(B) Read the passage and correct the errors, wherever
present.
(a) Epihydrophily occurs below the surface of water,
while hypohydrophily occurs over the surface of
water.
(b) Pollen tube travels chemotropically along the
concentration gradient of potassium - nitrogen -
thiamine complex.
Assertion & reason
In each of the following questions, a statement of
Assertion (A) is given and a corresponding statement
of Reason (R) is given just below it. Of the statements,
mark the correct answer as :
(a) if both A and R are true and R is the correct explanation
of A
(b) if both A and R are true but R is not the correct
explanation of A
(c) if A is true but R is false
(d) if both A and R are false.
- Assertion : A typical dicotyledonous embryo consists
of an embryonal axis and two cotyledons.
Reason : The portion of embryonal axis at the level
of cotyledons is called epicotyl, which terminates with
the plumule.
- Assertion: Most zygotes divide only after a certain
amount of endosperm is formed.
Reason : This is an adaptation to provide assured
nutrition to the developing embryo.
- Assertion : Artificial hybridisation is one of the major
approaches of crop improvement programme.
Reason : It is achieved by emasculation and bagging
techniques.
- Assertion : Pollen-pistil interaction is a dynamic
process involving pollen recognition.
Reason : It is followed by promotion or inhibition of
the pollination.
- Assertion : Wind pollination requires those pollen
grains which are light and non-sticky.
Reason : The large thread-like stigmas and styles
of cob of maize hang in air to catch wind borne
pollens.
- Assertion : Geitonogamy is the transfer of pollen
grains from anther to the stigma of different flowers,
of same plant.
Reason : Geitonogamy functionally resembles cross
pollination, but genetically it is similar to autogamy.- Assertion : Cleistogamous flowers are invariably
autogamous.
Reason : These flowers remain closed so that anthers
and stigmas are never exposed hence, there is no
chance of cross pollination. - Assertion : Not all aquatic plants use water for
pollination.
Reason : In some aquatic plants, flowers emerge
above the water level, hence, are pollinated by insects
or wind, as in most land plants. - Assertion : Pollen consumption has been claimed
to increase the performance of race horses and
athletes.
Reason : Pollen grains are rich in nutrients and available
as tablets and syrup in the Western countries. - Assertion : Synergids have special cellular thickenings
called filiform apparatus at the micropylar tip.
Reason : The filiform apparatus plays an important
role in guiding the pollen tubes into the synergid.
Figure Based Questions - Refer the given figures and identify A, B, C, D, E and
F. - Fill in the blanks using the letters assigned to figures
in previous question. You may also use appropriate
phrases, wherever required.
(a) (i) is the most common type of ovule found in
82% of angiosperms.
(b) In (ii) , the (iii) is fused with the body of the
ovule, forming a longitudinal ridge called (iv).
(c) Nucellus and integuments lie more or less at right
angles to the funiculus in (v).
(d) The funicle is exceptionally long and form almost
complete circle around the ovule in (vi).
(e) In (vii) , micropyle, chalaza and funicle lie in one
straight line.