December 3, 2015

Senior Inter Botany Important Questions - Mineral Nutrition - 4 Marks

Q: 'All elements that are present in a plant need not be essential for
its survival'. Justify.

A: Plants absorb 60 or even more mineral elements from the soil. All
60 are not present in one plant. In the same way all elements present
in a plant are useful to it. Only the useful elements are called
essential elements.

Q: Name at least five different deficiency symptoms in plants.
Describe them, and correlate them with concerned mineral deficiency.
A: Deficiency symptoms of
1. Zinc:
1) Little leaf disease
2) Leaf rosette
3) Mottled leaf
4) Interveinal Chlorosis - Necrosis

Zinc is a mobile, micro mineral essential element. It is an activator
for Carboxylase. It is needed for the synthesis of Auxins. It is
absorbed in the form of Zn2+.

2. Copper:
1) Die back disease of shoots in Citrus
2) Necrosis of young leaf tips
3) Exanthema
4) Reclamation disease of cereals and legumes
5) Blackening Potato tubers

3. Boron:
1) Heart rot in beets (Brown heart)
2) Water core in turnip
3) Heart rot in carrot
4) Fibres in apple fruit
5) Death of root tip and stem tip

4. Molybdenum:
1) Whiptail disease in Cauliflower
2) Interveinal Chlorosis
3) Inhibition of flowering
4) Mottled Chlorosis
5) Upper half leaf shows withering

5. Chlorine:
1) Bronzing in legumes
2) Flower abseision
3) Swollen root tips

Q: Some angiospermic plants adapted to absorb molecular nitrogen from
atmosphere. Explain, citing two examples.

A: Leguminaceae members and some plants like Myrica, Alnus, Casuarina
have adapted to absorb molecular nitrogen with the help of bacteria.
It occurs through symbiotic nitrogen fixation.

Rhizobium fixes molecular nitrogen to Legumes, and also to a
non-leguminous member called Parasponia.

Filamentous, Actinomycetus bacteria like Frankia fixes atmospheric
molecular nitrogen in Alnus, Casuarina and Myrica.

Nostoc fixes nitrogen in the stem glands of Gunnera.
Azospirillum, an associated symbiont fixes nitrogen in Maize, Sorghum,
Wheat, Barley and Finger millets.

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