Which of the following statements best explains the change in herbicide-resistant horseweed populations over time? Individual horseweed plants that are resistant to the herbicide increased over time by surviving and reproducing, and passing their herbicide-resistant genes to their offspring. Horseweed plant populations resistant to the herbicide increased over time by growing in areas where the herbicide is not present, increasing their chance of survival. Numbers of individual horseweed plants remained the same over time, however they reproduced at different rates. Since the herbicide-resistant individuals can C reproduce faster and increase their genes in the population, the population became more resistant over time. Numbers of individual horseweed plants remained the same over time, however they developed genes that make them more resistant to herbicides. As the resistant individuals pass their genes on to other populations, the horseweed plants become more resistant over time.

Figure 5. This figure shows the number of individuals of three tree species (Blue Pine, Black Oak, and Rusty Cactus) on a woodlot in eastern Ontario, Canada. For each statement, select TRUE if it is consistent, or FALSE if it is not consistent with the information presented above. In 1990, the births and immigration of Blue Pine approximately equal the deaths and emigration of Blue Pine.     options:   True   False

Aphids and ants can have a mutualistic relationship. Aphids exude sugary substances that provide energy for ants and ants can defend aphid colonies from predators. This experiment measured the population growth rate of aphids vs the number of aphids at the start of the experiment on plants where ants were present or absent. Please select all the statements that are reasonable interpretations of this graph. Select all that apply. A. When starting populations are low, the presence of ants does not matter. Their importance increases with higher starting population densities.   B. It appears that aphid populations founded with 12 individuals grow faster than aphid populations founded with 24 individuals when compared to each other in the same ant treatment.. C. none of the above.   D. The growth of rate of aphid populations was significantly higher when tended by ants than aphid population that were not tended   E. Ants seem to be necessary for small founding populations of…

Intraspecific competition is a competition between members of the same species and is commonly observed in crop plants. Table 6.2 shows the results of a greenhouse experiment which examined the effects of density on the germination and growth of barley. Plants were grown for two weeks in 10- cm diameter pots kept in identical environmental conditions and watered regularly. At the end of the experiment the plants were cropped by cutting the stems at the soil surface. In the given context, can you explain thoroughly the meaning of plant density that this passage is talking about?