Biology HL 2024/2025 Paper 2 IB: Question & updated Answers for Exam Revision

Calculate the total number of M. lucifugus fl ights that were recorded in the summer of 2007 - Ans .(32 × 79) = 2528 Suggest one limitation of this recording method in determining the accurate mean number of individual bats flying. - Ans .same bat may be recorded more than once or some bats may not fly over the recording station Calculate the percentage decline in the mean number of M. lucifugus flights for 2009 when compared to 2008. - Ans .82 / 82.1 / 82.14 (% decline) Evaluate the conclusion that the decline in the population of M. lucifugus is due to infection by the fungus. - Ans .(2008 to 2009) M. lucifugus declines more (than L. cinereus) Distinguish between the patterns of hibernation of the uninfected and infected bats - Ans .more fluctuation in (body) temperature (during hibernation) in infected (than uninfected bats Based on the data and your biological knowledge, suggest how the infection could lead to premature death in a bat. - Ans .1. energy needed to raise body temperature / lost during temperature spikes 2. (more) heat loss/hypothermia (in winter/cold weather 3. bats die/starve if fat/energy/food stores used up Outline the relationship between date of death and the mean interval between hibernation emergence periods. - Ans .later date of death with longer/bigger intervals (between hibernation emergence)/with less frequent interruptions (to hibernation) Discuss whether the data in the graph show that there is a causal link between the date of death and the interval between hibernation emergence periods. - Ans .d. more data/further research is needed to show the causes e. there is (much) variation/spread in the data Suggest one reason, other than the interval between hibernation emergence periods, for some infected bats surviving longer than others. - Ans .differences in body mass Using all of the data, predict the effect of WNS on bat populations. - Ans .a. higher mortality/more deaths b. extinction/reduction in (size of) of bat populations c. bats will emerge more from hibernation/in winter State two features that are found only in mammals - Ans .a) hair/fur b) sweat glands Birds, bats and humans are all vertebrates with pentadactyl limbs. Birds and bats use their forelimbs to fly whereas humans can use them to lift and manipulate objects. Outline how the bird, bat and human forelimb can be used to illustrate the concept of homologous structures. - Ans .a. (homologous structures have evolved) from a common ancestor b. different uses/functions C. nemoralis is a mollusc. Identify two external features that distinguish this snail from an arthropod. - Ans .b. shell (versus exoskeleton in arthropods) c. muscular foot (which arthropods do not have) State the major chemical component of the shell in molluscs. - Ans .calcium carbonate/ CaCO3 Distinguish between sex-linked genes and genes with linked loci. - Ans .sex-linked genes are on sex/X chromosome(s)/on chromosome 23