Practise IB Biology HL A Unity and Diversity through questions on water, nucleic acids, cells, viruses, biodiversity, classification and evolution, including the wider HL…
The image shows the results of Griffith's experiment with S and R strains of Streptococcus pneumoniae in mice (Mus musculus).
What is an explanation for the results?
Mice vary in their resistance to bacteria.
The R strain and S strain mated.
R strain bacteria are more heat-stable than S strain.
DNA was transferred from heat-killed S cells to R cells.
The synthesis of complex organic molecules in sea water is believed to be an important step in the evolution of life on Earth. Researchers investigated whether the evaporation of sea water containing amino acids could catalyse the formation of dipeptides such as divaline (valine-valine) under prebiotic Earth conditions. They placed different amino acid combinations in a chamber to simulate the evaporation cycles between high tides in shallow seas. In one investigation the amino acid valine was used as the substrate and the percentage yield of divaline was measured after different numbers of evaporation cycles. The experiment was repeated without a catalyst and with either glycine or histidine as catalysts.
This investigation was performed in a chamber at leading to total evaporation of the salt water within one day. The atmosphere inside the chamber consisted of nitrogen, carbon dioxide and water vapour. Evaluate the experiment on the basis of similarity with conditions that existed on the prebiotic Earth.
Outline other possible locations where conditions could have allowed the synthesis of organic molecules under prebiotic conditions.
Outline the cell theory.
Calculate the magnification of the electron micrograph.
The table shows the number of amino acids that are different in the sequences of the protein FOXP2 from a human compared with four other primate species.
Identify the total number of different genera named in the table.
Using evidence from the diagrams, justify the hypothesis that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 with a shared primate ancestor.
Some infectious diseases in humans are caused by viruses that originated in other primates.
State one structural feature of a virus.