Tag: cross pollination

Questions Related to cross pollination

An advantage of cleistogamy is

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. It leads to greater genetic diversity.

  2. Seed dispersal is more efficient and wide spread.

  3. Each visit of pollinator brings hundreds of pollen grains.

  4. Seed set is not dependent upon pollinators.

Show answer
Correct Option: D
Explanation:
Cleistogamy is the phenomenon, where flowers never open and in such flowers, only self-pollination occurs within the bud (unopened flower). Bisexual flowers which do not open at all are called cleistogamous. In such flowers, anthers and stigma lie close to each other. When the anthers dehisce in the flower buds, pollen grains come in contact with the stigma and pollination occurs. Cleistogamous flowers are not dependent on external agencies for pollination. Hence, seed setting is not dependent on pollinators and will occur even in the absence of pollinators.
So, the correct answer is D.

Cleistogamy is effective in

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Oryza sativa

  2. Brassica campestris

  3. Allium cepa

  4. Pisum sativum.

Show answer
Correct Option: A
Explanation:
Cleistogamy is the phenomenon, where flowers never open and in such flowers, only self-pollination occurs within the bud (unopened flower). Bisexual flowers which do not open at all are called cleistogamous. In such flowers, anthers and stigma lie close to each other. When the anthers dehisce in the flower buds, pollen grains come in contact with the stigma and pollination occurs. In Oryza sativa (rice), anther and stigma mature before the opening of the flower and thus, self-pollination is promoted.
Hence, cleistogamy is effective in Oryza sativa.
So, the correct answer is A.

Bisexual flower which never opens is

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Homogamous

  2. Heterogamous

  3. Dichogamous

  4. Cleistogamous

Show answer
Correct Option: D
Explanation:

A bisexual flower which never opens is cleistogamous. It is a condition in which flower does not open. It is an adaptation seen in plants to ensure self-pollination. In such flowers, the anthers and stigma lie close to each other. When anther dehisces in the flower buds, pollen grains come in contact with stigma to effect pollination, e.g., Arachis hypogaea. 

Thus, the correct answer is  D.

Cleistogamous flower is found in

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Tobacco

  2. Mirabilis

  3. Viola

  4. None of the above

Show answer
Correct Option: C
Explanation:

Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. The largest genus of cleistogamous plants is Viola.

So the correct option is 'Viola'.

In Catharanthus ($=$ Vinca) anthers occur near the mouth of corolla tube. Self pollination is performed by.

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Growth of style

  2. Bending of filaments

  3. Shedding of pollen and falling on the low lying stigma

  4. Entry of insect

Show answer
Correct Option: A
Explanation:

The anthers and stigmas of chasmogamous or the open flowers are brought together by the growth, bending as well as by folding. In Catharanthus, the growth of style brings the stigma in contact of ripe anthers present on the mouth of corolla tube When cross-pollination fails in Sunflower, the bifid bent style stigma curls back so as to pick the pollen sticking to the surface of style. It is a fail-safe mechanism of self-pollination.

So the correct option is A.

Cleistogamous flowers are

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Male female which never open

  2. Female flowers which never open

  3. Bisexual flowers which never open

  4. Open bisexual flowers which perform self pollination in bud condition

Show answer
Correct Option: C
Explanation:
Cleistogamy is the phenomenon, where flowers never open and in such flowers, only self-pollination occurs within the bud (unopened flower). Bisexual flowers which do not open at all are called cleistogamous. In such flowers, anthers and stigma lie close to each other. When the anthers dehisce in the flower buds, pollen grains come in contact with the stigma and pollination occurs. 
So, the correct answer is C.

In Tape Grass ($=$ Vallisneria).

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Both male and female flowers break from the plant and float on the surface of water

  2. Only the female flowers break from the plant while the male flowers are brought to the surface by long stalks

  3. Only the male flowers break from the plant and rise to the surface while the female flowers are brought to the surface by long pedicels

  4. Any of the two types of flowers can break

Show answer
Correct Option: C
Explanation:

Tape grass is a submerged hydrophyte. It is a dioecious plant with the flowers borne underwater. The male flowers detach on maturity and float on the surface of the water while the female flowers grow underwater and they come up to the surface with the help of their thin long stalk.

So the correct option is C.

Lever or turn - pipe mechanism of pollination occurs in.

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Salvia

  2. Antirrhinum

  3. Phlox

  4. Gloriosa

Show answer
Correct Option: A
Explanation:

In Salvia, pollination is entomophilous, which means it occurs by insects. Pollination occurs by the lever or turns pipe mechanism. The petals of the Salvia are bifurcated. When the insect visits some flower and sits on the petals, then the stamens are brought down to the touch the back of insect and pollen are laden on it.

When the insect visits another flower, cross-pollination occurs.

 Thus, the correct answer is A.

Continued self pollination results in

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. Self incompatibility

  2. Gametes lose vigour

  3. Inbreeding depression

  4. Formation of unisexual flowers.

Show answer
Correct Option: C

Identify the correct pair of statements.
(i) White kernel of Coconut is a free nuclear endosperm
(ii) In dioecious plants, autogamy is prevented but geitonogamy occurs
(iii) Cleistogamous flowers are always self pollinated
(iv) Castor is an endospermic seed.

biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

  1. i, ii

  2. iii, iv

  3. ii, iv

  4. ii, iii

Show answer
Correct Option: B
Explanation:
•Coconut has free nuclear endosperm. During the development of a nuclear type of endosperm, the primary endosperm mother cell divides by free nuclear divisions, and these divisions are not followed by cell wall formation. Thus, the free nuclei remain in the cytoplasm of the embryo sac. These nuclei now arrange themselves towards the periphery of the embryo sac and centripetal wall formation occurs that finally leads to a cellular type of endosperm. Thus, the kernel of coconut is cellular endosperm.
•Dioecious plants have unisexual male and female flowers on different plants i.e. a plant may have either male flowers or female flowers but not both. Dioecious plants prevent Autogamy which is the transfer of pollen from the anther to the stigma of the same flower, as only unisexual flowers are there. Also, Geitonogamy which is the transfer of pollen from the anther to the stigma of another flower on the same plant is prevented because male and female flowers are not present on the same plant.
•Cleistogamy is the phenomenon, where flowers never open and in such flowers, only self-pollination occurs within the bud (unopened flower). Bisexual flowers which do not open at all are called cleistogamous. In such flowers, anthers and stigma lie close to each other. When the anthers dehisce in the flower buds, pollen grains come in contact with the stigma and pollination occurs.
•Castor is an endospermic seed in which endosperm is not fully consumed by the growing embryo and it is persistent in the seed.
Hence, from all the statements given in the question, statements (iii) and (iv) are correct.
So, the correct answer is B.