1. Which of these is not an environmental effect of building dams

A. Reduced fertility downstream<<<
B. Weed growth downstream
C. Increased water temperature
D. Soil erosion upstream
2. Which of these is not an environmental effect of destroying wetlands
A.smog
B.unfiltered water
C.flooding
D.loss of habitat <<<<<
3. Which of these is not an environmental effect of deforestation
A.soil erosion
B.habitat loss
C.poisned wildlife from pedestrians
D.overcrowding<<<

Which of these is an environmental effect of destroying wetlands

To find the answer to these questions, we need to analyze each option and eliminate the one that is not an environmental effect. Let's go through each question one by one:

1. Which of these is not an environmental effect of building dams?
- Option A: Reduced fertility downstream. This can be considered an environmental effect of building dams as the reduced flow of sediments downstream can affect fertility.
- Option B: Weed growth downstream. This can be considered an environmental effect of building dams as the reduced flow of water and changes in water levels can create conditions for weed growth downstream.
- Option C: Increased water temperature. This can be considered an environmental effect of building dams as the dam alters the natural flow and temperature of the water.
- Option D: Soil erosion upstream. This can be considered an environmental effect of building dams as the changes in water flow and levels can lead to erosion upstream.

By analyzing each option, we find that all options in question 1 can be considered environmental effects of building dams. Therefore, the correct answer is A. Reduced fertility downstream.

2. Which of these is not an environmental effect of destroying wetlands?
- Option A: Smog. Smog is generally associated with air pollution and is not directly linked to the destruction of wetlands, so it can be considered as not an environmental effect.
- Option B: Unfiltered water. The destruction of wetlands can affect the quality of water and cause it to become unfiltered, so this option is an environmental effect of destroying wetlands.
- Option C: Flooding. The destruction of wetlands eliminates natural flood control mechanisms, making areas more prone to flooding. So, this option is an environmental effect of destroying wetlands.
- Option D: Loss of habitat. The destruction of wetlands leads to the loss of unique habitats that support diverse wildlife, so this option is an environmental effect of destroying wetlands.

By analyzing each option, we find that option A. Smog is not an environmental effect of destroying wetlands. Therefore, it is the correct answer.

3. Which of these is not an environmental effect of deforestation?
- Option A: Soil erosion. Deforestation can lead to soil erosion as the removal of trees exposes the soil to erosion by wind and water, so this option is an environmental effect of deforestation.
- Option B: Habitat loss. Deforestation results in the loss of habitats for various species, so this option is an environmental effect of deforestation.
- Option C: Poisoned wildlife from pedestrians. This option does not directly relate to deforestation, so it can be considered as not an environmental effect.
- Option D: Overcrowding. Overcrowding is a broader social issue and not directly linked to deforestation, so it can be considered as not an environmental effect.

By analyzing each option, we find that option D. Overcrowding is not an environmental effect of deforestation. Therefore, it is the correct answer.