Yr10 GCSE Core Biology

-                  Describe how a nervous response is brought about by stimuli, including the roles of receptors, sensory neurones, the coordinator and motor neurones.

        Stimulus (Light bulb) -> Receptor (Eye) -> impulse travels along the sensory neurone to -> Coordinator (Brain) -> impulse travels along the motor neurone to -> Effector (Eye muscle) -> Response

·         Neurone = A single nerve

-              Describe a reflex action and the role of the relay neurone in this action.

       Receptor (Finger) -> impulse travels along sensory neurone -> comes to synapse -> goes onto the relay neurone -> to synapse -> along the motor neurone -> Effector (Arm muscle)

·   Synapse = gaps between the end of a neurone and the start of another or an effector.

 ·         Axon = the end of a neurone.

-              Explain that four internal conditions controlled by the body include; water content, ion content, body temperature and blood sugar. Describe, in very broad outline, how they are controlled.

§  Ion content leaves body 1) in sweat 2) excess lost via kidneys in urine.

 §  The water content of body leaves body 1) in breath 2) as sweat 3) excess is lost via kidneys in urine.

 §  Temperature -> maintain temperature at which enzymes work best.

§  Blood sugar levels -> to provide the cells with a constant supply of energy. 

-              Describe hormones as chemicals which coordinate reactions in the body and that are secreted by glands and reach their target organs via the blood stream.

§  Pituitary glands -> FSH and LH.

§  Ovaries -> oestrogen and progesterone.

§  FSH (Follicle stimulating hormone) – egg mature + oestrogen to be released.

§  Oestrogen – thickens uterus lining + inhibits FSH

§  LH  (Luteinizing hormone) – egg is released from ovary + stimulates progesterone.

A balanced diet contains the correct balance of the different foods your body needs -

• Carbohydrates
• Fat
• Protein
• Fibre
• Vitamins
• Minerals
• Water

The different balance depends on the individuals lifestyle and body.

A person is malnourished if their diet is not balanced. A poor diet can lead to - A person being too fat or too thin. Or deficiency diseases such as scurvy which is lack of vitamin C.

A metabolic rate is the rate in which all the chemical reactions in the cells of the body are carried out. Metabolic rate can vary depending on -

The amout of exercise you do, it increases with the amount of exercise you do and it stays high for some time after you have stopped.

The proprtion of fat to muscle in your body.

And you families history, you have inherit a high or low metabolic rate.

In developed countries people are consuming too much food and doing to little exercise. The result is high levels of obesity and diseases linked to excess weight such as - Arthritis, diabetes, high blood pressure and heart disease

In developing countries people suffer from problems linked to lack of food such as - Reduced resistance to infections and irregular periods in women.