Use a light microscope to: make observations of (i) transverse sections of roots, stems, leaves; (ii) plant tissues; (iii) identify sclerenchyma fibres, phloem, sieve tubes, xylem vessels and their location OBJECTIVES ● To be able to use a microscope competently to...
Determine the tensile strength of plant fibres OBJECTIVES ● To know how to determine the tensile strength of plant fibres ● To be able to comment on experimental design and evaluate scientific methods SAFETY ● Use a sharp knife, place the celery on the tile and cut...
Investigate the antimicrobial properties of plants, including aseptic techniques for the safe handling of bacteria OBJECTIVES ● To successfully compare the effect of plants on microbial growth ● To understand the safety issues of microbiological work and how to apply...
Prepare and stain a root tip squash to observe the stages of mitosis OBJECTIVES ● To know how to prepare a temporary slide of a root tip to observe mitosis ● To recognise the stages of mitosis in dividing cells ● To identify hazards, associated risks and control...
Investigate the effect of temperature, pH, enzyme concentration and substrate concentration on the initial rate of enzyme-catalysed reactions. OBJECTIVES ● To be able to measure the initial rate of enzyme activity ● To understand why measuring the initial rate is...
(i) Use a light microscope to make observations and labelled drawings of suitable animal cells; (ii) Use a graticule with a microscope to make measurements and understand the concept of scale OBJECTIVES ● To be competent in the use of a microscope at high and low...
Investigate the vitamin C content of food and drink. OBJECTIVES ● To be able to calculate the vitamin C concentration of fruit juices using the titration method ● To solve problems set in practical contexts ● To process and analyse data using appropriate mathematical...
Investigate membrane properties including the effect of alcohol and temperature on membrane permeability. OBJECTIVES ● To know how the effect of temperature and alcohol on membranes can be determined ● To be able to recognise quantitative variables that should be...
SUMMARY • The Hardy-Weinberg equilibrium describes the phenomenon whereby allele frequencies in a non-changing population do not change between generation • This describes an idealise state that population geneticists use to study past and present genotype frequencies...
Use a semi-quantitative method with Benedict's reagent to estimate the concentrations of reducing sugars and with iodine solution to estimate the concentrations of starch, using colour standards. OBJECTIVES ● To understand what is meant by a semi-quantitative test ●...
XYLEM The xylem transports water and minerals from the roots up the plant stem and into the leaves. In a mature flowering plant or tree, most of the cells that make up the xylem are specialised cells called vessels. Vessels: • Lose their end walls so the xylem forms a...
CELL ULTRASTRUCTURE • Chloroplasts • Amyloplasts • Vacuole • Tonoplast • Plasmodesmata • Pits • Cellulose cell wall • Middle lamella CHLOROPLASTS belong to a family of closely related plant organelles called plastids. They contain pigment chlorophyll. They are the...
FOXGLOVES • Foxgloves – Digitalis purpurea • The leaves are poisonous when eaten by humans and animals. • They have a string bitter taste as a warning. • Symptoms of poisoning: o Dizziness o Vomiting o Diarrhoea o Hallucinations o Heart failure – irregular heart beat...
• The variety of living species • The degree of nature’s variety • It allows for the permanent stability of an ecosystem • Involves an equilibrium between species. Biodiversity can be considered at different levels. HABITAT • Range of habitats • Each may be occupied...
Species = group of organisms which are able to breed freely to produce fertile offspring. Courtship behaviour = precursor behaviour to mating. Courtship behaviours are often species-specific and therefore aid in species recognition. • Process by which we allocate...
• The epigenome influences which genes can be transcribed in a particular cell. • The attachment of X to the DNA of a gene prevents transcription to mRNA, by stopping the RNA polymerase binding. • The modification by addition of X affects how tightly the DNA is...
• Cell organelles - mitochondria, ribosomes, nucleus • Cells - white blood cell, villi, sperm, goblet • Tissues - Cardiac, muscle, epithelial, nervous, connective • Organs - liver, heat, kidney • Organ systems - respiratory, cardiovascular • Organisms...
Many genes coding for one phenotype. Each copy of the allele (found at loci on the chromosome) has a small effect on the characteristics. The effects of several alleles together contribute to the phenotype of an individual. TANNING • Melanin is made in melanocytes in...
Crossing over is when two sister chromatids join up together at the chiasma. At the chiasma, the chromatids break and exchange section of genetic material. [Prophase (I)] Independent assortment; the chromosomes line up along the equator in their homologous pairs. The...
Cells divide on a regular basis to bring about growth and asexual reproduction. The cells divide in a sequence known as the cell cycle. There is a period of non-division known as interphase, when cells increase in size, mass and carry out normal cellular activities...
Pollen grain lands on the stigma and pollen tube grows through the style. • Haploid generative nucleus divides to form two haploid gametes nuclei that move down the pollen tube. • Tube grows through embryo sac inside the ovule and the two male gamete nuclei enter the...
Gametes are formed from cells in the reproductive organs by a type of cell division called meiosis. The cells that are formed by meiosis have half the number of chromosomes as a body cell (they are haploid). The main features of meiosis are: - • The cell divides...
Totipotent: can mature into any type of body cell in an organism, including the cells that make up the placenta Pluripotent: can mature into any cell in the body, but not the placenta Multipotent: can mature into a few different types of cell Unipotent: only can...
Ribosome is attached to the rough endoplasmic reticulum. It's made up of proteins and RNA, and not surrounded by a membrane. Golgi apparatus is a group of fluid-filled, membrane-bound flattened sacs, vesicles are often seen at the edges of the sacs. • Transcription of...
MAGNIFICATION EQUATION Magnification = image length / actual length LIGHT MICROSCOPY AKA Optical Microscopes use light and several lenses to magnify a sample. Light from the Condenser Lens, and then through the Specimen where certain wavelengths are filtered to...
Sperm have special features that make them well adapted: flagella/streamline, acrosome, haploid nucleus and mitochondria for energy. The egg is large and unable to move independently. The cytoplasm contains protein and lipid food reserves. • Sperm reaches the ovum •...
EUKARYOTIC CELLS • Cell-surface (plasma) membrane • Nucleus • Mitochondria • Chloroplasts (plants) • Golgi apparatus • Golgi vesicle • Lysosome • Ribosome • Rough endoplasmic reticulum • Smooth endoplasmic reticulum • Cell wall (plants) • Cell vacuole • Centrioles...
GENE AND GENOME: a gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain. Together all genes in an individual are known as the genome. DNA is a chain of nucleotides: DNA is one type of nucleic acid, called...
CF PROBLEMS: • CF is caused by a faulty transport protein in the surface membranes of epithelial cells • CF creates a sticky mucus layer that lines the tubes and ducts in the gas exchange, digestive and reproductive systems. • The sticky mucus increases the chances of...
FEATURES OF A GOOD GAS EXCHANGE SURFACE: • large surface area for the alveoli • numerous capillaries around the alveoli • thin walls of the alveoli and capillaries meaning a short distance between the alveolar air and the blood in the capillaries THE RATE OF DIFFUSION...
WHY HAVE A HEART AND CIRCULATION? The purpose of the heart and circulation is to move substances around the body. In small creatures such as unicellular creatures- substances such as oxygen, carbon dioxide and digestive products are moved around the organism by...
• Body mass index (BMI): conventionally used method of classifying body weight relative to a person’s height. • To calculate BMI: o Body mass (Kg)/ height (meters) squared • Evidence suggests that waist-to-hip ratio is a better measure of obesity than BMI. o And it...
• Recommended amounts for nutrients and daily energy requirements GETTING IT RIGHT • Dietary reference values (DRVs): are estimates of the requirements and aren’t recommendations or goals for individuals • These include: o An estimated average requirement (EAR) o A...
• Obesity can increase the risk of CHD and stroke even without other risk factors being present • The more excess fat carried especially around the middle, the greater the risk is to the heart • Obesity can also increase the risk of type II diabetes o Which in turn...
Correlation: two variables are positively correlated when an increase in one is accompanied by an increase in the other • Large amounts of data are needed to ensure that the correlation is statistically significant o This ensures that it didn’t happen by chance •...
THE CELL SURFACE MEMBRANE CONSISTS OF: • Phospholipid bilayer (all the molecules are arranged so that the hydrophobic tails are inside the bilayer) • proteins • cholesterol • glycoproteins (protein molecules with polysaccharides attached) • glycolipids (lipid...
DIFFUSION: • High to low concentration until equilibrium reached • hydrophobic (lipid - soluble) or small uncharged molecules • through phospholipid bilayer • passive, no energy required FACILITATED DIFFUSION: • high to low concentration until equilibrium reached •...
Enzymes are globular proteins that act and biological catalysts (They speed up chemical reactions). There is a depression on the surface of the enzyme molecule called the active site. LOCK AND KEY THEORY: • a molecule with a complimentary shape can fit into the active...
Protein structure is key in protein function: Amino acids consist of an amine group, a carboxylic acid group, Primary structure - Two amino acids join in a condensation reaction to form a dipeptide (this can be more than two amino acids in length and they are joined...
LIPIDS Are organic molecules found in every type of cell Are insoluble in water but soluble in organic solvents g. ethanol SYNTHESIS OF A TRIGLYCERIDE Triglycerides are made up of 3 fatty acids + 1 glycerol molecule linked by condensation reaction Ester bonds form...
Understand the importance of water as a solvent in transport, including its dipole nature Water is a polar molecule= it has an unevenly distributed chemical charge The two hydrogens are pushed towards each other forming a V shaped molecule Hydrogen= slightly positive...
(i) know the difference between monosaccharides, disaccharides and polysaccharides, including glycogen and starch (amylose and amylopectin) (ii) be able to relate the structures of monosaccharides, disaccharides and polysaccharides to their roles in providing and...