Stomata close when the guard cells:
1. lose water.
2. photosynthesis begins and the internal CO2 concentration decreases.
3. gain chloride ions.
4. become turgid.
The pathway of water from the soil through the plant to the atmosphere is best represented by which of the following sequences?
1. endodermis- cortex - epidermis - vessel elements - intercellular spaces in mesophyll - stomata.
2. epidermis - cortex - Casparian strip - endodermis - sieve cells - intercellular spaces in the mesophyll - stomata.
3. Casparian strip - root hairs - epidermis - cortex - xylem - endodermis - intercellular spaces in mesophyll - stomata.
4. root hairs - cortex - endodermis - vessel elements - intercellular spaces in mesophyll - stomata.
Which is an incorrect statement.
1. Translocation of minerals up the xylem is an active process
2. The target cells unload the minerals by an active process
3. The absorption of minerals by plants is mostly an active process
4. Minerals usually flow up the vessels along with the transpiration stream.
Which of the following terms would be used to explain how trees can lift water to heights of ten stories or more?
2. adhesion and cohesion
3. tensile strength
4. all of the above
Which of the following will not cause the stomata to close?
2. increase in carbon dioxide concentration
4. increase in pH
Pick the incorrect statement
1. Guard cells help balance the photosynthesis-transpiration compromise.
2. Water tension in a transpiring plant will exert a pull on water molecules lower down in the plant's vascular system.
3. Plants that live in deserts have adapted to constant water stress by using hydrophilic colloids to increase the water potential of their tissues.
4. C3 plants can fix double the carbon dioxide for half the water transpired.
What seems to be the most valid statement about root pressure?
1. It is the positive pressure responsible for transport of water most commonly.
2. It may provide a considerable push to the water column during transport.
3. It may help re establish the broken water columns during transpiration
4. Its effect is most observable during mid day
A structural attribute of guard cells that aid in its effective functioning is
1. Large cell size
2. Radial micellation in walls
3. Thick walls
4. All of the above
Not an aid to water absorption is
1. The high surface area of roots
2. High water potential of root hair cells
3. Thin cellulosic walls of root hair zone
4. Low concentration of solutes in the soil
The water is free to move between the cells except through the