Tag: pollination, fertilization and development of endosperm and embryo

Questions Related to pollination, fertilization and development of endosperm and embryo

During self pollination of Mirabilis, 

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

  1. Flowers are closed

  2. Flowers are open and growing style brings the stigma in contact with anthers

  3. Filaments bring anthers in contact with stigma

  4. Style bends to bring stigma in contact with anthers

Show answer
Correct Option: C
Explanation:
Mirabilis has homogamous flowers. Homogamous flowers are the bisexual flowers in which anthers and stigma mature at the same time. Thus, self pollination occurs in Mirabilis. When the anthers and stigma mature, the filaments of anther recoil to bring them in contact with the stigma and as the anthers dehisce, pollen grains are deposited on the surface of the stigma. Thus, self pollination occurs in this way.
So, the correct answer is C.

A mechanism to prevent cross pollination is

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

  1. Protogyny

  2. Protandry

  3. Heterostyly

  4. Cleistogamy

Show answer
Correct Option: D
Explanation:

A mechanism to prevent cross-pollination is called cleistogamy. It is a condition in which flower does not open. In such flowers, the anthers and sigma 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 hypogea. It ensures seed formation even in the absences of any pollination agent. It is cheaper for the plant as there is no costly nectar or fragrance which the plant has to produce for pollination.

Assured seed set is possible even in absence of pollinators when flower is

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

  1. Xenogamous

  2. Chasmogamous

  3. Geitonogamous

  4. Cleistogamous.

Show answer
Correct Option: D
Explanation:
•Xenogamous flowers are the flowers in which pollen are transferred from the anther to the stigma of a different flower on different plant. Xenogamous flowers are cross pollinated and depend on external agencies for pollination.
•Chasmogamous flowers are the flowers which have exposed anthers and stigma and thus, both self pollination and cross pollination can occur. Chasmogamous flowers may also depend on external agencies for cross pollination.
•Geitonogamous flowers are the flowers in which pollen are transferred from the anther to the stigma of other flower on the same plant. These flowers also need external agencies for pollination.
•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.
Hence, assured seed set is possible even in the absence of pollinators when the flower is Cleistogamous.
So, the correct answer is D.

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.