What does Module 3 of the Virginia Biology SOL cover?

Module 3 covers BIO.3, that cells have structure and function, within the Cell Biology and Cellular Processes reporting category. It includes the cell theory and how prokaryotic, eukaryotic, plant, and animal cells differ; the major organelles and how each structure suits its function; the selectively permeable cell membrane and how diffusion, osmosis, and active transport move substances; the cell cycle and mitosis (two identical cells for growth and repair, and how loss of control causes cancer); and meiosis, which makes varied gametes with half the chromosome number.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells (bacteria) are small and simple, with no nucleus and no membrane-bound organelles; their DNA floats free in the cytoplasm. Eukaryotic cells (plants, animals, fungi, protists) are larger and have a true membrane-bound nucleus and many membrane-bound organelles such as mitochondria. Both share a cell membrane, cytoplasm, ribosomes, and DNA. Plant cells are eukaryotic cells that additionally have a cell wall, chloroplasts, and a large central vacuole, which animal cells lack.

How do diffusion, osmosis, and active transport differ?

Diffusion is the net movement of particles down their concentration gradient, from high to low, with no energy needed. Osmosis is the diffusion of water across a selectively permeable membrane, moving toward the side with the higher solute concentration. Both are passive transport. Active transport moves substances against their gradient, from low to high concentration, and requires energy as ATP and membrane proteins. To predict osmosis, find which side has more solute; water moves toward it because that side has less free water.

What is the difference between mitosis and meiosis?

Mitosis produces two genetically identical cells with the same chromosome number as the parent, for growth, repair, and asexual reproduction; it follows DNA replication so each cell gets a full copy. Meiosis produces four genetically varied cells with half the chromosome number, for sexual reproduction. Meiosis creates variation through crossing over and independent assortment, and fertilization then restores the full chromosome number and adds further variation through the random combination of gametes.

How is cancer related to the cell cycle?

The cell cycle is normally controlled at checkpoints that decide when a cell divides. Mutations in the genes that regulate division can disable this control, so the cell divides uncontrollably by mitosis. The dividing cells pile up into a mass called a tumor, and a tumor that invades and spreads is cancer. Factors that increase mutations, such as tobacco smoke, ultraviolet radiation, and certain chemicals, raise the risk. The key idea the EOC tests is that uncontrolled mitosis from loss of cell-cycle control leads to tumors.

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Virginia Biology SOL Module 3 cells: a complete overview of cell theory, organelles, transport, mitosis, and meiosis for BIO.3

A deep-dive guide to Module 3 of the Virginia Biology SOL: cell theory and types of cells, the organelles and their functions, the selectively permeable membrane and transport, the cell cycle and mitosis with its link to cancer, and meiosis and genetic variation.

Generated by Claude Opus 4.818 min readBIO.3Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

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What Module 3 actually demands
Cell theory and cell types
Organelles and structure-and-function
The membrane and transport
Mitosis and meiosis
Check your knowledge

What Module 3 actually demands

Module 3 is the cell core of the Virginia Biology SOL, standard BIO.3, the heart of the Cell Biology and Cellular Processes reporting category. It runs from what a cell is (cell theory and cell types), through how a cell is built (organelles) and how it controls its boundary (transport), to how cells divide (mitosis and meiosis). The crosscutting theme the EOC keeps testing is structure and function: each organelle's shape suits its job, the membrane's structure makes it selective, and the way DNA is handled in division explains whether the products are identical or varied.

This guide ties together the matching dot-point pages, each with its own practice questions: cell theory and types of cells, cell structure and organelles, the cell membrane and transport, the cell cycle and mitosis, and meiosis and genetic variation.

Cell theory and cell types

The cell theory has three parts: all living things are made of cells, the cell is the basic unit of life, and all cells come from pre-existing cells. It is a well-supported theory built on microscope evidence, a good example of how technology advances science. Prokaryotic cells (bacteria) have no nucleus and no membrane-bound organelles; eukaryotic cells (plants, animals, fungi, protists) have both. All cells share a membrane, cytoplasm, ribosomes, and DNA. Plant cells add a cell wall, chloroplasts, and a large central vacuole that animal cells lack.

Organelles and structure-and-function

Each organelle does a specific job: the nucleus stores DNA and controls the cell; ribosomes make proteins; the endoplasmic reticulum transports materials (rough ER with ribosomes makes proteins, smooth ER makes lipids); the Golgi apparatus packages and ships proteins; mitochondria carry out respiration and release ATP; chloroplasts (plants) carry out photosynthesis; the cell wall and vacuole (plants) give support and storage. The EOC's favorite reasoning is structure and function: a high-energy cell has many mitochondria, a secretory cell has lots of rough ER, and ribosome to ER to Golgi works as a protein production line.

The membrane and transport

The cell membrane is a selectively permeable phospholipid bilayer that controls what enters and leaves. Passive transport needs no energy and moves substances down the gradient: diffusion (particles) and osmosis (water, moving toward the higher solute concentration). Active transport moves substances against the gradient and needs ATP and membrane proteins. The classic EOC item gives a cell in a solution and asks which way water moves: find the side with more solute, and water moves toward it. A plant cell in pure water becomes turgid rather than bursting, because the cell wall resists.

Mitosis and meiosis

DNA replication in interphase comes first, which is why mitosis produces two genetically identical cells with the same chromosome number, for growth and repair. Losing control of the cell cycle (through mutations) causes uncontrolled mitosis and tumors, which is cancer. Meiosis instead produces four cells with half the chromosome number (haploid gametes), so fertilization can restore the full (diploid) number. Meiosis creates genetic variation through crossing over, independent assortment, and the random combination of gametes at fertilization. Keeping mitosis and meiosis straight, identical versus varied, same versus half, is essential, because the EOC contrasts them directly.

Module 3 of the Virginia Biology SOL covers BIO.3: cell theory (all living things are cells, the cell is the basic unit, cells come from cells) and cell types (prokaryotic versus eukaryotic, plant versus animal); the organelles and their functions (nucleus, ribosomes, ER, Golgi, mitochondria, chloroplasts, cell wall, vacuole) under the theme of structure and function; the selectively permeable membrane and transport (diffusion and osmosis down the gradient with no energy, active transport up the gradient using ATP); the cell cycle and mitosis (two identical cells for growth and repair, with uncontrolled division causing cancer); and meiosis (four varied haploid gametes, with variation from crossing over, independent assortment, and random fertilization). The recurring theme is structure and function and the contrast between identical and varied division.

Check your knowledge

A mix of recall and reasoning questions covering Module 3. Attempt them under timed conditions, then check against the solutions.

State the three parts of the cell theory. (3 marks)
Name two structures found in plant cells but not animal cells. (2 marks)
State the function of the mitochondria and explain why muscle cells have many. (2 marks)
Define osmosis and state which way water moves. (2 marks)
A red blood cell is placed in pure water. Predict what happens and explain. (2 marks)
State the result of mitosis in terms of cell number, genetic content, and chromosome number. (2 marks)
A body cell has 20 chromosomes. How many are in a gamete, and which division produces it? (2 marks)
Identify two processes during meiosis that create genetic variation. (2 marks)

Solutions

Q1: All living things are made of one or more cells; the cell is the basic unit of structure and function; all cells come from pre-existing cells.
Q2: Any two of: cell wall, chloroplasts, large central vacuole.
Q3: Mitochondria carry out aerobic respiration, releasing energy as ATP; muscle cells have high energy needs for contraction, so many mitochondria supply more ATP.
Q4: Osmosis is the diffusion of water across a selectively permeable membrane; water moves toward the side with the higher solute concentration (lower water concentration).
Q5: Water moves into the cell (the inside has more solute than pure water); with no cell wall, the red blood cell swells and may burst.
Q6: Mitosis produces two genetically identical cells, each with the same chromosome number as the parent.
Q7: A gamete has 10 chromosomes (half of 20), produced by meiosis.
Q8: Crossing over and independent assortment (both during meiosis).

Sources & how we know this

2018 Science Standards of Learning (Biology) — Virginia Department of Education (2018)
SOL Practice Items (All Subjects) — Virginia Department of Education (2024)