नमस्कार विद्यार्थी मित्रांनो Study of pollen germination on slide हे प्रॅक्टिकल Experiments to be performed - PART A मधील आहे. याचाच अर्थ तुम्हाला हे प्रॅक्टिकल Exam मध्ये Examiner ला Performe करून दाखवायचे आहे. म्हणूनच प्रॅक्टिकल Exam च्या दृष्टीने हे Experiment अतिशय महत्त्वाचे आहे. या ब्लॉग मध्ये आपण Practical Book मधील या Experiment Number - 4 ची उत्तरे पाहणारं आहोत. ही उत्तरे काळजीपूर्वक वाचून आपल्या Practical Book मध्ये लिहा किंवा तुमच्या कॉलेजमधील संबंधित विषय शिक्षकांची मदत घ्या.
4. Study of pollen germination on slide.
Pollen grains are the male reproductive units produced in the anther lope of stamens, producing pollen tube carrying male gametes, on germination.
Aim :- To study the process of pollen germination on slide while observing under the compound microscope.
Requirements :- Flower of Catharanthus (periwinkle) or Helianthus (sunflower) or Hibiscus (shoe flower), cavity slide/glass slide, cover slips, compound microscope, sucrose crystals (Table sugar), etc.
Principle :- Pollen grain after deposited over the stigma absorbs water and nutrients from the stigma and germinates to produce male gametophyte showing pollen tube with two non-motile male gametes and a large vegetative nucleus.
Figure :-
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| Pollen grain showing pollen germination |
Procedure :- 1. A nutrient medium is to be prepared using 20 grams of sucrose in 100 ml of water.
2. Take a few drops of this solution preferably on a cavity slide and dust a few pollen grains from mature, dehisced anther.
3. Place cover slip carefully.
4. Observe the slide under compound microscope after every 5 minutes continuously for 30 minutes.
Observations :- 1. In the nutrient medium, the Pollen will germinate the Pollen tube comes out through germ pore.
2. It is due to enlargement of tube cell and stretching of the intine, pollen tube comes out and grows.
Inferences :- The pollen grain is initially unicellular with a single nucleus. At the time of release, it develops into a two-celled structure consisting of a small generative cell and a vegetative cell. In a nutrient medium, the pollen grain germinates, and the tube cell enlarges and emerges from the pollen grain through one of the germ pores to form a pollen tube.
Questions
1. Note the shape, colour and ornamentation of pollen grain?
Ans :- Pollen grains of various species can be round, oval, disc-shaped, or bean-shaped, and sometimes they are flattened. Their color ranges from white, cream, yellow, to orange, and their texture varies from smooth to spiky.
2. What are the specific terms used for inner and outer walls of pollen grain?
Ans :- The pollen grain has two walls: the exine (outer wall) and the intine (inner wall).
3. Name the chemical component of the inner wall of pollen grain?
Ans :- The intine is primarily composed of pectin and cellulose.
4. What does a mature pollen grain represent?
Ans :- A mature pollen grain represents a male gametophyte.
5. Where do the pollen germinate naturally?
Ans :- Naturally, pollen grains germinate on the stigma.
6. Name the nutrient element which plays major role in pollen grain germination.
Ans :- Sucrose provides nutrition in the germ tube for its growth as a pollen tube.
7. Draw a well labelled diagram of male gametophyte in Angiosperms as observed by you.
Ans :-
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| Male gametophyte in Angiosperms |
Multiple Choice Questions
1. Movement of pollen tube towards an embryo sac is...
a. thermotactic
b. phototactic
c. chemotropic
d. thigmotropic
Ans :- c. chemotropic
2. Outer wall of pollen grain is made up of...
a. Sporopollenin
b. Pectocellulose
c. Protein
d. Lipids
Ans :- a. Sporopollenin
3. How many mitotic divisions take place during germination of pollen grain and its development into mature gametophyte?
a. 3
b. 1
c. 5
d. 2
Ans :- d. 2
4. Triporate pollen grain is commonly found in...
a. Monocot plants
b. Dicot plants
c. Pteridophytes
d. Gymnosperms
Ans :- b. Dicot plants
5. How many prothallial cells develop during the development of male gametophytes in Angiosperms?
a. One prothallial cell
b. No prothallial cells
c. Equal to number of gametes produced
d. Equal to number of tube cells produced
Ans :- b. No prothallial cells
6. Uniporate or monocolpate pollen grains are found in...
a. Monocot plants
b. Dicot plants
c. Gymnosperms
d. Pteridophytes
Ans :- a. Monocot plants
Observe the slide and draw the diagram.
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