Science end of year revision

What are the different types of energy transfers?

Mechanical work : When a force is applied to an object through a distance, like pushing.

Thermal : Energy transfers from a hot object to a cold object.

Electrical work: A charge moving through a potential difference (e.g. current)

Radiation : Energy is transferred through the movement of light or sound waves.

How do you calculate ‘work done’

work done = force × distance

E=F×d

This is when:

• work done (E) is measured in joules (J)

• force (F) is measured in newtons (N)

• distance (d) is in the same direction as the force and is measured in metres (m)

What is a force?

A push or pull that can cause an object to accelerate, measured in newtons (N).

Name three contact forces

Friction, tension, normal (also known as the reaction force) and air Resistance

What is a contact force

A force that acts between objects in direct contact with each other, resulting in interactions such as pushing, pulling, or resisting motion.

Name non-contact forces

Forces that act at a distance without physical contact, including gravity, magnetism, and static electricity.

What is a balanced force?

When forces acting on an object are equal in size and opposite in directions, resulting in no change in motion.

If forces are balanced, what is the resultant force?

The resultant force will be 0

What is tension?

A pulling force exerted by an object by a string, rope or rod.

What is friction?

A force that acts between two touching surfaces and prevents or resists them against each other. When two objects slide past each other they experience friction.

What is air resistance?

When an object moves through the air it experiences air resistance. This force acts against the direction the movement. The faster the object is travelling through the air - the greater the air resistance.

What is upthrust?

An upward force that acts on an object in a fluid.

What is thrust?

A driving force exerted by an engine to make an object move.

What is conduction?

Conduction is the flow of heat energy from a region of high temperature to a region of low temperature without overall movement of the material itself.

What conditions need to be met for an enzyme to be denatured.

If the temperature of pH level is high, enzymes can be denatured ; this means that their active site has been deformed so the substrate won’t bind with the active site anymore.

What is a biological catalyst?

A biological catalyst are proteins that speed up chemical reactions in living organisms without being used up in the process.

What are enzymes?

Enzymes are biological catalysts that speed up chemical reactions in the body. They help break down good into smaller molecules.

What is a substrate?

A substrate is the molecule that an enzyme will break down.

Where do reactions occur on enzymes?

The active site

What is the role of protease and where is it found?

Protease breaks down protein into amino acids and can be found in your mouth and small intestine.

Which enzyme breaks down starch?

Amylase

Which enzyme breaks form carbohydrates into smaller sugars and where can it be found?

Carbohydrase; it can be found in the mouth and small intestines.

What is the role of lipase and where can it be found?

Lipase breaks lipids into fatty acid and glycerol ; digestion of lipids takes place in the small intestine.

What is the role of stomach acid on the body?

Stomach acid breaks down food and also kills harmful microorganisms in food.

What is diffusion?

Diffusion is the movement of molecules from an area of a higher concentration to an area of a lower concentration.

What is the function of villi?

Villi absorb food molecules into the bloodstream. Villi increase the surface area of the intestines to allow nutrients and water to be efficiently absorbed into the bloodstream.

What happens in the mouth in digestion?

The teeth break down the food and mix it with enzymes in saliva.

What does the liver release into the intestines?

The liver releases bile which breaks down fats and oils in food.

The stomach mixes