Some me with the problem at certain times, the stomata on the tree leaves close. what environmental stimulus might cause this response?

Stomata close when the vacuoles in the guard cells fill with water and the cells become turgid.  The environmental stimulus that causes this response is the change from light to dark.  During the day, heat from the sun causes evaporation in the leaves, which leads to water loss from the leaves, by way of the stomata, in a process known as transpiration.  At night, the absence of the sun's heat slows the rate of evaporation, causing the vacuoles in the guard cells to fill with water by way of osmosis, causing the guard cells to become turgid and seal off the stomata.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.

events in order:

1.       vishnu schist

2. zoroaster granite

3. bass limestone

4. hakatar   shale

5. igneous intrusion

6. shinumo quartzite

7. dox sandstone

8. tapeats limestone

9. bright angel shale

10. muav limestone

11. temple butte limestone

12. redwall limestone  

nonconformity

answer: the unkar group shows angular unconformity because the layers are turned at angle.

unconformity

answer: specifically the angular unconformity occurs between the cambrian and precambrian rocks. the dox sandstone, shinumo quartzite, hakatar shale, and bass limestone have been filled. an angular unconformity occurs between the cambrian and precambrian rocks. the dox sandstone, shinumo quartzite, hakatar shale, and bass limestone have been filled.

disconformity

answer: the disconformities aremarked irregular lines between the sedimentaryrocks layers.