A.1 Diet

A.1.1. Diet is the total food taken in by an individual.
Nutrition can be defined as the study of the efficiency of food to nourish the body.

A.1.2. Nutrient- A substance needed in the diet of an organism.
Nutrients are the chemical components of food, which has the function of producing energy, promoting growth and repair of tissues, and regulates these processes, once it is absorbed by the body.

A.1.3/4/5 Constituents of a diet:

Carbohydrates- filling, slow-burning energy. It is stored in humans as glycogen in the liver and muscles. In plants, carbohydrates are synthesised during photosynthesis.
Found in bread/potatoes/cereals/pasta

Lipids (fats)- contain essential fatty acids which are necessary for the formation of cell membranes. Also provide energy. Lipids also influence the contraction of involuntary muscles  (e.g. intestine and blood pressure).
Found in butter/cooking oil/cream/chocolate

Proteins- needed for growth in tissues, and for tissues in repair or replacement. They are also necessary as a source of amino acids. Some amino acids are essential because they can’t be made by the body. A constant supply of amino acids is needed for the production of enzymes and proteins in the cell membrane.
Found in meat/eggs/fish

Water- takes part in body building when protein is laid down in body tissues. It also acts as a catalyst in some body reactions, and works as  a lubricant .
Found in everything wet.

Minerals- these are inorganic nutrients which participate in a wide variety of body functions.
Iron- making haemoglobin (found in liver/red meat)
Calcium- making teeth and bones (found in milk/cheese)
Sodium- proper function of nerves (found in salt)
Fluoride- hardening of tooth enamel. (found in milk)
 

Vitamins- are only required in trace amounts. They are essential for good health. They prevent deficiency diseases.
Found in vegetables/fruit/cereal

Fibre- It affects the balance of other nutrients present.  It protects against ‘diseases of affluence’; it basically regulates the amount of stuff you have in your body. It helps you do number 2s better too, as well as lowering cholesterol levels and blood-glucose levels.
Found in vegetables/fruit/cereals.

A.1.6 A balanced diet is an equilibrium between food intake and energy expenditure. It meets bodily needs for growth, replacement and heart functioning.

A.1.7 / 8 Self- explanatory stuff.

A.2 The Biochemistry of Nutrition

A.2.1
Monosaccarides: (glucose, dextrose) : grapes, honey, onions

Disaccharides: (maltose, lactose, sucrose) : milk, sugar cane, most fruits

Polysaccarides: (cellulose, starch) : most vegetables, potatoes, cereal grains.

A.2.2. Carbohydrates are broken down into simple sugars. Glucose is then oxidised to provide a continual source of energy which can be used for synthesising ATP (energy) for cell respiration.
The end products of digestion of carbohydrates, fats and proteins can all be used as energy sources. Energy release from these components occurs by a series of enzyme-controlled reactions. Energy is released when glucose forms the products carbon dioxide and water through catabolism (the breakdown of larger molecules).
The digested carbohydrates are diffused out of the small intestine into the hepatic portal vein and are transported to the liver.
Carbohydrates are the preferred substrate for cell respiration, and the brain cells of mammals can only use glucose. Fats from the ‘first reserve’ are mainly used when the carbohydrate reserves have been exhausted.
Excess carbohydrates are converted and stored as fats and glycogen.

A.2.3 Sources of lipids: margarine, pork, peanuts, olive oil

A.2.4 Fats are used as a source of energy when carbohydrates are in short supply or when the demand for energy is particularly high for cell respiration.
The products of fat digestion are transported to the surfaces of the intestinal epithelial cells into which they are absorbed through diffusion. These absorbed fats bypass the liver and travel to the thoracic lymphatic duct from where they enter the venous bloodstream.
Fats are also stored in tissue around the heart, the kidneys and in the mesenteries (fat which attaches the stomach and intestine to the peritoneal wall). The liver removes lipids from the blood and either oxidises them with the transfer of energy, or modifies them chemically before they are sent to the body’s fat depot for storage.
Fats may be oxidised in the body to give energy, carbon dioxide and water.
Fats are also used in the growth of membranes.

A.2.5  See Table 14.2, Page 244 Yellow Book.

A.2.6. Sources of Protein: meant, fish, eggs, cheese.

A.2.7 The liver’s main contribution to protein metabolism is to synthesise the non-essential amino acids by transamination. It also gets rid of excess proteins. This is because the body is unable to store proteins or amino acids, and any surplus is destroyed in the liver. The amino acids are first deaminated by the liver cells: the amino group is removed from the amino acid molecule with the formation of ammonia. The rest of the amino acid is then fed into carbohydrate metabolism and respired.

A.2.8 Essential amino acids are those which must be ingested and cannot be synthesised.

A.2.9
Calcium- Involved in selective permeability of plasma membranes and intracellular communication; activates certain enzymes; constituent of bones, teeth and plant cell walls.
Iron- Constituent of haemoglobin and myoglobin; involved in electron transfer, activates certain enzymes including catalase.
Iodine- Constituent of thyroxine.
Potassium- Helps determine anion-cation balance in cells. Activates many enzymes; involved in stomatal openings.

A.2.10
Retinol (Vitamin A) – enters into photochemical reaction in rods in retina of eye.
Cyancobalamin (Vitamin B12)- plays a vital role in the activities of several enzymes. Important in the production of the genetic material of cells and in the production of red blood cells in the bone marrow.
Ascorbic acid (Vitamin C)- Required for formation of intracellular material.
Calciferol (Vitamin D)- Absorption and utilisation of Ca2+ for bone formation.
Tocopherol (Vitamin E)-   Not known.
 

A.2.11 High fibre diets are known to prevent diverticulitis of the colon, and are thought to reduce the incidence of bowel cancer and colitis.

A.3 Diet and Health

A.3.1 People in the Western World have too much fat in their diet. Body fat acts as a store of energy, protects internal organs from injury and insulates the body. However, there are problems.

BMI (Body mass index) =    weight (kg)/height (m)2

The best range for health lies between 20 and 25.

People who are overweight have an increased risk of:
Gall bladder disease, high blood pressure, diabetes, some cancers.

Coronary heart disease (CHD):
Common in Western World. It arises from the failure of the coronary arteries to supply sufficient blood to the heart tissue. It is usually caused by:
- atherosclerosis  of the coronary arteries
- angina: a pain in the chest caused by exercise.

Excess amounts of fat in a diet cause the coronary arteries to become clogged up with fat which lessens the amount of blood which reaches the heart. To prevent cardiovascular disease, fibre and starch should be eaten while fat and saturated fats should be reduced.

Risk factors with CHD:
- Genetic History
- Lack of exercise
- Stress
- High blood pressure
- Diabetes
- Obesity
A.3.2 There are many kinds of fat. Each contains particular fatty acids. Now some fatty acids are saturated, whereas others are unsaturated (an unsaturated fatty acid is one which contains less than the maximum amount of hydrogen possible). Fatty acids which are very unsaturated are called polyunsaturates.
In general animal fats contain a high proportion of saturated fatty acids, whereas plant oils contain a high proportion of polyunsaturated fatty acids. For good health we should eat mainly polyunsaturates. The reason is that polyunsaturates reduce the amount of another substance in the body: cholesterol.

A.3.3 Cholesterol interacts with the hydrocarbon chains of the phospholipid molecules just behind the polar heads. This enhances the mechanical stability and flexibility of the membrane.
Cholesterol is found in the membranes of animals cells where it helps to keep the membranes fluid. Other important steroids are derived from cholesterol. They include the sex hormones progesterone and testosterone, and the hormone aldosterone secreted by the adrenal cortex. Bile salts, such as glycocholate and taurocholate, are polar metabolic products of cholesterol needed for the normal digestion of lipids.

A.3.4 The amount of cholesterol in the blood is largely determined by dietary intake in conjunction with the activities of the liver. If there is a considerable excess in the blood, some of it may be deposited in the walls of certain arteries, obstructing the smooth passage and often  leading eventually to an intravascular clot. If this occurs in one of the coronary arteries serving the heart, a coronary thrombosis (heart attack) may result.

A.3.5/6 Vegetarians’ diet includes animal products such as milk and eggs, but not the animals themselves. Vegans only eat food of vegetable origin.
A vegetarian diet that includes dairy products can provide everything needed for a healthy life. Plants can provide lots of fibre, vitamins and polyunsaturated fat, so a vegetarian diet is good in that respect.
Vegans have to make sure that their food gives them all the substances they need. In general their diet needs to be bulky and varied. This will ensure that they get enough carbohydrate and protein, together with the full range of vitamins and essential amino acids. Vegans have problems with vitamins D and B12 , neither of which are present in plant products. There should be no problem if vegans ensure that they have adequate exposure to sunlight and most vegans take vitamin B12 supplements. Iron and calcium are also important (must be taken in supplement form). Often vegetarian diets are high in fibre which tends to bind minerals and render them unavailable.
There are also lacto-vegetarians, pesco-vegetarians (fish) and ovolacto-vegetarians (egg and milk products).

A.3.7 Calcium-  If a child does not get enough calcium, its bones remain soft and become deformed (rickets). Calcium is also needed for making muscles contract, and it helps blood to clot when you cut yourself.
Iron- Iron is needed for blood. Shortage of iron results in the blood containing too little haemoglobin (this is a type of anaemia). The oxygen-carrying ability of the blood is reduced, resulting in tiredness and lack of energy.
Calciferol- deficiency may occur in people with poor diet, premature infants, in those deprived of sunlight  and in dark-skinned people, particularly in foggy urban areas. Deficiency develops rickets.
Cyancobalamin- deficiency is usually due to an inability to the intestine to absorb the vitamin, most commonly due to pernicious anaemia.

A.3.8 Malnutrition-  The result of feeding on a diet that is not balanced.

A.3.9 Self-explanatory

A.3.10 Find this online

A.3.11 Vitamin Deficiency-  Deficiency in fat soluble vitamins is due to a disorder in which intestinal absorption of fats is impaired or to a poor/restricted diet. Deficiencies in water-soluble vitamins is more common due to prolonged cooking, storage, processing.

A.3.12 Chemical additives can act as preservatives, antioxidants, colouring, flavouring, stabilisers and acid-regulators.

A.3.13  Some additives may have deleterious effects. Some individuals seem to be sensitive to certain colourings, flavourings or preservatives. For example:
Tartazine (E102)- a commonly used yellow colouring in fizzy drinks, convenience foods and medicines. It can be the cause of skin rashes, hay fever, blurred vision, purple patches on the skin, and may possibly be linked with hyperactivity in children, or with asthma.
Sunset Yellow (E110)- A yellow colour widely used in convenience foods. It may produce skin rashes.

A.3.14 Self-explanatory
 
 

Option D Evolution

D.1 Origin of life on Earth

D.1.1. The Earth was formed approximately 4.6 billion years ago from a cloud of dust particles orbiting the sun. This compacted due to gravity and together with the decay of radioactive elements generated heat that caused the interior to melt and form a central dense core of iron and nickel. Lighter materials formed the mantle around the core and the lightest silicates solidified into an outer crust, the continents and the outer floors.
The atmosphere was formed from gases escaping through volcanoes and consisted of H₂ ,  H₂O, CH₄, NH₃, N₂, H₂S, but no O₂. This mixture of gases was strongly reducing because it contained a lot of compounds that could donate hydrogen (and electrons). The oceans formed by the condensation of water vapour.

D.1.2 Over 4 billion years ago, simple organic compounds including monomers of biological macromolecules formed in shallow warm seas forming a mixture called the ‘primordial soup’. These compounds may have been the result of reactions between the various gases of the primitive atmosphere and natural energy sources such as lightening, UV and other radiation.
Muller conducted an experiment using voltage discharge. After a week, there were amino acids and small organic acids. Methane and ammonia are the only way to make organic acids. However, Muller used sterile glass, distilled water and enclosed gas. Who says the Earth was like that back then?

D.1.3 The complexity of organic molecules increased in the primordial soup as a result of polymerisation. Clay particles could have acted as catalysts by absorbing monomers and facilitating polymerisation. Polypeptides, polysaccarides and polynucleotides could have formed like this.
Once formed, the first polynucleotide RNA, was capable of self-replication. It is now suggested that this so-called RNA World then invented protein synthesis. By adhering to clay particles RNA could provide a pattern for protein synthesis. Thus RNA was the first enzyme or ribozyme. Clefts in RNA helix each formed from three bases match the shapes of various amino acids and could catalyse peptide bond formation. The triplets may survive today as the genetic code.

D.1.4 RNA (ribonucleic acid) being simpler than DNA is the most likely candidate for the first replicating molecule and also template and catalyst for protein synthesis. Soon some of the proteins synthesised in this way could have had catalytic properties, the first enzymes. These primitive RNA molecules could have also have been forerunners of ribosomes as it is thought that peptide bond formation is catalysed by ribosomal RNA. At some later stage DNA replaced RNA as the carrier of the genetic code since its double-stranded structure is more stable.
D.1.5 A parallel development was the formation of coacervate droplets, aggregations of hydrocarbon molecules organised into sheets and forerunners of today’s phospholipid membranes. The first cells may have been such hollow droplets that contained RNA, which could synthesise structural proteins and enzymes. These droplets can grow by incorporating more molecules from the primordial soup and spontaneously split (binary fission) when they get too big. One of the commonest metabolic pathways is glycolysis and ATP synthesis.. The result of these developments was heterotrophic anaerobic prokaryotes that absorbed substrates from primordial soup through their membranes and were forerunners of the first methanogenic bacteria.
A later development was photosynthesis when the more primitive chlorophyll a molecules held in the membranes could trap light and synthesise ATP. Thus the first autotrophic bacteria came into existence whose presence assured the survival of heterotrophs which were then able to use an inexhaustible biomass supply.

D.1.6 See endosymbiotic theory (you’ve already done it in Topic One). These are the 4 eukaryotic kingdoms:
Animal Kingdom- Multicellular eukaryotes which feed heterotrophically by ingestion
Plant Kingdom- Multicellular eukaryotes which feed heterotrophically by ingestion.
Fungus Kingdom- Multicellular eukaryotes which feed heterotrophically by absorption
Protist Kingdom- Unicellular eukaryotes which feed by a variety of different methods.
 

D.2 The origin of species

D.2.1 Evolution- The process of slow change by which organisms alive today are descended from ancestral forms.

Lamarck’s Theory of Evolution – In 1809, Lamarck proposed a mechanism for evolution summarised as ‘evolution by the inheritance of acquired characteristics.’

D.2.2 Lamarck suggested that:
- Organisms used or under-used parts of their body.
- Such parts became well or under-developed.
- These acquired characteristics were inherited.

There is no evidence that evolution could happen like this. There is no known way for body changes to alter the inherited DNA in the gametes of an individual. Lamarck also proposed that some internal force propelled organisms to greater complexity, with humans at the end of this process.
D.2.3 The Darwin-Wallance theory of evolution- the natural selection and inheritance of favourable characteristics. This is the most accepted theory. It came about through a series of observations:
- Species overproduce young
- Population size remains stable
- There is competition for survival
- Individuals vary
- Natural selection favours good variations
D.2.4 In the 1950s the scientist Kettlewell released peppered and white moths onto tree trunks and observed insectivorous birds (robins, thrushes etc) feed on them. On trees, the white ones were most visible- survival of the fittest.

D.2.5 Another theory for the origin of life is Panspermia- the theory that is concerned with the arrival of material from outer space, which has evolved.  Another theory is Special creation- the belief held by many religions in a mythology which explains the origin of the species ready formed (and unchangeable) by a supernatural being/beings.

D.2.6 The scientific method (hypothesis,, experiment, analysis, and reformulation of the hypothesis) is largely inapplicable to both beliefs and evolution. Because we are unsure of past conditions, it is impossible to try and rerun evolution experimentally. We can not be sure that Miller or Kettlewell’s simulations had occurred in the past. Apart from the study of fossils, evidence for evolution is circumstantial; it is based on deductions made from the observation of differences between living organisms.

D.3 Evidence for evolution

D.3.1. Biogeography- geographical distribution of species.
Why the strange distribution? Why don’t areas with similar climates necessarily have similar animals? Why does Australia have many marsupials, but almost no placental mammals (which it can support)? We find species where they are because  they evolved from ancestors that inhabited certain regions. Australia has no placental mammals because they never evolved there and there wasn’t any contact with other places where they had evolved.
It is thought that ancestral mammals originated in Eurasia and migrated to the southern continents via land bridges, which were later cut off by continental drift and sea level changes. Mammals reaching each continent then evolved into many new species to occupy the various niches. This process is called Radiative Adaptation.

D.3.2 Fossil- any preserved remnant or impression left by a past organism.
If an organism happens to die somewhere where it can be preserved (acid bogs, ice, amber), whole specimens including soft tissue can be found.
Mainly fossils are the only mineral rich parts (like bones) of animals which have been buried. Especially aquatic things often settle into water where sand and mud made sandstone and shale (respectively) over them, preserving them. Sometimes mineral rich parts become petrified (made into stone) when more minerals come in to replace organic material.
Sometimes fossils are just rocks which have formed in spaces the shape of animals where organic material has dissolved away and other things (like hard minerals) have taken its place.

D.3.3 Radiocarbon dating can be used to date fossils containing the remains of organic compounds. A small proportion of carbon atoms exists as the heavier 14C isotope. These become incorporated into organisms during life but not after death when 14C atoms slowly decay to the lighter 12C and release radiation in the process. The range of time that this technique can be effectively used is dependant on the half-life.
Pg 778 Yellow Book

D.3.4 Half life- The time during which the radioactivity falls to half its original level.

D.3.5 Find current amount of element. Find normal amount of element (the amount it would have had in its environment). Already know half-life. Find out how many half-lives it took to get to the current levels. Convert into corresponding number of years.

D.3.6 Pg 779-781

D.3.7 All organisms use DNA as their hereditary material and together with RNA carry out protein synthesis in the same way. The 3 base triplet code for each amino acid is also the universally used genetic code. This is strong evidence for a common ancestor for all living things on this planet.
Similarly the use of proteins as structural units and enzymes is common to all living things and specific proteins (e.g. haemoglobin) are found among groups of organisms further suggesting common ancestry. Furthermore, proteins are built from a selection of only twenty specific amino acids out of a potentially infinite variety.

D.3.8 By comparing nucleic acids and specific proteins from different organisms, it is possible to construct phylogenetic (evolutionary) trees. A lot of different changes in one place are usually an indication of a species coming from one common ancestor.

D.3.9 Techniques are now available for comparing the nucleotide differences between DNA taken from different organisms, For example, human and chimpanzee is 1.2% different. These differences are due to mutations; accidental uncorrected changes to DNA. By relating these genetic diseases to dates of fossil remains, a mutation rate is obtained which is the basis of an evolutionary clock.

D.3.10 Closely related organisms go through similar stages in their embryonic development. For example, all vertebrate embryos go through a stage in which they have gill pouches on the sides of their throats. In humans, these structures change into other things.
The same skeletal elements make up the forearms of humans, cats, whales, bats etc, though they have different functions. This doesn’t make any sense unless they share some common ancestor.
Homology- similarity in characteristic resulting from common ancestry.
Pg 770- Yellow Book Fig 42.12

D.3.11
Heavy metal tolerance in plants- One of the most convincing examples of natural selection is provided by the evolution in certain grasses of tolerance to heavy metals, such as copper, zinc and lead, enabling them to flourish on the spoil from mines. Various physiological mechanisms have evolved to allow these plants to grow and reproduce in soils where heavy metals are present at concentrations that kill normal plants. In some species, the toxic metals bind to organic molecules in the cell walls where they remain trapped, unable to harm the cell’s contents. In other species, the metals are stored in the vacuole, out of harm’s way etc etc. Indeed, the plants have become so well adapted to living in such conditions that on unpolluted soil they do not fare so well and are out-competed by normal plants.
Antibiotic resistance in bacteria- bacteria have very short generation times, are haploid and can reproduce sexually in a variety of ways. These features enable bacteria to evolve rapidly in response to changes in their environment. With the widespread use of antibiotics over the last 40 years, many bacteria have evolved cellular mechanisms enabling them to grow in the presence of a great many antibiotics- some have even developed to feed off certain antibiotics.

D.4 Human Evolution

D.4.1
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Sub-class: Placental mammals
Order: Primates
Family: Hominidae
Genus: Homo
Species: Sapiens
Sub-species: Sapiens

D.4.2.
- Long limbd and gripping hands and feet with opposable thumbs and big toes
- Fingers with nails, not claws, and fingertips sensitive to touch
- Large forward facing eyes for stereovision and distance judgment
- Colour vision to identify other primates and identify food
- Larger brains than other mammal groups for motor-coordination and social behaviour.

D.4.3. Anotomical changes- Apes can only stand for short periods of time because their lower backs and legs are not designed to support the weight of the upper body.
Humans are neotenous apes (neoteny is when infant characteristics persist into the adult). Adult humans have chimp features. Baby chimps have large brains, relative to body size, protected by bulbous craniums, small jaws and no brow ridges. The spinal cord enters the skull by a hole under the centre of the skull.
Neotony can be explained in terms of small hormonal changes controlling bone growth and the onset of sexual development. A delayed onset of puberty has lead to an increased period of parental care.
In the lower body, the spine and hip joint have been strengthened to support and transfer weight to the legs. The knee can be locked straight and the feet have become support platforms, with the toes all in a straight line.
Molecular similarities- Differences between human and ape DNA and particular proteins can be used to estimate when we shared a common ancestor. Nucleotide sequence in human and chimp DNA differ by little over 1%.
When species undergo divergent evolution, accidental changes in the nucleotide order (i.e. mutations) occur to the chromosomes. As time progresses, the nucleotide sequence of a particular shared gene becomes increasingly different. When compared to fossil evidence an approximate data, and thus a rate of change can be estimated.
 

D.4.4
Australopithecines- human-like hands and teeth. Walked upright. Brain was 1/3 size. (Lived about 1.5-3.7 million years ago)
A. afarensis- a different species of Australopithecine (2.8 – 3.7 million years ago) and gave rise to
A. africanus- African ape (2 – 3 million years ago)
A. robustus- (1.3 –2.4 million years ago) overlapped with H. habilis for about ½ a million years, but may have not competed directly.
H. Erectus- (300,00 – 1.6 million years ago) was taller and had a bigger brain; almost full size)
H. Sapiens- Us  (130,000 years ago).

D.4.5 Global changes resulting in ecological changes in Africa may have prompted the evolution of new hominid species. Between 7 and 5 million, there was a general cooling and drying of the earth’s climate. In Africa, the tropical rainforests shrank and were largely replaced by savannah. The apes retreated with the forests except for a group that took this ecological opportunity to adapt to open woodland on the grassland fringes. There were the first Australopithecines and rapidly evolved in bipedalism.
Again 3 million years ago another deterioration in global climate may have prompted the evolution of the first Homo species characterised by an increase in brain size. In the past two million years, the Quaternary, the world has experienced more or less regular cycles of glaciation each lasting 100,000 years.

D.4.6 By arranging extinct animals and plants into some kind of geological sequence, it is possible to suggest how one group may have evolved into another.

D.4.7 Bidepalism- may be an adaptation to open woodland and savannah grassland. Energetically, bipedalism is more efficient than knuckle-walking and it may have evolved as a way to cover the large distances between food more quickly. An upright stance is cooler due to faster air movements and only the head is expected to the sun retaining protective hair.
Brain expansion- The primates show a brain size increase from prosimians through monkeys and apes. The primates are intensely social, political animals and extra brain tissue may be learning to be socially adept with other animals of the group. The Australopithecine had brains no larger than their ape ancestors did. The expansion of Savannah about three million years ago, due to another global cooling and drying, may have prompted the evolution of the first Homo line with significantly larger brains suggesting an increase in lifestyle complexity.

D.4.8 The evolution of speech and the development of the reflective mind (consciousness) occurred at some time in the Homo lineage.

D.4.9 Cultural evolution is the passing down of knowledge and ideas between generations,
Examples: art /agriculture/ language / technology
It has been argued to be more important than genetic evolution. There may be an inherited capacity to acquire culture knowledge. Education increases survival chances.
Cultural evolution is rapid, human lifestyles therefore change rapidly, and some traditions have been lost.
Cultural evolution was not as important in early evolution.
Different cultural evolutions:
Tool making revolution- 20, 000 years ago. Associated with the use of tools which allowed improvements in hunting and food-gathering techniques.
Agricultural revolution- 10,000 – 6, 000 years ago, Improvements in farming and widespread domestication of animals and plants.
Scientific- industrial revolution- 300 years ago. Improvements in food production, industry and medicine.

D.4.10 Genetic evolution is a change in traits that are heritable through DNA. It happens relatively slowly (over generations)
Cultural evolution is the accumulation of learned things.

D.4.11. Bullshit alert
 
 

Option G- Ecology and Conservation

G.1.1. Factors which affect plant species distribution:
Temperature- few organisms can grow in temperatures outside the range of       0 – 40 C (enzyme activity is stopped)
Water- necessary for life. Usually, areas with higher rainfall levels have more growth.
Light- vital for photosynthesis.
Soil pH- certain plants favour acidic soils, others alkaline (bog stuff)
Salinity- excessive salinity is not favoured by plants
Mineral nutrients- without many minerals, especially in areas where minerals are leached downslope, plant distribution decreases.

G.1.2. Factors which affect animal species distribution:
Temperature- few organisms can grow in temperatures outside the range of        0 – 40 C. Most animals have physiological / behavioural adaptations to avoid extremes of temperature.
Water- vital for life. Animals who live in dry areas usually have specialised mechanisms for water loss.
Territory- can allow exclusive access to food. Also allow one sex (usually male) to defend an area to which the opposite sex is attracted for mating.
Breeding sites
Food Supply- more distribution where much food is found.

G.1.3 –
 
 
 
 
 
 

 
= mean
= standard deviation
     = number of entries in a set of data
     = variance
     =the positive difference between the 2 means
 
The t-test is used to compare 2 sets of data and measure the amount of overlap.
Factors of concern:
- Nearness of the mean values of the 2 sets
- Size of the variance (how tightly clustered the data is)

Large t-values = little overlap and therefore a difference between the 2 sets of data.
Small t-values = Much overlap and probably no difference
A probability of 0.05 = significant and a critical value read off from a table.

This test should be used on normally distributed data, ideally with large samples. The value of ‘t’ should be compared with the critical value at  infinity degrees of freedom. For sample sizes lower than 30, the t-value is only approximate and the degrees of freedom is n1 + n2 – 2. If t is equal to or larger than he critical value, then it is possible to reject the null hypothesis.

G.1.4/5 The competitive exclusion principle states that 2 species can not coexist unless there are significant differences in their ecologies; i.e. ‘Each species has its own unique niche’. The niche of an organism is its role in the community, the habitat of an organism is where it lives. The feeding niche focuses on what the animal eats etc.
Fundamental niche- the niche a species would occupy in the absence of any competitors, predators or parasites.
Realised niche- the niche a species actually occupies.

G.2. The ecology of communities

G.2.1
Competition- where species are both predators of the same food
e.g. tigers/hyenas and owls/weasels

Herbivory- feeding solely on plants
e.g. slugs/snails and cows/sheep

Predation- animals which kill their prey before eating it
e.g. lions/tigers and wolves/foxes

Parasitism- where one organism (the parasite) lives in or on another (the host)
e.g. hedgehogs/ticks and dogs/fleas

Mutualism- where two members of different species benefit and neither suffers
e.g. rumen bacteria/ protozoa and chlorella/ chlorohydra

G.2.2. Gross production– the amount of organic matter produced by photosynthesis in plants.

G.2.3  Net production – The part of gross production that is not used in plant respiration

G.2.4 Gross production – respiration = Net production

G.2.5 The highest photosynthetic efficiencies are found in tropical rainforests. Water, CO2, light and good temperatures are all present.
Temperate forests- cold winters/warm summers/intermittent rain. Quite good photosynthesis due to presence of water (though not always) and other factors present.
Deserts- Too hot and not enough water.
Polar ecosystems- Too cold
 
G.2.6 There are species that cross over the producer / consumer / decomposer levels (e.g. sundews which are both producers and consumers). The trophic level of an organism will depend on the food chain and organism.

G.2.7  Self explanatory- there are less of them because they eat such large quantities.

G.3. The ecology of ecosystems

G.3.1 See Page 75, Green Book.

G.3.2
- Oxygen is converted from gas to water by respiration.
- Water is hydrolysed in photosynthesis to produce gaseous oxygen.
- Nitrites are converted to nitrates by some bacteria using oxygen.
- Ammonia is converted to nitrites using gaseous oxygen by some bacteria.
- Nitrates are reduced back to nitrogen and the oxygen is converted to water. These conversions are carried out by enzymes.
- Light energy is used to hydrolyse water in photosynthesis.

How oxygen contributes to ozone layer hole:
The chemicals found to be damaging the ozone layer are CFCs. In the atmosphere, these break down, releasing atoms of chlorine. The chlorine atoms then react with ozone as follows:

Cl + O₃  -> ClO + O₂

The ClO formed then reacts with an oxygen atom thus:

The ClO + O -> Cl + O₂

As a result of these two reactions, a molecule of ozone is destroyed without any chlorine being used up. Chlorine atoms can therefore be said to catalyse the destruction of ozone.

G.3.3 The progressive colonisation of a previously unoccupied area is called a primary succession. At the end of a succession, a climax  community establishes itself.
Soil development- Young soils area stabilised when they become colonised by plants and animals. Eventually, dead organic matter builds up and a mature soil is formed.
Accumulation of minerals- The nature of the dissolved minerals in soil water depends on a number of factors, including the organisms growing in and above the soil. This is because the dead organic matter (including dead organisms) are decomposed into humus by fungi and bacteria. This leads to an accumulation of minerals.
Reduced erosion- Caused by increasing vegetation protecting soils.
River flows and increased rainfall are also affected by organisms (how??)

G.4. Biodiversity and conservation

G.4.1 The current estimate of the number of species of organisms living in the world is 1,659,700. It was 1.7 million at one point, but various estimates place the number between 5 – 30 million. It is impossible to know the exact number of organisms in the world because some become extinct before they are find, and, more recently, because human activity is killing an increasing number of organisms. Also, the species is the basic taxonomic unit, but the gene pool which unites the members of species is often large and may be continually changing. Consequently within a species there exists a considerable variety of forms. These may be sufficiently different to warrant the status of subspecies or race.

G.4.2 The Dodo became extinct because, in adapting to life on the island of Mauritius, where there were no ground-living predators, it lost the ability to fly. As a result it was helpless when hunted by humans and the predators that humans brought with them (e.g. rats and cats)
The Everglades Kite became extinct because it had very specialised habit. It is adapted to feed exclusively on a particular species of snail, and it is endangered because its prey species has declined.
The Wine Palm plant, originally from the Dominican Republic, became extinct in 1926. I have no idea why.

G.4.3  The biosphere can be sub-divided into large areas which, though separately spatially, are linked by a common type of vegetation. These are known as biomes.
The 2 most important environmental variables for life in land are rainfall and temperature.

Biodiversity- diversity of plants and animal life.

Tropical Rainforest- Found in South-East Asia, Western Central Africa, the Amazon Basin, Indonesia and parts of Australia. It is hot and wet throughout the year.  Men monthly temperatures usually lie between 24 and 28 C, and frosts are unknown. The annual rainfall is between about 2000 and 3000 mm and rain falls throughout the year; there is no dry season.
The vegetation: There are occasional very large trees, typically 35-45 m tall. Beneath these emergents is the second layer of large trees, which, together with the emergents, make up a continuous canopy. A third tree layer is made up of smaller trees which complete their life cycle without ever reaching the main canopy. Still nearer to the ground are young trees, palms, vines and herbs. By the time sunlight reaches the forest floor, most of it has already been intercepted so that it is dark with relatively sparse vegetation.
Epiphytic orchids grow on the branches of the trees. Insects and birds live here without ever descending to the ground- they feed on the copious flowers and fruits available throughout the year. A single hectare of tropical rain forest may contain over 100 different tree species.  Tropical rainforest s contain more species than any of the world’s other biomes. However, their soils are generally nutrient poor. Sloths also found here, and have adapted to life by using very little energy and having very slow metabolisms.

Temperate forest- Located between the Tropic of Cancer and the Arctic Circle, and between the Tropic of Capricorn and the Antarctic Circle. This type of forest is dominated by broad-leaved trees that lose their leaves in winter. The biome experiences of cold winters, warm summers and intermittent rain throughout the year with a peak in summer.
Main trees- Oak, hazel, birch and beech.
Few examples of undisturbed temperate forest are to be found.

Tundra- Tundra occurs at low altitudes and is characterised by the absence of trees and permanently frozen subsoil. True tundra is found in Northern Canada, Northern Asia, and parts of Northern Europe. Here it is impossible for trees to grow because the growing season is too short and the soil is too unstable. For much of the year, the soil is frozen. Only in summer does the surface thaw. Beneath the surface is soil with water that never melts (permaforst).
For much of the year, the tundra is virtually lifeless. Then, during the brief growing season, which may only last 6 weeks, many plants produce spectacular flowers which attract insects for pollination.
The most abundant large herbivores of this biome are reindeer, who graze on lichens. Lemmings are also common.

Desert- Found throughout the world. Examples include Sahara of Northern Africa, The Kalahari of Southern Africa, The Gobi of Central Asia and the Atacama of Peru and Chile.
To survive in a desert, organisms have to be able to take advantage of the sudden rains. Many of the smaller desert plants survive as seeds. When it rains heavily, they germinate, mature, flower and produce seeds within as little as 2 weeks. Other plants are perennials, surviving the dry periods in the vegetative state. Some desert perennials survive the long periods of drought as underground bulbs or corns. They produce their leaves only when it rains.
Animals have physiological adaptations- certain frogs can survive for years without water by burying themselves deep into the sand. When the rains eventually come, they dig themselves out, mate and lay their eggs in shallow puddles. Here the tadpoles grow very quickly, metamorphosing into adults before the puddles disappear.

G.4.4 The Simpson Yale Species Diversity Index is a measure of species  richness. A high value of D suggests a stable and ancient site and low D values could suggest pollution, recent colonisation or agricultural management. It is normally used in studies of vegetation but can also be applied to comparisons of animal (or even of all species) diversity.

Simpson Yale Species Diversity Index

D =    N (N – 1) / sum_of(n (n – 1))

Where D = Species Diversity
n  = number of individuals in one species
N = total number of individuals in all species

G.4.5 I don’t know. Use your common sense.

G.4.6 Ethical reasons- Organisms have an intrinsic value that is greater than the one we have given; they have an unquestionable right to existence.

Aesthetic reasons- we are able to derive great enjoyment from the natural environment (manifested by countless zoos, botanical gardens etc). Wildlife if also a popular subject for film makers. Natural history programmes are now a regular feature in the TV schedules.

Economic reasons-
- Plants which carry out photosynthesis are essential for agriculture.
- When some plants are susceptible to a disease or pest, other similar plants can be found that are resistant.
- Selective breeding of the best plants (e.g. those which have conquered problems  of low light levels, high salinity, low nutrient levels, extremes of temperature) can bring about a plant super-race.
- Similarly, stock animals which are reared in high density are vulnerable to disease and pestilence. They too may be made resistant by incorporating genes from wild relatives.
- Some plants have medicinal benefits to humans. ELDCs are more reliant upon these types of drugs.
- Animals serve for a better understanding of human bodies (that’s why rats and stuff are used in scientific experiments).
- Plants are needed to make many material goods, especially wood for people in ELDCs.

Ecological reasons-
- The presence of plant and animal communities serve humans indirectly. They maintain the integrity of the environment by regulating ecological cycles such as water, carbon, nitrogen. Undisturbed these cycles remain relatively stable.
- Vegetation also prevents soil erosion.
- Individual organisms, particularly in the upper trophic levels, act as pollution monitors- e.g. lichens are found to be sensitive to air pollution.

Relate all of the above to the Rainforest. Also:

- Rainforest has a very important role in terms of oxygen output.
- Tribes lose their habitat.
- Non-sustainable environment. Once its gone, its gone forever.
 

G.4.7 In situ- ‘in its original place’

Plants are ideally conserved in situ, because in this way large numbers of individuals can be preserved with minimal management. Species are also able to continue evolving alongside their pollinators, symbionts and consumers.
G.4.8 Control of alien species- “National trust”- as part of the conservation programme, alien species such as Sweet Chestnut trees are being destroyed, and restoring woodland to what would be British woodland.

Restoration of degraded areas- Some areas can become degraded due to overuse by the public- damage to vegetation by trampling, soil loss and erosion, and pollution from litter, waste and vehicle emissions etc. Unfortunately, it is often the habitats most sensitive to trampling (including dunes, heathlands, uplands and mountainous areas) which are under greatest pressure. There are 5 main ideas to keep in mind according to Goldsmith:
1) Use local indigenous material, especially if the area is of ecological importance;
2) Use small-scale machinery to minimise any further damage during restoration;
3) Ensure that non-natural features bland with the natural features
4) Invest in good environmental interpretation and information for the visitors;
5) Work with rather than against people using the area.

Promotion of recovery of threatened species-  Pandas, whales and red squirrels are examples of species which are being conserved due to threat of extinction. Recovering species need to have protected environments and breeding areas. There are some designated areas of Special Scientific Interest (SSI), and access to these areas is limited. Some zoos have special breeding recovery programmes.

Control of exploitation by humans-
I don’t know. Common sense.

G.4.9 Captive breeding- The aim of captive breeding is to preserve the genetic stocks of threatened species so that they can be re-introduced into the wild when conditions permit. Zoos, though, tend to have only a few individuals of each species and, unless there is close co-operation with other zoos, lines would soon become inbred and seriously weakened as a result. However, methods such as artificial insemination have made captive breeding successful. This has led to overproduction, but stopping reproduction may destabilise a family group.

Botanic gardens- Botanic gardens were originally set up to cultivate medicinal species and later to house and display new plants which had been collected from abroad. In the past, botanic gardens operated completely independently and their collections were acquired for their attractiveness of economic value. As a result, some species have been widely collected while other are under-represented. There are also few, unevenly distributed botanic gardens in the world. In response to these problems, a number of initiatives have been taken, for example, the FAO have started a programme of genetic resource conservation.

Seed banks- These represent a convenient and space-saving method of conserving germplasm. Some seeds can remain dormant for long periods if maintained at low humidity and low temperature (these seeds are known as orthodox). A number of problems are yet to be solved, however. There is no non-destructive way of telling whether a seed is viable. It is therefore necessary to carry out regular germination tests; a time-consuming and costly exercise. Also, some seeds are recalcitrant (they are damaged by drying and can only be stored for a few weeks or months). Seed banks are also unsuitable for species which do not breed true, such as apples, species which depend on fungal symbionts, such as orchids, and species which normally reproduce vegetatively, such as potatoes.

G.4.10 Data collection- A detailed management plan can’t be prepared without information on the area and obviously sources of information need to be considered. The obvious and easily recorded taxonomic groups form the basis for any biological inventory

The rest I found nothing on. Common sense.

G.4.11 Ditto.

G.4.12   IUCN - The World Conservation Union was founded in 1948.
Its mission is to influence, encourage and assist societies throughout the world to conserve the integrity and diversity of nature and to ensure that any use of natural resources is equitable and ecologically sustainable.

CITES- The international wildlife trade, , has caused massive declines in the numbers of many species of animals and plants. The scale of over-exploitation for trade aroused such concern for the survival of species that an international treaty was drawn up in 1973 to protect wildlife against such over-exploitation and to prevent international trade from threatening species with extinction.
Known as CITES, the Convention on International Trade in Endangered Species of Wild Fauna and Flora, entered into force in 1975 and now has a membership of 152 countries. These countries act by banning commercial international trade in an agreed list of endangered species and by regulating and monitoring trade in others that might become endangered.
 
WWF- WWF's goal is to stop, and eventually reverse, the worsening degradation of the planet's natural environment, and build a future in which humans live in harmony with nature. WWF is working to achieve this goal through:
· preserving genetic, species, and ecosystem diversity
· ensuring that the use of natural resources is sustainable both now and in the longer term, for the benefit of all life on Earth
· promoting action to reduce pollution and wasteful consumption to a minimum.

Forty years ago, WWF's work consisted mainly of protecting animals and plants threatened with extinction. Not just because they are beautiful and rare, but because they are part of a complex chain in which the disappearance of even a single species can have far-reaching consequences. Since then, the scope of the work has broadened. Today, the organisation also tackles the many forms of pollution that are harming the soil, atmosphere, freshwater and oceans, which ultimately sustain life. It also looks for new and sustainable ways of using the planet's natural resources.

Rio Convention on Biodiversity- At the 1992 Earth Summit in Rio de Janeiro, world leaders agreed on a comprehensive strategy for "sustainable development" -- meeting our needs while ensuring that we leave a healthy and viable world for future generations. One of the key agreements adopted at Rio was the Convention on Biological Diversity. This pact among the vast majority of the world's governments sets out commitments for maintaining the world's ecological underpinnings as we go about the business of economic development. The Convention establishes three main goals: the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits from the use of genetic resources.

Red Data Books- Red Data Books give information on the threatened plant and animal species of the world and are produced with the voluntary help of many hundreds of scientists and lay people. That information is essential for the design of conservation programmes

The Human Genome Project

Advantages-
- The new information could allow us to find cures for previously incurable diseases; cancer, down’s syndrome etc.
- Development in the organ transplant field; improvements in helping the receptor’s body accept a new organ. Also, doctors may one day be able to originate laboratory- produced new organs out of simply collecting the receptor’s DNA code.
- New drugs manufactured; enhancing current treatment of diseases aesthetic uses: promote or inhibit hair growth / slimming.

Disadvantages-
- Designer babies
- Cloning
- Biological weapons which only affect a certain race / skin colour.
- Ethical (Playing God / who would we grow the organs from?)