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The triploid or the primary endosperm nucleus is formed as a result of the fusion of
A
Two synergids and a sperm nucleus
B
One egg and two sperm nuclei
C
Two polar nuclei and a sperm nucleus
D
Three antipodal cells
Correct Answer:
Two polar nuclei and a sperm nucleus
Consider the following statements regarding Xenia and choose the correct answer:
1. If a white variety (yy) is pollinated with pollen from a yellow variety (YY), one of the male gametes (Y) will unite with the egg (y) to produce a hybrid embryo (Yy) which will act as a heterozygote for yellow endosperm in the next generation
2. The second male gamete (Y) will unite with the two polar nuclei (y, y) and produces the primary endosperm nucleus (Yyy) which is triploid
3. If a yellow endosperm variety (YY) is crossed with pollen from a white grained variety, the grains produced are white like the pollen parent
A
Only 1 and 2 are true
B
Only 2 and 3 are true
C
Only 1 and 3 are true
D
1, 2 and 3 are true
Consider the following statements and choose the correct answer:
1. For the development of viable seeds the double fertilization is very necessary
2. The net result of double fertilization is the formation of endosperm from the triploid nucleus
3. In Angiosperms very free nuclear divisions take place as in Gymnosperms
4. The endosperm nucleus has both maternal and paternal characters showing physiological importance like hybrid vigour
A
Only 1, 2 and 3 are true
B
Only 2, 3 and 4 are true
C
Only 1, 3 and 4 are true
D
Only 1, 2 and 4 are true
In which of the following types of endosperm, the first nuclear division of the primary endosperm nucleus is followed by the formation of either a longitudinal or transverse wall in the central cell?
A
Helobial endosperm
B
Nuclear endosperm
C
Cellular endosperm
D
Both A and B
Consider the following statements regarding double fertilization and choose the correct answer:
1. At the time of the sperm's approach to the egg nucleus, the male nucleus has the appearance of a continuous thread rolled into a ball
2. It is only the presence of the two nucleoli which serves to distinguish the fertilized egg from the unfertilized egg
3. Finally, the male nucleolus increases in size and fuses with the female nucleolus thus closing the phenomenon of sexual union of the nuclei
4. The fusion of the male gamete with the secondary nucleus results in the formation of a sister embryo
A
Only 1, 2 and 3 are true
B
Only 2, 3 and 4 are true
C
Only 1, 3 and 4 are true
D
Only 1, 2 and 4 are true
Consider the following statements.
1. Fertilisation of the egg takes place inside the embryo sac.
2. Fertilised ovum form the embryo.
3. Endosperm is generally triploid.
Which of the statements given above are correct?
A
1, 2 and 3
B
1 and 2
C
2 and 3
D
1 and 3
Consider a nucleus with N neutrons and Z protons. If m
p
, m
n
and BE represents the mass of the proton, the mass of the neutron and the binding energy of the nucleus respectively and c is the velocity of light in free space, the mass of the nucleus is given by
A
Nm<sub>n</sub> + Zm<sub>p</sub>
B
Nm<sub>p</sub> + Zm<sub>n</sub>
C
Nm<sub>n</sub> + Zm<sub>p</sub> + $$\frac{{BE}}{{{c^2}}}$$
D
Nm<sub>p</sub> + Zm<sub>n</sub> + $$\frac{{BE}}{{{c^2}}}$$
Study the following statements.
1. Control room of the cell is Nucleus.
2. Nucleus was discovered by Robert Brown.
3. Nuclear envelope is absent in bacteria.
Which of the statement(s) given above is/are correct about nucleus?
A
Only 1
B
Only 2
C
1 and 2
D
1, 2 and 3
In _______, the endosperm is a special tissue which is formed as a result of vegetative fertilization.
A
gymnosperms
B
angiosperms
C
dichosperms
D
parenchyma
Which will be the unknown nucleus formed when 22Ne10 decays into two α-particles and an unknown nucleus?
A
Fluorine
B
Carbon
C
Neon
D
Oxygen
The tetraploid secondary nucleus after fertilization by a male gamete produces a pentaploid endosperm in which of the following plants?
A
Erythronium
B
Sambuscus
C
Ulmus
D
Lilioideae