Act Science

Lesson 1: ACT Science Mastery

Passage

Succession is the way species change composition in an area over time. For example, a grass land may eventually become populated by trees. This would be an ecological succession. Ecologists have conducted a study of Brazilian rainforests that have been subjected to slash-and burn agriculture. The Brazilian natives burn the rainforest and use the resulting highly fertilized land for farming. After many years, wildlife and vegetation begin to return to the area. 

Passage

Table 1 shows the various bird species dominant (most prevalent) plants, as well successional time in years of various plots of forest subjected to slash and burn agriculture. The estimated changes in net productivity (measured as grams of organic mass produce per square meter per year [g/m²yr]) of plan the plots of land studied are shown on Note that the successional periods are in die at the bottom of the chart and are named based on the dominant plants during each time period.

Multiple Choice

According to Table 1 and Figure 1, what type of dominant plant is associated with the most net productivity

• grasses

• weeds

• canopy trees

• shrubs

The correct answer is C.

The highest point of Net Productivity on the graph is during the 64 - 256 Successional Years period. On Table 1, both Small Trees and Canopy Trees are dominant during this stretch of time, but only Canopy Trees are offered as a choice in the question.

Multiple Choice

According to Table 1 and Figure 1, what type of dominant plant is associated with the least net productivity?

• grasses

• weeds

• canopy trees

• small trees

The correct answer is B. 

The lowest point of Net Productivity on the graph is during the 1 Successional Year period. On Table 1, Weeds are the dominant plant under the 1 Year column. 

Multiple Choice

During what period of succession is there the greatest change in net productivity?

• 16-64 years

• 64-256 years

• 1-4 years

• 4-16 years

The correct answer is A. 

We are looking for an area of the graph that has the most change. In other words, this will be the steepest line or the one that has the biggest difference in height between where it starts and ends. This is the 16 - 64 year period on the graph. 

Multiple Choice

What is a bird species that is present in a density of at lease one pair per 20 acres when the net productivity of the plot of land is over 1000 g/m²/yr?

• Black-faced cuckoo shrike

• Boatbill

• Cicada Bird

• Cockatoo

The correct answer is A.

The line on Figure 1 stretches past the 1000 ductility row a little after 32 Years, so we 1 for a bird species present after 32 years one that is an option is the Black-faced cuch 

Multiple Choice

What is a bird species that is not present in a density of at least one pair per 20 acres when the net ductility of the plot of land is less than 600 g/ m²/yr?

• Dollarbird

• Boatbill

• Cicada Bird

• Cockatoo

The correct answer is A. 

The line on Figure 1 stretches past 600 Net Productivity a little after 16 Years, so we look on Table 1 for a bird species that is not present before 16 years. The only one that is an option is the Dollarbird.