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...
CIE A Level Biology复习笔记14.1.5 Formation of Urine
Formation of Urine in the Nephron The nephron is the functional unit of the kidney – the nephrons are responsible for the formation of urine The process of urine formation in the kidneys occurs in ...
CIE A Level Biology复习笔记14.1.4 Nephron Structure
Nephron Structure Each kidney contains thousands of tiny tubes, known as nephrons The nephron is the functional unit of the kidney – the nephrons are responsible for the formation of urine The loca...
CIE A Level Biology复习笔记14.1.3 Kidney Structure
Structure of the Human Kidney Humans have two kidneys The kidneys are responsible for carrying out two very important functions: As an osmoregulatory organ - they regulate the water content of the ...
CIE A Level Biology复习笔记14.1.2 Production of Urea
Production of Urea Many metabolic reactions within the body produce waste products The removal of these waste products is known as excretion Many excretory products are formed in humans, with two i...
