The graph in figure 5-7 shows the changes in population of bass in a lake. describe the trend in population growth from 1950 to 1990. give an example of something that may have happened in 1990 to effect the bass population. explain your answer.

In exponential growth, the growth rate of population per capita remains the same in spite of the size of the population, thus, resulting in the population to grow faster and faster as it gets bigger. However, in nature, the populations may grow exponentially for certain time duration, and they eventually get restricted due to limited availability of resources.  

In the graph, it is evident that from 1950 to 1990 there is exponential growth, signifying that the fish exhibited almost optimal conditions of living. However, in 1990 the population started to decline steadily, demonstrating an extreme lack of resources or enhancement in predatory species.  

the last one: artificial selection/genetic engineering

plant breeding is modifying the genetic composition of the plant - but this isn't cloning (which is specifically introducing a gene into a genome). but you are artificially selecting for the phenotype that you want.

the second one is literally genetic engineering - the gene would have been cloned first and then inserted or genetically engineered into the new plant cell (the cotton).