BiologyQ&A by dot point

The ultrastructure of animal, plant, fungal and bacterial cells, the function of each organelle, and the differences in cell wall composition and the presence of a true nucleus, plasmids, chloroplasts and vacuoles.

The double-stranded structure of DNA with complementary base pairing, the role of the base sequence as the genetic code for the order of amino acids, and how mRNA carries a complementary copy from the nucleus to the ribosome for protein synthesis.

Genetic engineering as the transfer of a gene from one organism to another, the ordered stages using a bacterial plasmid and enzymes, and the production of human insulin by genetically modified bacteria as the key example.

Proteins as chains of amino acids whose sequence sets their shape and function, the range of protein functions, and enzymes as biological catalysts with a specific active site, an optimum temperature and pH, and denaturation outside these conditions.

Respiration as the release of energy from glucose to make ATP, the word equation and stages of aerobic respiration including glycolysis, and the fermentation pathways to lactate in animals and to ethanol and carbon dioxide in plant and yeast cells.

Passive transport by diffusion and osmosis down concentration gradients, the effects of osmosis on animal and plant cells in hypertonic, hypotonic and isotonic solutions, and active transport against the gradient using energy from respiration.

The effect of abiotic and biotic factors on the distribution of organisms, the use of indicator species to judge environmental conditions, and sampling techniques such as quadrats and pitfall traps with their sources of error.

Ecosystems as communities of organisms with their abiotic environment, the meaning of biodiversity and niche, the biotic and abiotic factors that affect organisms, and competition within and between species.

Food chains and food webs and the flow of energy from producers through consumers, pyramids of numbers and of energy, and the loss of energy at each level that limits the length of food chains.

Mutation as the source of new alleles, variation and natural selection, and speciation through isolation by geographical, ecological or behavioural barriers followed by independent mutation and selection.

Food security and the need to increase food production, the use of fertilisers and the problem of algal blooms, the use of pesticides and bioaccumulation, and the alternatives of biological control and GM crops.

The word equation for photosynthesis, the two stages of the light reactions and carbon fixation, the uses of the sugar made, and the limiting factors that control the rate of photosynthesis.

The need for efficient exchange surfaces with a large surface area, and the adaptations of the alveoli for gas exchange in the lungs and of the villi for the absorption of nutrients in the small intestine.

The nervous system with the CNS and the three types of neuron and the reflex arc, the endocrine system using hormones and target tissues with receptors, and the control of blood glucose by insulin and glucagon from the pancreas.

The stages of mitosis and its role in growth, repair and maintaining the diploid chromosome number, stem cells and meristems as sources of unspecialised cells, and the specialisation of cells into tissues, organs and systems.

The production of haploid gametes in animals and plants, fertilisation as the fusion of two haploid gametes to form a diploid zygote, and how this restores the diploid chromosome number.

The four-chambered heart and the pathway of blood, the structure and function of arteries, veins and capillaries, and the components of blood including red and white cells, platelets and plasma.

The structure and function of xylem and phloem, the transpiration stream and the factors affecting its rate, and the role of stomata, guard cells and root hair cells in water movement and exchange.

Discrete and continuous variation and their genetic basis, the genetics terms phenotype, genotype, dominant and recessive, homozygous and heterozygous, and the use of Punnett squares to predict the outcomes of monohybrid crosses.