Topic 1
State where proteins synthesised by free ribosomes are used. [1]
Within the cytoplasm.
State the three components of a DNA nucleotide.
Phosphate, deoxyribose and base (e.g. adenine, guanine, cytosine and thymine)
State an application of plasmids in biotechnology. [1]
Used as a vector to transfer genetic material and produce a useful protein, like insulin.
State one role of saprotrophic organisms in the ecosystem. [1]
Decomposer / recycle nutrients / break down organic material into inorganic material.
State the name of the domain to which birds, such as the Elf owl, belong. [1]
Eukaryote
Outline the effects of putting plant tissue in a hypertonic solution. [4]
Hypertonic solution has a higher solute concentration than the cells. [1]
Water moves out of the cells by osmosis. [1]
In osmosis, water moves from lower solute concentration to higher solute concentration. [1]
Cell is plasmolysed and no longer turgid. [1]
Reject answers based on water concentrations. Reject cell decreases in size. Reject plant cells shrink or shrivel.
Outline the properties of water molecules that permit them to move upwards in plants. [2]
Water molecules are polar and can form hydrogen bonds [1].
This promotes cohesion between water molecules, which allows a transpiration stream to form in the xylem [1].
Outline the causes of sickle cell anaemia. [2]
Base substitution (GAG → GTG ) [1]
Leads to change in amino acid sequence in haemoglobin (glutamic acid → valine) [1]
Outline causes of ocean acidification. [2]
Carbon dioxide from burning fossil fuels/forest fires [1] dissolves in water to form carbonic acid [1].
Outline the process of adaptive radiation. [2]
Different members of a species occupy different niches and are exposed to different selection pressures [1]. This gives rise to new species that share common structures adapted to the new environment [1] (e.g. Galapagos finches and vertebrate pentadactyl limb) [1].
Distinguish prokaryotic cells and eukaryotic cells [1].
Prokaryotic cells are not compartmentalised (no membrane-bound organelles / 70s ribosomes), while eukaryotic cells are compartmentalised (have membrane-bound organelles / 80s ribosomes).
Distinguish between the thermal properties of water and methane. [4]
Water is polar, whereas methane is non-polar. [1]
Water forms strong hydrogen bonds between the molecules, whereas methane doesn't. [1]
Water has a higher boiling point, whereas methane has a lower boiling point. [1]
Water has a higher melting point, whereas methane has a lower melting point. [1]
Water has a higher specific heat capacity, whereas methane has a lower specific heat capacity. [1]
Distinguish between mitosis and meiosis. [4]
In meiosis, there is a random separation of homologous chromosomes, whereas in mitosis there is no random separation of homologous chromosomes. [1]
Meiosis produces four cells, whereas mitosis produces two. [2]
Meiosis produces genetically different cels, whereas mitosis produces genetically identical cells. [3]
Meiosis occurs in gamete cells, whereas mitosis occurs in somatic cells. [4]
Distinguish between the exchange of matter and energy with the surroundings in a closed mesocosm. [1]
Matter does not exchange/enter/leave, whereas energy exchanges/enters/leaves. [1]
Distinguish archaea from eubacteria. [3]
Archaea has DNA with histone proteins, whereas eubacteria has DNA with no histone proteins. [1]
Archaea usually has introns, whereas eubacteria seldom have introns. [1]
Archaea cell walls lack peptidoglycan, whereas eubacteria cell walls have peptidoglycan. [1]
Archaea are found in extreme environments, whereas eubacteria are not in extreme environments. [1]
Draw a labelled diagram of a eukaryotic plant cell as seen in an electron micrograph. [4]
Cell wall shown with two continuous lines to indicate the thickness
Plasma membrane/cell membrane shown as a single continuous line
Nuclear membrane/nucleus shown with double membrane and nuclear pores
Vacuole shown as a single continuous line
Chloroplast/plastid shown with a double line to indicate the envelope and thylakoids/grana
Mitochondrion shown with double membrane/cristae
Draw a graph to show the effect of increasing light intensity on the rate of photosynthesis. [1]
Graph shows light intensity increases with a plateau shown as a flat line parallel to the x-axis. Do not accept sigmoid curves.
Draw a pedigree showing the inheritance of red-green colour blindness or haemophilia.
Red-green colour blindness and haemophilia are examples of X-linked recessive conditions. Two unaffected parents can have an affected offspring; more common in biological. males.
Draw a labelled diagram of a pyramid of energy. [4]
a. drawn in steps rather than triangle [1]
b. drawn to scale (should be at least 1/5 of the box below it) OR annotated with appropriate numeric values [1]
c. producer [1]
d. primary consumer, secondary consumer [4]
Draw a diagram to represent an organism in the following phyla: annelida, cnidaria, coniferophyta and angiospermophyta.
Annelida: segmented worm
Cnidaria: radial symmetry: jellyfish + coral
Coniferophyta: pine tree / cones
Angiospermophyta: flowering plant
Explain how the cell cycle is controlled. [4]
Cell cycle is a sequence of stages (G1, S, G2 and mitosis) [1]
The cell cycle is controlled by cyclins [1]
Levels of cyclins fluctuate during the cell cycle [1]
Four cyclins regulate different stages of the cell cycle [1]
Cyclin-dependent kinases activate cyclins (via phosphorylation) [1]
Explain the process of photosynthesis. [6]
Autotrophs perform photosynthesis [1]
Carbon dioxide and water are the reactants required for photosynthesis [1]
Light energy is converted into chemical energy [1]
Photosynthesis produces organic compounds / glucose / carbohydrates [1]
Photosynthesis occurs in chloroplasts [1]
Chlorophyll absorbs red and blue light [1]
Different pigments absorb different wavelengths of light [1]
Carbon dioxide concentration/temperature/light intensity are limiting factors [1]
Explain the roles of specific enzymes in DNA replication. [4]
Helicase breaks hydrogen bonds between the two strands of DNA [1]
Helicase uncoils/unwinds the DNA/double helix [1]
DNA polymerase adds DNA nucleotides/replicates DNA/synthesises complementary strand [1]
DNA polymerase uses pre-existing strand of DNA as template [1]
DNA polymerase makes covalent bonds between nucleotides [1]
Explain the interaction of short and long wave radiation with greenhouse gases in the atmosphere. [3]
Short wave radiation (UV) from the sun passes through greenhouse gases [1]
The reflected radiation from Earth is long wave (heat / infrared) radiation [1]
Long wave radiation (infrared) is absorbed and reflected by greenhouse gases [1]
Explain how the process of evolution occurs. [8]
Evolution is a change in population/species over time [1]
A population has variations amongst the individuals [1] due to mutation [1] and meiosis / sexual reproduction [1]
Populations/species produce more offspring than the environment can support (overpopulation) [1]
Individuals of the species compete for the same resources [1]
Certain variations give an advantage to some organisms over others in certain environments [1]
The better-adapted organisms tend to survive and reproduce (reproductive advantage) [1]
Individuals that reproduce pass on their characteristics/alleles/genes to their offspring [1]
Natural selection increases the frequency of characteristics/alleles/genes of the better-adapted organisms [1]