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ARTICLE

Digestive enzymes

Enzymes are globular proteins that control biological reactions. Digestive enzymes speed up the breakdown (hydrolysis) of food molecules into their ‘building block’ components. These reactions ...

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Waves as energy transfer

‘Wave’ is a common term for a number of different ways in which energy is transferred: In electromagnetic waves, energy is transferred through vibrations of electric and magnetic fields. In sound ...

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Mitochondria – cell powerhouses

Mitochondria are tiny organelles inside cells that are involved in releasing energy from food. This process is known as cellular respiration. It is for this reason that mitochondria are often ...

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Carbon cycle

The carbon cycle can seem like a complex process because there are many interacting parts. Carbon is found in both organic (living) and inorganic (non-living) forms. Before we discuss the cycle ...

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What are ceramics?

A ceramic is an inorganic non-metallic solid made up of either metal or non-metal compounds that have been shaped and then hardened by heating to high temperatures. In general, they are hard ...

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Digestion – breaking the large into the small

Digestion of food involves both physical and chemical processes. Through digestion, large food particles are converted into smaller components that can be readily absorbed into the bloodstream. ...

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The human digestive system

The human digestive system consists of a long muscular tube and several accessory organs such as the salivary glandspancreas and gall bladder. It is responsible for food ingestion and digestion ...

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Insulation

In Antarctica, winter temperatures can vary from -70ºC to -15ºC – it is one of the coldest places to live on earth. To survive in the Antarctic, keeping warm becomes a very important focus, and ...

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Behaviour of waves

All waves behave in certain characteristic ways. They can undergo refraction, reflection, interference and diffraction. These basic properties define the behaviour of a wave – anything that ...

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Non-renewable energy sources

Energy comes from many sources, and to describe these sources we use two terms: renewable and non-renewable. Non-renewable energy resources cannot be replaced – once they are used up, they will ...

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Rate of digestion

Digestion of food involves chemical reactions that break up large food molecules into their ‘building block’ components. There are a number of factors that affect the rates of these reactions ...

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Hormonal control of digestion

It has now been well established that gut hormones have a key role in controlling food intake and energy expenditure. The gut is the body’s largest hormone-producing organ, releasing more than 20 ...

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Causes of aerodynamic drag

Aerodynamics is the study of how air flows over objects and the forces that the air and objects exert on each other. Drag is the force of wind or air resistance pushing in the opposite direction ...

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Digestion chemistry – introduction

Food plays an extremely important part in the lives of all humans. After ingestion, the food is mechanically broken down into smaller pieces and then chemically digested through the action of ...

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Energy requirements of the body

The macronutrients (carbohydrates, proteins, fats and oils) we consume in our diet help to supply the energy needed by the body to keep it working. This energy is used to drive the complex ...

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What is energy?

This is both a simple and complex question. Energy is in everything – it is often described as ‘the ability to do work’. Almost all food energy comes originally from sunlight. The chemical ...

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Unlocking the energy in foods

The foods we eat supply the energy needed by the body to drive its complex chemical, mechanical and electrical systems. Where does this energy come from, how is it locked into food molecules and ...

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Fundamentals of waves

Seeing, hearing, feeling warmth, surfing, tuning the radio, using a cellphone – these and many more activities involve waves. But what is a wave? In this article, we get to grips with the ...

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Measuring muscle strength

How do you go about finding just how strong you are in a particular exercise? You could try using larger and larger loads until you reach the limit of your strength – but this is dangerous ...

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Pedal power

Competitive cyclists have power meters to carefully monitor their training and race performance. Power is a measure of how much energy is being changed every second. For cyclists, the effort they ...

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Healthy gut bacteria

For most of the time, the population of bacteria in the large intestine lives in balance within its confines. The relationship that exists between the body and its resident bacterial population ...

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