Fig. 1 shows seaweed growing at different heights on a rocky shore. At low tide, plants high on the shore are exposed to air and lose water. Some seaweed pl...
Question 1 Report
Fig. 1 shows seaweed growing at different heights on a rocky shore. At low tide, plants high on the shore are exposed to air and lose water. Some seaweed plants have a thicker outer layer that slows water loss from their cells. Other plants dry out quickly before releasing reproductive cells into the water. Marine students survey the shore along a line from low water to high water, using equal-sized sampling frames. They notice that thick-layered seaweed is common near the high-tide mark. Wave action and grazing animals also affect survival.
(a) Identify the seaweed feature likely to be favoured high on the shore. [1]
(b) Explain how exposure to air acts as a selection pressure. [2]
(c) Use the investigation to give one reason for using equal-sized sampling frames. [1]
(d) Give one factor, other than water loss, that could affect seaweed survival. [1]
Answer Details
(a) Thick outer layer / layer that reduces water loss [1] (b) Plants that lose too much water dry out and fail to reproduce [1]; plants with the thick layer survive and pass alleles for it to offspring / reproductive cells [1] (c) They sample the same area, making counts comparable [1] (d) Wave action / grazing / light intensity / temperature / competition [1]
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