#240.
In nematology, a variety is said to be resistant if it
A
Produce good yield despite of high level of nematode infestation
B
Suppresses the multiplication of nematodes
C
Supports multiplication of nematodes
D
Leaves of plants appear normal
Answer: Suppresses the multiplication of nematodes
#241.
A variety is said to be tolerant if it
A
Produce good yield despite of high level of nematode infestation
B
Suppress the multiplication of nematodes
C
Does not show symptoms
D
Low levels of nematode population
Answer: Produce good yield despite of high level of nematode infestation
#242.
The permanent nurse cells induced by ROOT KNOT NEMATODES in roots are called
A
giant cells
B
galls
C
syncytia
D
nodules
Answer: giant cells
#243.
The permanent nurse cells induced by CYST NEMATODES in roots are called
A
giant cells
B
root nodules
C
root galls
D
syncytia
Answer: syncytia
#244.
Tylenchulus semipenetrans is the most widespread and serious nematode pest of citrus in the Philippines. What citrus disorder is caused by this nematode?
A
citrus decline
B
citrus tristeza
C
toppling disease of citrus
D
citrus root rot
Answer: citrus decline
#245.
Which of the following is NOT true about the nature of plant parasitic nematodes?
A
Worm-shaped except for females of some genera which are swollen
B
Two or more species/ genera may infect a singie host
C
Parasitizes plants but in their absence, may feed on soil fungi and bacteria
D
Needs a thin film of water for movement
Answer: Parasitizes plants but in their absence, may feed on soil fungi and bacteria
#246.
Which of the following methods primarily determines a biological property of a plant virus?
A
ease of inoculation
B
shape and size of its particle
C
positive reaction of certain stains
D
positive reaction of certain hosts
Answer: positive reaction of certain hosts
#247.
A plant virus is not stable when
A
its infectivity is retained even with harsh environments
B
it infects only one host
C
it has a vector
D
it has a wide host range
Answer: it infects only one host
#248.
In polyacrylamide gel electrophoresis, the smaller/shorter species of proteins and nucleic acids
A
occupy the upper (top) part of the gel
B
occupy the bottom part of the gel
C
remain stationary
D
occupies the middle part of the gel
Answer: occupy the bottom part of the gel
#249.
Which of the following is true of non-persistent viruses?
A
infects and multiplies in specific tissues/cells of the host
B
is transmitted by both aphids and leafhoppers
C
its vectors loss the ability to transmit them after molting
D
its vectors do not loss the ability to transmit the virus after molting
Answer: its vectors loss the ability to transmit them after molting
#250.
A plant infected with a virus and shows severe symptoms, high virus concentration in it but shows no significant reduction in its yield is considered
A
Susceptible
B
Resistant
C
tolerant
D
semi-tolerant
Answer: tolerant
#251.
In general, plants infected with persistent viruses show symptoms that are mostly
A
dwarfing/stunting and mosaics/mottles
B
dwarfing/stunting and leaf curls/cupping
C
dwarfing/stunting and yellowing/chlorosis
D
dwarfing/stunting and leaf fall
Answer: dwarfing/stunting and yellowing/chlorosis
#252.
Who among the scientists named below is considered the Father of Virology?
A
Newton
B
Galileo
C
Berkeley
D
Beijerinck
Answer: Beijerinck
#253.
The shape of the virus particle is a stable characteristic. Which of the following is not a known shape of the plant viruses?
A
geminae or double spheres
B
triangle
C
rod
D
spherical
Answer: triangle
#254.
An example of a rod-shaped plant virus is
A
rice tungro
B
banana bunchy to
C
citrus tristeza virus
D
tobacco mosaic
Answer: tobacco mosaic
#255.
A virus is different from a viroid in that the viroid is composed of
A
single stranded circular RNA and a protein coat
B
single stranded RNA alone with extensive base paring
C
single stranded DNA alone with extensive base paring
D
single stranded circular DNA and a protein coat
Answer: single stranded RNA alone with extensive base paring
#256.
Pioneering experiments that laid the foundations of virology as a discipline of biology were those by
A
Shepherd and co-workers
B
Stanley, Markham and Smith
C
Schramm, Frankael-Conrat and Williams
D
Mayer, Iwanowski and Beijerinck
Answer: Mayer, Iwanowski and Beijerinck
#257.
The early works on plant diseases due to viruses were based on the simple fact that they are
A
very infectious and cause mosaic/mottle symptoms
B
very infectious and very small
C
are transmitted by aphids
D
associated with leafhoppers
Answer: very infectious and very small
#258.
The plant viruses have been labeled as genetic parasites in that they...
A
take over the genetic machinery of their host cells for their own reproduction
B
allow continuous and uncontrolled division of their host cells
C
take over the DNA of their host cells and package it as their own
D
use the enzymes of the host for their assembly into particles
Answer: take over the genetic machinery of their host cells for their own reproduction
#259.
The most important group of véctors of plant viruses, both in terms of number et the viruses they transmit and the economic importance of the diseases thee viruses cause, is the