DP Biology practicals

Design Statements:

• Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes. (2.5)

• Design of experiments to investigate the effect of limiting factors on photosynthesis. (2.9)

• Design of an experiment to assess one factor affecting the rooting of stem-cuttings. (3.5)

• Design of an experiment to test hypotheses about the effect of temperature or humidity on transpiration rates. (9.1)

• Design of experiments to test hypotheses about factors affecting germination. (9.4)

Drawing Statements:

• Drawing of the ultrastructure of prokaryotic cells based on electron micrographs. (1.2)

• Drawing of the ultrastructure of eukaryotic cells based on electron micrographs. (1.2)

• Drawing of the fluid mosaic model. (1.3)

• Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid. (2.1)

• Drawing molecular diagrams to show the formation of a peptide bond. (2.4)

• Drawing simple diagrams of the structure of single nucleotides of DNA and RNA, using circles, pentagons and rectangles to represent phosphates, pentoses and bases. (2.6) please note that there is a typo on this assessment statement.

• Drawing an absorption spectrum for chlorophyll and an action spectrum for photosynthesis. (2.9)

• Drawing diagrams to show the stages of meiosis resulting in the formation of four haploid cells. (3.3)

• Construct a diagram of the carbon cycle. (4.3)

• Production of an annotated diagram of the digestive system. (6.1)

• Draw a diagram of an alveolus and an associated capillary (6.4)

• Drawing the structure of primary xylem vessels in sections of stems based on microscope images. (9.1)

• Drawing internal structure of seeds. (9.4)

• Drawing of half-views of animal-pollinated flowers. (9.4)

• Drawing diagrams to show chiasmata formed by crossing over. (10.1)

• Drawing labelled diagrams of the structure of a sarcomere. (11.2)

• Drawing and labelling a diagram of the human kidney. (11.3)

Required Practicals:

• Use of a light microscope to investigate the structure of cells and tissues, with drawing of cells. Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. (Practical 1)

• Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. (Practical 2)

• Experimental investigation of a factor affecting enzyme activity. (Practical 3)

• Separation of photosynthetic pigments by chromatograph. (Practical 4)

• Setting up sealed mesocosms to try to establish sustainability. (Practical 5)

• Monitoring of ventilation in humans at rest and after mild and vigorous exercise. (Practical 6)

• Measurement of transpiration rates using potometers. (Practical 7)

Database links

• Use of a database to determine differences in the base sequence of a gene in two species. (3.1)

• Use of databases to identify the locus of a human gene and its polypeptide product. (3.2)

Classic Experiments referred to in the syllabus:

• Davson & Danielli experimental evidence for the structure of cell membranes.

• Evidence from Pasteur’s experiments that spontaneous generation of cells and organisms does not now occur on Earth. (1.5)

• Serendipity and scientific discoveries—the discovery of cyclins was accidental. (1.4)

• Falsification of theories—the artificial synthesis of urea helped to falsify vitalism. (1.9)

• Application: Crick and Watson’s elucidation of the structure of DNA using model making. (2.6)

• Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA. (2.7)

• Developments in research follow improvements in techniques—autoradiography was used to establish the length of DNA molecules in chromosomes. (1.8). 

• Application: Cairns’ technique for measuring the length of DNA molecules by autoradiography.

• Application: Description of methods used to obtain cells for karyotype analysis e.g. chorionic villus sampling and amniocentesis and the associated risks.

• Application: Changes in beaks of finches on Daphne Major.

• Application: Reclassification of the figwort family using evidence from cladistics.

• Application: William Harvey’s discovery of the circulation of the blood with the heart acting as the pump.

• Application: Florey and Chain’s experiments to test penicillin on bacterial infections in mice.

• Application: William Harvey’s investigation of sexual reproduction in deer.

• HL Only

• Application: Rosalind Franklin’s and Maurice Wilkins’ investigation of DNA structure by X-ray diffraction.

• Application: Use of nucleotides containing dideoxyribonucleic acid to stop DNA replication in preparation of samples for base sequencing.

• Skill: Analysis of results of the Hershey and Chase experiment providing evidence that DNA is the genetic material.

• Application: Calvin’s experiment to elucidate the carboxylation of RuBP.

• Skill: Analysis of data from experiments measuring phloem transport rates using aphid stylets and radioactively-labelled carbon dioxide.

• Application: Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species.

• Application: Morgan’s discovery of non-Mendelian ratios in Drosophila.