A-Level Biology OCR A H420

5.1.1: Communication and homeostasis

#5.1.1a

the need for communication systems in multicellular organisms

To include the need for animals and plants to respond to changes in the internal and external environment and to coordinate the activities of different organs.

#5.1.1b

the communication between cells by cell signalling

To include signalling between adjacent cells and signalling between distant cells.

#5.1.1c

the principles of homeostasis

To include the differences between receptors and effectors, and the differences between negative feedback and positive feedback.

#5.1.1d

the physiological and behavioural responses involved in temperature control in ectotherms and endotherms

*To include,

  • endotherms – peripheral temperature receptors, the role of the hypothalamus and effectors in skin and muscles; behavioural responses
  • ectotherms – behavioural responses. PAG11*
4.2.2
Classification and evolution
5.1.2
Excretion as an example of homeostatic control