It is now thought that the atmosphere of the primitive Earth was composed largely of carbon dioxide, nitrogen, and water vapor. The composition of certain iron-containing minerals suggests that the carbon dioxide began to be replaced by oxygen about 2 billion years ago.   Which of the following is the best explanation for the change in atmospheric composition?

TLS Online TPP Program

#Question id: 13189

#Unit 10. Ecological Principles

The relative abundance of C plant species increases with latitude because of the associated temperature gradient. A study in North America found that at  42°  North,  C3  plants  become more  abundant than  C4  plants. Given  an  increase in  mean global  temperatures by  10°C and no  other changes in  environmental conditions,  the latitude at which C3 plants become more abundant:

TLS Online TPP Program

#Question id: 13190

#Unit 10. Ecological Principles

During the evolution of life on Earth, the photosynthetic organisms initially responsible for raising atmospheric oxygen concentrations from less than 1 percent to about 20 percent were

TLS Online TPP Program

#Question id: 13191

#Unit 10. Ecological Principles

Which of the following statements about circadian rhythms is correct?

TLS Online TPP Program

#Question id: 13192

#Unit 10. Ecological Principles

In the schematic below, the left panel represents climatic zones occupied by two different biomes, X and Y, along gradients of temperature and precipitation. The right panel depicts the expected species-area relationships of these two biomes. From the figures below, which of the following are most likely to be true?

TLS Online TPP Program

#Question id: 3296

#Unit 10. Ecological Principles

Some beetles and flies have antler-like structures on their heads, much like male deer. The existence of antlers in beetle, fly, and deer species with strong male-male competition is an example of

TLS Online TPP Program

#Question id: 12640

#Unit 10. Ecological Principles

Plant species produce a which type of  defensive proteins that bind to carbohydrates or carbohydrate-containing proteins. After being ingested by an herbivore, that bind to the epithelial cells lining the digestive tract and interfere with nutrient absorption