions covering the cellular half of Reporting Category 1. Attempt them under timed conditions, then check against the solutions.

1. State the three parts of cell theory. (3 marks)
2. State the one feature that defines a eukaryotic cell. (1 mark)
3. Name the three structures found in plant cells but not animal cells. (3 marks)
4. Put these in the order a protein passes through them: Golgi apparatus, ribosome, vesicle, rough ER. (2 marks)
5. State the difference between diffusion and active transport in terms of energy. (2 marks)
6. A cell is placed in a hypertonic solution. State which way water moves and what happens to the cell. (2 marks)
7. List the four phases of mitosis in order. (2 marks)
8. Explain how a mutation can lead to cancer. (2 marks)
9. A light microscope has a 10x eyepiece and a 40x objective. Calculate the total magnification. (1 mark)