GCSE Biology Unit 1, WJEC

active site

the site on an enzyme where the reactants bind

active transport

the movement of substances against a concentration gradient and/or a cell membrane using energy

aerobic respiration

Respiration using oxygen; releases energy and produces carbon dioxide and water

Alveoli

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

amino acids

building blocks of proteins

Amalyse

The enzyme made in the salivary gland and pancreas which speeds up the breakdown of starch into simple sugars

anaerobic respiration

Respiration in the absence of oxygen. Incomplete breakdown of glucose without oxygen to produce a small amount of energy very quickly. produces lactic acid

Atrium

The small upper chambers of the heart. The right atrium receives blood from the body and the left atrium receives blood from the lungs

Arteries

Blood vessels that carry blood away from the heart

Bile

A yellowy-green liquid made up in the liver and stored in the gall bladder. It is released into the small intestine and emulsifies fats.

Biodiversity

The number and variety of different organisms found in the specified area.

Biomass

The mass of a plant or animal minus the water content

Breathing system

The stems involved in breathing; the ribs, intercostal muscles, diaphragm as well as the lungs and the tubes which bring air into the body from the outside

Capillary

The smallest type of blood vessels which run between individual cells. They have a wall which is only one cell thick

catalyst

a substance that speeds up the rate of a chemical reaction. Enzymes are biological catalysts

Cell

The basic unit of structure and function in living things

Chlorophyll

A green pigment found in most plants, responsible for photosynthesis

Chloroplast

Tiny structures in the cytoplasm cells that contain chlorophyll; photosynthesis occurs here

Community

The total collection of living organisms within a defined area or habitat

concentration gradient

A difference in the concentration of a substance across a distance whether it is high or low concentration

Cytoplasm

Jellylike fluid where most chemical reactions take place

Denatured

Change the shape of an enzyme (by temperature or Ph levels) so that it can no longer speed up a reaction.

deoxygenated

Blood carrying little or no oxygen

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

environment

the area and conditions in which an organism exists or lives

Enzyme

A type of protein that speeds up a chemical reaction in a living thing

Food chain

the feeding relationships between organisms in an environment

guard cells

The cells which surround stomata in the leaves of plants and control their opening and closing.

Haemoglobin

The red pigment which carries oxygen around the body. Found in red blood cells.

Lactic acid

A compound produced when cells respire without oxygen (i.e anaerobically)

Lipase

An enzyme that breaks down fat into fatty acids and glycerol.

Limiting factors

Factors which limits the rate of a reaction e.g temperature, light levels, pH (photosynthesis)

Mitrochondria

Found in all cells, Aerobic respiration takes place to provide the cell with energy

Neutralise

To make the pH neutral (pH 7)

Nucleus

The control centre of the cell. Contains DNA which controls the cell's activities

Organ

a group of tissues working together, e.g heart, liver, pancreas

Osmosis

Diffusion of water from an area of high concentration to an area of low concentration through a selectively permeable membrane

Oygenated

used to describe blood that is carrying oxygen in the form of haemoglobin

Partially permeable

a membrane that allows some substances to cross but not others.

Phloem

Tissue for transporting sugars around a plant

Photosynthesis

the process by which plants and some other organisms use light energy to convert water and carbon dioxide into glucose and oxygen

pH

Measure of strength of an acid or alkali

Plasma

The yellowish liquid part of the blood which carries dissolved substances and blood cells around the body

predator

An animal that hunts, kills, and eats other animals

Protease

enzyme that breaks down proteins into amino acids

Quadrat

A piece of apparatus for sampling organisms in the field.

Respiration

The process by which food molecules are broken down to release energy for the cells

Root Hair cells

A cell on the root of the plant with microscopic hairs which increases the surface area for the absorption of water from the soil

Specialised

Adapted for a particular function

Stomarta

Openings in the leaves of plants (particularly the underside) which allows gases to enter and leave the leaf. They are opened and closed by the guard cells.

surface area

the external area of a living thing

Tissue

A group of similar cells that perform the same function.

Transpiration

loss of water vapour from a plant through its leaves through the stomata

Valve

The structure which prevents the backflow of liquid e.g the valves of the heart or the veins

Vein

Blood vessel which carries blood away from the heart. It usually carries deoxygenated blood and has valves to prevent the backflow of blood

Ventricles

the two lower chambers of the heart, the right pumps blood out to the lungs and the left to the body.

Ventilated

movement of air into and out of the lungs

Villi

projections on the walls of the small intestine that increase the surface area over which nutrients can be absorbed

Xylem

Plant tissue that transports water and minerals from the roots to the leaves / flowers