5.9 fish farming

• fish have low fat and high protein
• they are efficient at changning nutrients unto fish mass

pros
control over water
control over predators
control over pests
control over diseases

high density of fish -> possiblity of disease

some farmers use antibiotics which are a concern to human health

fish farmers also uses pesticides to keep pests away, which is also a concern to human health

5.8 fermentor

fermentor = vessel where fermentation occurs (made out of copper, steel)

to maintain optimum temperature:
• there is water between the two metal jackets as a 'cooling jacket' since fermentation heats up the fermentor. this cooling jacket will keep the fermentor at an optimum temperature
• steam, which sterilises the fermentor in between fermentations
• there is a heater inside the heater to raise temperature

we also need
• for fermentation to occur, nutrients must be placed inside the fermenter as food for microorganisms
• a probe to measure temperature. informs whether to turn on heater or cooling jacket
• a ph probe to keep ph at the optimum rate
• microorganisms
• turning device to agitate mixture, spreading microorganism
• method of draining product = it will then go into a process called downstream processing which will also purify the product

the idea of the fermentor is the keep the reaction at it's optimum level the whole time, so it will be able to produce the product more efficiently

5.7 yoghurt production

understand the role of bacteria (Lactobacillus) in the production of yoghurt




• the cow produces the milk
• the milk is then pasteurized, which kills any pathogens that might be in the milk
• milk sugars are converted into lactic acids, by incubating the milk at 45-46 degrees in a process called lactobacillus
•lactobacillus produces an enzyme which breaks the milk sugars into lactic acid
• this then solidifies and becomes yoghurt

5.4b biological control

another way to get rid of pesticides:

2. biological control

pros
no toxic chemicals
less impact on wildlife

cons
not 100% effective
hard to control (new species will find alternate prey to feed on and not actually die out)
hard to match predator to prey

5.4a pesticides

large fields of crops all of the same type = monoculture
they tend to be susceptible to pests which feed off the crops which reduces the productivity of farming

1. pesticides (chemicals designed to kill pests)

pros
they are easily obtained
easily applicable
very effective

cons
toxic - might kill plants in the process
bio accumulation - pesticides build up in a food chain causing harm to a food source of a higher trophic level
pests mutate and resist the chemicals - more toxic pesticides have to be used

5.3 fertilisers

•fertilizers increase crop yield by taking the form of nitrates or phosphates (sometimes both)
• they are applied into the soil but are absorbed by the roots into the plant, eventually into the leaf and used in the leaf

• nitrates are used to form proteins inside the leaf
• phosphates are used to help form DNA and membrane structures inside the leaf

fertilizers are divided into two groups:

organic
produced from animal waste which goes through the process of decomposition and fermentation which forms slurry. Slurry provides fields with a supply of nitrates and phosphates to help growth.

artificial
take the form of chemicals, synthetically produced e.g. potassium nitrate solution and ammonium nitrate solution. These are bought and applied to fields and supply the fields nitrates and phosphates.

5.2 crop yield

CO2 + H2O --->(light enzyme) C6H12O6 + O2 = rate of p/s

increasing the concentration of CO2 will result in an increase in the rate of p/s
this will mean an increase in the crop yield

increasing the temperature will result in an increase in the rate of p/s again, but after it peaks you have reached the optimum level (increasing the temperature further would result in a decrease in the rate of p/s

increasing temperature also:
- avoids frost damage
- provides constant temperature

5.1 glass houses

• glasshouses/greenhouses have frameworks made of glass which lets light penetrate through
• the frame is made out of polythene which also lets light penetrate

how greenhouses work:
• solar radiation from the sun
• light goes through glass
• light is absorbed by surfaces inside greenhouse e.g. soil, plants
•  these surfaces will re-emit this energy as heat
• the heat warms the air raising its average KE, raising the overall temperature
• the warm air is trapped

warm air glasshouse = higher crop yield

this is because:
- high temp = optimum temperature for enzyme reactions (photosynthesis)
- temperature is constant throughout the year
- prevention of loss of water vapour - crops do not dry out, because they have a constant supply of water (vapour)
- avoid frost damage (especially seedlings)
- glasshouses are warmed by the burning of fossil fuels which leads to an increase in the CO2 levels inside the glasshouse (increased substrate for photosynthesis, increasing growth). inefficient burning of fossil fuels results in ethane being produced which is a gas that stimulates fruit ripening

2.89

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

2.88

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


our skin has many different sensors. our fingers tips have the greatest amount of sensors
they protect skin,stops too much water loss, help you keep your body temperature constant, stop germs getting in and ket you feel pain, temperature.


vasoconstriction: happens when cold, the blood vessels become narrower and the flow of blood is constricted, resulting in retained body heat. your skin turns paler as less blood is reaching the surface, reducing the radiation of heat.


vasodilation: happens when hot, blood vessels widen, resulting in increased blood flow and lower blood pressure

2.87

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

bending the light rays is done by the curved cornea and lens

cilary muscles control the shape of the lens

focusing on close objects

contraction of cilary muscles, which slackens the suspensory ligament and the lens becomes rounder. this image is then focused on the retina

focusing on distant objects

cilary muscles relax, which tightens the suspensory ligament and the lens becomes flatter. this image is then focused on the retina

2.86

describe the structure and function of the eye as a receptor


eyes are located in two sockets in the skull and moved by 3 pairs of muscles
the light enters the eyes through the cornea, which is transparent and at the front of the eye
then the light goes through the pupil
the cornea has a delicate and transparent layer in front of it called the conjuctiva
this kept moist by tear glands which 'wash' your eyes when you blink
























process of seeing things
after the light enetering through the cornea, it passes through the lens and hits the retina 
the retina contains cells called rods and cones which are sensitive to light.
as light hits and stimulates them, they send signals down the optic nerve to the brain.
your brain then interprets the impulses as images


the image is actually inverted but the brain has adapted to turning it the right way around
rod cells = react to dim light
cone cells = react to colour and detail

2.85

describe the structure and functioning of a simple reflex arc illustrated by the withdrawalof a finger from a hot object


reflexes happen very fast so you dont harm yourself
reflex arc = the pathway to an impulse along the neurons


stimulus: hot object


receptor: skin


coordinator: brain (hypothalamus) 


effector: muscles in hand


response: hand pulls away from/drops hot object

2.84

understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses

neurons: 

-nerves have cell membranes, cytoplasm, and nucleus but are a different shape to other cells

-part of the cell is stretched to form the axon.

-the axon can be many meters long

how nerve messages travel

- the messages that nerves carry are sent by nerve impulses, which are electrical

- as a result of this the message travels very fast through the axon

some axons (such as mammals') have fatty sheaths around them that make the nerve impulses travel faster since the fat insulates the axon and makes the impulse travel faster

2.83 central nervous system

brain + spinal chord = central nervous system (cns)

the brain is protects by the skull and the spinal chord by the back bone

the cns is connected to different parts in the body and each nerve is made up of millions of neurons

2.82

1. Motor nerve
 - coordinator - orange part on the left embedded in spine
- effector - embedded in effector (muscle)

• electrical impulse is carried inside nerve from the cell body to the synaptic knob, where it connects to the muscle
• pulse travels down long structure (axon) which can me meters long
• in mammals these cells are surrounded by schwann cells which contain fat. these schwann cells increase the speed of the nerve conduction

2. endocrine system
• endocrine glands produce hormones, in this case proteins or steroids.
• the hormone is secreted into the blood (travels through blood)
• the hormone will reach the muscle it will have an effect on, known as the target tissue/ organ
• hormones may have multiple targets and effects (nerves cant)

nerves are fast, focus on one target at a time

hormones are slow, have multiple effects on multiple targets

2.77b thermoregulation

• negative feedback look - method of control/ mantaining constant conditions

in humans = body temp is constantly 37/8 degrees
• body temperature is feeds into the brain (hypothalamus) and is compared to the theoretical optimum body temp
• if the body temp needs to be changed then this is done by the effector, skin.
• the response will either be a decrease or a increase and feeds this information once again to the brain (hypothalamus)

components that control body temp in skin are sweat glands and the capillary network [which allows blood to move closer or further away from the surface of the skin].

if your body temperature gets too high your hypothalamus regulates to your skin which bring around cooling, like sweating, hairs being flat and blood flow to the surface of the skin increases as blood vessels dilate (get bigger, also called vasodilation) which increases the exchange of heat to the outside of the body e.g. evaporation of sweat and radiation

if your body temperature gets too low your hypothalamus sends messaged to your skin which causes shivering, vasoconstriction and raised hairs. vasoconstriction reduces heat exchange and forces blood to travel further down the tissues

the efficiency of both of these regulations increases the further away your body temperature gets from your optimum temperature

2.77a thermoregulation

• homeostasis - that the conditions are kept constant
• homeothermic temperature is kept constant
• some organisms (mammals) who's body temperature remains the same and carry out a process called thermoregulation
• other organisms body temperature varies on the environment
• the optimum temperature for max rate of reaction for enzyme reactions is approximately the same as the temp as mammals body temeperature

2.76 sensitivity

• sensitivity is what organisms use to respond to changes in the environment
• changes in the environment (stimuli) include changes in:
-light
-temperature
-pressure
-chemical
• in order to be able to detect these changes organisms require to have receptors
• in order to respond to changes in the environment organisms require effectors e.g. muscles, glands
• the response ensures that the organism can survive the changes of the environment