Tag: botany

Questions Related to botany

Which one of the following statements is not true?

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Stored pollen in liquid nitrogen can be used in the crop breeding programme.

  2. Tapetum helps in dehiscence of anthers.

  3. Exine of pollen grains is made of sporopollenin.

  4. Pollen grains of many species cause severe allergies.

Show answer
Correct Option: B
Explanation:

Tapetum is the innermost layer and completely surrounds the sporogenous tissue. The cells of Tapetum have dense cytoplasm and generally possess more than one nuclei. Tapetum nourishes the developing pollen grains.

The layer of the anther wall that helps in anther dehiscence is endothecium. The cells of endothecium develop fibrous thickenings at maturity which radiate from the inner tangential walls. These thickenings are made up of alpha cellulose and traces of lignin. These thickenings are hygroscopic and thus, help in anther dehiscence.
Hence, statement B is not true. So, the correct answer is B.

Male gametophyte in angiosperms produces

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Two sperms and a vegetative cell

  2. Single sperm and a vegetative cell

  3. Single sperm and two vegetative cells

  4. Three sperms

Show answer
Correct Option: A
Explanation:
In angiosperms the pollen grain is the male gametophyte. It consists of 2 generative nuclei/cell and 1 vegetative nucleus/cell
So, the correct answer is 'Two sperms and a vegetative cell'

Germ pores in the pollen grains are regions.

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. That can withstand high temperature, strong acids and alkalies

  2. Through which sperms are released into the female gametophyte

  3. Which are made of lignin and suberin

  4. Which lack sporopollenin

Show answer
Correct Option: D

Consider the following statements with respect to pollen grains.
(a) Exine is thin, continuous layer made up of cellulose and pectin
(b) Hard outer layer called exine is made of sporopollenin
(c) Sporopollenin is present in germ pores
(d) Exine exhibits a fascinating array of patterns and designs. Of the statements.

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. a and b alone are correct

  2. a and c alone are correct

  3. b and d alone are correct

  4. b and c alone are correct

Show answer
Correct Option: C
Explanation:
•Exine is a thick layer made up of sporopollenin. The exine is discontinuous in some regions where sporopollenin is absent. These regions mark the germ pores. Hence statement (a) is incorrect.
•Hard outer layer of Exine is made up of sporopollenin which is one of the most resistant known biological material. Hence statement (b) is correct.
•Sporopollenin is absent at the site of germ pores. Hence statement (c) is incorrect.
•Exine shows different patterns or sculptures due to Tectum and Bacula layers. Hence statement (d) is correct.
Therefore, statements (b) and (d) are correct.
So, the correct answer is C.

Choose the correct options for statements P, Q, R in relevance to grass.
Statement P: Flowers possess attractive colour and fragrance.
Statement Q: Pollen grains are small, dry and light in weight.
Statement R: Grass is air pollinated plant.

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Both P and Q are true, R is correct explanation of Q

  2. P is true and Q is false, R is correct explanation of P

  3. P is false and Q is true, R is correct explanation of Q

  4. Both P and Q are false, R has no relation with P and Q

Show answer
Correct Option: C

Discontinuous layers in the wall of pollen grain are

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Absent

  2. Foot layer

  3. Baculate layer

  4. Baculate layer and tectum

Show answer
Correct Option: D
Explanation:
Pollen wall comprises of two layers: outer layer exine and inner layer intine. The exine is chemically differentiated into two layers: an outer layer called "ektexine" and an inner layer called "endexine". Ektexine is further comprised of tectum, bacula and a foot layer. Above the foot layer is present a layer of rod like elements called columella or bacula, which is covered over by a roof like layer called the tectum.
The Tectum and Bacula layers form different patterns on the pollen grains as they are discontinuous at some regions and thus various types of sculptured patterns are seen in pollen grains.
So, the correct answer is D.

Pollen tube is covered by

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Exine only

  2. Plasmalemma only

  3. Intine only

  4. Exine and intine

Show answer
Correct Option: C
Explanation:
Pollen tube emerge out from the germ pore. Exine is very thin at the site of germ pores. The pollen grain gets hydrated at the time of germination. There occurs swelling in the outer pectic layer of intine that leads to rupture of Exine. Thus, its intine that comes out in the form of pollen tube.
Hence, pollen tube is covered by Intine.
So, the correct answer is C.

The smallest pollen grain occurs in

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Myosotis

  2. Mirabilis

  3. Zostera

  4. Eucalyptus

Show answer
Correct Option: A
Explanation:

The smallest pollen grain is found in the plant Myosotis. It is about 0.006 mm in diameter.

So, the correct answer is A.

Choose the correct answers from the alternatives given.
Which of the following is mismatched?

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Polle grain-microgametophyte

  2. Ovule-megagametophyte

  3. Seed-immature sporophyte

  4. Pollen tube-spores

Show answer
Correct Option: D
Explanation:

Pollen tubes are the structure that helps in the entry of the male nuclei into the ovule and then the fertilization takes place. Pollen tube does not form spores. It is just a medium that carries the male gametes.

So, the correct option is 'Pollen tube-spores'

The ploidy of the stamen is equal to the

botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

  1. Ploidy of all the four pollen grains

  2. Ploidy of one pollen grain

  3. Ploidy of 8 male gametes

  4. Ploidy of two microspores

Show answer
Correct Option: A