Samacheer Class 11 Bio Botany - Mineral Nutrition

1. Plants absorb minerals from the soil along with water with the help of Roots. Minerals are absorbed as salts.
2. Nitrogen is present in large quantities in the atmosphere in a gaseous form, the gaseous nitrogen must be fixed in the form of Nitrate salts in the soil to facilitate absorption by plant roots.
3. Nitrogen fixation can occur 2 ways by
* Non – Biological means (Industrial process or by lighting)
* Biological means (Bacteria / Cyanobacteria Fungi)
* Therefore higher plants con not utilize the atmospheric Nitrogen.

When deficiency symptoms appear first, we can notice the differences in old and younger leaves. It is mainly due to mobility’ of minerals. Based on this, they are classified into
1. Actively mobile minerals and
2. Relatively immobile minerals
a) Actively mobile minerals: Nitrogen, Phosphorus, Potassium, Magnesium, Chlorine, Sodium, Zinc and Molybdenum. Deficiency symptoms first appear on old and senescent leaves due to active movement of minerals to younger leaves, than the older leaves.
b) Relatively immobile minerals: Calcium, Sulphur, Iron, Boron and Copper. Here, deficiency symptoms first appear on young leaves due to the immobile nature of minerals.

Nitrogen fixation is the first step in Nitrogen cycle, during which gaseous nitrogen from the atmosphere is fixed. It required nitrogenase enzyme complex nitrogenase is active only in anaerobic condition. To create this anaerobic condition, a pigment known as leghaemoglobin is synthesized in the nodules which acts as oxygen scavenger and removes oxygen.

Plants which are growing in nitrogen deficient areas develop insectivorous habit to resolve nitrogen deficiency.
* Nepenthes (Pitcher plant): Pitcher is a modified leaft and contains digestive enzymes. Rim of the pitcher is provided with nectar glands and acts as an attractive lid. When insect is trapped, proteolytic enzymes will digest the insect.
* Drosera (Sundew): It consists of long club shaped tentacles which secrete sticky digestive fluid which looks like a sundew.
* Utricularia (Bladder wort): Submerged plant in which leaf is modified into a bladder to collect insect in water.
* Dionaea (Venus fly trap): Leaf of this plant modified into a colourful trap. Two folds of lamina consist of sensitive trigger hairs and when insects touch the hairs it will close.
Insectivorous Plants
1. Nepenthes (Pitcher Plant)
2. Drosera (Sundew)
3. Dlonaca (Venus Fly tray)
Part – II
11th Bio Botany Guide Mineral Nutrition Additional Important Questions and Answers
I. Choose the Correct Answers

c) (I) is wrong (II) is correct
Assertion ‘A’ & Reason ‘R’
a) Both ‘A’ and ‘R’ are True and ‘R’ is the correct explanation of A
b) Both A and R are True, but R is not the correct explanation of A
c) A is True but ‘R’ is False
d) A& Rare False

5ome minerals Such as Sodium, Silicon, Cobalt and Selenium some minerals are not included in the list ol essential nuitrients by they play some specific roles.
Eg. Silicon
* essential for pest resistance
* prevent water lodging
* aids in cell wall formation in Equisetaceae, Cyperaceae & Gramineae

Hydroponics: Growing plants in nutrient solution with roots immerse in it and air is supplied with the help of tube.
Hydroponics: It Is a system where roots suspended in air and nuitrients solution in a tank is sprayed over the roots by motor driven rotor – in the form of mist.

• Macro elements which commonly remain deficient in the soil are called Critical elements, (ie) N.P.K.
• The fertilizer which contain critical elements are called complete fertilizer. They are expressed in the ratio 15: 15: 15(N:P: K)

If mineral nuitrients lesser than critical concentration cause deficiency, where as when there is increase in
mineral nuitrients more than normal concentration cause Toxicity Toxicity ¡s that particular concentration at which 10% of the dry weight of tissue is reduced.

Two examples of symbiotic mode of nutrition:
* Lichens: It is a mutual association of Algae and Fungi. Algae prepares food and fungi absorb water and provides thallus structure.
* Mycorrhizae: Fungi associated with roots of higher plants including Gymriosperms. eg: Pinus.

Close relationship between two organism, both being benefitted out of it is known as symbiosis.
Eg. 1. Nitrogen fixing bacteria Nitrosomonas living in the root nodules of leguminous plants.
2. Fungi associated with roots of higher plants is a symbiotic association known as Mycorrhiza

• FTWS – means floating treatment wet lands.
• It works on the principle of hydroponics recently FTWS work on the principle of hydroponics, helping to solve pollution that come up due to Eutrophication.

Total parasitic or partial parasites they have some special structures to absorb food or water from the host plant phloem and xylem. These special absorbing structures are known as Haustoria.

Minerals like Sodium,Silicon, Cobalt and Selenium are not included in the list of essential nutrients but are required by some plants, these minerals are placed in the list of unclassified minerals. These minerals play specific roles for example, Silicon is essential for pest resistance, prevent water lodging and aids cell wall formation in Equisetaceae (Equisetum), Cyperaceae and Gramineae.

Functions: Maintains turgidity and osmotic potential of the cell, opening and closure of stomata, phloem translocation, stimulate activity of enzymes, anion and cation balance by ion – exchange. It is absorbed as K + ions. Deficiency symptoms: Marginal chlorosis, necrosis, low cambial activity, loss of apical dominance, lodging in cereals and curled leaf margin.

To increase productivity and also to avoid mineral toxicity knowledge of critical concentration is essential. Mineral nutrients lesser than critical concentration cause deficiency symptoms. Increase of mineral nutrients more than the normal concentration causes toxicity. A concentration, at which 10% of the dry weight of tissue is reduced, is considered a toxic critical concentration.

Nitrogen fixation is the phenomenon that occurs in Prokaryotes but not in Eukaryotes, because the enzymes nitrogenase, which is capable of nitrogen reduction is present exclusively in prokaryotes and such microbes are often called fixers.

Hydroponics or Soil less culture: Von Sachs developed a method of growing plants in nutrient solution. The commonly used nutrient solutions are Knop solution (1865) and Amon and Hoagland Solution (1940). Later the term Hydroponics was coined by Goerick (1940) and he also introduced commercial techniques for hydroponics. In hydroponics roots are immersed in the solution containing nutrients and air is supplied with help of tube.
VI. 5 Mark Questions

Name of the deficiency disease and symptoms:
* Chlorosis (Overall)
* Interveinal chlorosis
* Marginal chlorosis
* Necrosis (Death of the tissue)
* Stunted growth
* Anthocyanin formation
* Delayed flowering
* Die back of shoot, Reclamation disease, Exanthema in citrus (gums on bark)
* Hooked leaf tip
* Little Leaf
* Brown heart of turnip and Internal cork of apple
* Whiptail of cauliflower and cabbage
* Curled leaf margin
Deficiency minerals:
* Nitrogen, Potassium, Magnesium, Sulphur, Iron, Manganese, Zinc and Molybdenum. Magnesium, Iron, Manganese and Zinc Potassium
* Magnesium, Potassium, Calcium, Zinc, Molybdenum and Copper.
* Nitrogen, Phosphorus, Calcium, Potassium and Sulphur.
* Nitrogen, Phosphorus, Magnesium and Sulphur
* Nitrogen, Sulphur and Molybdenum
* Copper
* Calcium
* Zinc
* Boron
* Molybdenum
* Potassium

Nitrogen: It helps in plant growth and development.
* It required in large amount
* It is essential component of Proteins, Amino acids, Nucleic acids, Vitamins, Hormones, Chlorophyll etc.
Phosphorus:
It is an important constituent of Cell membrane, Proteins, Nucleic acids, ATP, NADP etc.
Potassium:
* It is essential to maintain turgidity and osmotic potential of the cell.
* Opening and closure of stomata.
* Phloem translocation.
* Ion exchange etc.
* So overall all the three in right proportion is used by farmers for various plants to enhance yield.

1. Attraction:
Legume roots secretes Phenolics to attract Rhizobium.
2. Infection:
* Rhizobium – reaches rhizosphere
* Rhizosphere – to root hair.
* Curling of root hairs.
3. Spreading & multiplication:
Infection thread grows inwards and infected area is separated from normal tissue.
4. Bacteriod formation:
A membrane bound bacterium is formed inside the nodule ……………. called Bacterioid.
5. Nodule formation:
* Cytokinin from Bacteria.
* Auxin from legume roots together promote cell division and nodules are formed.

* Ammonia ions are quite toxic to plants, and hence cannot accumulate in the plants.
* It should be converted into Amino acids.
There are 3 methods by which it is done.
I) Reductive amination:
In this ammonia reacts with Ketoglutaric acid and form glutamic acid.
II) Transamination:
* It involves the transfer of amino group from one amino acid to the ketogroup of another keto acid.
* Glutamic acid is the main amino acid from which the transfer of NH2 (amino group) takes place and other amino acids are fonned through transamination.
* The enzyme Transaminase + Pyridoxus phosphate (COenz) reactions.
Example:
III) Catalytic Amination (GS/GOGAT path way)

Definition:
Organism deriving their nuitrients from another organism (host and causing damage/disease to the host is known as parasite. Stem parasite Root parasite Stem parasite Root parasite.
I) Obligate or Total parasite:
* Completely depends on host for their survival produce haustoria.
Total stem parasite:
* Leafless plant twine around the host. Eg. Cuscuta on Zizipus, citrus etc.
Total root parasite:
* Plants do not have stem axis – so grow in the roots of host plants produce haustoria.
Eg. Rafflesia, Orobanche and Balanophora.
II) Partial parasite:
Plant have chlorophyll on their leaves dependent on water and mineral requirements.
* Partial stem parasite: The plant grow an fig and mango and absorb water and minerals from xylem of host through haustoria.
Eg. Loranthus.
* Partial root parasite: This plant in its juvenile stages produces haustoria which grow on roots of many forest trees.
Eg. Sandal wood tree (santalum album)

Definition:
Derving nuitrients from dead and decaying organic matter is known as saprophytic – nuitrition.
Eg. Bacteria, Fungi
Saprophytic Angiosperms:
* Neottia: (Bird’s nest orchid) Roots of Neottia get associated with the mycorrhizae and absorb nuitrients from the litter in the soil.
* The plant leaves lack chlorophyll so dependon mycorrhiza to absorb nuitrients from the decomposed litter in the soil.
* Monotropa: (Indian pipe) It also lack leaves, so absorb nuitrients from the soil through the mycorrhizal association.