Biology · OCR Paper 1
Supplying the Cell
How substances move into and out of cells by diffusion, osmosis and active transport, how cells divide by mitosis, and how cells become specialised, including the stem cells that can become many types. Matches OCR GCSE Biology A (Gateway Science) B2.1 (supplying the cell). Every lesson is for both Combined Science and separate Biology, at Foundation and Higher.
Lessons
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1
Diffusion
Cells constantly need to take things in and get rid of waste. Much of this happens by diffusion, with no energy needed. This lesson explains what diffusion is…
9 terms -
2
Osmosis
Water moves in and out of cells too, and it follows its own rule. This lesson explains osmosis, how to predict which way water will move, and what it does to…
11 terms -
3
Investigating Osmosis in Plant Tissue
This is the core practical on osmosis. You put pieces of plant tissue in solutions of different concentrations and see whether they gain or lose mass. This…
10 terms -
4
Active Transport
Diffusion and osmosis only move things down a gradient. Sometimes a cell has to move a substance the other way, and that costs energy. This lesson covers…
9 terms -
5
The Cell Cycle and Mitosis
New cells are made when existing cells divide. This lesson follows a cell through the cell cycle, shows what happens to the chromosomes in mitosis, and…
10 terms -
6
Cell Specialisation and Differentiation
A human body has about 200 different types of cell, and each is built for its own job. This lesson looks at how specialised cells are adapted, and how a cell…
10 terms -
7
Stem Cells
A stem cell has not yet decided what to become. This lesson explains what makes a cell a stem cell, where stem cells are found in embryos, in adult animals and…
8 terms
Key terms in this chapter
All 67, gathered from every lesson.
- Diffusion
- The spreading out of particles of a gas, or of a substance in solution, resulting in a net movement from an area of higher concentration to an area of lower concentration.
- Concentration
- The amount of a substance in a given volume.
- Concentration gradient
- The difference in concentration between two places.
- Net movement
- The overall movement of particles in one direction, after those moving the other way are taken into account.
- Particle
- A very small piece of a substance, such as a molecule of oxygen.
- Cell membrane
- The thin layer around a cell that controls what enters and leaves it.
- Urea
- A waste product made in cells, which diffuses into the blood plasma and is excreted by the kidneys.
- Rate
- How much something changes in a given time.
- Surface area
- The total area of the outside of an object, or of a membrane.
- Water potential
- The tendency of water to move. It is higher in a dilute solution than in a concentrated one.
- Osmosis
- The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
- Partially permeable membrane
- A membrane that lets some substances, such as water, pass through but not others, such as large dissolved molecules.
- Dilute solution
- A solution with a low concentration of dissolved substance.
- Concentrated solution
- A solution with a high concentration of dissolved substance.
- Solute
- A substance that is dissolved in a liquid, such as sugar in water.
- Turgid
- Firm and swollen with water. A turgid plant cell is pressed against its cell wall.
- Flaccid
- Soft and limp after losing water.
- Plasmolysis
- When a plant cell loses so much water that its membrane pulls away from the cell wall.
- Cell sap
- The solution inside the vacuole of a plant cell.
- Isotonic
- Having the same concentration of dissolved substances as the body's fluids.
- Independent variable
- The variable that is deliberately changed in an investigation.
- Dependent variable
- The variable that is measured in an investigation.
- Control variable
- A variable that is kept the same so that the test is fair.
- Percentage change
- The change in a value divided by the starting value, multiplied by 100.
- Cork borer
- A metal tube with a sharp edge used to cut cylinders of equal width from potato.
- Anomalous result
- A result that does not fit the pattern of the other results.
- Reliable
- Giving similar results when the investigation is repeated.
- Mean
- The sum of the values divided by the number of values.
- Cell sap
- The solution inside the vacuole of a plant cell.
- Isotonic
- Having the same concentration as the solution inside the cells, so there is no net movement of water.
- Active transport
- The movement of substances from a more dilute solution to a more concentrated solution, against a concentration gradient, using energy from respiration.
- Against the concentration gradient
- From a lower concentration to a higher concentration.
- Respiration
- The process in cells that releases energy from glucose.
- Mineral ions
- Dissolved substances, such as nitrate ions, that plants take up from the soil for healthy growth.
- Carrier protein
- A protein in the cell membrane that picks up a particular substance and moves it across.
- Root hair cell
- A root cell with a long thin extension, adapted to take up water and mineral ions from the soil.
- Mitochondria
- The sub-cellular structures where aerobic respiration releases energy.
- Absorption
- Taking a substance in, for example sugar moving from the gut into the blood.
- Passive
- Not needing energy from the cell. Diffusion and osmosis are passive.
- Cell cycle
- The series of stages a cell goes through to grow, copy its DNA and divide into two cells.
- Mitosis
- The stage of the cell cycle in which one set of chromosomes is pulled to each end of the cell and the nucleus divides.
- DNA replication
- The copying of DNA, so that there are two identical copies of each chromosome.
- Daughter cell
- One of the two cells formed when a cell divides.
- Genetically identical
- Having exactly the same genes.
- Clone
- An organism, or cell, that is genetically identical to its parent.
- Growth
- An increase in the number of cells (and so in the size of an organism).
- Repair
- Replacing damaged cells with new ones made by mitosis.
- Asexual reproduction
- Reproduction with one parent only, using mitosis, so the offspring are genetically identical to it.
- Sub-cellular structure
- A structure inside a cell, such as a nucleus, a mitochondrion or a ribosome.
- Specialised cell
- A cell that has a structure suited to its particular job.
- Differentiation
- The process by which a cell changes to become specialised.
- Adaptation
- A feature of a cell that helps it carry out its function.
- Acrosome
- The part of a sperm cell that contains enzymes to break into the egg.
- Axon
- The long extension of a nerve cell that carries impulses.
- Myelin sheath
- A fatty layer around a nerve cell's axon that insulates it and speeds up impulses.
- Root hair cell
- A cell on the surface of a root with a long projection that absorbs water and minerals.
- Xylem
- Tubes made of dead cells that carry water and mineral ions up a plant.
- Phloem
- Living tubes that carry dissolved sugars around a plant.
- Tissue
- A group of similar cells that work together to do a particular job.
- Stem cell
- An undifferentiated cell that can divide to make more cells of the same type and can differentiate into specialised cells.
- Undifferentiated
- Not yet specialised for any particular job.
- Differentiation
- The process by which a cell changes to become specialised for its job.
- Specialised cell
- A cell with structures that suit it to doing one job, such as a nerve cell or a red blood cell.
- Embryo
- An organism in the earliest stage of development, before it is born or hatched. A human embryo begins as a ball of cells.
- Embryonic stem cell
- A stem cell from an early embryo, able to become most types of human cell.
- Bone marrow
- The soft tissue inside bones, where stem cells make blood cells.
- Meristem
- Plant tissue at the tips of shoots and roots that contains stem cells and can become any type of plant cell.