Glycolate induces the opening of stomata when: 
1.  Presence of oxygen
2.  Low $C{O}_2$ conc.
3.  High $C{O}_2$
4.  $C{O}_2$ absent

Opening and closing of stomata are due to the:

1. Hormonal change in guard cells

2. Change in Turgor pressure of guard cells

3. Gaseous exchange

4. Respiration

Stomata of a plant open due to:

1. Influx of potassium ions

2. Efflux of potassium ions

3. Influx of hydrogen ions

4. Influx of calcium ions