IB myp 4-5 Biology – Practice Questions- All Topics
Topic :Organsims-Ecosystem
Topic :Organisms– Weightage : 21 %
All Questions for Topic : Habitat,Ecosystem,Inter dependency,Unity and diversity in life forms,Energy transfer and cycles,Classification
Summative assessment
Water evaporation in forests
Question:
The data below shows the annual rate of water evaporation per square metre from forests of different ages and different types.
a) State the rate of evaporation from a 60-year-old pine forest.
▶️Answer/Explanation
Ans: 530 mm yr–1
b) Calculate the mean evaporation rate for each age of forest, using the data from all forest types. Construct a graph to display these mean evaporation rates.
▶️Answer/Explanation
Ans: 40 years: 557;
60 years: 563;
100 years: 470;
140 years: 433.
Plot a line graph with all points plotted correctly; x–axis for age with suitable scale and legend; y–axis for evaporation rate with suitable scale and legend.
c) Outline the trends in the data displayed in the graph.
▶️Answer/Explanation
Ans: For example, with birch and aspen, evaporation rate increases until 60 years old; then decreases slightly.
d) Suggest reasons for these trends.
▶️Answer/Explanation
Ans: Surface area of leaves/leaf area index increases as forest grows older; more transpiration with more leaf area; decrease in evaporation in oldest forests due to loss of ground flora/decrease in water transport to the top of tall trees/slower water transport in older wood.
e) Summarize the types and causes of water movement in the water cycle in a forest ecosystem
▶️Answer/Explanation
Ans: Water uptake by trees; loss of water from trees by transpiration; evaporation of water from soil/trunks/rocks/surfaces; rainfall; percolation of water into soils; drainage of water through soil.
In tropical forests such as the Atlantic Forest there is high rainfall and river flow rates. The “biotic pump” hypothesis has been developed by Makarieva and Gorshkov to explain how plants within these forests could increase rainfall and river flows. The diagrams shown on the next page illustrate the hypothesis. Diagram I shows forest adjacent to ocean and diagram II shows desert adjacent to ocean.
Question:
Using scientific reasoning, formulate a hypothesis for whether there will be more evaporation from the intact Atlantic Forest of Brazil, or from the surface of the Atlantic Ocean off the coast of
Brazil.
▶️Answer/Explanation
Ans: More evaporation from forest; larger total surface area from which water can evaporate; many leaves; large area of spongy mesophyll inside leaves; water only evaporates from the surface of an ocean; leaves at higher temperature than ocean surface; more heat energy for evaporation.