CHT Plant Physiology & Growth 3

Question 1

Apical dominance occurs when the apical bud suppresses the growth of lateral buds. Which hormone is primarily responsible for this effect?

Accepted Answer

Auxin produced in the apical meristem

Answer

High auxin concentrations from the apical meristem inhibit lateral bud development; removing the apex releases lateral buds from this suppression.

Question 2

Which plant hormone primarily promotes root initiation on stem cuttings?

Accepted Answer

Auxin

Answer

Auxins (often IBA or NAA in rooting powders) stimulate root initiation on stem cuttings by promoting cell division in the cambium region.

Question 3

The Casparian strip, found in root endodermis cells, functions to:

Accepted Answer

Force water and ions to pass through cell membranes rather than between cells, allowing selective uptake

Answer

The Casparian strip is a band of waxy suberin that blocks apoplastic movement, forcing ions through the symplast where selective transport occurs.

Question 4

A day-neutral plant will flower:

Accepted Answer

Regardless of photoperiod, when mature enough

Answer

Day-neutral plants flower based on developmental maturity rather than day length; tomatoes and cucumbers are common examples.

Question 5

Phototropism is the directional growth of a plant in response to:

Accepted Answer

Light direction

Answer

Phototropism causes shoots to bend toward light (positive) and roots to grow away from it (negative), mediated by uneven auxin distribution.

CHT - Certified Horticultural Technician Practice Test