Mineral Nutrition Test - 69

Insect resistance in host crop is due to morphological, biochemical or physiological characteristics. Some characters make the plant's resistance to insects are. 

Correct Option: A

Explanation:

• Molecular nitrogen which is present within the air can't be utilized directly by plants, it has to be converted into compounds before utilization.
• Rhizobium species are included in the Symbiotic organic process which occurs on the roots of leguminous plants.
• But to make nodules so on, convert it into compound nitrogen, non-leguminous plants like Alnus are involved.
• The best example involved in nodule formation is actinomycetes called Frankia.

Hence, nitrogen fixation in root nodules of Alnus is brought about by Frankia.

• The primary symptom of iron deficiency is interveinal chlorosis, the development of a yellow leaf with a network of dark green veins.
  
•  Plants deficient in phosphorus are stunted in growth and often have an abnormal dark-green color. Sugars can accumulate and cause anthocyanin pigments to develop, producing a reddish-purple color. This can sometimes be seen in early spring on low phosphorus sites.
• A magnesium-deficient crop will tend to have a pale overall color. The earliest specific symptom of magnesium deficiency is interveinal chlorosis of older leaves. Chlorosis generally progresses to yellowing and necrosis of the oldest leaves.

Root nodules are present in those plant roots which has a symbiotic association with nitrogen-fixing bacteria. This relationship is very common in nitrogen-limited conditions. A specific strain of bacteria known as rhizobia converts nitrogen gas from the atmosphere to ammonia which is then used in the formation of amino acids and nucleotides. Whereas acetobacter is a free-living nitrogen-fixing bacteria. E-coli live in the intestine and Granulobacter is associated with fermentation of pentose. 

The constituent of ash depends upon the substance that is burnt. The plant ash contains oxides of essential elements like silicon, sodium, calcium, potassium and magnesium. It contains trace elements like zinc, lead, nickel. It also contains nitrogen. 

The nutrients plants need are categorized into three different categories main nutrients, micronutrients and trace elements. Calcium along with Iron, Zinc, Manganese, Magnesium, etc is a micronutrient. In the form of Calcium Pectate, calcium holds the cell walls of plants together. It also activates specific plant enzymes, which send signals to the plant cells that coordinate certain growth activities. 

Seedlings grown in the dark develop long hypocotyl and their cotyledons remain closed around the epicotyl in an apical hook. This is referred to as skotomorphogenesis or etiolation. Etiolated seedlings are yellowish in color as chlorophyll synthesis and chloroplast development depend on light

Manganese competes with iron and magnesium for uptake due to their relative affinity and oxidation state. It plays a catalytic role in the evolution of oxygen during photolysis in the light reaction of photosynthesis.

The deficiency of micro-nutrient boron leads to Killing of terminal buds leaving a rosette effect on the plant. While, deficiency of calcium leads to stunted plant growth, necrotic leaf margins, etc. Deficiency of cobalt in uncommon - cobalt generally shows toxicity in plant tissue. The deficiency of Phosphorus produces general stunted growth in plant tissue .

Biological nitrogen fixation can be represented by the following equation, in which two moles of ammonia are produced from one mole of nitrogen gas, at the expense of 16 moles of ATP and a supply of electrons and protons.