January 6, 2014

Senior Inter Botany Imp 2 Marks QAs - Plants, Growth and Developmet

Respiration in plants, Plant growth and development, Bacteria, Viruses: Growth is one of the most conspicuous events in any living organism. It is an irreversible increase expressed in parameters such as size, area, length, height, volume, cell number etc. Let’s learn some important questions and answers related to growth and development in plants.

2 Marks Questions

Q: What is the common pathway for aerobic and anaerobic respirations? Where does it
take place?
A: Glycolysis. It takes place in the cytoplasm of the cell.

Q: Which substance is known as the connecting link between glycolysis and Kreb’s
cycle? How many carbons does it have?
A: Acetyl Co-A. It contains 2 carbons.

Q: Name the mobile electron carriers of the respiratory electron transport chain in the
inner mitochondrial membrane.
A: Ubiquinone. Cytochrome c.

Q: What is the final acceptor of electrons in aerobic respiration? From which complex
does it receive electrons?
A: Oxygen. It receives electrons from Cytochrome c oxidase complex
(a complex with cytochrome a and a3 and 2 copper centres).

Q: What is the disease that formed the basis for the identification of gibberellins in plants? Name the causative fungus of the disease.
A: Bakane or foolish seedling disease. Giberella fuzikuroi is the causative fungus.

Q: What is apical dominance? Name the growth hormone that causes it.
A: The inhibition of lateral bud growth by apical bud due to presence of auxins is called apical dominance. Auxins are responsible for apical dominance.

Q: What is meant by bolting? Which hormone causes bolting?
A: Inter nodal elongation prior to flowering is called bolting. Gibberellins cause bolting.

Q: Define respiratory climacteric. Name the PGR associated with it.
A: The increase in rate of respiration during fruit ripening is called respiratory climacteric. Ethylene is associated with respiratory climacteric.

Q: Which of the PGRs is called stress hormone and why?
A: Abscisic acid is called stress hormone. It reduces the rate of transpiration under
drought conditions by causing closure of stomata.

Q: Define the terms quiescence and dormancy.
A: Quiescence is the inability of the seed to germinate due to unfavourable conditions
like low or high temperature and moisture. Dormancy is the inability of the seed to germinate even under favourable conditions of temperature and moisture.

Q: Name the bacterium which is common inhabitant of human intestine. How is it used
in biotechnology?
A: Escherichia coli. The plasmids of E.coli are used as vectors during genetic engineering in biotechnology.

Q: What are pleomorphic bacteria? Give an example.
A: The bacteria that change their shape depending upon the type of environment and nutrients available are called pleomorphic bacteria. Ex: Acetobacter.

Q: What is Genophore?
A: Genophore is the bacterial chromosome which acts as the main genetic material.

Q: What is plasmid? What is its significance?
A: Small circular double stranded DNA molecules in bacterial cells are called plasmids.
They contain few genes and confer resistance to drugs. They also produce toxins and enzymes. As they can be readily manipulated and transferred they are used in genetic engineering.

Q: What is conjugation? Who discovered it and in which organism?
A: Conjugation is the direct transfer of DNA between the living donor and the living
recipient bacterial cells through a conjugation tube. It was first discovered by Lederberg and Tatum in Escherichia coli.

Q: What is transformation? Who discovered it and in which organism?
A: Transformation is the uptake of naked DNA fragments from the surrounding environment and incorporation of DNA into the genome of a bacterial cell and expression of that genetic information in it. It was discovered by Frederick Griffith in Streptococcus
pneumoniae.

Q: What is transduction? Who discovered it and in which organism?
A: Transduction is the transfer of genetic material from one bacterium to another through a bacteriophage virus. It was discovered by Lederberg and Zinder in Salmonella
typhimurium.

Q: What is the shape of T4 phage? What is its genetic material?
A: Tad pole shape with polyhedral head and helical tail.
Genetic material – RNA.

Q: What are virulent phages? Give an example.
A: The bacteriophages that attack bacterial cells and cause lysis of the cells are called virulent phages. Ex: T-even phages (T4 phage)

Q: Define ‘lysis’ and ‘burst size’ with reference to viruses and their effects on host cells.
A: Lysis: The breakage of bacterial cell wall to release newly synthesized phage particles is called lysis.
Burst size: The number of newly synthesized phage particles released from a single host
cell is called burst size (50 to 200).

Q: What is lysozyme and what is its function?
A: Lysozyme is a viral enzyme that is produced by bacterial cell and causes dissolution of plasma membrane of the host cell. It helps in breaking of bacterial cell wall to liberate newly synthesized bacteriophages.

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