The adult damselfly uses a tracheal system for gas exchange.

Explain three ways in which an insect's tracheal system is adapted for efficient gas exchange.

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The damselfly larva is a carnivore that actively hunts prey. It has gills to obtain oxygen from water.

Some other species of insect have larvae that are a similar size and shape to damselfly larvae and also live in water. These larvae do not actively hunt prey and do not have gills.

Explain how the presence of gills adapts the damselfly to its way of life.

A scientist measured the size of each gill lamella of the gills of 40 damselfly larvae. His results are shown in Table 5.

Calculate the mean surface area of one side of one gill lamella. Assume that a gill lamella is rectangular and give your answer to an appropriate number of significant figures.

Include the percentage error (uncertainty) of surface area in your answer. Show your working.

Mean surface area =

Percentage error (uncertainty) of surface area =

A student used an optical microscope to observe part of a damselfly larva gill.

Figure 5 shows the drawing the student produced.

Suggest two ways the student could improve the quality of her scientific drawing of this gill.

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