DEFINITIONS SUCH AS: Inheritance The transmission of genetic information from generation to generation Allele Different versions of a particular gene Gene A short length of DNA found on a chromosome that codes for a specific protein Chromosome Thread-like structures of DNA, carrying genetic information in the form of genes, located in the nucleus of the cell Genotype The combination of alleles that control each characteristic Phenotype The observable characteristics of an organism Codominance Both dominant and recessive alleles are both expressed in the same phenotype Stem cells Unspecialised cells that undergoes mitosis to produce new daughter cells that can be specialised Fitness The probability of an organism surviving and reproducing in the environment in which it is found Adaptive feature(s) An inherited feature(s) that helps an organism to survive and reproduce in its environment Hormones A chemical substance produced by a gland and carried by the blood, which alters the activity of one or more specific target organs Synapse The junction between two neurones Drugs Any substance taken into the body that modifies or affects chemical reactions in the body Excretion The removal of the waste substances of metabolic reactions, toxic materials and substances in excess of requirements Accomodation The way the lens brings about fine focusing Mutation A change in the base sequence of DNA Population A group of organisms of one species, living in the same area at the same time Community All of the populations of different species in an ecosystem Ecosystem A unit containing the community of organisms and their environment, interacting together Accommodation: Viewing Near & Distant Objects OBJECT FAR AWAY OBJECT CLOSE Ciliary muscles Relax Contract Suspensory ligaments Pulled tight Slack Lens Thinner Bulging Pupil Reflex Stimulus Radial muscles Circular muscles Pupil size Amount of light enters DARK LIGHT Contract Relax Wide More BRIGHT LIGHT Relax Contact Narrow Less Lungs movement during inhalation and expiration External intercosta l muscles INHALATION EXHALATION Internal intercostal muscles Pull ribs up and out Pull ribs down and in Volume of thorax Diaphragm Pressure inside lungs Increase Contracts, move downwards Decrease Decrease Relax, move upwards Increase Blood clot - When the skin is broken (a wound) platelets arrive to stop the bleeding. - A series of reactions occur within the blood plasma - Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot. - The clot eventually dries and develops into a scab to protect the wound from bacteria entering Lymph fluid - The walls of the capillaries are so thin that water, dissolved solutes and dissolved gases easily leak out of them / pass through the walls from the plasma into the tissue fluid surrounding the cells - Cells exchange materials (such as water, oxygen, glucose, carbon dioxide, mineral ions) across their cell membranes with the tissue fluid surrounding them by diffusion, osmosis or active transport - More fluid leaks out of the capillaries than is returned to them and this excess fluid passes into the lymphatic system and becomes lymph fluid. Protein synthesis - DNA in the nucleus/bacterium will unzip where the gene is located. Then a Protein will come read one side of the DNA and make a complementary section called mRNA. - MRNA will leave the nucleus and find a ribosome. - Then the ribosome will read the mRNA and attach amino acids in order based on the mRNA code to produce a protein. Type 1 diabetes symptoms - Extreme thirst - Weakness or tiredness - Blurred vision, - Weight loss - Loss of consciousness in extreme cases Kidney: Ultrafiltration - Arterioles branch off the renal artery and lead to each nephron, where they form a knot of capillaries (the glomerulus) sitting inside the cup-shaped Bowman’s capsule. - The capillaries get narrower as they get further into the glomerulus which increases the pressure on the blood moving through them (which is already at high pressure because it is coming directly from the renal artery which is connected to the aorta) - This eventually causes the smaller molecules being carried in the blood to be forced out of the capillaries and into the Bowman’s capsule, where they form what is known as the filtrate The substances forced out of the capillaries are: glucose, water, urea, salts Kidney: Selective Reabsorption - After the glomerular filtrate enters the Bowman’s Capsule, glucose is the first substance to be reabsorbed at the proximal tubule. - This takes place by active transport. - As the filtrate drips through the Loop of Henle necessary salts are reabsorbed back into the blood by diffusion - As salts are reabsorbed back into the blood, water follows by osmosis - Water is also reabsorbed from the collecting duct in different amounts depending on how much water the body needs at that time Component Reabsorbed at WATER Loop of Henle and collecting duct SALTS Loop of Henle GLUCOSE Proximal tubule UREA Not reabsorbed Immune system response to invasion of pathogens - Lymphocytes make antibodies which would attach to the antigens and cause agglutination (clumping together). - Chemicals are released that signal phagocytes to destroy these ‘clump’ cells. - Phagocytosis occurs when phagocytes engulf and digest the pathogens. Vaccination - Dead or altered form of pathogen introduced - Provokes immune response - Lymphocytes produce antibodies complementary to antigens of pathogens - Some remaining antibodies becomes memory cells - The next invasion of the same pathogen is faster and shorter - This immunity is long-lasting Pollination - Pollen grain has landed on the stigma of the same flower species - The nucleus inside the pollen grain grows down the style towards the ovary in the carpel - The ovary contains one or more ovules which each contain an ovum with a female nucleus that a male pollen nucleus can fuse with - Once the nuclei (pl) have joined together, that ovule has been fertilised and a zygote has been formed - The zygote will start to divide by mitosis and eventually form a seed within the ovule Sexual reproduction vs Asexual reproduction Asexual Reproduction Sexual Reproduction Adaptations of Gametes Explained Fertilisation - the fusion of the nuclei from a male gamete and a female gamete - Fertilisation happens when a sperm cell and an egg cell fuse their nuclei together. - When the sperm cell reaches the egg cell, it must digest the wall of the cell so - that it can fuse their nuclei. This is done using enzymes located in the acrosome. The egg contains a jelly coat which changes after fertilisation and ensures that only one sperm cell can enter. - Once fertilisation has occurred, the zygote undergoes mitosis (cell-division) to produce many cells which make up a ball of cells, embryo. - The embryo is implanted into the wall of the uterus, where it grows. Birth - Amniotic sac breaks, releasing amniotic fluid Muscles in the uterus wall goes through a wave of contractions Cervix dilates (gets wider) Baby passes out through the vagina Umbilical cord is tied and cut Afterbirth is delivered Resistance of antibiotic resistance Natural selection: - A population of bacteria is exposed to an antibiotic, which would kill and wipe out almost all of the bacteria. - The surviving bacteria would reproduce and produce offspring that have this resisting trait against an antibiotic. - The process continues and there will be a large population of bacteria resistant to the antibiotic. Mutation: - There would be a variation within a population caused by mutation. - A chance mutation might cause some bacteria to become resistant to an antibiotic. - When the bacteria population is treated with antibiotics, the resistant bacteria do not die. - The resistant bacteria survive and reproduce with less competition with the non-resistant bacteria. Plasmids with antibiotic-resistance genes can be shared between bacteria of both the same and different species. Hydrophytes ADAPTATION FUNCTION Large air spaces To keep leaves close to the surface of the water where there is more light for photosynthesis Small roots Extract nutrients from the surrounding water through their tissues Easy diffusion of water Open stomata Gas exchanges more easily Thin/no waxy cuticle No need water loss Xerophytes ADAPTATION FUNCTION Thick waxy cuticle Barrier to evaporation Sunken stomata Moist air trapped here lengthens the diffusion pathway and reduces evaporation rate Leaf rolled Traps moist air and prevents air movement across stomata which reduces transpiration Small leaves Reduce the surface area and therefore the evaporating surface Extensive shallow roots Quick absorption of large quantities of water Thickened leaves or stems Store water Energy up the food chain - At each stage in a food chain only about 10% of the energy received by an organism gets passed on - Energy is lost through excretion, respiration, movement and heat - Energy can be left in leftover unfinished food - Inefficient loss of energy is the cause of lesser animals up the food chain and trophic levels never more than 5. Nitrogen cycle Process By? Where? How? Nitrogen fixation Nitrogen fixing bacteria Root nodules Take N2 gas and change it into nitrates in the soil Lightning Turn splitted bonds into nitrous oxides like N2O and NO2 that dissolve in rainwater and ‘leach’ into the soil Nitrification Nitrifying bacteria Soil Convert the ammonium compounds to nitrites and then to nitrates Denitrification Anaerobic bacteria Soil with NO oxygen Take the nitrates out of the soil and convert them back into N2 gas Genetic engineering using bacteria - Selected gene is isolated - Restriction enzymes are used to cut the gene, leaving sticky ends - A bacteria plasmid is also cut by the same restriction enzymes and leaving sticky ends - The plasmid and gene is joined together by DNA ligase enzyme - The genetically engineered plasmid is inserted into a new bacteria cell - The gene is copied when the bacteria produce - OR the bacteria is placed into a fermenter to make more copies of the gene faster. Fermenters Prokaryotes: Bacteria ( x nucleus) 1. Bacteria are prokaryotes because it has no: - nucleus - membrane-bound organelles (mitochondria or chloroplast) - rough endoplasmic reticulum 2. Some bacteria has circular DNA that are called plasmids 3. Cell wall are made up of peptidoglycan (not cellulose) Viruses 1. Often considered as non-living. 2. Thus they do not carry out the 7 life processes (MRS GREN) 3. They are parasites as they reproduce only in a host cell. 4. They consist strand of nucleic acid: - DNA - RNA 5. The DNA is surrounded by a protective protein coat (capsid) 6. No cell wall Fungi 1. The example of fungi includes: - mushrooms - moulds (bread) - yeast 2. Fungal cells have a cell wall made of chitin. 3. A fungus is made of hyphae, collectively they are called mycelium., and form branches. 4. Each hypha contains : many nuclei. 5. Fungi cannot carry out photosynthesis.. 6. Instead they use saprotrophic nutrition (feed on others). - They secrete enzyme onto their food - They then absorb the digested organic products. Vertebrates Class External/visible features Other features Mammals - Fur and hair Four limbs External ears Nipples Whisker - Give birth to young Internal fertilisation Warm blooded Has mammary gland Birds - Feather Scales on legs Beak Two wings Two legs - Hard-shelled eggs Internal fertilisation Warm blooded Fish - Scale Fins Eyes on lateral sides Streamlined body - Jelly-covered eggs External fertilisation Cold blooded Amphibians - Moist skin Four limbs - Jelly-covered eggs External fertilisation Cold blooded Reptiles - Dry and scaly skin Four limbs - Soft-shelled eggs Internal fertilisation Cold blooded Invertebrates (ARTHROPODS) Class External features Insects - 3 pairs of legs 3 body parts (head, thorax, abdomen) 2 pairs of wings antennae Arachnids - 4 pairs of legs 2 body parts (cephalothorax, abdomen) No antennae Myriapods - >10 pairs of legs Many body segments Each segment at least 1 pair of legs Antennae Crustaceans - 5 pairs of legs 2 body parts antennae Monocots vs Dicots Monocots Dicots 1 cotyledon 2 cotyledon Parallel veins Narrow veins Vascular bundles scattered Vascular bundles in rings 3 flower parts 4 or 5 flower parts Risk Factors for Coronary Heart Disease - Poor diet - Stress - Overweight/Obese - Smoking - Age - Gender - Genetics Prevention - Quit smoking - Reduce in animal fats - Exercise regularly Treatment 1. Aspirin - Thins the blood and makes platelets less likely to clump together to block the artery. - Reduce high blood pressure. 2. Stent - Tube inserted to keep artery open, allowing blood flow 3. Angioplasty - Helps widen the artery by inserting a deflated balloon into the artery, widening the artery 4. Coronary bypass - An artery from the patient's leg or arm is grafted onto the damaged artery to divert the blood flow Kidney transplant Advantage Disadvantage Patient has much more freedom Risk of rejection Diets can be much less restrictive Need to be on medication - pills - so organ won’t get rejected Cost of using dialysis machine is removed Not enough donors Long term Kidney dialysis process During dialysis, blood is taken from the arm and travels through the dialysis machine. Inside, the blood flows past a solution called dialysis fluid, containing glucose and ions. The blood and fluid are separated by a partially permeable membrane, allowing diffusion between the blood and fluid. As the fluid contains no urea, there is a high concentration gradient and urea exits the blood into the dialysis fluid by diffusion. The levels of glucose and ions in the dialysis fluid are similar to that of the blood, thus there is usually no net diffusion of ions or glucose across the membrane, unless the blood is lacking in ions, in which case ions will diffuse into the blood from the dialysis fluid. Clean blood then exits the machine and re-enters the patient's arm.
