Section 4.1 Structure of the human gas-exchange system
All aerobic organisms require a constant supply of oxygen to release energy in the
form of ATP during respiration.
The volumes of oxygen that need to be absorbed and the volumes of carbon dioxide
Section 6.1 Defence mechanisms
Non-specific mechanisms that do not distinguish between one type of pathogen and
another, but respond to all of them in the same way. These mechanisms act
immediately and take two forms:
A) barrier of entr
Section 1.1: Causes of Disease - Pathogens
Health A state of physical and mental well-being, free from disease.
Disease An abnormal condition of an organism that impairs bodily functions
and is associated with specific symptoms.
Non-infectious Sometimes c
Section 3.1 Investigating the structure of cells
Lenses work more effectively if they are in a compound light microscope.
Light waves a have a relatively long wavelength; therefore, they can only distinguish
between objects that are at least 0.
Section 2.1: Enzymes and Digestion
Glands produce enzymes that are used to break down large molecules into
smaller ones that are ready for abortion.
The digestive system provides an interface between the body and the
environment because it allows food to
Section 5.1 The heart and heart disease
Mammals are too large to rely on diffusion.
They need a circulatory system to move substances around the body.
Blood moves down pressure gradients, from high to low pressure.
The heart produces the main pressure gra
Interspecific variation: When one species differs from another species.
Intraspecific variation: When members of the same species differ from each other.
Sampling: This involves taking measurements of individual, selected from the population