5.11 Selective breeding of animals

E.g --> The cow

• Desired characteristic - milk yield 
• 50ml - each time 
• However other cows produce 150ml of milk or 100 ml  
• The farmer will collect all the milk, but he chooses the milk that produces the most milk to become his breeding cows 
• This goes on as the generations come 
• They are selected for the desired characteristics 
• This will be developed as the selective breeding gets better 
• The characteristic wanted must be controlled by the gene 

5.10 Breeding of plants

Selective breeding of plants 

• E.g Rice 
• The number of rice grains is based on the number of genes 
• The farmer wants to increase his yield 
• Farmers decide to harvest the plants with the least grains, but leaves the plants with the most grans, so that they can breed 
• Slowly, it will increase, and the farmer will harvest the smallest again and leave the most for breeding 
• This way, the rice plant produces the most grains possible --> increasing the yield 
• This is an example of selective breeding 
• Applied to most characteristics of the plats 

Fish Farming

5.9 

Advantages 

• Water quality can be controlled 
• Predators are removed 
• Pests can be removed 
• Disease can be removed or controlled 
• All these different things contributing to increasing the yield of the fish

It is attractive to farmers as the demand for fish is too much for traditional fishing, also the fish are low in fat, and high in protein and highly efficient at transferring nutrient into fish matter 

However, because of the large masses of fish in a pod, the transmissions of diseases and a number of pesticides greater, since they are closer together and are enclosed in that space. Farmers try to counter this by using antibiotics however this can cause harm to humans who eat the fish and can even cause harm to the environment 

B) Microorganisms

5.5 Yeast in the production of beer 

• Anaerobic respiration of yeast produces ethanol <-- the basis to alcoholic drinks 
• Glicose ----> alcohol + CO2 + H2O
• Starch breaks down the sugars 
• Beer is largely ethanol, an alcohol molecule 
• Produced from glucose 
• Microorganism that does this is Yeast, it is able to supple the enzymes to bring about the conversion  and that is where the ethanol (alcohol) in beer comes from 
• Ethanol is then flavored by plants to change the flavor 
• The glucose comes from the starch ---------converted-------> maltose ------converted---> glucose 
• Starch broken down by amylase and the maltase broken by  maltose  
• This applies to barley seeds, wheat and rice 
• Starch is broken down into amylase through the germination, process called MALTING, providing us with the sugar needed (glucose) 

5.6 Experiment to investigate CO2 production by yeast in different conditions 

1. Mix 10ml of yeast with 15ml of sucrose 
2. add 5ml of the solution to 5 test tubes (ready to capture gas) 
3. add different amounts of ethanol to each tube 
4. put olive oil on top of the water (to ensure anaerobic conditions) 
5. Heat to 35 degrees in a water bath for 30 mins 
6. Measure the height of the small test tube showing above the solution 

5.7 The production of yoghurt (Lactobacillus) 

• After the milk is pasteurized, the lactobacillus is added 
• The bacteria feeds on the milk releasing lactic acid 
• The acid acts as a preservative 
• The increased pH causes the protein in the milk to come together

5.8 Industrial Fermenter

• Reaction vessel in which fermentation occurs 
• Made out of steel or copper 
• Has an extra steel jacket around it that acts as a cooling jacket 
• Fermentation produces heat so the enzymes must be keeps at a certain temperature to increase the rate of reaction and prevent denaturing 
• There is also a heating plate that can increase the temperature at any time. With the cooling jacket, the temperature can be altered easily to reach its optimum 
• Sterile air (containing oxygen) needs to be pumped in so aerobic respiration can occur, the mixer is there to make sure that the O2 is distributed throughout the chamber 
• Before the reaction, it needs to be sterile, so super heated steam is put into it to kill all bacteria 
• So that fermentation can occur, nutrients have to be added to the tank and will act as food for the microorganism 
• pH probes are also inserted so optimum pH can be controlled to increase the rate of reaction 
• The mixer stirs the reaction to make sure that there are no clumps of substances left and that the microorganism is distributed 

Extra notes 

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5a Food Production

5.1 Glasshouses and Polythene tunnels 

• Protect the crops from the environment 
• Temperature 
• Water levels 
• Fertilisers 
• Carbon Dioxide levels 
• all controlled to maximise yield 

5.2 Effects of increased CO2 and temperature 

• Temperature 
• Increase rate of metabolic reactions 
• Too much heat can effect growth in a negative way 
• CO2 Levels 
• Increase rate of photosynthesis 
• Therefore increasing the growth 

5.3 Fertilisers --> To increase crop yield 

• To return nitrates and other minerals to the soil 
• Nitrogen is used to make proteins, nucleic acids and chlorophyll 
• To give the plants nutrients they need in order to grow 

5.4 Pest control --> Pesticides and Biological control 

• Advantages to pesticides
• Doesn't harm humans 
• Only pests harmed 
• Helps keep a strong yield 
• All crops are capable 
• Easy to apply 
• Disadvantages to Pesticides 
• Expensive 
• Pest can become resistant 
• Environmental damage 
• Can kill pollinating insects 
• Can wipe out a food chain 
• Advantages to biological control
• Not 100% effective 
• No poison involved 
• Almost all crops effected 
• Disadvantages to biological control 
• Difficult to apply 
• Expensive 
• Not suitable for all crops 

Endocrine system

• Made up of endocrine glands 
• Structures that produce chemical systems known as hormones 
• It needs to have a target tissue 
• At the target tissue, it has an effect
• Endocrine gland ----Hormone------> Target ------------> Effects 
• ADH --> produced in the pituitary --> target : collecting duct  --> Increase the H20 in the blood 
• Adrenaline --> Adrenal gland --> The heart, brain, muscles --> Breathing rate, heart rate, muscle strength
• Insulin --> Pancreas --> Controls blood sugar levels --> storage of glucose 
• Testosterone -> testes --> target is the testes --> controls puberty 
• Oestrogen -->  ovary --> controls female puberty, builds the lining of the uterus (produced first) 
• Progesterone --> Ovary --> Maintain uterus lining (produces after oestrogen to maintain the uterus lining) <-- this is only for the mensural cycle, 28 days 

2.88 Skin - classwork

• To ensure maximum rate of reaction, we need to keep it at the optimum temperature --> 37 degrees 
• Temp decreases --> movement decreases, hypothermia 
• Temp increases --> Heat stroke 
• Body temperature needs to be regulated 
• Starts the stimulus, blood 
• The receptor is the hypothalamus, monitoring the blood temperature 
• The response we produce relate to whether we're trying to cool, or heat up 
• Cooling down --> Vasodilation --> sweating (too hot)
• Warming up --> Vasoconstriction --> shiver (too cold) Shivering increases heat as it wants to keep the core organs hot, even if it means to allow the other muscles to cool down. It optimizes 

1. Vasodilation --> blood goes to the surface of the skin to radiate the heat, relating to sweating.
1. Latent heat of evaporation, the heat goes into the sweat, causing it to evaporate, loosing the heat. 

2.89 Hormones

2.88 Skin

1. Effecter and receptor 
2. Reacts to change in temperature, send the information to the CNS 
3. CNS responds to the change 
1. Done by sweating, to cool the body down 
2. The flow of blood is directed to the surface of the skin to increase the amount of heat lost due to conduction. This is called  Vasodilatation 
4. When temperate decreases
1. The body shivers
2. Blood is kept away from the skin to reduce heat loss, called vasoconstriction 

2.87 Focusing

Focusing

• We focus by changing the shape of our lens 

Distant Objects 

1. Light rays don't have to be bent that much 
2. The ciliary muscles relax 
3. Suspensory ligaments pull tight 
4. The lens is thin (pulled outwards) 

Near Objects 

1. Light rays have to be bent a lot 
2. Ciliary muscles contract 
3. Suspensory ligaments relax 
4. The lens is thick (pushed inwards) 

                                    

2.86 The Eye

The eye is a receptor in light, it detects its changes 

1. After the light enters, it gets focused by the cornea and the lens 

2. The light is focused on the retina, which leads into the optic nerve 

3. Rods and cones cells transfer the electrical impulse to the CNS
4. The brain takes in the impulse and turns it into an image, in the visual part of the brain

2.85 Reflex Arc

• Reflex arcs are fast responses to protect the body 
• Does not involve the brain as this increases the reaction time 
• Involuntary action

EG. 

Stimulus --> Hot object 

Receptor --> Heat sensor in the skin 

 Impulse travels to the spinal chord along the sensory neuron 

Impulse traveled from the spinal chord to the relay neuron 

Then to the motor neuron which carries the impulse to the muscle, making it move in response 

2.84 Electrical impulses

Stimulation of receptors in the sense organs send electrical impulses along nerves into and out of the central nervous system
The messages the nerves send are through electrical impulses, they pass along the axon of the neuron

2.83 Central nervous system

• Controls our actions and different parts of our body 
• Consist of he brain and spinal chord, they are linked to the sense and effector organs by nerves or neurons 
• Protected by the bones as it is important for the bodies functions, the brain is inside the skull, protecting it, the spinal chord is protected by the backbone 
• Motor neurons carry instructions from the CNS to the effector organs.

2.82 Communication

Nervous or hormonal systems can control responses

The Nervous System 

• Central nervous system -->Consists of the brain, spinal chord, linked by nerves 
• Uses information from the sensory organs to coordinate reflexes and other actions
• Stimulus --> Receptor --> coordinator --> effector --> response 
• An individual nerve cell is a neuron, it responds to a stimuli and can conduct electrical impulses. A bunch of neurons is called a nerve 
• Peripheral nervous system --> consists of nerves and nerve networks throughout the body 
• The nerve system is actually made up of bundles of axons. The axon is a thread like structure that conducts the electrical impulses and passes them on to other cells or the muscle fibres.
• In a motor neuron the connection between the axon and the muscle fiber is called the nerve-muscle-junction  
• One way of connecting the coordinator to the effector is through Schwann Cells. These contain fat that cover the axon, the fat forms the myelin sheath. The Myelin sheath also increases the speed of nerve conduction 

The Endocrine System 

• Involves the endocrine gland which produces hormones. EG. adrenal gland producing adrenaline and insulin. 
• The hormones are secreted into the blood and affect the organs with the correct receptors, sometimes known as the target tissues 

The difference between the two 

1. Nerve system travel along neurons 
2. Chemical messages travel in the blood 
3. Hormonal system sends messages slower, Chemical is very fast 
4. Chemical take longer to have effect
5. Sometimes, chemical effects are widespread throughout the body, unlike nerves 
6. Chemical effects last long 

External stimuli

External stimuli -Light, chemical, pressure -->  receptors (then changed to electrical impulse) --> to the coordinator then to the  --> effector as impulse

Coordination

Stimuli - Chemical, light, pressure, temperature
Chemical - taste and smell
light - Eyes - changes in light
Pressure - Ears -> equalizing the pressure --> touching
Sound - ears

2.77b Thermoregulation

1. Negative feedback loop, a method of control and constant conditions
2. this is achieved at 37 Degrees C
3. Receptor --> hypothalamus <-- responds to the stimulus
4. Body temp feats into the brain, then is compared to optimum figures, then goes into the effector
where the temperature can be altered
5. This feeds back to the hypothalamus on the basis of the input and new output will be produced

Skin - what controls the body temp
1. Sweat glands
2. capillary network - blood to move closer or further away from the skin
3. If body temperature increases the input hypothalamus stimulates responses in the skin that bring around cooling, e.g. Sweating or increase in blood flow to the surface and the blood vessels dilate (whiten) increasing the exchange of heat to the outside of the body with sweat and radiation, cooling the blood, returning to body temp.

4. When cold, the opposite happens, the blood moves further away from the skin as it wants to keep all the heat it can. Countered by shivering, Vasoconstriction and hair raised.

2.77a Thermoregulation

Homeostasis -
Homeo - 'same'
Stasis - 'fixed point'
1. the condition are kept the same/constant
2. Thermoregulation - keeping the same temperature - 37 degrees for humans
3. Homeothermic organisms (mammals) when env temp changes
their body temperature remains constant
4. Mammals carry out a process called thermoregulation
5. Mammals want to maintain a constant temp because it is optimum for rate of reaction (enzyme reaction)

2.76 Sensitivity

--> MRS GREN
S = sensitivity - the part where organisms respond to changes in the environment
Stimuli =
--> Light
--> pressure
--> Temperature
--> Chemical
- in order to be able to detect the changes in the environment, organisms have receptors
--> the sensory nerve
- in order to respond to the changes, organisms have effectors, like muscles and glands

- response ensures that the organism is able to survive the changes of the environment