Cross section of a kidney - Taken in biology class dissection.

2.75 Urine

Key Points:
1. ADH influences the kidneys filtration of blood, in which more water may be retained.
2. Urine contains salts, water and urea.
3. The salts and h2o affect the composition of tissue fluid which is called osmoregulation (isotonic, hypertonic and hypotonic states)
4. The composition of urine varies upon the conditions in which a person is operating.

2.74 ADH

Key Points:
1. ADH = Anti Diuretic Hormone. ADH is produced in the hypothalomus of the brain. This flows through the blood stream and targets the kidney.
2. The effect of ADH is to control and alter the composition of water which is in blood. ADH has the ability to make the blood more or less concentrated. This is important because of the dangers of not having isotonic status.
3. ADH targets the collecting duct, where the water goes out, and the effect of ADH is that it allows more water to exit the collecting duct.
4. The collecting duct is responsible for the recycling of blood back into the bloodstream. ADH makes the collecting duct walls more porous, so the water can escape easier.
5. The consequence of the ADH secretion is that the urine would be more concentrated with a less volume. ADH secretion causes this.

On a hot day we lose water through sweat, and this means less water will be in the blood when it goes to the kidneys for ultrafiltration. As there is less water already, the ADH response would most likey be more than usual, causing us to retain more water and recycle it back into the blood stream. This is probably amplified with dehydration, as the loss of water through urine may be a life/death scenario, so it is probably likely that the ADH will have a greater effect upon the recycling of water, and more water will re-enter the bloodstream so that our bodies can keep going.
This is probably the opposite with a cold day.

2.73 Glucose Re-absorption

Key Points:
1. Selective reabsorption means the molecule is selected, and is reabsorbed from the glomerula filtrate back into the blood.
2. The filtration occurs in the Bowmans Capsule. In the formation of the fluid, high pressure, glucose is in the plasma which is then known as the filtrate.
3. Water is removed back into the blood via the collecting duct. At the end of the nephron is the urine, and normally urine doesn't contain glucose. If glucose is present in the urine, then that is a condition known as diabetes.
4. Glucose is in the filtrate at the proximal convoluted tubule, and then it is removed and is taken back into blood. Glucose is selectively reabsorbed into the blood via the proximal convoluted tubule.

2.72 Water re-absorption

Key Points:
1. In the Bowmans capsule, ultrafiltration takes place. The blood goes into the kidney under high pressure, and the plasma is forced into the bowmans capsule tube, or the glomerula filtrate, and this contrains glucose water, salts and urea. When the filtration occurs, too much water is filtered.
2. As the filtrate passes along the tubule, when it reaches the collecting duct, what happens is that water is removed from the filtrate.
3. That water is returned back to blood vessels.
4. The water has been selected and has been re-absorbed into the blood, or selective re-absorption.

2.71 Ultrafiltration

Key Points:
1. The diagram is of the nephron, and this is the part of the kidney that filters our blood. And the waste product is urine. The urine emerges from the bottom of the tubule. Urine is composed mostly of water, salts, and urea.
2. Urine is formed by a process. This starts in Bowmans capsule, and the process is known as ultrafiltration. The filtration of blood begins with blood in the kidney. When the blood enters the kidney it has a high pressure, and the blood enters a series of capsules known as the glomerialis, made up of smaller blood capsules. As the blood leaves, it goes through a blood vessle coming out of the bowmans capsule, and the diameter of this blood vessel is smaller. This is so that the blood pressure increases.
3. The high pressure forces the liquid within blood, plasma, and plasma contains all the useful things in blood such as salts urea glucose. These are all forced out of the blood vessel and into the inside of the Bowmans Capsule. The plasma becomes known as the filtrate, the glomarelia filtrate.

2.70 Nephron Structure

Key Points:
1. The nephron is the functioning area of the kidney. The Aorta passes by the kidneys, and the artery that branches off and connects to the kidney is called the renal artery. The kidney filters the blood, and the excretion is called urine. This is collected in the bladder and prepared for release.
2. The vein carrying the filtered blood from the kidney to the bladder is called the renal vein. The renal vein eventually returns to the vena cava.
3. If the kidney was sliced across exposing the different layers of the kidney, different things would be seen. The outer lighter region is called the cortex, and the inner region is called the medulla. The space at the very edge of the kidney is called the pelvic, and this is where the urine collects. The reason for the different colours is because the kidney is made of many tubular structures. The dead end structure is known as the bowmans capsule.
4. In more detail, the tube structure is known as a nephron. In the diagram, the dotted line shows the separation between cortex and the medulla. The tube is made up of twisted sections, convoluted tubules, and the tube on the end is known as the collecting duct. The tube dips back down into the medulla, and this is known as the loop of henele. This returns back to the cortex and comes to the dead end structure, Bowmans Capsule.
5.The tight knot of blood capsules around Bowmans Capsule is known as the glomarialis. The first twisted section is known as the proximal convoluted tubule, and the second section is known as the distill convoluted tubule

2.69 Urinary System

Key Points:
1. In the urinary system there are two kidneys, the left and right, each with its own separate bloody supply. The kidneys carry out excretion and filtration and osmoregulation.
2. Each kidney has a tube which leads to the bladder.
3. This is called the ureter, and this carries urine from kidneys to the bladder
4. Then there is one bladder.
5. Then the urine is excreted through a structure called the urethra, then excreted out of the vagina or out of the penis

2.68b Osmoregulation

Key Points:
1. Osmoregulation: Osmo = Osmosis and Regulation = To control
2. Ideally, the tissue fluid surrounding cells in the body should be isotonic with the cytoplasm of the cells. This means the amount of water going in and out is equal and they will maintain their size.
3. The danger is that the blood going into the tissue may be concentrated causing a hypertonic tissue fluid. Or it could be dilute causing a hypotonic tissue fluid. The aim would be to maintain a isotonic tissue fluid.
4. This is done by controlling the composition of blood.
5. The kidney controls the composition of the blood. Blood flows into the kidney and excess water or salts will be excreted. The tissue fluid will maintain an isotonic behaviour.

2.68a Excretion

1. The role of the kidney in excretion, is the excretion of urea.
2. Urea is poisonous to the human body because it contains nitrogen.
3. The original form of the nitrogen is in our bloodstream as amino acids, which are used for growth, but if there are any in excess they have to be removed.
4. Blood cirulates into the liver, where the amino acids are broken down and converted into urea. This reenters the blood stream into both the kidneys.
5. The kidneys filter the urea from the blood, and add it with water to form urine and this flows down the uretus into the bladder.

2.67b Human Organs of Excretion

Key Points:
1. The major organs of excretion include the lungs, which waste carbon dioxide,the kidneys, which excrete excess water, urea and salts. Urea is the nitrogen waste from amino acids.
2. The third organ of excretion is the skin, which excretes water, salts and to a partial degree, urea but not in large amounts.
3. All of these organs display the loss of metabolic waste

2.67a Excretion in Plants

Key Points:
1. Photosynthesis involves the leaf absorbing light energy and combines CO2 with H2O to make C6H12O6 and O2
2. The release of oxygen is classified as excretion, the release of metabolic waste.
3. The process of respiration is the second excretion example. C6H12O6 -> ATP + CO2 + H20
4. In that process the CO2 is the waste product, so the plant excretes CO2 while respiring and excretes O2 during photosynthesis.

3.34 Causes of mutation

Key Points:
1. Mutation is a change in the base sequence of the gene. New alleles are produced.
2. An example of what causes this is radiation, or ionising radiation like x-rays or sunlight which cause skin cancer.
3. A second example is chemicals, such as tar in tobacco changing the base sequence of the gene. Chemicals which do this are called mutagens. Carcinagens are mutagens which also cause cancer.

3.33 Antibiotic resistance

Key Points:
1. The bacterial population in here is known as staphlococcus aureus.
2. Those who are infected can be treated with methecilline, which is an antibiotic. This chemical will kill the susceptable form of bacteria. There may be a random mutation to the genotype of the bacteria which lets the bacteria survive the chemical. This is known as the resistant form of bacteria.
3. Their mutation has created genes which allow it to break down the antibiotic.
4. The resistant form will survive, and will become more common.

3.32 Types of mutation

Key Points:
1. We begin with the first copy of the gene, and the process of mutation produces new alleles which in turn make new genes. The alleles are responsible for the phenotype and they can be either, beneficial, harmful or neutral.
2. An example of a beneficial mutation might be a boosted efficiency of an enzyme. Or harmfully a enzyme could be rendered useless. A neutral mutation might be an enzyme with no use at the present time, but in time, when the environment changes there could be some beneficial or harmful purpose of this.

3 31 Evolution

Key Points:
1. Evolution : A change in the form of organisms.
                     A change in the frequency of alleles.
2. Natural selection is the mechanism of evolution, and was proposed by Charles Darwin.
3. A chemical called Methecilline can kill Staphlococcus Aureus. The ones that can be killed are known as the succeptable. A random mutation to the genotype of Staphlococcus Aureus may cause it to be able to methecilline, and this kind of staphlococcus aureus is known as the resistant form.
4. There are now forms of the bacteria, when antibiotics are applied to the population (change in environment) then the susceptable form lowers in numbers, and the resistant ones gain numbers.
5. There are two features to be noticed: 1. Random mutation 2. Non random selection
This is known as natural selection

3.30 Mutation

Key points:
1. In the diagram there is a molecule called DNA.
2. Certain events can result in a change in this sequence, such as UV radiation.
3. Having a mutation in the gene can result in the production of a completely different type of protein.
4. Different alleles exist because of mutation, which changes the base sequence of the gene.

3.29 Species Variation

Key points:
1. Variation can be described as the differences in the phenotype of individuals. How things appear.
2. It is possible to count or measure these differences and show them in a graph form. The appearance is because of their genotype, which can be modified by the environment. Variation is a variation of all these factors.
3. Variation in population = Variation in genotype + Variation in the environment.
4. Blood groups are an example of where the environment has no effect whatsoever on the variation in population.
5. The height of individuals can be affected by both the environment AND the genotype.
6. A third possibility is that the variation in the population is entirely due to environmental variation, so genes have no role in the differences, an example of this would be language.

3.21a Genetic Probabilities

3.20b Pedigree 2

3.20a Pedigree diagrams

3.18C Codominance

As seen in the photo above, the homozygous pairs both have either BB or WW, and are either blue or white. The heterozygous plant's phenotype is orange, and seeing as BB and WW reproduced, they each contributed only one allelle, therefore making the heterozygous plant's genotype BW.

3.18b

3.18a

3.19b

3.19a

3.2 Fertilisation

Key points:
1. The process begins with the adult male and the adult female. The cells which make up an adult have a complete set of chromosomes. Diploid means that they have a complete set of chromosomes. These cells divide in the testis to produce a half set and in males this is the sperm cell, and in females its the egg. This is known as meiosis, and this will half the number of chromosomes. From 2n -> n. So 23 chromosomes.
2. In sexual reproduction these two cells are brought together and they are joined together so that it forms just one cell. This process is known as fertilisation. It involes combining two half sets into one diploid. 23 from sperm + 23 from egg = 46 known as zygote.
3. This new cell is a combination of the male and female chromosomes. This goes through a process known as mitosis, where the cells will divide. One cell -> Two cells. They will both contain 46 chromosomes, and they will divide and the cell divisions will also have 46 chromosomes. All will contain 2n diploid number of chromosomes. Once there are a group of divided cells, this structure will be known as an embryo.

3.9b Female reproductive system

Key Points:
1. Before pregnancy occurs, the uterus structure is no larger than an orange.
2. The ovary is where meiosis occurs and where the eggs are made.
3. The oviducts carry the eggs to the uterus, but also the location where fertilisation may take place.
4. The uterus is in the centre, and the uterus wall is made of muscle and will stretch to accomadate pregnancy. The lining of the uterus accepts and develops the fertilised egg and would develop into an embryo. The development of the placenta would be seen here.
5. Sperm cells enter the uterus through the cervix which is the entrance to the uterus. Uterus space is where the sperm cells move and egg cells move, and its better known for where the baby develops.
6. The vagina is where the penis is introduced and the vagina collects the sperm cells and allows them to pass through the cervix into the uterus.

3.9a Male reproductive system

Key Points:
1. The function of the bladder is to store urine.
2. The function of the testis is to carry out meiosis that produces the gamete called a sperm cell. Sperm cells are stored in the epididymis.
3. The vas deferens carries sperm cells to the penis during sexual stimulation. The walls of this tube pulse.
4. The prostate adds 20-30% of the volume of semen and contains sugars and its also alkaline. The alkaline is thought to neutralise the acidic secretions of the vagina.
5. The seminal vesicles produce sugar based secretions, and they're also alkaline. They make up 70% of the semen.
6. When sperm cells are combined with the prostate and seminal vesicles then it is called semen, and this is carried through a tube into the urethra. The urethra is the common tube that joins the left and right testis. Takes semen down the penis, and is also the exit for urine.
7. The function of the penis is to carry the sperm cells into the vagina during sexual intercourse.

3.12 Amniotic Fluid

Key Points:
In the diagram, surrounding the rest of the embryo is a fluid. That fluid is called the amniotic fluid. One function of the amniotic fluid is that it protects the embryo, the fluid which is largely water, cannot be compressed. If the fluid was squeezed, it would absorb the pressure. Any blows or hits or force applied to the uterus wall will be nullified because the amniotic fluid absorbs the pressure and prevents the embryo from getting damaged.

http://www.nlm.nih.gov/medlineplus/ency/imagepages/17008.htm

3.11 Placenta

Key Points:
1. The structure is known as the uterus, and on one side of the uterus there is a structure known as the placenta. The role of the placenta. When the child is in the uterus, its a water filled environment, amniotic fluids, at this time child cannot breathe or digest. Also unable to properly carry out excretion. So how does the child obtain nutrition?
2. Growing out of the embryo is the placental structure, there's something known as the umbilical cord. In the diagram, the embryo would be at the end of the cord. There are blood vessels on the umbilical cord and these blood vessels lead from the embryo to the placenta and they spread out to form a structure known as the placenta.
3. The placenta biological grows out of the developing embryo, NOT the mother. The blood vessels are the childs blood vessels.
4. The structure on the side is the lining of the uterus. The placenta grows into the wall of the uterus. In the blood stream of the mother there would be stuff like glucose, fats and amino acids. These would travel through her blood stream and into her uterus, and they'll cross into the childs blood at the placenta.
They go from the mothers blood to the childs blood through the placenta. To make this efficient the placenta has a LARGE surface area.

3D easy to understand animation on the stages of Mitosis

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html beast animation on mitosis

3.24c mitosis

Key points:
The nucleus of the cell contains chromosomes. During the resting stage of the cell cycle known as the interphase, the chromosomes undergo a process called DNA replication. This creates two copies of each chromosomes which are held together by a structure called the central mere.

Normally, you would see the nucleus as a spherical structure and you would not be able to see any chromosomes. The first sign that a cell is going into mitosis is when you see the nucleus membrane breaking down. Called pro phase. Then the chromosomes become visible. Visible as a pair of Chromatids. Each chromosome has been copied, held together by central mere. The cell division continues, inside the cell a network of protein molecules, spindle and the spindle fibres, extend from one pole of the cell to the other. Late pro phase, chromosome pair will move towards the spindle and will join to one spindle fibre at the central mere. Next stage, metaphase. To show it easily, its only showing one pair of chromatids. The pair of chromatids join on the spindle fibre at the equator, or middle of the fibre. The next phase is known as the Anaphase. In the anaphase, the spindle fibre shortens and pulls the chomatids in opposing direction. They separate and move to the poles of the cell. The end of mitosis is shown by telophase, in which the nucleus begins to reform around the chromosomes which have been pulled to the poles of the cell. So in the telophase we see the formation of 2 nuclei at opposite ends of the cell. Finally, a phase known as cytokinesis, the cell splits into two. This is NOT part of mitosis. The cell divides itself, and the membrane will fuse across the middle. They each contain a chromosome which is the same as the parental chromosome. Basically, both cells each contain the same amount of chromosomes as the parent cell, eg. if the parent cell had 23 chromosomes, then both of the cells created would EACH have 23 chromosomes.

3.24 b Mitosis

Key Points:
1. Covering the basics, mitosis is the process in which a cell divides into two cells, which have identical properties such as sets of chromosomes.
2. This requires that the first cell has to copy its chromosomes. This process is known as DNA replication. In the process, each chromosome undergoes a copy process to produce a replica of it with the same genes and alleles and they are held together by a structure called the central mere.
3. While the chromosomes are held together, they are referred to as a pair of chromatids.
4. The process of DNA replication takes place inside the nucleus, while its still intact. Its not visible. This is known as the inter phase.

3.24 a Mitosis

Key points:
1. Mitosis is a form of cell division which results in growth. Increase in number of cells.
2. A normal cell has a nucleus, and the number of chromosomes in there is known as the diploid number, or substituted as 2n. For humans, 2n = 46, for cats 2n = 38.
3. During mitosis, a cell will divide into two cells, each with a nucleus. Inside the nucleus of each one you'll find it has a diploid nucleus. These cells are identical, or daughter cells. They are identical in 2 ways. They have the same number of chromosomes, and the second is that they have the same set of chromosomes.
4. This means that one chromosome in one cell is identical to the same version on it in the other cell.

How are the copies of chromosomes made?
How do they separate?
For the answers, look to the blog posts above.

Key Points:
1. The chromosome on the left is likely to contain thousands of genes. Selecting one area of this chromosome, called the gene loci, and zooming in will show the individual strands of DNA. What you see is a double helix shape. They appear to be parallel.
2. By zooming in again, you will be able to see what's holding the two strands together. The sections on the diagram on the right are known as the sugar-phosphate backbone. In the centre there are a group of molecules called bases.
3. There are 4 different types of bases. Adenine (A), Thymine (T), Cytosine (C), Guanine (G).
4. These bases are holding together the two helix's and they're held together by A-T and G-C bonds. These are known as the base pairs. This is always found in DNA. They glue one side of the double helix to the other.
5. The order on the right side is A-C-T-G-A-A-C-C-A-G. Order of the bases. It's this order that we call the gene. The gene is inside the nucleus. Gene - Order of bases and number of bases ---> Protein in cytoplasm. And in the end this gives the characteristic. The gene is the order of the bases on one side of the double helix.

3.15 Genes

Key Points:
1. A gene is a section of a molecule of DNA.
2. Once again the double helix shape is shown. A section of the DNA is called a gene. This gene carries the information which forms the characteristic of the organism, eg. Blood group, petal colour..
3. The genes are all located in the nucleus, and the information is passed to the cytoplasm and then it gets transformed into a protein and its this protein which controls the production of the characteristic.

This is a strand of DNA, each section is called a gene. As you can see, DNA has a double helix shape because of the homologous pairing.

3.14 Chromosomes

Key Points:
1. The nucleus of a cell contains genes, and the genes are located in the chromosomes.
2. Chromosomes are the genetic information within a cell. In a normal cell, the nucleus would contain a number of chromosomes.
3. The photograph shows a single human chromosome. The chromosome is composed of DNA, which stands for Deoxyribonucleic acid, and this forms a shape known as the double helix. 
4. Sections of this molecule are called genes, one chromosome will have many genes eg. 1000
5. Each gene carries the information for the construction of a protein. The protein has a characteristic associated with the gene, eg. Blood group. 
6. Different organisms have different numbers of chromosomes. Cats have 38, Chickens have 78, and Humans have 46 chromosomes per cell.
7.  Chromosomes operate in pairs, homologous pairs. The next diagram shows the homologous pairs. The homologous nature is based on the length of the chromosomes. A gene located on a chromosome is called the gene loci. If you go to the same position on the other gene in the homologous pair, the same gene will be there. Basically 2 versions of each gene for one characteristic. These versions are called alleles.

3.1 Sexual and Asexual reproduction

1. Organisms that show sexual production show genders, male and female
2. This doesn't occur in asexual reproduction
3. Organisms that show sexual reproduction produce cells gametes, in the male this is a sperm cell and in the female it is the egg. In plants the sperm cell is known as the pollen, and the egg is the ovule.
4. Asexual populations produce no gametes
5. The type of cell divisions that produce gametes is called meiosis. One of its effects is to half the total adult number of chromosomes in the gamete cell
6. In humans the total number of chromosomes in an adult is 46 per cell, however there are only 23 per gamete cell. The process in which is halves is called meiosis
7. In asexual reproduction there is no meiosis, there is mitosis and binary fission in procariotic bacterial cells. The number of chromosomes is maintained constantly. A cell with 20 chromosomes would divide into 2 cells, both with 20 chromosomes. These 2 cells are identical.
8. In sexually reproducing populations there is the process of fertilisation. This is where the sperm cell of a male and the egg cell of the female fuse together.
9. In asexually reproducing organisms there is no fertilisation.
10. In sexually reproducing organisms, there are variations, and these variations are broad. There are many differences. In asexually reproducing organisms, there is small variation and very little differences but in large, they are identical.

Question: When the amount of chromosomes is halved, are they randomly picked or are there specific types of chromosomes that are needed?

This is an example of a sexually reproducing organism

Mushrooms are an example of asexually reproducing organisms

4.10 Nitrogen Cycle

Key Points:
1. Nitrogen is the most abundant atmospheric gas and it isnt very reactive. Makes up around 78% of the atmosphere.
2. Nitrogen is very important for DNA and RNA
3. Nitrogen is present in amino acids, which make up protein which make up enzymes which convert, lets say, proteins into amino acids. Basically, if a producer, such as a plant, were to take nitrate ions from the soil and convert them into amino acids and form proteins and then form enzymes, when the primary consumer comes along and eats the plant, it will digest the amino acids and proteins inside the producer.

4.9 Carbon Cycle

Key Points:

 Photosynthesis. Co2 and H20 are combined in photosynthesis using chlorophyll and the light energy is trapped and is used to form organic molecules such as glucose

Carbon dioxide comes from the atmosphere, makes up 0.03% of the atmosphere. Photo synthesis is responsible for reducing the atmospheric CO2.

   
      Feeding. The food chain and the passage of carbon through the various trophic levels. The Producer -> Primary consumer, and in doing so the primary consumer takes the carbon from the producer and uses it to grow. Eaten by secondary consumer, and the carbon passes along the food chain

      At each stage in the chain, each form carries out respiration. 
     C6H12O6 + O2---enzymes---> energy and carbon dioxide. Respiration adds CO2 to the atmosphere.

      Producers respire sending out carbon dioxide sending out carbon dioxide to the atmosphere, therefore all organisms are putting CO2 to the atmosphere through the process of respiration

       
      Decomposition. All of the organisms in the food chain eventually will die, and organic molecules which remain are broken down by the decomposer organisms which include the bacteria and the fungi. And this results in the release of the carbon dioxide back to the atmosphere.

   
      Combustion. Fossil fuels (oils and coals)-> CO2 they are combusted. The best known examples are the industrial applications but also there is the motor vehicle such as cars, Lorries, airplanes which all combust fuel to release energy. Combustion can also occur in the environment such as the idea of lightening striking the vegetation causing fire, also forest fires and grassland fires. These are some of the stages of the carbon cycle.

      For an animation on the Carbon cycle go to this URL: http://www.biology.ualberta.ca/facilities/multimedia/uploads/alberta/CarbonCycle.html

    

       Images: 

Click for full size
Taken from 

http://oceancolor.gsfc.nasa.gov/SeaWiFS/LIVING_OCEAN/carbon_cycle.png

Click for full size
Taken from

http://www.gcsescience.com/Carbon-Cycle.gif

4.14 Enhanced Greenhouse effect

Key point:
The enhanced greenhouse effect is brought about my pollution, molecules such as CO2 H20 known as greenhouse gases, increase the concentration in the upper atmosphere and this causes the infra-red light would be remitted back to the surface, and this would raise the average global temperature. This is called global warming. An increase in the average temperature.
The consequences might include the melting of ice caps in the polar regions resulting in more water in the oceans, raised sea levels and this would change ocean currents and change winds and this start to contribute to the larger picture known as climate change. This would result in the redistribution of the worlds biomes, polar ice caps would melt, deserts would expand and distribution would change.

4.13 Greenhouse gases

Key points:
1. Human activity includes the burning of fossil fuels, and the emmisions such as carbon dioxide and nitrous oxide are created
2. They absorb infra-red light and redistribute it back to earth. The burning of fossil fuels from out factories and from vehicles, and perhaps from the burning of coals. Industrial, cars and domestic combustion.
3. Farming. Animals, such as cows emit methane gas for the process of digestion which is considered to be significant, around 9%, to greenhouse gases. Evaporation of water to form water vapour. Clouds are a significant contributer ot the greenhouse effect.
4. Refrigeration, solvents and propellents and CFCs. Chlorine carbon and flourine such as CCL3F.

4.12 Greenhouse Effect

Key points:
1. A represents UV light from the sun, short wavelength or high energy. B represents that about 50% of the light is reflected back out into outer space. C represents absorption on the earth's surface, where the UV light is converted into infra-red. D is when the infra-red light (long wave) being emitted back outwards.
2. F represents some of the greenhouse gases such as water vapour and CO2, and the infra-red hits the greenhouse gas and it will absorb this energy and it re-emits it in all directions, including downwards. So it remits infra-red but it redistributes with some of those waves hitting the surface raising the temperature a bit higher.
3. Enhanced greenhouse effect is where if the levels of greenhouse gases are increased, they will absorb more infra-red and deflect it back to the earth causing higher temperature and climate change.
4. CFCs, chlorofluorocarbons are well known for their effect of the ozone layer, some layers of gases O3

CCL3F ---> with sunlight ---> CCL2F- + CL-

The CL- catalyses the breakdown of O3 gases to O2, and this affects it because O3 is much better at absorbing UV Light than O2, and were effectively removing the protection of the ozone layer.

4.11 Gas Pollution

Key Points:
1. Sulphur dioxides formula is SO2, and sulphur dioxide as a gas is added to the atmosphere when we ahve the combustion of fossil fuels in factories. Such a coals and oils give off SO2. Also a significant contribution comes from vehicles and the combustion of oils and petrols and gas.
2. In the atmosphere SO2 combines with H2O and forms what is known as sulphuric acid. It is found within the water which condenses as clouds, and when it rains it is called acid rain. Acid rain affects plants and animals. Trees and plants are often burned by the direct effect. Top tree is often dead.
3. Another way is the root system, and the sulphuric acid causes calcium ions and magnesium to be leached out of the soil. This means the plant cant obtain it and suffers chlorosis.
4. The acid will form with rainwater to make streams, and then lakes and the acid reduces the pH and the effect of this brings about the effect of aluminium ions, and this affects fish. The aluminium causes a thickening of the mucous that lines the gills and reduces the fishes ability to take oxygen from water. The fish suffocates. Kills the fish. Acid frees aluminium ions which thicken the mucous which suffocates the fish. Effects of sulphur dioxide.
5. Carbon monoxide is produced when fossil fuels such as coal and gas are burned with insufficient oxygen, so we get CO. Carbon monoxide combines with haemoglobin inside the red blood cells and makes a molecule called carbinohaemoglobin, and the problem is that it blocks haemoglobin from carrying oxygen. Reducing the oxygen circulation, this is toxic and too much CO can be fatal.Very difficult to get the carbon monoxide off the haemoglobin.

4.5b Food Webs

Key points:
1. The food web allows people to provide a much better description of an ecosystem. The eco system is composed of organisms within a community interacting, and in this case that interaction is feeding.
2. The food web shows organisms feeding at different trophic levels
3. Feeding at different trophic levels has consequences, organisms can have multiple predators, or organisms feeding on multiple prey. This results in the linking of food chains.
4. In this case, the producer is grass. The primary consumers are rabbits, beetle, slugs, mice. The woodlice would also be considered a primary consumer. The secondary consumers would be the small bird, badger.
5. The grass is eating by the rabbit, the hawk eats the rabbit, making it a secondary consumer. However, if the hawk feeds on the small birds as well its acting in the tertiary consumer.
6. The slug is the prey to birds and hedgehogs.
7. The fox is feeding on mice, rabbits and shrews, making links in the food chains.

4.5a Food Chains

Key Points:
1. The food chain linked together the producer to the primary consumer, to the secondary consumer and possibly over to the teritiary consumer.
2. At the moment, there is only one organism per trophic level.
3. In a food chain, omnivores cannot be shown
4. Food chains show the flow of matter and the flow of energy.

4.4 Tropic levels

Key Points:
1. The word trophic means to feed. Names given to the different feeding levels.
2. The carrot plant is doing photosynthesis, the carrot fly is eating the carrot plant and it makes it a herbivore. Higher up in the chain would be the fly catcher, presumably some sort of bird, making it a carnivore. And finally, the animal that feeds upon the flycatcher would the the top food carnivore.
3. However there are other names, the carrot plant would be called the producer. Producers convert light energy into chemical energy. The carrotfly would be called the primary consumer. The primary consumer takes in the chemical energy of the plant and turns it into the chemical energy OF the fly. The flycatcher is the secondary. This is again changing the chemical energy. The next feeding level is called the teriary consumer. Taking in the molecules of the fly catcher, and the chemical energy is made into the tertiaries chemical energy instead.
4. When they die, there are a special type of organisms called decomposers which dispose of the body. There are two, fungi and bacteria.
5. They break them down into nitrates and phosphates.

4.3 Quadrates samples

Key points
1. The quadrating technique can be used to sample the population distribution of organisms within their habitats.
2. The quadrat sample must be random, so there is no bias
3. It also has to be representative, a large enough sample which is similar to the true population
4. A grid system works very similarly to the X Y coordinates on a graph, and the grids are supposed to be equal sizes.
5. A random number generator can be used to randomly choose a number on the x axis and on the y axis, so that there is a quadrat to be examined without bias
6. Once the quadrat has been found, counting the organisms, in this case daisies, will show you how many there are.
7. A representative sample must be found, ideally the bigger the better
8. It can be found in about 10 quadrats
9. The data must be collected in a table, like this:

Quadrat                  Number of daisies (per mete squared)
     1                                                       x
     2                                                       y
     3                                                       n

10. Once the collection has finished, we would add up the 2nd colomn, and divide the total by the number of quadrats., to find the mean.

4.2 Quadrates

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4.1 Ecosystems

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Studying the seed and adaptations within an apple.

The fruit part of the apple is the ovary  wall, which has been filled with nutrients to become a pay off to the animal which eats it for dispersing the seed. 

The seed has a coating called a Testa, and this protects the seed and holds the cotyledons.

The ovary layer grows around the seed, and becomes more enriched with nutrients, and grows bigger. The colour and the scent of an apple attracts animals, and they eat it, and the seed goes through the digestive system and gets eliminated and the seed ends up in a mound of compost, theoretically with the required germinating conditions.

3.4 Plant Fertilisation

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3.3b Wind Pollination

Key Points:

1. Its the transfer of pollen grains from the anther to the stigma through air carried by the wind
2. An adaptation of the pollen is lightweight grains, probably with some kind of wing feature which allows them to move through the air more efficiently
3. The anthers will hang well clear of any basic flower structure so that they are exposed to the wind
4. Third feature is the stigmas, and again they have a large surface area, and a kind of feather like structure to catch the pollen grains as they pass through the air on the wind and will be caught onto the stigma structure
5. No colour in the petals, no scent in the grass, and also have no nectaries because this is a waste of energy, because they don't need to attract insects.

3.3a Insect Pollination

Key Points:

1. In the process of pollinating, there has to be a transfer of pollen from the anthers to the stigma of the flower
2. Pollen contains the male nuclei
3. The pollination takes place from insects, and the flower has to attract the insect
4. If pollen goes from one plant to another, its called cross pollination
5. The adaptations to attract the insect have signals such as colour of petals, scents which attract insects, and a pay off or value of the insect going to the flower which is given as a food in the nectaries producing a sugar called fructose
6. Stamen is the male part of the plant, composing of an anther which produces pollen, and is on a filament
7. The female part consists of a stigma in which the pollen falls on, and the style connects the stigma to the ovary, which contains the eggs and these are called ovules. The whole structure is called the Carpel

Example of Phototropism

2.81 Phototropism

Key Points:

1. Phototropism is the growth in response to light
2. Positive phototropism is the growth of the plant towards the light. With uniform light coming from all directions, the stem will grow upwards
3. However, with the same stem, and light coming from a lateral light source, the stem begins to grow towards the light source
4. In the example in which the stem grows towards the lateral light source, that is called positive phototropism
5. The understanding of this is that a compound called Auxin, which is a plant hormone and it causes more growth on one side, causing the bending of the stem and making the entire stem positively phototropic 

2.80 Geotropism

Key Points:

1. Geotropic responses are growth responses to gravity
2. An example is that in a seed, the embryonic roots grow downwards, and this makes it positively geotropic, or makes positive geotropism
3. And in the seed, the embryonic shoot will grow upwards, making negative geotropism
4. If the seed is rotated, the embryonic roots will continue to grow downwards showing positive geotropism, as will the embryonic shoot, which will grow upwards making negative geotropism
5. This shows that no matter which way you turn the seed, it the shoot will always grow upwards, and the roots will always grow downwards, showing the growth responses to gravity from the seed

2.79 Plants and Stimuli

Key Points:

1. Plants have receptors which detect the stimuli and turn it into a response
2. The responses often take the form of growth, and this is called a tropism
3. Tropisms that involve light are called phototropism, and ones that involve the response to gravity and called a geotropism
4. The connection between the receptor and the response takes the form of plant growth regulators, or hormones
5. Stimuli are usually changes in the environment, such as light and temperature

2.54 Transpritation

Key points:

1. Transpiration is the evaporation of water from the surface of a plant
2. Heat is needed to carry out the evaporation, and this heat comes from sunlight which is absorbed through the leaf's structure
3. Light energy (High Frequency, UV) converted into heat energy (Low frequency) from the leaf's structure
4. Evaporation is right above the stomatal pores, water is delivered there from the xylem, moves through the spongy layer. 
5. Liquid to gas. Evaporation happens in the area right above the stomatal pore. Not all the light energy is used for photosynthesis so some of it converts into heat energy and heats up the water, causing the average kinetic energy of the atoms in the water to increase, turning it into a gas.

2.53 Uptake of Water

Summary

1. Roots branch out to collect more water. Increased surface area means increase water intake.
2. At a closer glance, there are hairs on the roots. They are called root hair cells.
3. Root hair structure is for maximum water intake
4. The mechanism involves active transport of minerals, and this causes osmosis in which the water moves from the dilute region to the concentrated region, in this sense, the water moves from the soil into the roots.
5. The root hair cells are epidermal, meaning they are on the outside of the tissue.

2.53 Root water uptake