Sexual Reproduction in flowering Plants

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Question
CBSEENBI12002449

Compared with the gametophytes of the bryophytes the gametophytes of vascular plants tend to be
  • larger but to have smaller sex organs

  • larger and to haver larger sex organs

  • smaller and to have smaller sex organs

  • smaller but to have larger sex organs

Solution

C.

smaller and to have smaller sex organs

As we proceed from thallophyta to angiosperms, there is gradual reduction in gametophte with reduced size of sex organs. From thallophyta to angiosperms, there is progressive elaboration of sporophytes. 

Phase Thallophyta  Bryophyta Pteridophyta Gymnosprems Angiosperms
Gametophyte(%) 90 75 50 25 10
Sporophyte(%) 10 25 50 75 90

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Question
CBSEENBI12002806

A dioecious flowering plant prevents both:

  • Autogamy and xenogamy

  • Autogamy and geitonogamy

  • Geitonogamy and xenogamy

  • Cleistogamy and xenogamy

Solution

B.

Autogamy and geitonogamy

Question
CBSEENBI12002203

Advantage of cleistogamy is 

  • higher genetic variability

  • more vigorous offspring

  • no dependence on pollinators

  • vivipary

Solution

C.

no dependence on pollinators

In cleistogamous flowers, anthers and stigma lie close each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, these flowers produce assured seed set even in the absence of pollinators. The higher genetic variability and more vigorous offsprings are the produced to variations obtained by sexual reproduction. Vivipary relates to the birth of young babies from mammals.

Question
CBSEENBI12002798

An enzyme that can stimulate germination of barley seeds is

  • α-amylase

  • lipase

  • protease

  • invertase

Solution

A.

α-amylase

Barely seeds are rich in carbohydrate (Starch). The starch is hydrolysed by α-amylase to monosaccharides unit at the time of germination of seeds.

Question
CBSEENBI12002656

An example of a seed with endosperm, perisperm and caruncle is 

  • Cotton

  • coffee

  • lily

  • castor

Solution

D.

castor

The seeds of castor (Ricinus communis, family -Euphorbiaceae) are endospermic dicot seeds. They possess  endosperm which acts at the food storgage tissue of seed. They also possess perisperm and cruncle.

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