Conservation of Biodiversity Zoos and seed banks help to conserve endangered species. The extinction of a specie or the loss of genetic diversity can cause a reduction in global biodiversity. Some species such as the Dodo have already became extinct, and many and...
Measuring biodiversity Specie richness is the simplest way to measure biodiversity, this involves counting all the species present in a given habitat. Specie evenness is when you use specie richness but you take into account the population size of each of the species....
Starch, cellulose and fibres Starch is the main energy storage material in plants, cells get energy from glucose. Plants store excess glucose a starch. Starch is a mixture of two polysaccharides, these are Amylose which is a long unbranching polysaccharide. It is a...
Drug testing and drugs from plants Before drugs become available to the general public they need to be tested to make sure they work, and don’t have any horrible side effects. We know this through the past, experiments such as William withering digitalis soup, he...
Biodiversity and Endemism Biodiversity is the variety of all living organisms in an area. It includes species diversity (the number of different species, and abundance of each species in a area) and genetic diversity (the variety of alleles within a specie)....
Plant cell structure and plant stems Different part of the plant stems have different functions there are two main things, these are xylem vessels and the sclerenchyma fibres. Water is transported through xylem vessels through diffusion gradients. When water...
Adaptation and evolution A niche is a role of specie within a habitat. A niche a specie occupies within a habitat includes its interactions with other living organisms, and its interactions with the non-living environment. Every specie has a unique niche, and a niche...
Cell differentiation Stem cells are unspecialised and they can develop into any type of cell. Totipotency which is when it has the ability to produce all cell types including the specialised cells in an organism and extra-embryonic cells. The second type is...
Variance Continuous variation is when individuals in a population vary within a range with no distinct categories; these can be things like height, mass or skin colour. Discontinuous variation is when individuals are in a specific category, and will fall into only one...
Production of a gametes In animals the male gamete is sperm, and in female it is an egg cell (ova). In plants the male gamete is pollen grains, and the female gametes are ovules. Gametes contain only half the normal amount of chromosomes, so in one gamete in humans it...
Fertilisation Fertilisation is where male and female gametes fuse. In mammals fertilisation occurs in the oviduct, and in flowering plants it occurs in the embryo sac. Sperm is deposited high up in the vagina, near the cervix. Once there the sperm makes its way up the...
The Cell cycle and Mitosis The cell cycle consists of a period of cell growth and DNA replication called interphase and a period of cell division called mitosis. Interphase is sub divided into three separate growth stages These are called G,S and G2. Mitosis is used...
Difference between Prokaryotes and Eukaryotes The organelles found inside a Eukaryotic cell are: There are many differences between Eukaryotes and prokaryotes,:
Protein Transport Transcription occurs when changing DNA to mRNA, where the mRNA leaves the nucleus via pores in the nuclear envelope. Proteins are made on ribosome’s The ribosomes sometimes attach to the rER where the protein made moves through making the 3-D shape...
Cell organisation Genes are expressed through master genes. Such as in fruit flies once the main body segment have been determined, the cells in each segment become specialised for the appropriate structure, (Wings Antennae) The master genes control the development...
8.4 Brains, the genome and medicine Neurotransmitters in the brain The brain contains neurones, which transmit nerve impulses to each other across synapses. Many different neurotransmitters are involved, including dopamine and serotonin. Dopamine and...
8.2 How the nervous system works The nervous system The nervous system is the network of nerve cells and fibres that transmits impulses around the body. The nervous system is divided into the central and peripheral nervous systems. Central nervous...
8.3 Brains and behaviour The human brain The brain is part of the CNS, its role is to initiate and coordinate activities of the body. It receives input from receptors inside and outside the body, and the information from these is integrated to produce appropriate...
7.3 The heart, energy and exercise Controlling the heart The heart is myogenic – it contracts and relaxes automatically without stimulation from nerves to pump blood around the body. It is specific and made of specialised tissue called cardiac muscle. Rhythmic...
7.4 Health, exercise and sport Benefits of exercise Increasing arterial vasodilation lowers blood pressure and reduces the risk of cardiovascular disease and stroke Increases the level of blood HDLs which transport cholesterol to the liver where it is broken down...
Topic 8: Grey matter 8.1 Sensitivity in plants Photoreceptors: A structure in living organisms, especially a sensory cell or sense organ that responds to light. Coordination: The interaction of cells enables them to coordinate their activities appropriately....
Topic 7: Run for your life: 7.1 Cellular respiration Respiration = The chemical process of releasing energy from organic compounds (respiratory substrates) such as glucose through oxidation. The energy released is used to combine ADP with inorganic phosphate to...
7.2 Muscles and movement Structure and function of muscles Muscle tissue is made of specialised cells that use energy from the hydrolysis of ATP to become shorter by contraction. Striated (skeletal/voluntary) muscle attaches to the bones by tendons and appears...
CLIMATE CHANGE Climate change is supported by evidence from temperature records, pollen grains in peat bogs and tree rings. Temperature records Some go back 2 or 3 centuries – long-term data can be recorded with thermometers. Pollen analysis Pollen grains are...
GLOBAL WARMING The sun radiates energy and is absorbed by the earth which re-emits infra-red radiation. Gases that stop infrared radiation escaping from the earth are greenhouse gases. This keeps the earth warm enough for life and is called the greenhouse effect....
CARBON CYCLE The circulation of carbon Carbon dioxide levels have been rising, suggesting the cycle isn’t in balance due to mainly combustion of fossil fuels and deforestation. Coal is a fossil fuel formed from trees fallen into anaerobic conditions millions of years...
MAINTAINING THE BALANCE Biofuels – fuels directly from biomass which are burnt to release energy, producing carbon dioxide. Because the amount of carbon dioxide released when burnt is the same removed by photosynthesis, plants are carbon neutral so have no net...
ENZYME ACTIVITY Temperature has a direct effect on enzyme activity – at low temperatures enzyme activity is low because substrate and enzyme don’t collide often. This increases with temperature until optimum temperature is reached. Any higher than the optimum...
SPECIATION Speciation is the formation of a new species. Species = A group of organisms with similar morphology, physiology and behaviour which can interbreed and are reproductively isolated from other species. For a new species to arise, a group of individuals has to...
VALIDATING SCIENCE In order to test theories, data needs to be collected to prove or disprove it. Scientists within the scientific community accept evolution as there is evidence to make it reliable and valid. Scientists validate data in 3 ways: Scientific journals –...
CALCULATIONS Percentage increase = bigger – smaller / original x 100
INVESTIGATING POPULATIONS Looking at the abundance and distribution of a species in an area Abundance = number of individuals of one species in a particular area. Distribution = a particular species within the area being investigated Random sampling: Choose an area to...
EVOLUTION Evolution is a change in allele frequency in a population of organisms over time. Natural selection Many organisms are unable to move to new habitats and will only survive if they can adapt to new conditions – there is a struggle for existence. Organisms...
ENERGY TRANSFER Energy is transferred in an ecosystem. Autotrophs make their own food, heterotrophs cannot so eat to gain energy. Primary consumers (herbivores) eat plants (autotrophs). Secondary consumers (carnivores) eat secondary consumers and are sometimes the top...
ON THE WILD SIDE PHOTOSYNTHESIS Producers (autotrophs) make their own food by photosynthesis 6CO2 + 6H20 à 602 + CH12O6 (in the presence of light and chlorophyll) Photolysis is used, the process of splitting water using light energy Photosynthesis stores energy as...
CHLOROPLASTS Photosynthesis occurs in the chloroplasts (small, flattened organelles). Thylakoid membranes: A system of interconnected, flattened fluid filled sacs. Proteins including photosynthetic pigments and electron carriers are in the membrane and are involved in...
LIGHT DEPENDENT REACTIONS In the thylakoid membrane ADP + Phosphate à ATP Produce reduced NADP, ATP and waste oxygen Light energy provided by sun Light absorbed by chlorophyll pigment in chloroplasts Light energy excites electrons in the chlorophyll so they get...
LIGHT INDEPENDENT REACTIONS In the stroma Also called the Calvin Cycle ATP à ADP + Phosphate RuBP combines with carbon dioxide from the air to form an unstable 6C compound The enzyme RUBISCO catalyses the break down of the unstable 6C compound into two molecules of a...
PHOTOSYNTHESIS KEY WORDS Phospohorylation: Adding phosphate to a molecule (ADP is phosphorylated into ATP) Photophosphorylation: Adding of a phosphate molecule using light Photolysis: Splitting of a molecule using light Hydrolysis: Splitting of a molecule using water...
ATP (ADENOSINE TRIPOSPHATE) Immediate source of energy in cells Respiration: energy released from glucose is used to make ATP Carries energy around the cell where it is needed ATP is synthesised from ADP and inorganic phosphate using energy ATP diffuses to the part of...
ECOSYSTEMS The biosphere is the part of the earth inhabited by living organisms. Ecosystems exist in the biosphere, and within ecosystems, there can be different habitats, each with its own distinct conditions. A community of organisms live in ecosystems because they...
SUCCESSION = The process by which an ecosystem changes over time – the biotic conditions change as the abiotic conditions change. A pioneer species is the first plant to colonise the bare ground. Only the species that can cope with the extreme conditions will grow and...
FORENSICS Investigating time of death: As soon as a person dies, chemical changes occur in order, so can be used to estimate the time of death. Rigor mortis/degree of muscle contraction: · Begins when muscle cells become deprived of oxygen · ...
BACTERIA AND VIRUSES Infectious diseases are mostly caused by bacteria and viruses. Bacteria: Useful bacteria are found on the skin and in the digestive tract Prokaryotic cellular structure, single celled organelles Prokaryotic cells store carbon compounds in the form...
BARRIERS TO PATHOGEN ENTRY Pathogens enter through areas not covered by skin – nose, mouth, eyes, gas exchange surfaces, gastrointestinal tract and genital tract and through wounds. Eyes, nose, mouth: Tears contain the enzyme lysozyme which helps to digest microbes –...
NON SPECIFIC RESPONSE Inflammation: At the site of infection, damaged white blood cells and mast cells release histamines that cause arterioles to dilate and capillaries to become more permeable. Blood flow to the area increases and plasma, white blood cells and...
SPECIFIC RESPONSE Relies on lymphocytes which respond to foreign antigens on the surface of bacteria and viruses Can take two forms – Humoral response (B cells) and cell mediated response (T cells) Humoral response Has two main stages Pathogen with antigens on...
TYPES OF IMMUNITY Immunity is the ability of microorganisms to resist infection by protecting against disease causing microorganisms. When the body has enough antibodies (or can produce quickly enough) to fight infection. Active Natural: Exposed to foreign antigen by...
ANTIBIOTICS Antibiotics are used to fight bacterial infections. There are 2 main types: Bactericidal: Antibiotic that kills bacteria Bacteriostatic: Inhibits growth of bacteria When bacteria are no longer affected by an antibiotic they are resistant. Resistance...
PROTEIN SYNTHESIS DNA is the molecule that carries instructions for our development. The genetic code is the sequence of nucleotides and amino acids in a polypeptide chain. DNA is a polynucleotide made up of nucleotides containing deoxyribose (a sugar), a phosphate...
TREATMENTS
ETHICAL DECISIONS 1.RIGHTS + DUTIES Human rights – right to life = fair trial Guardians have duty to their ward Rights occur from religion + social conventions 2.MAXIMISING THE AMOUNT OF GOOD IN THE WORLD Utilitarianism believe that you should to the best thing for...
GENETIC COUNSELLING Helps us to understand how disease is inherited and the chance so children being carriers or victims of the disease Explain available tests Explains possible courses of action to take place after test...
GENETIC TESTING What is genetic testing? Genetic testing is the use of laboratory tests to determine the genetic status of individuals already suspected to be at high risk for a particular genetic disorder based on...
GENETIC TESTING Ethical Issues: (Germ line therapy is illegal due to these reasons) Might affect the development of a fetus in unexpected ways Long-term side effects that are not yet known. People who would be affected by germline gene therapy are not yet born, so...
GENE THERAPY Gene therapy involves inserting copies of a normal allele into the chromosomes of an individual who carries a faulty allele. If a mutated gene causes a necessary protein to be faulty or missing, gene therapy may be able to introduce a normal copy of the...
DNA REPLICATION The Process: DNA strands run anti-parallel to one another Enzyme helicase unzips the double helix and the hydrogen bonds between bases break Free nucleotides line up with their complimentary bases and hydrogen bonds form DNA polymerase allows the free...
MUTATIONS There are many environmental factors (e.g. UV radiation) that could cause gene mutations but it can also be inherited. When the DNA is being built an incorrect base may slip into place which could cause a mutation in the...
COMPLIMENTARY BASE PAIRING Genetic Code A triplet code is a sequence of three bases along a single strand of DNA. Each triplet code is ‘read’ and calls for a specific amino acid. Each triplet is code for one amino acid. There are 20 different amino acids in the body...
RNA RNA is a type of nucleic acid called ribonucleic acid. The RNA nucleotides are joined to form a single strand. The nucleotides are joined by a bond between the sugar of one nucleotide and the phosphate of the next. TYPES of RNA Messenger...
THE HUMAN GENOME A genome is all the DNA of an organism or species. In 2001, the Human Genome Project published a working draft of the sequence of bases in human cells. Work continues to identify specific genes and establish their function. Part of the budget for the...
GENE TRANSCRIPTION The specialised function of a cell depends upon the proteins it synthesises ie which genes are expressed. Transcription of a gene is initiated by RNA polymerase and transcription factors binding to a promoter region (section of DNA adjacent to...
CORE PRACTICAL Sometimes the gene for an enzyme required for the metabolism of a particular substrate can be expressed only when that substrate is present (induction) e.g. and lactose in prokaryotes.
PHENOTYPE Differences in phenotype between members of a population are caused by: genetic make-up (genotype) the environment in which the individual develops Some are due completely to genotype eg blood groups and show discontinuous variation: they fall into...
CANCER Cancer occurs when the rate of cell multiplication is faster than the rate of cell death. This causes the growth of a tumour. Cancer is caused by environmental damage to DNA from physical factors such as UV light and asbestos chemical carcinogens such as those...
GAMETES The sex cells or gametes are adapted for sexual reproduction.
GAMETE PRODUCTION Gametes are produced in the ovaries and testes of animals by meiosis which: produces haploid cells (contain half the number of chromosomes found in a body cell: one of each homologous pair) creates genetic variation among offspring...
DEVELOPMENT OF THE ZYGOTE Fuelled by nutrients from the ovum, the zygote divides rapidly to form smaller cells – the embryo remains the same size. After 3 divisions, there are 8 totipotent stem cells – each could form a total human being. After 5 days, a blastocyst (a...
MITOSIS Mitosis, with identical daughter cells, ensures genetic stability - important for: growth: development from a single cell to a multicellular organism repair: regeneration of lost or damaged parts or replacement of old or damaged cells asexual reproduction eg...
THE CELL CYCLE Mitosis is a type of cell division, which retains the full or diploid number (2n) of chromosomes.In humans, a cell with 46 chromosomes divides to form 2 identical daughter cells, each with 46 chromosomes.Before nuclear division, a copy of each...
CELL ORGANELLES (EUKARYOTIC CELL)
PROKARYOTIC CELLS The cells described above, with membrane-bound organelles are eukaryotic.Organisms with eukaryotic cells are classified into 4 kingdoms: Animals, Plants, Fungi and Protoctists.
REDUCING RISK A person’s risk of developing coronary heart disease can be reduced by: DIET should be energy balanced reduced cholesterol, saturated fats and salt more polyunsaturated fats, including omega-3 fatty acids found in oily fish more fruit and vegetables...
LIPIDS Lipids contain the elements carbon, hydrogen and oxygen. They are insoluble in water but soluble in organic solvents (ethanol). They provide twice as much energy as carbohydrates and supply the body with essential fatty acids. Vitamins are often found dissolved...
CHOLESTROL Insoluble cholesterol combines with proteins to form soluble lipoproteins so that it can be carried in the bloodstream. Eating both monounsaturated and polyunsaturated fats reduces the level of LDLs in the blood.
TISSUE FLUID How is Tissue Fluid formed? At the start of the capillary bed, the arteriole end, there’s high pressure due to the contraction of the ventricle This pressure is called hydrostatic pressure and it forces fluid out of the capillaries into the spaces...
ENERGY BUDGET + DIET Carbohydrates, proteins, lipids and alcohol all contain energy: used to be measured in calories; the SI unit is the Joule. Average person requires 8,000-10,000 kilojoules per day. Dietary Reference Values encourage balanced & healthy diets and...
STUDIES Epidemiologist – studies patterns in the occurrence of diseases Cohort studies – follows a group of people over time to see who develops the risk and who doesn’t Case-control studies – people with the disease are compared to people without Controls should be...
BLOOD PRESSURE Blood pressure is higher in arteries and capillaries than in veins. Systolic blood pressure is highest and occurs when the ventricles contract (ventricular systole) Diastolic blood pressure is at its lowest in the arteries when the ventricles...
BLOOD CLOTS Platelets are cells with no nucleus. But when platelets come in contact with the damaged vessel their shape changes into a “spiky” shape – they stick to each other and the collagen in the wall: a platelet plug is formed. They then release more substances...
RISK Probabilities E.g. 24,000 people died in 2005. The population was 72,200,000. What is the average risk in: Percentage: 24,000 / 72,200,000 = 0.033% Fraction: 72,200,000 / 24,000 = 1 in 3008 people These averages make the assumption that everyone has the same...
RISK FACTORS FOR CVD The following factors increase a person’s risk of developing cardiovascular disease: GENETIC Risk is increased if your parents have CVD. Different chances of inheriting the defective genes; two recessive / one dominant allele = inherited...
ATHEROSCLEROSIS
BLOOD VESSELS When muscles relax, the lumen widens thus decreasing B.P There is no pulse and pressure is low. Valves prevent backflow.
PROPERTIES OF WATER Thermal Properties Large amounts of energy are needed to break the hydrogen bonds. Because organisms have a high water content, a large amount of energy only results in a small increase in body temp. This means that water warms and cools slowly....
TRANSPORT IN ANIMALS Circulatory Systems OPEN CIRCULATORY SYSTEM- In invertebrates (e.g. insects), blood isn’t held within vessels always It’s free to circulate the body cavities (spaces) Only works for insects because they’re small Cannot contain any pressure,...