Biology A1, A2, B1

Active transport

The movement of substances from a dilute solution to a more concentrated solution against a concentration gradient, requiring energy from respiration.

Algae

Simple aquatic organisms (protista) that make their own food by photosynthesis.

Alveoli

Tiny air sacs in the lungs that increase the surface area for gaseous exchange.

Bacteria

Single-celled prokaryotic organisms.

Cell membrane

The membrane around the contents of a cell that controls what moves in and out of the cell.

Cell wall

The rigid structure around plant and algal cells. It is made of cellulose and strengthens the cell.

Cellulose

The complex carbohydrate that makes up plant and algal cell walls and gives them strength.

Chlorophyll

The green pigment contained in the chloroplasts.

Chloroplasts

The organelles in which photosynthesis takes place.

Cytoplasm

The water-based gel in which the organelles of all living cells are suspended and most of the chemical reactions of life take place.

Diffusion

The spreading out of the particles of any substance in a solution, or particles in a gas, resulting in a net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient.

Eukaryotic cells

Cells from eukaryotes that have a cell membrane, cytoplasm, and genetic material enclosed in a nucleus.

Hypertonic (osmosis)

A solution that is more concentrated than the cell contents.

Hypotonic (osmosis)

A solution that is less concentrated than the cell contents.

Isotonic (osmosis)

A solution that is the same concentration as the cell contents.

Mitochondria

The site of aerobic cellular respiration in a cell.

Nucleus

Organelle found in many living cells containing the genetic information surrounded by the nuclear membrane.

Osmosis

The diffusion of water through a partially permeable membrane from a dilute solution (which has a high concentration of water) to a concentrated solution (with a low concentration of water) down a concentration gradient.

Partially permeable membrane

A membrane that allows only certain substances to pass through.

Permanent vacuole

Space in the cytoplasm filled with cell sap.

Phloem

The living transport tissue in plants that carries dissolved food (sugars) around the plant.

Plasmolysis

The state of plant cells when so much water is lost from the cell by osmosis that the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall.

Prokaryotic cells

Cells from prokaryotic organisms that have a cytoplasm surrounded by a cell membrane, and a cell wall that does not contain cellulose. The genetic material is a DNA loop that is free in the cytoplasm and not enclosed by a nucleus, sometimes with one or more small rings of DNA called plasmids.

Resolving power

A measure of the ability to distinguish between two separate points that are very close together.

Ribosomes

The site of protein synthesis in a cell.

Sperm

The male sex cells or gametes that carry the genetic material from the male parent.(the head has acrosome whic is a cap like organelle that stores and releases digestive enzymes to break down the eggs outer protective layer to fertilize the egg)

Stomata

Openings in the leaves of plants, particularly on the underside and opened and closed by guard cells, allowing gases to enter and leave the leaf.

Turgor

The pressure inside a plant cell exerted by the cell contents pressing on the cell wall.

Ventilated

Movement of air or water into and out of the gas exchange organ, for example lungs or gills.

Xylem

The non-living transport tissue in plants that transports water from the roots to the leaves and shoots.

Adult stem cells

Stem cells that are found in adults that can differentiate and form a limited number of cells.

Cell cycle

The three-stage process of cell division in a body cell that involves mitosis and results in the formation of two identical daughter cells.

Cloning

The production of identical offspring by asexual reproduction.

Differentiate

The process where cells become specialised for a particular function.

Embryonic stem cells

Stem cells from an early embryo that can differentiate to form the specialised cells of the body.

Mitosis

Part of the cell cycle where one set of new chromosomes is pulled to each end of the cell forming two identical nuclei during cell division.

Stem cells

Undifferentiated cells with the potential to form a wide variety of different cell types.

Therapeutic cloning

A process where an embryo is produced that is genetically identical to the patient so the cells can then be used in medical treatments.

Zygote

The single new cell formed by the fusion of gametes in sexual reproduction.

Active site

The site on an enzyme where the reactants bind.

Amino acids

Molecules made up of carbon, hydrogen, oxygen, and nitrogen that are the building blocks of proteins.

Amylase

Enzyme that speeds up the digestion of starch into sugars.

Bile

Neutralises stomach acid to give a high pH for the enzymes from the pancreas and small intestine to work well. It is not an enzyme.

Carbohydrases

Enzymes that speed up the breakdown of carbohydrates into simple sugars.

Carbohydrates

Molecules that contain only carbon, hydrogen, and oxygen. They provide the energy for the metabolism and are found in foods such as rice, potatoes, and bread.

Catalyst

A substance that speeds up the rate of another reaction but is not used up or changed itself.

Denatured

The breakdown of the molecular structure of a protein so it no longer functions.

Digestive system

Organ system where food is digested and absorbed.

Enzymes

Biological catalysts, usually proteins.

Fatty acids

Part of the structure of a lipid molecule.

Glycerol

Part of the structure of a lipid molecule.

Lipase

Enzymes that speed up the breakdown of lipids into fatty acids and glycerol.

Lipids

Include fats and oils and are found in foods such as butter, olive oil, and crisps. They are made of carbon, hydrogen and oxygen.

Metabolism

The sum of all the reactions taking place in a cell or the body of an organism.

Organ

An aggregation (collection) of different tissues working together to carry out specific functions.

Organ system

A group of organs that work together to carry out specific functions and form organisms.

Proteases

Enzymes that speed up the breakdown of proteins into amino acids.

Proteins

Molecules that contain carbon, hydrogen, oxygen, and nitrogen and are made of long chains of amino acids. They are used for building the cells and tissues of the body and to form enzymes.

Simple sugars

Small carbohydrate units, for example glucose.

Tissue

A group of specialised cells with a similar structure and function.