Misc.

Question 1

Dorsi-ventral vs isobilateral leaves?

Answer 1

Dorsiventral leaves: have distinct upper (adaxial) and lower (abaxial) sides with different characteristics.
- Usually stomata on abaxial side to protect them from water loss, and more loosely packed epidermal cells to help stomata, palisade mesophyll on the adaxial, spongy mesophyll on the abaxial. In aquatic plants its reversed. Xerophytes (desert plants) have sunken stomata and trichomes, thick epidermis, to increase humidity and reduce water loss.

Isobilateral leaves: have no distinct top or bottom e.g. eucalypts.

Question 2

What is adventitious growth?

Answer 2

Adventitious growth occurs when (parenchyma) cells re/dedifferentiate to form a structure outside of its usual location.

E.g. adventitious roots are the roots that form from the stem, separate to original root growth, after a cutting has been taken.

Question 3

What is turgor pressure?

Answer 3

Turgor pressure is water pressing against the plasma membrane of the cell wall creating pressure. Only in plant cells because animal cells don’t have a cell wall, so would burst.

Question 4

Hypertonic cell, isotonic cell, hypotonic cell?

Answer 4

remember: water moves to area of high solute conc. where there is less water and more solute, so it will balance. Thus, balance of water changes according to solute concentrations.

Hypertonic: low solute conc. inside cell so water leaves cell leading to falling turgor pressure + cell shriveling up.

Isotonic: equal conc. of solute inside and outside cell, causing equilibrium of water entering and leaving cell. Stable turgor pressure maintained.

Hypotonic: high solute conc. inside cell so water moves into cell, increasing turgor pressure + causing cell to swell, increasing turgor pressure.