partB

Autotrophic

Organisms that can make all necessary organic compounds from inorganic compounds.

Essential nutrients

Substances that can be metabolised by an organism to give energy and build tissue for growth and development.

Macronutrients

Nutrients required by plants in larger quantities, including nitrogen, phosphorus, and potassium.

Micronutrients

Nutrients needed by plants only in minute quantities, such as iron, boron, and copper.

Mobile nutrients

Nutrients that can be moved from one part of the plant to another.

Chlorosis

Yellowing of leaves due to chlorophyll degradation.

Necrosis

Death of leaf tissue.

Meristems

Sites of repeated cell division of unspecialized cells where plant growth occurs.

Indeterminate growth

Growth that occurs when apical meristems of roots and stems remain permanently embryonic.

Circadian rhythms

Periodic oscillations in plant behaviour that occur over a period of about 24 hours.

Phototropism

Plant growth towards light.

Gravitropism

Growth movements in response to gravity.

Phytohormones

Naturally-occurring organic substances that modify plant growth and development.

Auxins

Plant hormones that promote cell elongation and inhibit lower bud activation.

Cytokinins

Plant hormones that promote cytokinesis and enhance axillary bud growth.

Gibberellins

Plant hormones that promote growth, such as flower bolting and fruit enlargement.

Abscisic Acid

A hormone that inhibits growth and promotes seed dormancy.

Ethylene

A gaseous plant hormone that promotes flowering and leaf senescence.

Dormancy

A slowdown in an organism's metabolic rate, particularly in seeds.

Senescence

The collective term for aging processes that lead to the death of a plant or plant part.

Turgor movements

Movements resulting from volume changes in certain cells due to changes in osmotic potential.

Photoperiodism

The physiological reaction of organisms to the length of day or night.