Biology 9700 — specification explorer

1. The microscope in cell

• 1.1.1make temporary preparations of cellular material suitable for viewing with a light microscope
• 1.1.2draw cells from microscope slides and photomicrographs
• 1.1.3calculate magnifications of images and actual sizes of specimens from drawings, photomicrographs and electron micrographs (scanning and transmission)
• 1.1.4use an eyepiece graticule and stage micrometer scale to make measurements and use the appropriate units, millimetre (mm), micrometre ( µ m) and nanometre (nm)
• 1.1.5define resolution and magnification and explain the differences between these terms, with reference to light microscopy and electron microscopy

2. Cells as the basic units of

• 1.2.1

  recognise organelles and other cell structures found in eukaryotic cells and outline their structures and functions, limited to: and mitochondria) continued:

  • cell surface membrane
  • nucleus, nuclear envelope and nucleolus
  • rough endoplasmic reticulum
  • smooth endoplasmic reticulum
  • Golgi body (Golgi apparatus or Golgi complex)
  • mitochondria (including the presence of small circular DNA)
  • ribosomes (80S in the cytoplasm and 70S in chloroplasts
  • lysosomes
  • centrioles and microtubules
  • cilia
  • microvilli
  • chloroplasts (including the presence of small circular DNA)
  • cell wall
  • plasmodesmata
  • large permanent vacuole and tonoplast of plant cells
• 1.2.2describe and interpret photomicrographs, electron micrographs and drawings of typical plant and animal cells
• 1.2.3compare the structure of typical plant and animal cells
• 1.2.4state that cells use ATP from respiration for energy-requiring processes
• 1.2.5

  outline key structural features of a prokaryotic cell as found in a typical bacterium, including:

  • unicellular
  • generally 1–5 µ m diameter
  • peptidoglycan cell walls
  • circular DNA
  • 70S ribosomes
  • absence of organelles surrounded by double membranes
• 1.2.6compare the structure of a prokaryotic cell as found in a typical bacterium with the structures of typical eukaryotic cells in plants and animals
• 1.2.7state that all viruses are non-cellular structures with a nucleic acid core (either DNA or RNA) and a capsid made of protein, and that some viruses have an outer envelope made of phospholipids

1. Testing for biological

• 2.1.1describe and carry out the Benedict’s test for reducing sugars, the iodine test for starch, the emulsion test for lipids and the biuret test for proteins
• 2.1.2describe and carry out a semi-quantitative Benedict’s test on a reducing sugar solution by standardising the test and using the results (time to first colour change or comparison to colour standards) to estimate the concentration
• 2.1.3describe and carry out a test to identify the presence of non-reducing sugars, using acid hydrolysis and Benedict’s solution

2. Carbohydrates and lipids

• 2.2.1describe and draw the ring forms of α-glucose and β-glucose
• 2.2.2define the terms monomer, polymer, macromolecule, monosaccharide, disaccharide and polysaccharide
• 2.2.3state the role of covalent bonds in joining smaller molecules together to form polymers
• 2.2.4state that glucose, fructose and maltose are reducing sugars and that sucrose is a non-reducing sugar
• 2.2.5describe the formation of a glycosidic bond by condensation, with reference to disaccharides, including sucrose, and polysaccharides continued
• 2.2.6describe the breakage of a glycosidic bond in polysaccharides and disaccharides by hydrolysis, with reference to the non-reducing sugar test
• 2.2.7describe the molecular structure of the polysaccharides starch (amylose and amylopectin) and glycogen and relate their structures to their functions in living organisms
• 2.2.8describe the molecular structure of the polysaccharide cellulose and outline how the arrangement of cellulose molecules contributes to the function of plant cell walls
• 2.2.9state that triglycerides are non-polar hydrophobic molecules and describe the molecular structure of triglycerides with reference to fatty acids (saturated and unsaturated), glycerol and the formation of ester bonds
• 2.2.10relate the molecular structure of triglycerides to their functions in living organisms
• 2.2.11describe the molecular structure of phospholipids with reference to their hydrophilic (polar) phosphate heads and hydrophobic (non-polar) fatty acid tails

3. Proteins

• 2.3.1describe and draw the general structure of an amino acid and the formation and breakage of a peptide bond
• 2.3.2explain the meaning of the terms primary structure, secondary structure, tertiary structure and quaternary structure of proteins
• 2.3.3

  describe the types of interaction that hold protein molecules in shape:

  • hydrophobic interactions
  • hydrogen bonding
  • ionic bonding
  • covalent bonding, including disulfide bonds
• 2.3.4state that globular proteins are generally soluble and have physiological roles and fibrous proteins are generally insoluble and have structural roles
• 2.3.5describe the structure of a molecule of haemoglobin as an example of a globular protein, including the formation of its quaternary structure from two alpha (α) chains (α–globin), two beta (β) chains (β–globin) and a haem group
• 2.3.6relate the structure of haemoglobin to its function, including the importance of iron in the haem group
• 2.3.7describe the structure of a molecule of collagen as an example of a fibrous protein, and the arrangement of collagen molecules to form collagen fibres
• 2.3.8relate the structures of collagen molecules and collagen fibres to their function

4. Water

• 2.4.1explain how hydrogen bonding occurs between water molecules and relate the properties of water to its roles in living organisms, limited to solvent action, high specific heat capacity and latent heat of vaporisation

1. Mode of action of enzymes

• 3.1.1state that enzymes are globular proteins that catalyse reactions inside cells (intracellular enzymes) or are secreted to catalyse reactions outside cells (extracellular enzymes)
• 3.1.2explain the mode of action of enzymes in terms of an active site, enzyme–substrate complex, lowering of activation energy and enzyme specificity, including the lock-and-key hypothesis and the induced-fit hypothesis
• 3.1.3investigate the progress of enzyme-catalysed reactions by measuring rates of formation of products using catalase and rates of disappearance of substrate using amylase
• 3.1.4outline the use of a colorimeter for measuring the progress of enzyme-catalysed reactions that involve colour changes

2. Factors that affect enzyme

• 3.2.1

  investigate and explain the effects of the following factors on the rate of enzyme-catalysed reactions:

  • temperature
  • pH (using buffer solutions)
  • enzyme concentration
  • substrate concentration
  • inhibitor concentration
• 3.2.2explain that the maximum rate of reaction (V ) is used to max derive the Michaelis–Menten constant (K ), which is used to compare the affinity of different enzymes for their substrates
• 3.2.3explain the effects of reversible inhibitors, both competitive and non-competitive, on enzyme activity
• 3.2.4investigate the difference in activity between an enzyme immobilised in alginate and the same enzyme free in solution, and state the advantages of using immobilised enzymes

1. Fluid mosaic membranes

• 4.1.1describe the fluid mosaic model of membrane structure with reference to the hydrophobic and hydrophilic interactions that account for the formation of the phospholipid bilayer and the arrangement of proteins
• 4.1.2describe the arrangement of cholesterol, glycolipids and glycoproteins in cell surface membranes
• 4.1.3describe the roles of phospholipids, cholesterol, glycolipids, proteins and glycoproteins in cell surface membranes, with reference to stability, fluidity, permeability, transport (carrier proteins and channel proteins), cell signalling (cell surface receptors) and cell recognition (cell surface antigens – see
• 4.1.4

  outline the main stages in the process of cell signalling leading to specific responses:

  • secretion of specific chemicals (ligands) from cells
  • transport of ligands to target cells
  • binding of ligands to cell surface receptors on target cells

2. Movement into and out of

• 4.2.1describe and explain the processes of simple diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis
• 4.2.2investigate simple diffusion and osmosis using plant tissue and non-living materials, including dialysis (Visking) tubing and agar
• 4.2.3illustrate the principle that surface area to volume ratios decrease with increasing size by calculating surface areas and volumes of simple 3-D shapes (as shown in the Mathematical requirements)
• 4.2.4investigate the effect of changing surface area to volume ratio on diffusion using agar blocks of different sizes continued
• 4.2.5investigate the effects of immersing plant tissues in solutions of different water potentials, using the results to estimate the water potential of the tissues
• 4.2.6explain the movement of water between cells and solutions in terms of water potential and explain the different effects of the movement of water on plant cells and animal cells (knowledge of solute potential and pressure potential is not expected)

1. Replication and division of

• 5.1.1

  describe the structure of a chromosome, limited to:

  • DNA
  • histone proteins
  • sister chromatids
  • centromere
  • telomeres
• 5.1.1a

  2 replication in S phase) 4 outline the role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication 5 outline the role of stem cells in cell replacement and tissue repair by mitosis 6 explain how uncontrolled cell division can result in the formation of a tumour:

  • mitosis
  • cytokinesis
• 5.1.2

  explain the importance of mitosis in the production of genetically identical daughter cells during:

  • growth of multicellular organisms
  • replacement of damaged or dead cells
  • repair of tissues by cell replacement
  • asexual reproduction
• 5.1.3

  outline the mitotic cell cycle, including:

  • interphase (growth in G and G phases and DNA

2. Chromosome behaviour in

• 5.2.1describe the behaviour of chromosomes in plant and animal cells during the mitotic cell cycle and the associated behaviour of the nuclear envelope, the cell surface membrane and the spindle (names of the main stages of mitosis are expected: prophase, metaphase, anaphase and telophase)
• 5.2.2interpret photomicrographs, diagrams and microscope slides of cells in different stages of the mitotic cell cycle and identify the main stages of mitosis

1. Structure of nucleic acids

• 6.1.1describe the structure of nucleotides, including the phosphorylated nucleotide ATP (structural formulae are not expected)
• 6.1.2state that the bases adenine and guanine are purines with a double ring structure, and that the bases cytosine, thymine and uracil are pyrimidines with a single ring structure (structural formulae for bases are not expected)
• 6.1.3

  describe the structure of a DNA molecule as a double helix, including: the 5 ′ to 3 ′ strand and the 3 ′ to 5 ′ strand (antiparallel strands) base pairs:

  • the importance of complementary base pairing between
  • differences in hydrogen bonding between C–G and A–T
  • linking of nucleotides by phosphodiester bonds
• 6.1.4

  describe the semi-conservative replication of DNA during the S phase of the cell cycle, including: of other enzymes in DNA replication in cells and different types of DNA polymerase is not expected) replication as a consequence of DNA polymerase adding nucleotides only in a 5 ′ to 3 ′ direction:

  • the roles of DNA polymerase and DNA ligase (knowledge
  • the differences between leading strand and lagging strand
• 6.1.5describe the structure of an RNA molecule, using the example of messenger RNA (mRNA)

2. Protein synthesis

• 6.2.1state that a polypeptide is coded for by a gene and that a gene is a sequence of nucleotides that forms part of a DNA molecule
• 6.2.2describe the principle of the universal genetic code in which different triplets of DNA bases either code for specific amino acids or correspond to start and stop codons continued
• 6.2.3

  describe how the information in DNA is used during transcription and translation to construct polypeptides, including the roles of:

  • RNA polymerase
  • messenger RNA (mRNA)
  • codons
  • transfer RNA (tRNA)
  • anticodons
  • ribosomes
• 6.2.4state that the strand of a DNA molecule that is used in transcription is called the transcribed or template strand and that the other strand is called the non-transcribed strand
• 6.2.5explain that, in eukaryotes, the RNA molecule formed following transcription (primary transcript) is modified by the removal of non-coding sequences (introns) and the joining together of coding sequences (exons) to form mRNA
• 6.2.6state that a gene mutation is a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide
• 6.2.7explain that a gene mutation is a result of substitution or deletion or insertion of nucleotides in DNA and outline how each of these types of mutation may affect the polypeptide produced

1. Structure of transport tissues

• 7.1.1draw plan diagrams of transverse sections of stems, roots and leaves of herbaceous dicotyledonous plants from microscope slides and photomicrographs
• 7.1.2describe the distribution of xylem and phloem in transverse sections of stems, roots and leaves of herbaceous dicotyledonous plants
• 7.1.3draw and label xylem vessel elements, phloem sieve tube elements and companion cells from microscope slides, photomicrographs and electron micrographs
• 7.1.4relate the structure of xylem vessel elements, phloem sieve tube elements and companion cells to their functions

2. Transport mechanisms

• 7.2.1state that some mineral ions and organic compounds can be transported within plants dissolved in water
• 7.2.2

  describe the transport of water from the soil to the xylem through the: cellulose Casparian strip and suberin:

  • apoplast pathway, including reference to lignin and
  • symplast pathway, including reference to the endodermis,
• 7.2.3explain that transpiration involves the evaporation of water from the internal surfaces of leaves followed by diffusion of water vapour to the atmosphere
• 7.2.4explain how hydrogen bonding of water molecules is involved with movement of water in the xylem by cohesion-tension in transpiration pull and by adhesion to cellulose in cell walls
• 7.2.5make annotated drawings of transverse sections of leaves from xerophytic plants to explain how they are adapted to reduce water loss by transpiration
• 7.2.6state that assimilates dissolved in water, such as sucrose and amino acids, move from sources to sinks in phloem sieve tubes
• 7.2.7explain how companion cells transfer assimilates to phloem sieve tubes, with reference to proton pumps and cotransporter proteins
• 7.2.8explain mass flow in phloem sieve tubes down a hydrostatic pressure gradient from source to sink

1. The circulatory system

• 8.1.1state that the mammalian circulatory system is a closed double circulation consisting of a heart, blood and blood vessels including arteries, arterioles, capillaries, venules and veins
• 8.1.2describe the functions of the main blood vessels of the pulmonary and systemic circulations, limited to pulmonary artery, pulmonary vein, aorta and vena cava
• 8.1.3recognise arteries, veins and capillaries from microscope slides, photomicrographs and electron micrographs and make plan diagrams showing the structure of arteries and veins in transverse section (TS) and longitudinal section (LS)
• 8.1.4explain how the structure of muscular arteries, elastic arteries, veins and capillaries are each related to their functions
• 8.1.5recognise and draw red blood cells, monocytes, neutrophils and lymphocytes from microscope slides, photomicrographs and electron micrographs
• 8.1.6state that water is the main component of blood and tissue fluid and relate the properties of water to its role in transport in mammals, limited to solvent action and high specific heat capacity
• 8.1.7state the functions of tissue fluid and describe the formation of tissue fluid in a capillary network

2. Transport of oxygen and

• 8.2.1

  describe the role of red blood cells in transporting oxygen and carbon dioxide with reference to the roles of:

  • haemoglobin
  • carbonic anhydrase
  • the formation of haemoglobinic acid
  • the formation of carbaminohaemoglobin
• 8.2.2describe the chloride shift and explain the importance of the chloride shift
• 8.2.3describe the role of plasma in the transport of carbon dioxide
• 8.2.4describe and explain the oxygen dissociation curve of adult haemoglobin
• 8.2.5explain the importance of the oxygen dissociation curve at partial pressures of oxygen in the lungs and in respiring tissues
• 8.2.6describe the Bohr shift and explain the importance of the Bohr shift

3. The heart

• 8.3.1describe the external and internal structure of the mammalian heart
• 8.3.2

  explain the differences in the thickness of the walls of the:

  • atria and ventricles
  • left ventricle and right ventricle
• 8.3.3describe the cardiac cycle, with reference to the relationship between blood pressure changes during systole and diastole and the opening and closing of valves
• 8.3.4explain the roles of the sinoatrial node, the atrioventricular node and the Purkyne tissue in the cardiac cycle (knowledge of nervous and hormonal control is not expected)

1. The gas exchange system

• 9.1.1

  describe the structure of the human gas exchange system, limited to:

  • lungs
  • trachea
  • bronchi
  • bronchioles
  • alveoli
  • capillary network
• 9.1.2describe the distribution in the gas exchange system of cartilage, ciliated epithelium, goblet cells, squamous epithelium of alveoli, smooth muscle and capillaries
• 9.1.3recognise cartilage, ciliated epithelium, goblet cells, squamous epithelium of alveoli, smooth muscle and capillaries in microscope slides, photomicrographs and electron micrographs
• 9.1.4recognise trachea, bronchi, bronchioles and alveoli in microscope slides, photomicrographs and electron micrographs and make plan diagrams of transverse sections of the walls of the trachea and bronchus
• 9.1.5describe the functions of ciliated epithelial cells, goblet cells and mucous glands in maintaining the health of the gas exchange system
• 9.1.6describe the functions in the gas exchange system of cartilage, smooth muscle, elastic fibres and squamous epithelium
• 9.1.7describe gas exchange between air in the alveoli and blood in the capillaries

1. Infectious diseases

• 10.1.1state that infectious diseases are caused by pathogens and are transmissible
• 10.1.2

  state the name and type of pathogen that causes each of the following diseases: falciparum , Plasmodium malariae , Plasmodium ovale and Plasmodium vivax tuberculosis and Mycobacterium bovis (HIV):

  • cholera – caused by the bacterium Vibrio cholerae
  • malaria – caused by the protoctists Plasmodium
  • tuberculosis (TB) – caused by the bacteria Mycobacterium
  • HIV/AIDS – caused by the human immunodeficiency virus
• 10.1.3explain how cholera, malaria, TB and HIV are transmitted
• 10.1.4discuss the biological, social and economic factors that need to be considered in the prevention and control of cholera, malaria, TB and HIV (details of the life cycle of the malarial parasite are not expected)

2. Antibiotics

• 10.2.1outline how penicillin acts on bacteria and why antibiotics do not affect viruses
• 10.2.2discuss the consequences of antibiotic resistance and the steps that can be taken to reduce its impact

1. The immune system

• 11.1.1describe the mode of action of phagocytes (macrophages and neutrophils)
• 11.1.2explain what is meant by an antigen (see 4.1.3) and state the difference between self antigens and non-self antigens
• 11.1.3

  describe the sequence of events that occurs during a primary immune response with reference to the roles of:

  • macrophages
  • B-lymphocytes, including plasma cells
  • T-lymphocytes, limited to T-helper cells and T-killer cells
• 11.1.4explain the role of memory cells in the secondary immune response and in long-term immunity

2. Antibodies and vaccination

• 11.2.1relate the molecular structure of antibodies to their functions
• 11.2.2outline the hybridoma method for the production of monoclonal antibodies
• 11.2.3outline the principles of using monoclonal antibodies in the diagnosis of disease and in the treatment of disease
• 11.2.4describe the differences between active immunity and passive immunity and between natural immunity and artificial immunity
• 11.2.5explain that vaccines contain antigens that stimulate immune responses to provide long-term immunity
• 11.2.6explain how vaccination programmes can help to control the spread of infectious diseases