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

Cytokinin produced in the shoot tip

Answer

Gibberellin released from young leaves

Answer

Abscisic acid produced in the roots

Question 2

Which plant hormone primarily promotes root initiation on stem cuttings?

Accepted Answer

Auxin

Answer

Gibberellin

Answer

Ethylene

Answer

Abscisic acid

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

Store starch reserves for the root

Answer

Anchor root hairs to soil particles

Answer

Transport sugars from phloem into root tissue

Question 4

A day-neutral plant will flower:

Accepted Answer

Regardless of photoperiod, when mature enough

Answer

Only when nights are shorter than a critical length

Answer

Only when nights are longer than a critical length

Answer

Only during the spring equinox when day and night are equal

Question 5

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

Accepted Answer

Light direction

Answer

Gravity

Answer

Touch or mechanical stimulation

Answer

Water availability

Question 6

Magnesium is an essential macronutrient in plants primarily because it:

Accepted Answer

Is the central atom in the chlorophyll molecule

Answer

Activates phosphate transfer reactions in ATP synthesis

Answer

Is required for cell wall formation and structural rigidity

Answer

Regulates stomatal opening through guard cell osmosis

Question 7

Biological nitrogen fixation, the conversion of atmospheric N2 into plant-available ammonia, is carried out by:

Accepted Answer

Nitrogen-fixing bacteria such as Rhizobium in root nodules of legumes

Answer

Mycorrhizal fungi in association with plant roots

Answer

Nitrifying bacteria like Nitrobacter in the soil

Answer

Denitrifying bacteria that break down nitrates in anaerobic conditions