ADDITIONAL QUESTIONS :
The diagram below shows a germinating pollen grain and a mature ovule from an insect-pollinated flower. Some parts have been labelled.

Give the letter of the nucleus which fuses with a male nucleus to form each of the following :
(i) The zygote (ii) The endosperm

ADDITIONAL QUESTIONS : The diagram represents a flower. Label the parts and answer the following : (a) Give the letter of the structure which : (i) becomes the fruit wall, (ii) becomes the testa (seed coat), (iii) produces pollen grains. (b) Explain two ways, shown in the diagram, in which this flower is adapted for insect pollination.

ADDITIONAL QUESTIONS :. (a) Give reason for each of the following : (i) Anthers of angiospermic flowers are described as dithecous. (ii) Hybrid seeds have to be produced year after year.

Give reason for the following In angiosperms, one of the male gametes fuses with egg to form zygote and second male gamete fuses with polar nuclei to form primary endosperm nucleus.

Short Answer Questions Three mark Each (a) The diagram given below shows the transverse section of a young anther. Identify the parts a, b, c and d. (b) The developmental stages of male gametes in plants consist of microsporogenesis and male gametophyte. Arrange the following terms in their correct developmental sequence. Pollen grain Sporogenous tissue Anther Microspore tetrad Pollen mother cell Male gamete.

Long Answer Questions Five mark Each QUESTIONS FROM CBSE BOARD EXAMINATIONS : (a) Draw a diagrammatic sectional view of a mature anatropous ovule and label the following parts in it: (i) that develops into seed coat. (ii) that develops into an embryo after fertilization. (iii) that develops into an endosperm in an albuminous seed. (iv) through which the pollen tube gains entry into the embryo sac. (v) that attaches the ovule to the placenta (b) Describe the characteristic features of wind pollinated flowers.

Long Answer Questions Five mark Each QUESTIONS FROM CBSE BOARD EXAMINATIONS : A flower of tomato plant following the process of sexual reproduction produces 240 viable seeds. Answer the following questions giving reasons: (a) What is the minimum number of pollen grains that must have been involved in the pollination of its pistil? (b) What would have been the minimum number of ovules present in the ovary? (c) How many megaspore mother cells were involved? (d) What is the minimum number of microspore mother cells involved in the above case? (e) How many male gametes were involved in this case?

Long Answer Questions Five mark Each QUESTIONS FROM CBSE BOARD EXAMINATIONS : Give reasons why : (i) most zygotes in angiosperms divide only after certain amount of endosperm is formed. (ii) groundnut seeds are exalbuminous and castor seeds are albuminous. (iii) micropyle remains as a small pore in the seed coat of a seed. (iv) integuments of an ovule harden and the water content is highly reduced as the seed matures. (v) apple and cashew are not called true fruits.