• Created by: judy
  • Created on: 25-02-13 12:47


1.    Explain why it can be difficult to give up smoking

Nicotine is addictive causing you to want more.


1.    Explain the effect of breathing in carbon monoxide on the function of the blood.

Carbon monoxide binds with red blood cells containing haemoglobin; this reduces the oxygen carrying capacity of the blood.


2.    Explain how an antibacterial drug may become ineffective over time.

To treat bacterial infection antibacterial drugs are used. Antibacterial drugs many be overused so some bacteria resistant to the antibacterial drug may survive.

3.    Describe how different pathogens are spread within human populations

·         Cholera bacteria is ingested through drinking dirty water

·         Salmonella bacteria is ingested through contaminated food products

·         Influenza virus is spread through droplet inhalation

·         Athletes foot fungus is spread by contact with fungal spores

·         HIV is spread by exchange of contaminated body fluids

·         Dysentery infection is spread through housefly vector

4.    State the type of medication to treat athletes foot.



5.    Explain how chemical defence mechanisms in the body reduce the chance of infection.

Lysozymes found in tears and hydrochloric acid in the stomach are chemical defences that destroy bacteria.


6.    Explain the trend in the graph, even though the patients were  testes with antibiotics.

The number of patients suffering from MRSA has increased by over 366 000 since 1993 this could be from the poor hygiene in hospitals. MRSA is a bacterium that is resistant to antibiotics, individual bacteria show variation. When a bacterial infection is treated with antibiotics those bacteria with low resistance are destroyed first and the more resistant bacteria survive. If a patient stops taking the antibiotics then the resistant bacteria will live to reproduce and the new bacteria will also be resistant to antibiotics. These bacteria will not be able to be treated with antibiotics, so the number of cases continues to rise.


The nervous system

1.    Explain how information travels along the axon of a sensory neurone.

From receptor cells to the brain as an electrical impulse.


2.    Describe the role of the myelin sheath

Insulates the axon and speeds up the impulse.


3.    Describe the pathway of a nerve impulse through a reflex arc

Receptor cells pick up a stimulus, then the sensory neurone sends a message to the spinal cord, the message travels from the spinal cord to motor neurone, this initiates a response in the effector.


4.    Explain how impulses are transmitted in a reflex arc to prevent a person from injuring themselves.

A reflex response is an involuntary response, reflex responses do not involve the brain, and they involve sensory neurones, relay neurones and motor neurones. Relay neurones are in the spinal cord, impulses travel along neurones as electrical signals, the axon is insulated by the myelin sheath which ensures the electrical signal does not lose energy. At the junction


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