DIGESTION IN THE DUODENUM (first part of the small intestine, receives juices from 2 different places):
The Liver: -All digested food passes from the intestine to the liver in the Hepatic Portal Vein.
-stores glucose as glycogen, also stores minerals Iron, Copper and Potassium as well as vitamins A, B and D.
-breaks down excess Amino Acids to the Urea which are then excreted.
-Detoxifies some poisons (alcohol)
-Makes bile (greenish alkaline liquid, not an enzyme) fore digestion. Bile neutralises the acid mixture from the stomach, emulsifies fats, stops pepsin working.
-Stores the bile in the gall bladder.
-Releases the bile through the bile duct into the duodenum.
-Makes Fibrinogen which is used in clotting the blood
-Produces heat to maintain body temperature
The Pancreas: Juices from this gland pass down the pancreatic duct. The juices contain amylase, protease and lipase in an alkaline solution.
DIGESTION IN THE SMALL INTESTINE:
Glands in the intestine walls produce enzymes in an alkaline solution:
Carbohydrase completes digestion to Glucose
Protease completes digestion to amino acids
Lipase completes digestion to fatty acids and glycerol.
WHY IS THE INTESTINE A GOOD ORGAN FOR FOOD ABSORPTION?
- It has a large surface area: It is five meters long and food is in contact with the surface for a long time. It has tiny projections called villi that increase surface area.
- It has a thin lining so that food molecules can pass through easily.
- It has a plentiful blood supply to carry away the products of digestion.
ABSORPTION OF WATER:
-Water is absorbed in the colon, part of the large intestine.
-Most of the water in the intestine needs to be reabsorbed so that we do not become dehydrated.
BLOOD:
-Consists of blood cells, chemicals of various sorts, plasma and platelets.
-Its volume is approximately 5.5 litres of which 50% is plasma.
-The pulse beat is a reflection of the heart beat and can be used to measure it.
-The blood transports food substances, gases, various chemicals and waste materials. It also distributes heat throughout the body and protects our body from infection.
WHITE BLOOD CELLS:
RED BLOOD CELLS:
PLATELETS:
PLASMA:
ENTRY OF INFECTION TO THE BODY:
-NOSE: airborne
-MOUTH: contaminated food and drink, fingers, mouth to mouth contact.
-SKIN: bites, cuts (eg: tetanus), direct contact.
-REPRODUCTIVE ORGANS: Sexually transmissible diseases.
Pathogens: (pathogens infect body, build up numbers, release poisons, symptoms appear.) =Incubation period.
Isolation period = time when infected person should be kept away from others.
Quarantine period = time when contacts of infected person should be kept away from others.
DISEASE:
A healthy person is one whose mental, physical and chemical processes are working in balance. Many things can upset this can cause disease.
Diseases can be transmissible (caused by Pathogenic micro-organisms such as viruses eg the common cold, bacteria eg tuberculosis, fungi eg athletes foot, protocoa eg malaria.) and non-transmissible (metabolic disorders eg diabetes, nutritional deficiency diseases eg rickets, degenerative diseases eg arthritis, cancer, mental illness eg schizophrenia, genetic eg haemophilia.)
Endemic disease: always present in an area eg malaria in some parts of Africa.
Epidemic disease: sudden outbreak spreads through a population.
Pandemic disease: spreads through several countries.
Notifiable disease: must be reported to the Local Health Authority eg Typhoid.
Chemicals in the medicine cupboard: -DRUG: a chemical which changes the way our bodies work.
-MEDICINE: mixture of ingredients, one or more of which may be a drug. Taken to prevent, cure or diminish the symptoms of an illness. Most medicines contain drugs but not all drugs are medicines.
-DISINFECTANT: germ killer
-ANTISEPTIC: germ killer mild enough to be used on the skin.
-ANALGESICS: pain relievers, many dangers involved: no aspirin for under 12’s as can implicate development of Reye’s syndrome and can have fatal effects on the liver and brain. Aspirin can also cause stomach can also cause stomach irritation and internal bleeding. Even small overdoses of paracetamol can cause liver failure. If an antidote is not given rapidly the failure becomes irreversible and can cause death.
ADAPTATION AND COMPETITION:
Habitat: place where an organism lives.
Population: number of organisms of the same type that live in a habitat.
Community: groups of organisms sharing a habitat.
Environment: all the things around an organism that can affect it’s way of life.
Ecology: the study of the inter dependant organisms and the non organic world.
SEASONAL FACTORS AFFECTING ANIMAL POPULATION: -Hibernation, Migration, Breeding cycle, young and adult occupying different habitats and changing abruptly eg: water living larvae becoming air living adults.
SEASONAL FACTORS AFFECTING PLAN POPULATION: -Annual plants only present in their growing season, herbaceous perennials only visible in their growing season.
ADAPTATIONS FOR SURVIVAL:
Organisms adapt to the place where they live, their way of life and the climate. They will be adapted in size, shape and other features.
Adaptations of animals to desert and arctic:
OTHER ANIMALS: -Cold blooded animals need warm temperatures to be active because their body temperature is the same as their surroundings.
ADAPTATIONS OF PLANTS TO DRY CONDITIONS:
-Thick cutide to reduce water loss.
-Swollen stem, stalk or leaves to store water.
-Leaves reduced in size to reduce water loss.
-Leaves arranged in rosettes to shade each other.
-Stem ridged to cast shade.
-Spines to prevent animals eating swollen stem in order to obtain water.
-Stomata only open at night in order to reduce water loss.
-Shallow spreading roots to collect maximum moisture or deep to reach deep water.
HUMANS AND THE ENVIRONMENT:
Pollution from fossil fuels (fuels which are produced by heat and pressure acting on living material, the material lived millions of years ago and became buried over time. Eg: Oil, coal and natural gas…) domestic use, power stations, cars and other transport, industry etc…
Problems include…
Coal mining:
-Open cast mining leaves scars on the countryside and reduces land availability for farming. It may be expensive to restore the area to other use when the coal is exhausted.
-Waste form deep mine is dumped on the surface creating ugly tips which may be unstable and dangerous.
-Land above deep mines is liable to subsidence.
Oil production:
-Pollution from leaks or shipping accidents damages wildlife, the environment and human beings.
-There is risk of fires, and therefore air pollution, at production storage and processing areas.
General problems:
-Water used for cooling at power stations is released into rivers. It is clean but it is hot. It raises the temperature of the river and the wildlife is damaged.
-There is a belief that the increase in carbon dioxide produced by fossil fuels will cause heat to be trapped near the Earth’s surface. This so called ‘Greenhouse effect’ is thought to be responsible for global warming and causing climatic changes.
-Fuels burnt in vehicle engines release pollutants into the air. Sulphur dioxide and nitrogen dioxide contribute to acid rain. Carbon monoxide is a poison that causes suffocation. Lead damages the nervous system. Many hydrocarbons in exhaust fumes are thought to be carcinogens.
Acid rain wears away stonework and damages buildings, burns through leaves and can cause long term damages to vegetation, acidifies soil and effects the ecological balance, acidifies rivers and ponds killing aquatic organisms and acid gases in the air can affect the lungs when breathed in.
Sulphur Dioxide + water = sulphuric acid
Nitrogen Dioxide + water = nitric acid.
These are strong acids, they can do great damage to the environment.
Carbon Dioxide + water = carbonic acid.
This is a weak acid, it will have a long term effect on buildings and other stone structures but is not damaging in other ways.
DEFORESTATION:
-If forests are cut down, Carbon Dioxide in the atmosphere will Increase. There would be fewer trees to absorb Carbon Dioxide for Photosynthesis. (less oxygen produced for the same reason.)
-If forests are cut down, rainfall decreases as transpiration is not taking place so water’s not being moved from low in the soil to the atmosphere.
-If forests are cut down, the soil becomes thinner and is easily blown away. This is due to the fact that tree roots hold soil into place and fallen leaves add Humus (organic matter.)
Why cut down forests:
-land space for farming
-low materials for various industries
-fuel
-cleaning areas for mining
-space for building
WILDLIFE AND FARMING:
Monoculture = growing only one crop
Fertilisers
!Eutrophication! this is a problem with inorganic fertilisers where nitrates can easily be washed out of the soil.
Nitrates washed into rivers by rain – Causes excessive growth of surface plants – No light reaches lower plants in the water and no photosynthesis can occur – The plant die – Bacteria feed on the plants and use up the oxygen in the water – There is no oxygen for animals – water animals die.
Pesticides: used to destroy insects or other animals that destroy crops.
-May harm humans who eat the crops which have been sprayed
-May destroy helpful insects as well as unwanted ones
-May cause the production of ‘super pests’ when non resistant strains are destroyed leaving only resistant organisms to breed
-Poisons pass up the food chain and destroy higher organisms
eg: Insecticide washes into river, small quantity taken in by water plants, tine animals each eat lots of plants, small fish eat tiny animals, larger fish eat smaller fish, otter eats larger fish and dies.
Other methods of pest control:
-Using natural predators (eg: ladybirds bred in large numbers to eat green fly, parasitic wasps to eat white fly) These are known as Vectore Predators.
-Capturing the males of a species by luring them into chemical traps containing Pheromones (scents given out by the females) The males are then eradicated to make them infertile. When they are released they can mate but not produce offspring.
-Releasing pests which have been infected with disease so that the wild population is infected and destroyed.
GLOBAL WARMING:
THE GREENHOUSE EFFECT:
-High energy radiation from the Sun passes through the atmosphere and is reflected and radiated into space.
-Low energy radiation reflects from the Earth and back again to the Earth from the layer of gases. This acts like the glass of a greenhouse trapping heat within the atmosphere.
Carbon Dioxide: burning fuels, respiration
Methane: natural gases, rotting vegetation, cows and other herbivores.
EFFECTS OF GLOBAL WARMING:
-A rise in temperature causes climate to change around the world. Eg: draught in some places, excessive rainfall in others…
-Melting of ice caps would cause a rise in sea level
Ozone layer: ozone is a form of oxygen (O3.) It makes a layer within the atmosphere. It absorbs harmful radiation from the Sun. The radiation is ultraviolet.
CAUSE OF DAMAGE:
CFC’s (chloroflurocarbons) which are used as propellants in aerosols and refrigerants.
How: they rise through the atmosphere and react within the oxygen of the ozone layer and make a hole in it.
Result: UV light reaches the Earth and increases the incidence of skin cancer. There is the potential for genetic damage.
GROWTH:
Growth is a process involving cell enlargement, cell division and cell specialisation (differentiation)
It is an increase in size of an organism. Different parts may grow at different rates.
Because different parts have different growth rates, the young may look and behave differently than the adult.
Factors affecting the growth rate:
-genetics
-food availability
-illness (reduced growth as secondary effect eg: digestive disorders)
-growth disorders (main effect on growth eg: lack of growth hormones)
Measuring growth:
-linear measurements
-volume
-mass
Chromosomes:
-they are made of DNA
-they are thread like and only becomes visible when they thicken before cell division
-the DNA is organised in sections called Genes
-Genes carry the instructions needed to create a new organism
-in body cells chromosomes are found in pairs
-each gene controls a particular characteristic
-when a cell divides it makes a new set of chromosomes to pass on to the daughter cells
How do chromosomes double?
The chromosome consists of Chromatid and Centromere The Chromatid is made of coiled DNA. The DNA copies itself to make a doubled chromatid. These parts separate in cell division.
Cell division:
-Cells grow by increasing the quantity of cytoplasm.
-They grow in numbers by dividing
-The first part to divide is the nucleus.
-The nucleus contains the chromosomes.
Eg: Human body cell: 46 chromosomes in 23 pairs.
If there are paired chromosomes in a cell it is a DIPLOID cell.
If there are single chromosomes in a cell it is a HAPLOID cell.
REPRODUCTION:
VARIATION:
Organisms of the same species differ from one another. This is called variation.
Causes:
-environment factors: food, climate, disease and accidents
-genetic factors: each individual has a unique gene combination as the gametes are produced from the parent cells by meiosis, when gametes one of each pair of alleles comes from each parent, the alleles in a pair may vary and produce different characteristics.
-mutations: mutations are changes in chromosomes or genes. A mutation in a gamete will be passed on.
HEREDITY AND VARIATION:
-INHERITED CHARACTERISTICS: carried in the genes, passed on from parents (height, eye colour…)
-ACQUIRED CHARACTERISTICS: not born with these, acquired during life (tattoos, piercing’s, hairstyle…)
-CONTINUOUS VARIATION: many small differences (height, weight, hair length…)
-DISCONTINUOUS VARIATION: either one thing or another, no in between stages (blood groups, freckles o no freckles, ability to roll tongue…)
CHROMOSOMES AND GENES:
HOMOLOGOUS PAIRS: chromosomes that are the same shape, the same sizae and carry genes for the same range of characteristics. A human being has 22 homologous pairs and the sex chromosomes.
GENES: Genes operate in pairs. Each pair controls a particular characteristic. The site of the gene on a chromosome is called its Locus. Genes occupying the same site on homologous chromosomes and covering the same characteristics are called Alleles.
DOMINANT AND RECESSIVE GENES:
A dominant gene is a strong gene. If it is present, its characteristic will show. It is shown in diagrams by a capital letter. A recessive gene is a weak gene. It will only show when both members of the pair (both alleles) are recessive. It is shown in diagrams by a small case letter. The letter used is relative to the characteristic shown by the dominant gene.
HOMOZYGOUS AND HETEROZYGOUS:
HOMOZYGOUS: the alleles for a characteristic are identical (pure-bred.)
HETEROZYGOUS: the alleles for a characteristic are different (hybrid.)
Eg: Hair colours. Brown hair (H) blonde hair (h)
-Homozygous: HH or hh
-Heterozygous: Hh
PHENOTYPE AND GENOTYPE:
PHENOTYPE: what shows eg: black hair (B)
GENOTYPE: what genes are actually present (BB or Bb)
MONOHYBRID CROSS:
A cross involving only 1 set of alleles.
Eg: looking at tongue rolling only
F1 AND F2 GENERATION:
PARENTS – CHILDREN (F1) – GRANDCHILDREN (F2)
Usually the terms are used in animals or plants where the F1, first filial generation, members can be crossbred to produce the F2, second filial generation.
INHERITED DISEASE:
Most inherited disease is cause by recessive alleles. Both parents have to be carriers to pass on the disease.
DOMINANT INHERITANCE:
Only one damaged gene is needed for the disease to show.
SEX LINKED INHERITED DISEASE:
The alleles are carried on the sex chromosomes. The disease is carried by women and shown by men because the “Y” chromosome lacks a balancing gene.
HISTORY OF GENETICS: (MENDEL)
The science of modern genetics was founded on the work of the Augustinian monk GREGOR MENDEL (born in 1822) He worked with pea plants in the monastery gardens. He was trained as a mathematician and this enabled him to analyse his results. His theories were that:
-Each contrasting characteristic has its own separate controlling factor.
-The factors must operate in pairs.
-The pairs separate when sex cells are formed
-At fertilisation factors come together and pairs are restored.
-The pairing is random.
MUTATION:
A mutation is a change occurring in one or more of the chromosomes: a change in the number of chromosomes, a chemical change occurring in an individual gene.
Mutations take place because of Mutagens that include atomic radiation, x-rays, ultraviolet light, chemicals…
SELECTIVE BREEDING:
If an organism has advantageous characteristics, it is possible to produce more of that organism by controlling the way it breeds. Domestic animals, farm animals and crops have all been developed in this way.
With crops it is possible to breed with itself by self-pollination (controlled by the grower) to ensure that the characteristics are passed on.
With animals and plants you can cross related offspring or backcross to enhance characteristics.
GENETIC ENGINEERING:
Bacteria can be made to produce chemicals that we want by putting bits of DNA from other organisms into them.
Enzymes are used to ‘cut out’ the DNA form one chromosome and other enzymes to insert it where needed. This method is used to produce the hormone Insulin. It is also used to insert genes into other organisms.
CLONING:
Producing many organisms from tissue sample of a parent organism. Vegetative reproduction of plants (including cuttings) is an example of this and has been used for some time.
Now we can grow the plants from tiny sections. This system is called tissue culture. Sterile conditions have to be maintained so that the tiny samples can grow without damage or competitions form other organisms.
Using this method it is easy to produce enormous numbers of plants of high yield (or disease resistant) crops from a single parent.
