5.3 - Fertilisers

5.3 understand the use of fertiliser to increase crop yield


Fertilisers are used to promote the growth of plants.
Fertilisers usually consist of nitrates and phosphates
Nitrates: Forms proteins which is used to repair the plant cells
Phosphates: Are present in the membrane and DNA of plants


There are 2 kinds of fertilizers, organic and inorganic fertilisers.
The main difference is that organic fertilizers are just animal waste while inorganic ones are artificial and man made.

5.2- Crop Yield

5.2 understand the effects on crop yield of increased carbon dioxide and increased temperature in glasshouses

Relates to:

Rate of photosynthesis: CO2 + H2O ----------> C6H12O6 + O2

Increase in carbon dioxide means that the rate of photosynthesis will increase, which results in an increase in crop yield up to a point where it reaches  the optimum point of the rate of photosynthesis

The results of an increase of temperature is similar except that once the rate of photosynthesis reaches its optimum temperature the enzymes will denature, decreasing the rate of photosynthesis and therefore decreasing the total crop yield.

Increasing temperature in a greenhouse has other effects such as avoiding frost damage and keeping a constant temperature. Both of these also increase total crop yield.

5.1 - Glasshouses

5.1 describe how glasshouses and polythene tunnels can be used to increase the yield of certain crops


Glasshouses are used to to make the conditions ideal for a plant to grow.
Eg:

• Light enters the glasshouse and is absorbed by substances in the glasshouse such as soil and plants.
• The plants re-emit the light energy as heat and the average temperature in the glasshouse increases
• The trapped warm air is better for the plants because it is nearer to the plants optimum temperature which means the enzymes in the plants react faster and produce more
• Glasshouses also prevent things such as insects and animals to come and eat the plants. Not only that but it also protects the plants from natural things like wind, snow and changes in temperature
• Also since it is a closed area it prevents water vapour to escape therefore the plants wont dry out

Polythene tunnels work the same way as a glasshouse, heating up the environment making it more ideal for the plant to grow however it provides less protection for the plants. Polythene tunnels are more common because they are a lot cheaper/ affordable and can be set up more easily

Endocrine system

                                            Endocrine glands --------> Target -------------------> Effects
1. ADH                                 Pituitary                               Collecting duct              Inc amt of H2O in blood
2. Adrenaline                         Adrenal                               Heart                            Inc Heart rate
3.Insulin                                 Pancreas                             Liver                             Store glucose
4. Glycogen                           Pancreas                             Liver                             Put sugar into blood
5. Testosterone                      Testes                                Testes (sperm)               Sperm cell mature

2.89 - Hormones

2.89 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen.


Adrenaline: is produced by adrenal glands (above the kidney) and is released in times of excitement, fear or stress. Adrenaline helps prepare the body for action in the following ways:

• Glycogen is converted to glucose in the liver, so more glucose reaches the muscles as a source of energy for the rapid contractions needed for sudden action
• Increases heart rate so that more glucose and oxygen are delivered to the muscles for energy release
• The bronchioles widen so that more air reaches the lungs
• Blood vessels to the brain widen so that more glucose and oxygen is delivered to these organs
• Blood vessels to the gut and other organs narrows allowing blood to be diverted to more life-saving organs
• Hairs are raised

ADH: is made in a gland in your brain and controls the level of water in your body.


Insulin: The pancreas makes insulin. The insulin tells the liver to take glucose out of your blood so it is changed into glycogen in the liver . Insulin lowers blood glucose(sugar)  levels back to normal


Testosterone & Oestrogen are hormones that bring about the changes to our bodies that occur at puberty
Testosterone is the male hormone and brings out these changes in boys:

• the testes start making sperms
• hair starts to grow on the face and body
• The voice deepens
• the muscles develop

Oestrogen is the female hormone and brings out these changes in girls:

• The ovaries start to release eggs
• hair starts to grow on parts of the body
• the breasts develop
• the hips widen
• periods start

2.88 - Skin

2.88 describe the role of the skin in temperature regulation, with reference to sweating vasoconstriction and vasodilation


Stimuli: Body temp
Receptor/coordinator: Hypothalamus
Effector: Skin
Response:

Vasoconstriction (when its cold):

• Blood vessels at you skin surface close up. they cut down the flow of blood to the surface so less heat is lost by radiation
• Sweat glands stop making sweat
• Shivering: Your muscles start to contract quickly, this produces extra heat that warms your body

Vasodilation (when its hot):

• Blood vessels at your skin surface widen. They allow more blood to flow to the surface so more heat is lost by radiation
• Sweat glands in your skin make sweat. the sweat evaporates and cools you down

2.87 - Eye response/focus

2.87 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity

• Most of the bending of the light rays is done by the curved cornea but the lens can also bend the light rays but only slightly (focus)
• The shape of the lens is controlled by the ciliary muscles
• If you are looking at a distant object:
• The ciliary muscles relax
• This tightens the ligaments
• therefore the lens is pulled into a thin shape
• The distant object focuses on the retina
• If you are looking at a close object:
  • The ciliary muscles contract
  • This slackens the ligaments
  • therefore the lens becomes thicker
  • The near object focuses on the retina