Tag: pollen grain

Questions Related to pollen grain

Number of nuclei present in the mature male gametophyte of angiosperms is?

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

  1. One

  2. Two

  3. Three

  4. Many

Show answer
Correct Option: B
Explanation:
Pollen grain or the male gametophyte is formed from pollen mother cells through microsporogenesis and microgametogenesis. Each pollen mother cell (PMC) divide by meiosis to form four haploid microspores (this process is called microsporogenesis). Each microspore then develops into pollen grain (this process is called mocrogametogenesis).
Each microspore divides mitotically to form two cells: a large Vegetative cell and a small Generative cell. The generative cell resides within the cytoplasm of the vegetative cell. Later, the generative cell divides to form two sperm cells (i.e. male gametes or the male nuclei). At this stage, pollen grains are said to be 3-celled. If the generative cell divides inside the pollen tube, to form two male gametes the pollen is said to be liberated at 2-celled stage. 
Thus, a mature pollen grain will always have 2 nuclei , whether liberated at 2-celled or 3-celled stage.
So, the correct answer is B.

Ubisch bodies are connected with the formation of

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

  1. Sporopollenin

  2. Intine and pollenkitt

  3. Exine

  4. Pollenkitt and pollinia

Show answer
Correct Option: C
Explanation:
When the anther is young, at the stage of sporogenous tissue, the cells of the Tapetum possess numerous spherical bodies called pro-Ubisch bodies or pro-orbicules. The number of pro-Ubisch bodies increases when there is meiosis in pollen mother cells. These pro-Ubisch bodies can easily cross the tapetal membrane facing the locule and during this transfer, these pro-Ubisch bodies get coated by sporopollenin and are called ubisch bodies or orbicules.
Ubisch bodies are involved in external thickening of the outer layer of pollen grain i.e. these help in exine formation.
So, the correct answer is C.

Germ pore is the area where exine is

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

  1. Thick

  2. Thick and uniform

  3. Uniform

  4. Absent

Show answer
Correct Option: D
Explanation:

Germ pore is the area where pollen tube will grow and the exine is absent in that particular area.

So the correct option is 'Absent'.

Pollen grains are nongreen due to

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

  1. Absence of plastids

  2. Degeneration of plastids

  3. Conversion of plastids into chromoplasts

  4. Attraction of vectors

Show answer
Correct Option: C
Explanation:

Plastids are found in almost all cells of the plant body either in the form of colorless plastids or colored plastids or proplastids.

Chromoplasts are the plastids containing different colored pigments in which green colored plastids are called chloroplasts. All plastids other than chloroplasts are predominantly found in the certain class of plants and plant organs including floral parts. 
So, the correct option is 'Conversion if plastids into chromoplasts'.

Wheat root cells have $42$ chromosomes. The number of chromosomes in a cell of pollen grain is?

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

  1. $14$

  2. $21$

  3. $28$

  4. $42$

Show answer
Correct Option: B

Which is correct?

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

  1. Sporopollenin is made up of inorganic materials.

  2. Sporopollenin can withstand high temperature as well as strong acids and alkalies.

  3. Sporopollenin can withstand high temperatures but not strong acids.

  4. Sporopollenin can be degraded by enzymes.

Show answer
Correct Option: B
Explanation:
Sporopollenin is the most resistant known biological material which is found in the exine of the pollen grains. Sporopollenin is resistant to chemical and microbial decomposition. Thus, it can withstand high temperatures and strong acids and alkalies. Due to this, pollen grains are well preserved during fossilization. The exact composition of sporopollenin is not known but analyses and studies have revealed that it is composed of long chain fatty acids along with some other biopolymers like phenolics and carotenoids. 
So, the correct answer is B.

Sporopollenin is formed by the polymerization of

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

  1. Fat and phenols

  2. Fats and esters

  3. Carotenoids and fat

  4. Carotenoid and esters

Show answer
Correct Option: A
Explanation:
Sporopollenin is composed of carbon, hydrogen, and oxygen, though the exact chemical composition is not known, due to its unusual chemical stability and resistance to degradation by enzymes and strong chemical reagents. Analyses have revealed a mixture of biopolymers, containing mainly long chain fatty acids, phenylpropanoids, phenolics and traces of carotenoids. 
So the correct option is 'Fats and phenols'.

Which of the following statements about sporopollenin is wrong?

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

  1. Intine is formed of sporopollenin

  2. Sporopollenin is not degraded by any known enzyme

  3. Sporopollenin is most resistant organic material

  4. Sporopollenin can withstand high temperature and strong acids

Show answer
Correct Option: A
Explanation:

The exine of the pollen grains consists most resistant biological material known as Sporopollenin. It is resistant to both microbial and chemical decomposition by which it preserves pollen grains during fossilization. Exine consists of sporopollenin.

So the correct option is 'Intine is formed of sporopollenin'.

Which plant product is the hardest?

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

  1. Suberin

  2. Lignin

  3. Sporopollenin

  4. Cutin

Show answer
Correct Option: C
Explanation:
• Suberin is constituent of cork tissues. It is a waxy substance.
• Lignin is constituent of cell walls. It is an organic polymer.
• Sporopollenin is the most resistant known biological material which is found in the exine of the pollen grains. It is resistant to chemical and microbial decomposition. Due to this, pollen grains are well preserved during fossilization. The exact composition of sporopollenin is not known but analyses and studies have revealed that it is compose of long chain fatty acids along with some other biopolymers like phenolics and carotenoids. 
• Cutin is component of plant cuticle. It is an ester of fatty acids.
Thus, the hardest plant material is sporopollenin. So, the correct answer is C.

Identify the pair of wrong statements.
I. Intine of pollen grains is made up of sporopollenin.
II. Pollen grains are well preserved as fossils because of the presence of sporopollenin.
III. Enzymes can degrade the organic material of the pollen grain exine.
IV. Sporopollenin can withstand high temperature, strong acids and alkali.

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

  1. III, IV

  2. I, III

  3. I, II

  4. II, III

Show answer
Correct Option: B