Exam (elaborations)
BOT2603 EXAM PACK.
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- BOT2603
- Institution
- University Of South Africa
BOT2603 EXAM PACK.100% TRUSTED Answers, guidelines, workings and references.
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BOT2603 EXAMPACK.
,Essential elements: are elements which are required in a relatively small amount to
complete the plant life cycle. Elements are considered essential if (i) in its absence the plant
is unable to complete a normal life cycle, (ii) that element is part of some essential plant
constitute or metabolite. Example: magnesium would be considered essential because it is a
constituent of the chlorophyll molecule and chlorophyll is essential for photosynthesis.
Essential nutrient elements are elements that is needed for the plant to complete a normal
life cycle or when that element is part of some essential plant constituent or metabolite, for
example magnesium is considered essential because it is a constituent of the chlorophyll
molecule and chlorophyll is essential for photosynthesis.
Micronutrients: Most plants require a relatively small number of nutrient elements to
successfully complete their life cycle; these are called essential nutrient elements.
Micronutrients are those nutrients that are required in relatively small quantities (less than 10
mmole kg-1 of dry weight) and serve
catalytic and regulatory roles such as enzyme activators. There are eight micronutrients:
Chlorine (Cl), Boron (B), Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Nickel (Ni) and
Molybdenum (Mo).
Autotrophic
An autotroph is an organism that produces complex organic compounds (such as
carbohydrates, fats, and proteins) from simple substances present in its surroundings,
generally using energy from light (photosynthesis) or inorganic chemical reactions
(chemosynthesis).
Toxic concentration
When nutrients levels exceed the critical concentration, that nutrient is, with one
qualification, no longer limiting. The qualification is that at sufficiently high tissue levels,
virtually all nutrients become toxic. Toxic levels are seldom achieved with the macronutrients
but are common in the case of micronutrients.
Bundle sheath cells vascular bundles that are quite close together and each bundle is
surrounded by a tightly fitted layer of cells.
The bundle sheathe cells forms a layer or region of compactly arranged cells surrounding a
vascular bundle in a plant. The bundle sheaths regulate the movement of substances
between the vascular tissue and the parenchyma and, in leaves, protect the vascular tissue
from exposure to air.
,Guard cells pore surrounded by a pair of specialized cells.
Stomata is bordered by a pair of unique cells called guard cells and is part of the stomatal
complex. Guard cells take up water and swell to open the stomata when CO2 is required for
photosynthesis and lose water to close the stomata when CO2 is not required.
Stomatal transpiration
The loss of water in the form of water vapour from the leaves occurs mainly through the
stomata. So, this transpiration is called as the stomatal transpiration. The stomata are pores
in the epidermis which are guarded by two kidney shaped epidermal cell.
Stomatal transpiration is the diffusion of water vapor through the stomatal pore and accounts
for 90 to 95% of the water loss from leaves. Stomata allows for gas exchange where water
vapor leaves the plant and carbon dioxide enters, controlled by the special guard cells, when
stomata are open, transpiration rates increase and when stomata are closed transpiration
rates decrease.
Macronutrient : these are nutrients required by plant in larger amount, and they are
not involved in the structure of the molecule. E.g. Nitrogen, Potassium, Phosphorus,
Calcium, and Magnesium .
Macronutrients are nutrients required by plants in larger amount, and they are not
involved in the structure of the molecule. For example, Nitrogen, Potassium,
Phosphorus, Calcium, and Magnesium. They are also involved in the structure of
molecules, which can to some extent explain for the need for large quantities.
Deficient concentration
The concentration of a nutrient (in a plant tissue) just below the level that gives
maximum growth is defined as critical concentration. At concentrations below the
critical concentration i.e. deficient concentration, the nutrient content becomes
deficient (limiting to) and growth falls off sharply. On the contrary, when more of the
nutrient is provided and its concentration in the plant increases, growth increases
dramatically. Growth
Saturation vapour pressure
The pressure of water vapour where the saturated condensed phase at a specific
temperature is at equilibrium. The temperature is directly correlated to saturation
vapour pressure.
Saturation vapor pressure has been achieved when a gas phase has reached
equilibrium and is saturated with water vapor.
, Hydroponic is when growing plants without soil, usually by supplying nutrients to
the roots by immersing them in a specially prepared solution or with special sprays.
Critical concentration
When the supply of an essential element becomes limiting, growth is reduced. The
concentration of that nutrient measured in tissue, just below the level that gives
maximum growth is defined as the critical concentration. Anything above that level is
referred to as the adequate zone and anything below that level is regarded as the
deficient zone
Permanent wilting
the condition in which water remaining in a soil when a plant fails to recover from
wilting even if placed in a humid chamber. As the soil dries, the film of water around
each soil particles become so thinner and more tightly bound to the soil particles and
less likely to enter the root. If water is not added to the soil, eventually a point is
reached at which the rate of absorption of water by the plant is insufficient for its
needs, and plant wilts permanently
Permanent wilting happens when soil dries out to a certain point and the water
potential declines, plants may have trouble to extract water from the soil fast enough
to balance losses by transpiration, the plants then lose turgor and wilt, which will
become permanent.
Chlorosis
loss or reduced development of chlorophyll resulting from mineral deficiency, which
is nitrogen. It results in yellowing of the leaves.
Chlorosis can be described as a yellowing of leaf tissue due to a lack of chlorophyll,
that could be caused by various reasons for example nutrient deficiencies such as
manganese or zinc.
Beneficial elements: these are elements which are required at concentration well
below what can be reliably detected by present analytical technique. Examples of
beneficial elements are sodium, silicon, selenium, and cobalt.
Adequate concentration
The nutrient content above critical concentration, at which additional increments in
nutrient content have no beneficial effect on growth. When nutrient levels exceed the
critical concentration, that nutrient is no longer limiting (Hopkins & Hüner 2009,
pp68). The adequate zone is wide for macronutrients but is much narrower for
micronutrients. This means that toxic levels are seldom achieved with the
macronutrients but are common in the case of micronutrients. Continued increases
of any nutrient lead to toxicities and reduced growth; this is regarded as the toxic
zone
A hydroponic culture is when plants are grown in a defined nutrient solution and not
in soil and is the principal experimental system for the study of plant nutrient
requirements. Hydroponic can also be used for the commercial production of
vegetables such as lettuce, tomato and sweet peppers.
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