Andhra Pradesh BIEAP AP Inter 2nd Year Botany Study Material 2nd Lesson Mineral Nutrition Textbook Questions and Answers.
AP Inter 2nd Year Botany Study Material 2nd Lesson Mineral Nutrition
Very Short Answer Questions
The technique of growing plants in a specified nutrieht solution in complete absence of soil is known as hydroponics.
How do you categorize a particular essential element as a macro or micronutrient?
The elements which are present in large amounts i.e., in excess of 10m mole kg-1 of dry matter are called Macronutrients. The elements which are needed in small amounts i.e., less than 10m mole kg-1 of dry matter are called micronutrients.
Give two examples of essential elements that act as activators for enzymes.
Molebdinum, Magnesium and Zn+2.
Name the. essential mineral element that play an important role in photolysis of water.
Calcium and Manganese.
Out of the 17 essential elements, which elements are called non-mineral essential elements?
Carbon, Oxygen, Hydrogen and Nitrogen.
Name two amino acids in which sulphur is present.
Cysteine and Methionine.
When is an essential element said to be deficient?
The element said to be deficient when present below the critical concentration [The Cone, of the essential elements below which plant growth is retarded is termed as critical concentration].
Name two elements whose symptoms of deficiency first appear in younger leaves.
Sulphur and Calcium.
Explain the role of the pink colour pigment in the root nodule of legume plants. What is it called?
The enzyme nitrogenase is highly sensitive to the molecular oxygen. It is protected from oxygen by pink colour pigment cailed an oxygen scavenger, leg haemoglobin.
Which element is regarded as the 17th essential element? Name the disease caused by its deficiency.
Nickel. It’s deficiency cause Mouse ear in pecan. [Slightly wrinkled leaves round or blunt leaflets].
Name the essential elements present in nitrogenase enzyme. What type of essential elements are they?
Nitrogenase enzyme contains Mo and Fe elements. They are Micronutrients.
Write the balanced equation of nitrogen fixation.
N2 + 8H+ + 8e– + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Name any two essential elements and the deficiency diseases caused by them.
Chlorosis occurs due to the deficiency of N, K, Mg, S, Fe, Mn, Zn and Mo.
Neurosis occurs due to the deficiency of Ca, Mg, Cu, K.
Short Answer Questions
Explain the steps involved in the formation of root nodule.
- Roots of legumes release sugars, amino acids which attracted Rhizobium. They get attached to epidermal and root hair cells of the host.
- The root hair curl and the bacteria invade the root hair.
- An infection thread is produced, carrying the bacteria into cortex of the root.
- Bacteria initiate nodule formation in the cortex of the root. Then the bacteria released from the thread into the cortical cells of the host and stimulate the host cells to divide. Thus leads to the differentiation of specialized nitrogen fixing cells.
- The nodule thus formed establishes a direct vascular connection with the host for exchange of nutrients.
Write in brief, how plants synthesize amino acids.
Amino acids are synthesized into two ways. They are
1) Reductive Amination :
In this ammonia reacts with a-ketoglutaric acid and forms glutamic acid.
2) Transamination :
In this, transfer of an amino group from an amino acid to the keto group of a keto acid. Glutamic acid is the main amino acid from which the transfer of NH2 takes place and other amino acids are formed in the presence of transaminase.
Explain in brief, how plants absorb essential elements.
The process of absorption can be demarcated into two main phases. In the 1st phase, there is an initial uptake of ions into the free space or outer space of cells – the apoplast. It is a passive process. In the second phase of uptake, the ions are taken in slowly into the inner space – the symplast.
The passive movement of ions into the apoplast from the cell along the concentration gradient usually occurs through ion-channels. The entry or exit of ions to and from the symplast against the concentration gradient requires metabolic energy which is an active process.
Explain the Nitrogen cycle, giving relevant examples.
The cyclic movement of nitrogen from the atmosphere to soil and from soil back into the atmosphere through plants, animals and micro-organisms is termed as nitrogen cycle. Nitrogen cycle is a continuous pathway and it involves five steps.
- Nitrogen Fixation
- Nitrogen Assimilation
1) Nitrogen Fixation :
The gaseous dinitrogen is fixed into inorganic nitrogenous substances is called nitrogen fixation. It occurs by two methods.
a) Abiological or physical method,
b) Biological method – Dia2otrophy.
a) Abiological or physical method :
- It occurs in atmosphere. Due to thunders and lightening, dinitrogen is converted into nitric acid which is further oxidised to nitrogen dioxide.
- These oxides dissolves in rain water and reaches soil as nitrous and nitric acids.
- These acids react with alkali radicles of soil and form nitrates.
- The soluble nitrates are directly absorbed by plants. The reactions of physical nitrogen fixation are as follows.
1) N2 + O2 → 2NO
2) 2NO + O2 → 2NO2
3) 2NO2 + H2O → HNO2 + HNO3
4) HNO3 + Ca or K salts → Ca or K nitrates.
5) A biological nitrogen fixation is carried put on industrial scale by Haber Bosch process at 0°C with 1000°C bars pressure.
b) Biological method – Diazotrophy :
1) Conversion of dinitrogen into nitrogenous compounds by prokaryotes is called biological nitrogen fixation. Such microbes are called as diazotrophs or nitrogen fixers.
Eg : Free-living bacteria – Azotobacter, Clostridium.
Symbiotic bacteria – Rhizobium in the root nodules of Fabaceae members.
Blue green algae – Nostoc and Anabaena.
2) Nitrogen Assimilation :
- The process of absorbing nitrates, Ammonia to produce organic nitrogen constituents is called nitrogen assimilation. It is the second step of nitrogen cycle.
- Nitrates and Ammonia formed in the first step are absorbed by plants and converted and constitute the organic nitrogen.
3) When plants are eaten by animals, this Organic nitrogen is passed on into the animal body.
3) Ammonification :
- The process of conversion of organic nitrogenous compounds from the dead bodies of plants and animals into ammonia is called Ammonification. It is mineralization process.
- The bacteria responsible for this are called Ammonifying bacteria.
Eg: Bacillus ramosus, B. vulgaris, B. mycoides.
4) Nitrification :
- This is fourth step of nitrogen cycle. It is an oxidative and an exergonic process.
- The conversion of ammonia into nitrites and nitrates by bacteria is called nitrification. Sucfybacteria are called nitrifying bacteria. It occurs in two steps.
A) In the step, Ammonia is converted into nitrites by bacteria like Nitrosomonas and Nitrococcus.
2NH3 + 3O2 → 2NO2– + 2H+ + 2H2O
B) In the next step, the nitrites are further oxidised to nitrates by Nitrobacter.
2NO2– + O2 → 2NO3–
5) Denitrification :
This is final step in nitrogen cycle. It is also exergonic process released around 11,000 cal of energy. Conversion of nitrates of soil into molecular dinitrogen is called denitrification. Denitrification occurs in four steps
NO3– → NO2– → NO → N2
This process is brought about by denitrifying bacteria like Thiobacillus denitrificans, Pseudomonas denitrificans and Micrococcus denitrificans.
Who should be credited for initiation of Hydroponics?
Julius von sachs (1860).
Are all the essential elements required by plants mineral elements? Explain.
No. based upon the criteria of essentiality, only a few elements have been found to be essential for plant growth and metabolism. They are micro elements and microelements.
Which essential element is needed to activate the enzymes required for CO2 fixatin?
Name a cation and anion that maintain osmotic balance in cells?
K+ and Cl–
Which element is required for the formation of mitotic spidle?
What is the role of sulphur in plant life?
Sulphur is present in two amino acids, cysteine and methionine. It is the main constituent of several coenzymes, vitamins (Thiamine, biotin, coenzyme A) and ferredoxin. It forms disulphide bridges which help in stabilizing protein structure.
Which micro element is required in more quantify than die other micronutrients?
Which element is necessary for the synthesis of the chief photosynthetic pigment without being its structural component?
Which micronutrient necessary for photolysis of water is absorbed by plants in anionic form?
Which enzyme is activated by the 17th essential element?
Nickel acts as an activator for urease.
When is an element considered to be toxic?
Any mineral ion concentration in tissues that reduces the dry weight of tissues by about 10 percent is considered toxic.
Which element when supplied in excess leads to appearence of brown spots surrounded by chlorotic venis?
Name an anaerobic, free living, photo-hetrotrophic nitrogen fixing bacterium.
Which microorganism produces nitrogen-fixing nodules in Alnus?
When the cross section of root nodules of ground nut plants are observed under microscope, they appear pinkish, why?
This is due to the presence of leguminous haemoglobin or leg-haemoglobin which is a pink coloured pigment and is also called oxygen scavenger.
Apart from the cortical cells, which other cells are stimulated to divide by the bacteroids inside the root nodules?
Inner cortex and pericycle cells.
What is the ratio of electrons and protons required for the fixation of atmospheric molecular nitrogen through biological mode?
Ans. 8H+ + 8e– = 1 : 1.
What acts as oxygen scavenger in the legume-root nodule combination?
In what why does aspargine differ from aspartic acid?
Aspargine contains more nitrogen than aspartic acid.
Through which tissue the amino acids are transported inside the plant body?
Plants like the Picture and Venesfly trap have special nutritional adaptations. Name the essential element and its source for which they show such adaptations.
Excess ‘Mn’ in soils leads to deficiency of Ca, Mg and Fe. Justify.
Manganese competes with iron and Magnesium for uptake and with magnesium for binding with enzymes. Mn also inhibits calcium translocation in the shoot apex. Therefore excess of Mn may infact, induce deficiencies of Ca, Mg and Fe.
What acts as a reservoir of essential elements for plants? By what process is it formed?
Soil, it is formed due to weathering and breakdown of Rocks.
Nitrogen fixation is shown by prokaryotes only. Why not by eukaryotes?
In prokaryotes, nitrogenase enzyme which is a Mo-Fe protein is present and is capable of nitrogen reduction. It is absent in Eukaryotes.