© boardworks ltd 2004 1 of 30 ks4 biology what is energy used for?

© Boardworks Ltd 20041 of 30

KS4 Biology

What is Energy Used For?


Contents


Contracting muscles

Active transport

Thermoregulation

Processes that use energy

Building large molecules

Summary quiz


Respiration occurs in all body cells to release energy. What is this energy used for?

This energy is used by the many processes that sustain life, such as…

How does the body use energy?

building large molecules from smaller ones

the active transport of substances within the body

maintaining a steady body temperature

muscle contraction


Contents


Contracting muscles

Thermoregulation


Summary quiz


Active transport


Muscles work by contracting. When a muscle contracts it pulls a bone, creating lever.

bone

muscle

Using the energy generated in muscle cells, muscle contraction alters the position of the bones. This means that work can be done, such as something can be lifted.

Muscles use energy to contract

muscle relaxed

energy

muscle contracted


Contents


Contracting muscles

Thermoregulation


Summary quiz


Active transport


fats

proteins

minerals

vitamins carbohydrates

water fibre

The seven main food groups

In order for the human body to maintain the metabolic processes in its cells, it must obtain nutrients from the seven food groups.

What are these food groups?

A balanced diet should be made up of food from all sevenfood groups.


The digestion of food produces many useful substances.

The body uses the energy from respiration to turn these raw materials into useful substances.

energy

respiration digestion

useful raw materials

Converting food into respiration materials


An example of this use of energy is how the body builds new proteins from amino acids.

Step 1

Proteins are eaten as part of our food (e.g. protein in eggs).

Building a new protein molecule – step 1

albumin is the main protein in egg-whites


Step 2

These proteins are made of amino acid chains.

The order of the amino acids is specific to the protein.

amino acids



Step 3

This protein may not be the one that the body requires. Therefore, the digestive system uses protease enzymes to break up the amino acid chain.


enzymeaction


Step 4

This digestive process releases the individual amino acids.



Step 5

With the raw materials now free, the body can use energy from respiration to assemble them into new proteins.

A new protein will have a different order of amino acids.

new protein (old)

energy

respiration




Step 6

This new protein, and others like it, will now be used in different ways by the body.

The energy from respiration makes this possible.

new protein

protein moved to and then used

elsewhere in the body


Contents


Contracting muscles

Thermoregulation


Summary quiz


Active transport


The conditions outside your body are constantly changing.

One minute they can be hot, the next cold.

Thermoregulation

37oCThe body needs to remain at 37oC is because this is the temperature at which our enzymes work most effectively.

Despite these changes, your body must be kept at a constant temperature of…


Enzymes are temperature-sensitive chemicals that control many of the chemical reactions in the body.

How are enzymes are affected when body temperature changes?

37oC37oC

Enzymes work most effectively and body is fine.

Enzymes work slowly and the

body is suffering.

Enzymes are heat-damaged and body can

become ill.

Temperature and enzymes

hotterhottercoldercolder


Body temperature is controlled by a region of the brain.

As blood flows around the body,

it passes through the thermoregulatory centre in the brain. rest of

the body

The brain senses body temperature

by sensing the temperature of

the blood.

Once the brain knows what the body temperature is, it can act to keep it steady.

Sensing body temperature

How does the body react to hot and cold temperatures?


Feeling the heat

When you feel too hot, how does your body react?

You sweat, which helps to cool you down.

Another cooling effect is that blood vessels in the skin expand.

This means that more blood gets near the surface of the skin, which is why some people go red when they are too hot!

The expansion of blood vessels uses some of the energy released by respiration.

How do blood vessels use this energy?


The muscle cells are able to contract and relax using energy from respiration.

How does the contraction and relaxation of these muscles affect the blood flow through this blood vessel?

How do blood vessels use energy?

outer wall

blood

muscle cells

An artery wall is made of a thick inner layer of muscle.


If the muscle lining a blood vessel relaxes, the blood vessel becomes wider and the blood flow increases.

Blood vessels and blood flow

If the muscle lining a blood vessel contracts, the blood vessel becomes narrower and blood flow is constricted.

blood flowconstricted

blood flowincreased


The brain can cause the contraction and relaxation of the muscles within the walls of these blood vessels.

This means that blood can be forced to take different routes through the blood vessels in the skin.

Blood vessels in the skin

How do blood vessels affect blood flow in the skin?

blood vessels

direction of blood flow

skin surface

What happens to blood flow when the body is too hot?


Increasing blood flow to the skin

When the brain senses that the body is too hot, it acts to redirect the blood flow towards the surface of the skin.

increased blood flow

to the surface of the skin

blood vessel widens

blood vessel constricts

Energy from respiration is used to power the contraction of the muscle cells that allows this redirection to happen.

The contraction and relaxation of these blood vessels forces more blood to flow within the surface of the skin.

How does this help to increase heat loss from the body?


When blood flows to the surface of the skin, it passes near the air surrounding the body.

This air is much cooler than the temperature of the blood.

The heat within the blood escapes to the cool air.

This causes body temperature to drop and you feel cooler.

bloodskin

air heat heat heat

Increasing heat loss from the skin


Contents


Contracting muscles

Thermoregulation


Summary quiz


Active transport


Diffusion is the movement of substances down a concentration gradient from high to low concentration.

Comparing active transport and diffusion

diffusion active transport

high concentration

low concentration

Sometimes substances move up a concentration gradient from low to high concentration.

This process is called active transport and requires energy to make it happen.

Where does the energy for active transport come from?


high concentration

When does diffusion happen?

As an example, this particle could be an oxygen molecule in the lungs that is moving from an alveolus into a blood capillary.

Usually, substances move in and out of cells by diffusion from areas of high to low concentration.

low concentration

diffusion


When does active transport happen?

This is active transport, which needs energy from respiration to take place.

Sometimes, substances have to move in the opposite direction to the concentration gradient from areas of low to high concentration.

high concentration

low concentration

active transport

An example of active transport occurs can occur in the lungs when the oxygen supply is low but is still needed by the blood.


Contents


Contracting muscles

Thermoregulation


Summary quiz


Active transport


Multiple-choice quiz

© boardworks ltd 2004 1 of 30 ks4 biology what is energy used for?

Documents