Question 1

Coconut water from a tender coconut is:

Accepted Answer

Coconut water is free nuclear endosperm.

Question 2

Assertion : Nuclear endosperm is formed by subsequent nuclear division without wall formation. Reason : Coconut is an example of such endosperm, where the endosperm remains nuclear throughout the development of the fruit.

Accepted Answer

In nuclear type of endosperm the division of the primary endosperm nucleus and a few subsequent nuclear division are not accompanied by wall formation. So numerous nuclei are freely suspended in its sap. In coconut, the primary endosperm nucleus undergoes a number of free nuclear divisions. When the fruit is about 50 mm long before the embryo sac gets filled with a clear fluid in which float numerous nuclei of various sizes. At a later stage (about 100 mm long fruit) the suspension shows in addition to free nuclei, several cells each enclosing variable number of nuclei. Gradually these cells and free nuclei start setting at the periphery of the cavity and layers of cellular endosperm start appearing. In mature coconuts the liquid endosperm becomes milky and it does not contain free nuclei or cell.

Question 3

Assertion: Endosperm development precedes embryo development in angiosperms. Reason: Double fertilization ensures that the nutritive tissue is formed only when the formation of embryo has taken place so that the energy spent on the formation of endosperm does not get wasted.

Accepted Answer

During double fertilization occurs in angiosperms, one male gamete fuses with the egg to form the diploid zygote (syngamy or generative fertilization). the diploid zygote finally develops into embryo. The other male gamete fuses with the two polar nuclei (or secondary nucleus) to form the triploid primary endosperm nucleus, PEN (triple fusion or vegetative fertilization). Double fertilization ensures that the nutritive tissue is formed only when the formation of embryo has taken place by fertilization of the oosphere or egg so that the energy spent on the formation of endosperm does not go waste in case the fertilization fail.

Question 4

Assertion: Coconut water represents the cellular endosperm and the surrounding white kernel represents the free-nuclear endosperm in Cocos nucifera. Reason: PEN undergoes a number of free nuclear divisions all of which are subsequently followed by wall formation.

Accepted Answer

In Cocos nucifera (coconut), the coconut water is free-nuclear endosperm and the surrounding kernel represents the cellular endosperm. The primary endosperm nucleus (PEN) first undergoes a number of free nuclear divisions without wall formation to form a large number of free nuclei (free nuclear endosperm).

Question 5

Assertion: Formation of nucellar endosperm occurs by subsequent nuclear division without wall formation. Reason: Coconut is an example of such endosperm, where the endosperm remains nuclear throughout the development of the fruit.

Accepted Answer

The division of the primary endosperm nucleus and a few subsequent nuclear division are not accompanied by wall formation in nucellar type of endosperm. So numerous nuclei freely suspended in its sap. In coconut, the primary endosperm nucleus undergoes a number of free nuclear divisions. When the fruit is about 50 mm long before the embryo sac gets filled with a clear fluid in which float numerous nuclei of various sizes. At a later stage the suspension shows in addition to free nuclei, several cells each enclosing variable number of nuclei.

Question 6

Assertion: Cellular endosperm is formed by both nuclear division and wall formation. Reason: It lacks haustoria.

Accepted Answer

Cellular endosperm is characterized by the absence of free nuclear stage. The division of the primary endosperm nucleus and a few subsequent nuclear division are regularly followed by wall formation. The occurrence of haustoria is a common feature of this type of endosperm. The haustoria may be micropylar or chalazal. Occasionally, both types of haustoria are present in the same plant.

Question 7

Assertion: Endosperm development proceeds embryo development. Reason: It assures nutrition to developing embryo.

Accepted Answer

Endosperm is source of nutrition for the developing embryo, thus the nature ensures that endosperm is formed before starting the process of embryogenesis.

Question 8

Endosperm in angiosperms is formed from secondary nucleus -

Accepted Answer

In the case of double fertilization, which occurs in angiosperms, the primary nucleus fused with one of the nuclei of male gamete and produces zygote and secondary nucleus fuses with another nucleus of the male gametes and forms endosperm.

Question 9

(i) Describe the endosperm development in coconut. (ii) Why is tender coconut considered a healthy source of nutrition ? (iii) How are pea seeds different from castor seeds with respect to endosperm ?

Accepted Answer

(i) Coconut endosperm development is free nuclear type :The primary endosperm nucleus divides by free nuclear division. The nucleus divides repeatedly into at last 128 nuclei. Then by the process of cytokinesis it partly changes in to cellular endosperm.  (ii) The water of tender coconut, technically the liquid endosperm is rich in nutrients like fat, proteins, carbohydrates, minerals, vitamins as endosperm provides nutrition to developing embryo.  (iii) Pea seed is non-endospermic as endosperm is absent because endosperm is consumed completely during embryo development, while castor seed is endospermic as endosperm is present.

Question 10

Which of the following statement(s) is/are incorrect ?(i) Endosperm formation starts prior to first division of zygote.(ii) Angiospermic endosperm is mostly 3N while gymnospermic one is N.(iii) The most common type of endosperm is nuclear. (iv) Coconut has both liquid nuclear (multinucleate) and cellular endosperm.(v) Milky water of green tender coconut is liquid female gametophyte.

Accepted Answer

The coconut water from tender coconut is nothing but free nuclear endosperm (made up of thousands of nuclei) and the surrounding white kernel is the cellular endosperm. Female gametophyte is embryo sac.

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