Hybrid seeds have to be produced every year because:
(1) Hybrid plants become sterile in coming years
(2) They show more heterosis in coming years
(3) Hybrid vigour is not maintained beyond one generation as segregation of genes begins in the second generation
(4) Hybrid seed industry tends to increase cost of the seeds
Active research is going on in many laboratories around the world to understand the genetics of apomixis. What is the purpose of such active research?
(1) Hybrid plants are directly formed by apomixis
(2) Apomixis is the method to produce seed without fertilization
(3) To transfer apomictic genes into hybrid varieties which will prevent loss of hybrid vigour with successive years
(4) Apomixis produces genetically different individuals
Both, autogamy and geitonogamy are prevented in:
(1) Papaya
(2) Cucumber
(3) Castor
(4) Maize
A typical angiosperm anther is bilobed with each lobe having two theca i.e. dithecous. Theca is separated often by :
1. A longitudinal groove running lengthwise.
2. A longitudinal groove running breadth wise.
3. A transverse groove running breadth wise.
4. A transverse groove running lengthwise.
Four statements are given below. How many of them are correct?
(1) The anther is a tetragonal structure, with four microsporangia at corners, two in each lobe.
(2) Microsporangia develops further and becomes a pollen sacs.
(3) A typical microsporangia is surrounded by four layered wall, 3-protective and 1 nutritional.
(4) The nutritive layer is densely cytoplasmic with more than one nucleus
Options :
1. 3
2. 4
3. 2
4. 1
Which of the following statement is not correct for pollen grain?
1. It represents male gametophyte.
2. It is a spherical structure, about 25-50 micrometers in diameter.
3. Pollen grains are rich in nutrients.
4. In family rosaceae, leguminoseae and solanaceae pollen lose viability in 30 minute.
In which organ the growth of pollen tube is observed, till it reaches the ovules?
A.Pollen tube
B.Style
C.Ovary
D.Stigma
Read the statements and select option representing correct statements with respect to stamen.
A. The distal end of filament is attached to thalamus.
B. A typical anther is dithecous and bisporangiate.
C. Connective is sterile vasculated tissue.
D. Microsporangia develop further and become pollen sacs.
1. A & B
2. A & C
3. B & C
4. C & D
Genetically and functionally self-pollination is cent percent ensured with seed formation even in the absence of pollinators by
(1) Bisexuality
(2) Dicliny
(3) Geitonogamy
(4) Cleistogamy
How many statement(s) is/are correct for pollen grains?
a. Parthenium is a cause of bronhial afflictions
b. Intine exhibits fascinating array of patterns and designs
c. Cytoplasm of pollen grain is s urrounded by spermoderm
d. Generative cell is present when pollens are shed in 40 percent plants.
1. One
2. Two
3. Three
4. Four