BiologyQ&A by dot point

Eukaryotic and prokaryotic cells, the function of sub-cellular structures (nucleus, chromosomes, cytoplasm, cell membrane, mitochondria, ribosomes, chloroplasts, permanent vacuole, cell wall, plasmids, flagella), and how the structure of each is related to its function.

The structure of DNA as a double helix of two strands made of nucleotides, complementary base pairing (A-T, C-G), the gene as a section of DNA coding for a sequence of amino acids, and an overview of protein synthesis using mRNA and ribosomes.

Enzymes as biological catalysts, the lock and key model and active site specificity, the effect of temperature, pH and substrate concentration on the rate of enzyme-controlled reactions, and denaturing of enzymes.

The use of light and electron microscopy to study cells, the difference between magnification and resolution, the magnification equation, rearranging it to find real size or image size, and using standard form and SI units (mm, micrometre, nm) for cell sizes.

Photosynthesis as an endothermic reaction in chloroplasts, the word and symbol equations, the uses of glucose made by the plant, limiting factors (light intensity, carbon dioxide concentration, temperature), and the inverse square relationship between light intensity and distance.

Respiration as an exothermic series of reactions that releases energy from glucose in all living cells, the word and symbol equations for aerobic respiration, anaerobic respiration in animals (lactic acid) and yeast (ethanol and carbon dioxide), oxygen debt, and the uses of the energy released.

The levels of organisation (organism, population, community, ecosystem), abiotic and biotic factors, interdependence within a community, and competition between organisms for resources.

Food chains and food webs, the roles of producers, consumers and decomposers, the transfer and loss of energy along a food chain, and predator-prey cycles.

Using quadrats to estimate population size and to compare two areas, using transects to study how distribution changes across a habitat, random sampling to avoid bias, and improving the reliability of sampling.

The carbon cycle (photosynthesis, respiration, decomposition and combustion), the water cycle (evaporation, transpiration, condensation and precipitation), and how human activities such as burning fossil fuels affect the carbon cycle.

The nitrogen cycle and the roles of nitrogen-fixing, nitrifying, decomposing and denitrifying bacteria, the process of decomposition, and the factors affecting the rate of decay (temperature, water and oxygen).

The structure of DNA as a double helix of nucleotides with complementary base pairing, the genome as the entire genetic material of an organism, the value of sequencing the human genome, and the causes of genetic and environmental variation including mutation.

Alleles, dominant and recessive, genotype and phenotype, homozygous and heterozygous, monohybrid crosses and Punnett squares, the inheritance of sex by the X and Y chromosomes, and single-gene inherited disorders such as cystic fibrosis and polydactyly.

Variation and natural selection, Darwin's theory of evolution by natural selection, the development of antibiotic-resistant bacteria, the evidence for evolution from fossils and from resistant bacteria, extinction, and the formation of new species by isolation.

Protein synthesis as transcription of a gene into mRNA and translation at the ribosome, the role of the triplet code and amino acids, how the order of bases determines the protein made, and how mutations can change a protein and its function.

Sexual and asexual reproduction, the formation of gametes by meiosis, how meiosis halves the chromosome number and produces genetically varied cells, and the advantages and disadvantages of each type of reproduction.

Selective breeding (artificial selection) and its uses and risks, the process and uses of genetic engineering including genetically modified crops and bacteria producing insulin, the benefits, risks and ethics of genetic modification, and an outline of tissue culture and cloning.

Communicable diseases and the four types of pathogen (bacteria, viruses, fungi and protists), how pathogens are spread, examples of human and plant communicable diseases, and the non-specific physical and chemical defences of the human body and of plants.

The discovery of drugs from plants and microorganisms, the stages of developing and testing a new drug (preclinical testing and clinical trials), the use of placebos and double-blind trials, and why each stage is needed to check a drug is safe and effective.

Food security and the factors that threaten it, methods used to increase food production including fertilisers, pest control and intensive farming, biological control, the use of genetically modified crops, and sustainable approaches to feeding a growing human population.

Biodiversity and its importance, sampling and monitoring ecosystems using quadrats, transects and indicator species, the human activities that reduce biodiversity, and the methods used to maintain biodiversity such as conservation, reforestation and protecting habitats.

Non-communicable diseases and their risk factors (diet, exercise, smoking and alcohol), the difference between correlation and cause, the effects of risk factors on the body, cardiovascular disease and its treatments, and the use of data to evaluate the impact of lifestyle on health.

The role of white blood cells in the immune response (phagocytosis, antibodies and antitoxins), how vaccination produces immunity and protects populations, the action and limits of antibiotics including resistance, and the production and uses of monoclonal antibodies.

The control of blood glucose concentration by insulin and glucagon, the roles of the pancreas and liver, negative feedback, and the causes and treatment of type 1 and type 2 diabetes.

The hormones controlling the menstrual cycle (FSH, LH, oestrogen, progesterone), the events of the menstrual cycle, hormonal and barrier methods of contraception, and fertility treatments including IVF.

Auxins as plant hormones controlling growth, phototropism and gravitropism (geotropism), how auxin distribution produces tropic responses, and the commercial uses of plant hormones.

The functions of the main regions of the brain (cerebral cortex, cerebellum, medulla), the structure of the eye and how it focuses light, accommodation, and how the eye responds to changes in light intensity (Higher tier content).

The endocrine system as glands that secrete hormones into the blood, hormones acting on target organs with the correct receptors, the main endocrine glands, and a comparison of nervous and hormonal control.

The central nervous system, sensory, relay and motor neurones, synapses and neurotransmitters, the reflex arc as a fast automatic response, and reaction time and the factors affecting it.

Diffusion, osmosis and active transport as ways substances move across cell membranes, the factors affecting the rate of diffusion, the effect of osmosis on plant and animal cells, and calculating percentage change in mass in the osmosis practical.

Surface area to volume ratio and how it changes with size, why large organisms need specialised exchange surfaces and transport systems, and the adaptations of exchange surfaces such as alveoli, villi and root hairs.

The cell cycle (growth and DNA replication, mitosis, cytokinesis), mitosis producing two genetically identical diploid daughter cells, and the role of mitosis in growth, repair and asexual reproduction.

Stem cells as undifferentiated cells that can divide and differentiate, the sources of stem cells (embryonic, adult and plant meristems), the uses of stem cells in medicine and agriculture, and the ethical issues raised by their use.

The human double circulatory system, the structure and function of the heart, the differences between arteries, veins and capillaries, and the components of blood (red blood cells, white blood cells, platelets and plasma) and their functions.

Transport in plants by xylem (water and mineral ions) and phloem (dissolved sugars), the transpiration stream and translocation, the factors affecting the rate of transpiration, and the role of stomata and guard cells.