January 6, 2014

Senior Inter Botany 4 Marks Questions - Plants Growth and Development

Q: Pyruvic acid is the end produce of glycolysis. What are the three metabolic fates of
pyruvic acid under aerobic and anaerobic conditions?

A: The metabolic fate of pyruvic acid depends on the need of the cell. The three metabolic fates of pyruvic acid are:
1) Aerobic respiration
2) Lactic acid fermentation
3) Alcoholic fermentation
Aerobic respiration occurs when there is oxygen supply and the pyruvic acid converted
to Acetyl coenzyme a enters Kreb’s cycle for further oxidation.
Lactic acid fermentation occurs under inadequate supply of oxygen where pyruvic acid is
reduced to lactic acid by lactate dehydrogenase.
Ex: Muscle cells of animals.
Alcoholic fermentation occurs under anaerobic conditions where pyruvic acid is converted to CO2 and ethanol by the enzymes pyruvic acid decarboxylase and alcohol dehydrogenase.
Both lactic acid and alcohol fermentation
produce less energy compared to aerobic respiration.

Q: Which one of the plant growth regulators would you use if you are asked to
a. Induce rooting in a twig
b. Quickly ripen a fruit
c. Delay leaf senescence
d. Induce growth in axillary buds
e. ‘Bolt’ a rosette plant
f. Induce immediate stomatal closure in leaves
g. Overcome apical dominance
h. Kill dicotyledonous weeds

A: a) Auxins b) Ethylene
c) Cytokinins d) Cytokinins
e) Gibberellins f) Abscisic acid
g) Cytokinins h) Auxins (2, 4 D)

Q: Explain the importance of Microbiology.

A: Importance of microbiology: A large number of microorganisms are useful to man in many ways. Saprophytic bacteria and fungi cause decomposition of organic wastes and help in the process of humification and mineralization which are important to the nutrient cycles.

Many fungi and bacteria are used for production of antibiotics, alcohols, enzymes and hormones on industrial scale. Bacterial plasmids are used as tools in genetic engineering and bio technology. LAB is used for conversion of milk into curds. Bacteria are also used in sewage treatment.

Some bacteria like Methano coccus and Methano bacillus are useful in production of bio gas. Bacteria are also used as bio control agents in pest and diseases control in agriculture. Bacteria like Rhizobium, Azospirillum and Azotobacter are used as bio fertilizers.

Microorganisms like Nostoc and Anabaena are used as nitrogen fixers in agriculture.
Microbes are presently used in bio-mining for extraction of metals like uranium.
Bacterial DNA components are used as Biosensors to detect toxic pollutants.
They are also used in medical diagnostics, food and fermentation operations.
Bacteria are the real tools in genetic engineering.

Q: What is ICTV? How are viruses named?

A: ICTV stands for International Committee on Taxonomy of Viruses. It regulates the classification and nomenclature of viruses.
According to ICTV the viruses are classified into three levels, family, genus and species. Viruses are usually named after the disease they cause. Ex: Polio virus and Influenza virus. Using ICTV system AIDS virus is placed under the family Retroviridae, genus Lentivirus and Species Human Immune deficiency Virus (HIV).

Q: Explain the structure of TMV.
A: Structure of TMV (Tobacco Mosaic Virus):

Tobacco mosaic virus causes mosaic disease in Tobacco.
It is rod shaped with helical symmetry.
The size is approximately 300 nm long and 18 nm in diameter with a molecular weight of
39 × 106 Daltons.
The capsid is made up of 2,130 capsomeres which are arranged in a helical manner around the hollow core of 4 nm.
Each capsomere is made up of a polypeptide chain with 158 amino acids.
The spirally coiled RNA contains 6500 nucleotides.

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