1. Data analysis
Practice and review

2. What to do when given a graph?
Read the information ABOVE the graph and underline or highlight the important pieces of information.
Read the AXIS labels/legends of the graph
Read the question and underline or highlight the KEY words
Check the graph and make sure you SEARCH and USE for the correct information
Answer the question ALWAYS include UNITS in your answer.

3. The mountain yellow-legged frog (Rana muscosa) was once a common in habitant of the Sierra Nevada (California, USA). It has declined during the past century due in part to the introduction of non-native fish, such as trout, into naturally fish-free habitats. The bar chart shows the average number per lake of tadpoles (aquatic larval stage) and frogs in lakes with and without trout in 1996.
State the number of tadpoles per lake with and without trout.
Compare results for lakes with and without trout.
Suggest one way trout might affect the number of tadpoles or frogs in lakes.

4. The mountain yellow-legged frog (Rana muscosa) was once a common in habitant of the Sierra Nevada (California, USA). It has declined during the past century due in part to the introduction of non-native fish, such as trout, into naturally fish-free habitats. The bar chart shows the average number per lake of tadpoles (aquatic larval stage) and frogs in lakes with and without trout in 1996.
State the number of tadpoles per lake with (4) and without (700) trout.
Compare results for lakes with and without trout. There are more tadpoles/frogs without trout. (vice versa)
Suggest one way trout might affect the number of tadpoles or frogs in lakes. Tadpoles/frogs maybe eaten by the trout. Trout could catch or eat more tadpoles than frogs. Trout could introduce diseases.

5. There will be a second graph showing another aspect or another variable you should consider. This is often a map.
READ all the written information including axis/legends/scale.
Underline or highlight the KEY information.
Read the question and underline/highlight what you are being ASKED to do.
Think about what OTHER data you would need to answer the question. Is anything MISSING?

6. In order to restore the frog population, introduced trout were removed from the lakes. The map of the LeConte Basin study area shows the distribution of mountain yellow-legged frogs and trout populations just prior to the removal of the trout in The graphs show the population of tadpoles and frogs in the lakes before, during, and after the removal of the trout.
d. State the tadpole density in each lake in 2004.
Upper LeConte Lake:
Lower LeConte Lake:
e. Suggest a possible reason fro the difference in tadpole density between Upper and Lower LeConte Lakes.
f. What was the effect, if any, of removing trout on frog density in Upper and Lower LeConte Lakes?
g. Using the map and graph, predict if the frog/tadpole populations will remain high in the future (after the trout have been removed).

7. d. State the tadpole density in each lake in 2004.
Upper LeConte Lake: 210 tadpoles 10m-1 shoreline
Lower LeConte Lake: 6.4 tadpoles 10m-1 shoreline
e. Suggest a possible reason fro the difference in tadpole density between Upper and Lower LeConte Lakes. Disease. Predators. Upper lake has a supply stream, lower does not. Trout could have been reintroduced from a nearby stream. Lakes could have other differences (temperature, food etc.)
f. What was the effect, if any, of removing trout on frog density in Upper and Lower LeConte Lakes? Increased population in both lakes. Upper had rapid increase and then decrease (in 2004) but in lower there was only an increase no decrease. Very small difference after 1 year. Greater number of frogs in Upper than Lower.
g. Using the map and graph, predict if the frog/tadpole populations will remain high in the future (after the trout have been removed). Any sensible answer that is JUSTIFIED by the data. E.g. YES, because the data shows both lakes increased after the first three years because the tadpoles/frogs had no trout predators. OR, NO, because in Upper the numbers are descreasing after 2004 because tadpoles/frogs can migrate from Upper to Lower as there are no barriers. Also, this means that the trout can move from one place to another.
FINALLY – there is not enough data/data is missing so it is not possible to make predications with any certainty.