Cell Structure, Organisation and Transport

The living building block

Every living thing is built from CELLS, and a cell is not a simple blob: it is a tiny working unit with different PARTS, each doing a job, that must take in what it needs and get rid of waste. ⭐⭐ Animal and plant cells share several parts. The CELL MEMBRANE is the outer boundary that controls what enters and leaves. The CYTOPLASM is where reactions happen. The NUCLEUS controls the cell and holds the genetic material. The MITOCHONDRIA are where respiration releases energy. ⭐ Plant cells have three EXTRA parts: a rigid CELL WALL for support, CHLOROPLASTS where photosynthesis makes food using light, and a large VACUOLE holding sap to keep the cell firm. ⭐⭐ Substances move into and out of cells in three ways: DIFFUSION, the spreading of particles from where they are crowded to where they are not; OSMOSIS, the movement of water in the same way; and ACTIVE TRANSPORT, which moves substances the hard way and needs energy. This module is cell parts, organisation and transport. Other biology topics have their own module. ⚠️ Carry one question the whole way through: which part is this, what is its job, and is a substance moving in or out?

Parts and how things move

What cells are built from, what plants add, and how substances cross the membrane.

Tap the two plant-only parts

Tap the TWO parts that are found in PLANT cells but NOT in animal cells.

• Chloroplasts, where photosynthesis makes food using light.
• A rigid cell wall that supports the cell.
• A nucleus that controls the cell.
• A cell membrane controlling what enters and leaves.

Reading a cell under the microscope

A student looks at a cell and finds it has a cell wall, chloroplasts and a large central vacuole. What can they conclude?

• It is a plant cell, because the cell wall, chloroplasts and large vacuole are plant features
• It is an animal cell, because all cells have these
• It must be dead, because it has a wall
• It has no nucleus, because it is a plant

The words cell biology uses

Six terms this topic turns on. Learn them and a cell reads clearly.

Pair each part with its job

Two true things about cells

Select the TWO statements that are true.

• Diffusion moves particles from where they are crowded to where they are not, without needing energy
• Chloroplasts and a cell wall are found in plant cells but not animal cells
• Active transport happens without any energy
• Animal cells have no nucleus

Answering a cell question

Strong answers name the part, give its job, and get the transport process right. ⭐⭐ NAME THE PART AND ITS JOB. Do not just label a nucleus; say the nucleus controls the cell and holds the genetic material. The function alongside the name is where the marks are. ⭐ KNOW PLANT FROM ANIMAL. A cell wall, chloroplasts and a large vacuole mean a plant cell. If you are asked to compare, list the parts both share, then the extras plants have. ⭐⭐ GET THE TRANSPORT RIGHT. Diffusion and osmosis are passive, spreading from crowded to less crowded with no energy needed; active transport goes the other way and needs energy. Say which one, and whether energy is used. DO NOT DRIFT INTO OTHER TOPICS OR EQUATIONS. Respiration and photosynthesis have their own module; here, describe them in words, not as chemical equations, and keep the focus on cell parts and transport. ⚠️ A note on accuracy. This is a new specification, so check the exact content against the published specification; the science here is the standard, settled biology of cells and transport. Keep the one question to hand: which part is this, what is its job, and is a substance moving in or out?

Order how to prepare a slide

Put the steps for preparing and viewing a cell on a slide under a light microscope into a sensible order.

• Place a thin piece of the sample on the slide
• Add a drop of stain so the parts show up
• Lower a cover slip gently to avoid air bubbles
• Place the slide on the microscope stage
• Focus with the lowest power lens first, then increase

Build a transport point

Assemble one sentence that describes a transport process correctly.

The cell run

Five quick decisions about cells and transport. Three lives.

A walled market town

Leave biology aside for a moment. Picture a small walled town on market day, and how much it works like a tiny community with its parts and its comings and goings. ⭐ At the centre, the town hall keeps records and runs the place, giving the orders that keep everything organised. Around it, different workshops each do one job: the bakery, the forge, the mill. Each has its own task, and together they keep the town going, much as different parts each keep a community working. ⭐⭐ The stone WALL and its single gate decide what comes in and goes out; the gatekeeper lets some things through and turns others away, so the boundary is controlled, not open. And watch the goods on market day. When a full cart of apples arrives at one busy stall, the apples spread out through the crowd from that packed corner towards the empty edges, until they are shared fairly evenly across the square. Things drift from where they are crowded to where they are not, all on their own. ⚠️ Hold that picture. A cell is like the town: a part that runs it, workshops that each do a job, a controlled boundary at the edge, and substances that spread from crowded places to emptier ones.

Finish each cell line

The part that controls the cell and holds the genetic material is the _____. The parts where respiration releases energy for the cell are the _____. The boundary that controls what enters and leaves the cell is the cell _____. The spreading of particles from where they are crowded to where they are not is called _____. The movement of water from a weaker to a stronger solution across a membrane is called _____.

Three cells to reason about

Three situations are described. For each, choose the best scientific reading.

• Under the microscope a cell clearly has a rigid wall, green chloroplasts and a large central vacuole.
• A drop of coloured dye is placed at one edge of a dish of still water and slowly spreads until the colour is even throughout.
• A cell needs to take in a mineral even though there is already more of that mineral inside the cell than outside.

Explain cells and transport

Explain the biology of cells: name some parts of a cell and their jobs, explain how a plant cell differs from an animal cell, and explain the difference between diffusion and active transport. Describe respiration and photosynthesis in words, not as equations.

• Name at least three cell parts and give each a job
• Explain how a plant cell differs from an animal cell
• Explain what diffusion is and that it needs no energy
• Explain how active transport differs from diffusion
• Explain why a large surface area helps a cell exchange substances