CIE A Level Biology复习笔记15.1.3 Neurones
Neurones Neurones have a long fibre known as an axon The axon is insulated by a fatty sheath with small uninsulated sections along its length (called nodes of Ranvier) The sheath is made of myelin,...
CIE A Level Biology复习笔记15.1.2 The Nervous System
The Nervous System The human nervous system consists of the: Central nervous system (CNS) – the brain and the spinal cord Peripheral nervous system (PNS) – all of the nerves in the body It allows u...
CIE A Level Biology复习笔记15.1.1 The Endocrine System
The Endocrine System A hormone is a chemical substance produced by an endocrine gland and carried by the blood They are chemicals which transmit information from one part of the organism to another...
CIE A Level Biology复习笔记14.2.3 Abscisic Acid & Stomatal Closure
Abscisic Acid & Stomatal Closure During times of water stress, the hormone abscisic acid (ABA) is produced by plants to stimulate the closing of their stomata Certain environmental conditions c...
CIE A Level Biology复习笔记14.2.2 Guard Cells
Guard Cells Structure of guard cells Each stoma is surrounded by two guard cells Guard cells have the following features: Thick cell walls facing the air outside the leaf and the stoma Thin cell wa...
CIE A Level Biology复习笔记14.2.1 Stomata
Stomata Plants carry out homeostasis – just like animals they need to maintain a constant internal environment For example, mesophyll cells in leaves require a constant supply of carbon dioxide for...
CIE A Level Biology复习笔记14.1.8 Test Strips & Biosensors
Test Strips & Biosensors Measuring urine glucose concentration People with diabetes cannot control their blood glucose concentration so that it remains within normal, safe limits The presence o...
CIE A Level Biology复习笔记14.1.7 The Control of Blood Glucose
The Control of Blood Glucose If the concentration of glucose in the blood decreases below a certain level, cells may not have enough glucose for respiration and may not be able to function normally...
CIE A Level Biology复习笔记14.1.6 Osmoregulation
Osmoregulation The control of the water potential of body fluids is known as osmoregulation Osmoregulation is a key part of homeostasis Specialised sensory neurones, known as osmoreceptors, monitor...
