A Level Biology Revision Notes

Comprehensive A Level Biology revision notes providing information and assistance for all UK examination boards (AQA, OCR, Edexcel) as well as international curriculum (CIE).

Join now →

The Human Retina

Introduction Human eyes are a great gift of nature through which we can perceive different colors and objects present around us. This sense of vision makes our surroundings so beautiful. Eyes help us enjoy the splendid landscapes of nature. Our eyes consist of eyeballs fitted in the bony socket called the orbit. The eyeball is …

Read article →The Human Retina

Pacinian Corpuscle

Introduction The human skin is highly sensitive to changes in the external environment. Several different sensory receptors are present in the skin to detect an external stimulus. These include thermoreceptors, chemoreceptors, mechanoreceptors, nociceptors, and electromagnetic receptors. These receptors detect the external stimulus and signal the CNS to take necessary actions to cope with the changing …

Read article →Pacinian Corpuscle

Control of Heart Rate

Introduction The human heart is responsible for pumping the blood the distant locations in the body. It receives the deoxygenated blood from the body via systematic veins and the oxygenated blood from the lungs via pulmonary veins. The oxygenated blood is pumped to the rest of the body organs via the arterial system while the …

Read article →Control of Heart Rate

Structure of Motor Neuron

Introduction Animals have a highly complicated system for communication among different parts of the body called the nervous system. This system is a complicated network of interlinked neurons. Neurons are the basic structural and functional units of the nervous system. They are responsible for carrying and processing information from different parts of the body. Neurons …

Read article →Structure of Motor Neuron

Alcohol Fermentation

Introduction Alcohol fermentation is a complex biotechnological process in which sugars such as glucose, sucrose, and fructose are converted into energy molecules and produce ethanol, carbon dioxide, and metabolic by-products during this process. These products contribute to the sensorial properties and chemical composition of the fermented foodstuff. Alcohol fermentation also called ethanol fermentation is processed …

Read article →Alcohol Fermentation

Aerobic vs Anaerobic Respiration

Introduction All the living cells obtain energy for cellular processes via the process of cellular respiration. It is the process in which food particles are broken down into smaller molecules and energy is released. During cellular respiration, the carbon atoms present in the various food substances are oxidized to ultimately release carbon dioxide. A large …

Read article →Aerobic vs Anaerobic Respiration

Hemoglobin

Introduction Hemoglobin is the oxygen-carrying protein present in animals. It is a globular protein belonging to the group of hemeproteins. Such globular proteins have a heme group tightly bound to the protein structure. The function performed by the heme group depends upon the structure of the protein. In hemoglobin, heme group serves to bind oxygen …

Read article →Hemoglobin

Light-Dependent Reactions

Introduction Plants and some other autotrophs can make their food from carbon dioxide and water in the process of photosynthesis. The energy for this process is provided by the light rays coming from the sun. The light energy captured by the electrons is liberated while they travel down the electron transport chain. This energy is …

Read article →Light-Dependent Reactions

Chemiosmosis

Introduction ATP is an essential requirement for the various metabolic processes taking place in living organisms. The continuous supply of ATP is necessary for the continuity of life. Any interruption in the synthesis of ATP can result in harmful and life-threatening events. In most of the living systems, ATP is made by phosphorylation of already …

Read article →Chemiosmosis

Biomass

An Introduction to Biomass In this universe, anything having physical characteristics and exhibiting material nature occupies some space due to the ability which is referred to as mass. Such ability of biotic living organisms is termed as biomass. Simply, the mass of living beings in a certain area and during a specific period of time …

Read article →Biomass