When more than one pollen grain lands on a stigma whose ovary contains only one ovule, usually only one pollen tube can successfully enter the ovule while the other pollen tubes stop growing. Cases of strange pollen tube growth have been reported.
- 1 Where does the pollen tube reach?
- 2 How many types of pollen tube entry are there in ovule?
- 3 Are all the pollen tubes of equal length if not why?
- 4 Why does the pollen tube only grow towards the ovule?
- 5 What is the path that pollen takes during pollination?
- 6 What initiates the germination of pollen tube on the stigma?
- 7 What happens when the male pollen nucleus enters the ovule?
- 8 What is emasculation and why is it necessary?
- 9 What does the pollen tube carry?
- 10 Which one guides the entry of pollen tube?
- 11 How do pollen grains enter the ovary?
- 12 What guides and promotes the growth of pollen tube from the pollen towards the ovule for fertilization?
- 13 When pollen tube enters ovule through micropyle it is known as?
- 14 Which movement the pollen tube moves toward the ovum?
- 15 In which movement does the pollen tube move towards the ovum?
- 16 How does a pollen grain reach the ovule in conifers?
- 17 How does the pollen reach the egg?
- 18 What is the path followed by pollen to lead to fertilization?
- 19 How does a pollen tube form?
- 20 How does the pollen tube grow through the ovule state different pathway?
- 21 What is the difference between pollen tube and style?
- 22 Why must the pollen develop the pollen tube?
- 23 How does the pollen grains reach the stigma?
- 24 Do all pollen grains germinate?
- 25 Why should a breeder need to emasculate a flower?
- 26 What are the different methods of emasculation?
- 27 Which of the following plants require the union of the pollen and ovule from cones?
- 28 When the pollen tube enters through Chalazal end is called?
- 29 When the pollen tube enters into the ovule through?
- 30 Why is emasculation done in the evening?
- 31 What is the pollen tube called?
- 32 When pollen tube directly enters through the base of the ovule?
- 33 Which of the following part guides the entry of pollen tube into the ovule?
- 34 Where does the pollen tube break?
- 35 Why do pollen grains only produce tubes in flowers of their own species?
- 36 What guides and promotes the growth of pollen tube?
- 37 Are all the pollen tubes of equal length if not why?
- 38 What enzyme does pollen tube secrete?
- 39 Where are ovules located in a conifer?
- 40 Do conifers give off pollen?
- 41 What four cells make up the pollen grain in conifers?
- 42 How does the pollen tube enter the embryo sac to reach the egg?
- 43 Is pollen the carrier of the egg cell?
- 44 Where are pollen sacs present?
- 45 Where does the pollen tube grow quizlet?
- 46 What is the path that pollen takes during pollination?
- 47 How do you think pollen grains reach the ovary?
- 48 Which part of the carpel Does the pollen tube grow into to enable fertilisation to take place?
- 49 Which part of the pistil produces ovules?
Where does the pollen tube reach?
angiosperm fertilization
The pollen tube ultimately enters an ovule through the micropyle and penetrates one of the sterile cells on either side of the egg (synergids).
How many types of pollen tube entry are there in ovule?
Pollen tube enters into the ovule by any one of the three ways. 1) Porogamy : Pollen tube enters into ovule through Micropyle and then enters into embryosac by destroying one of the synergids. E.g. : Ottelia, Hibiscus. 2) Chalazagamy : Pollen tube enters into ovule through chalaza.
Are all the pollen tubes of equal length if not why?
4)No, pollen tubes are not of equal length. It is so because older germinated pollens will have longer developed tube as compare to newly germinated pollen which will have shorter pollen tube. 5)If pollen germinates on stigma, pollen tube will reach the stigma.
Why does the pollen tube only grow towards the ovule?
Question | The growth of pollen tubes towards ovules is due to |
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Chapter Name | Control And Coordination |
Subject | Biology (more Questions) |
Class | 10th |
What is the path that pollen takes during pollination?
Pollination occurs when pollen grains from the anther land on a stigma. After pollen grains land on the stigma, a pollen tube grows from the pollen grain, through the style, and into the ovary. Sperm cells inside the pollen grain travel down the pollen tube and into the ovary which contains the ovules.
What initiates the germination of pollen tube on the stigma?
Once a pollen grain has implanted on a compatible stigma, its germination is initiated. During this process, the pollen grain begins to bulge outwards to form a tube-like structure, known as the pollen tube.
What happens when the male pollen nucleus enters the ovule?
Fertilisation. When a pollen grain lands on the stigma of a flower of the correct species , a pollen tube begins to grow. It grows through the style until it reaches an ovule inside the ovary. The nucleus of the pollen then passes along the pollen tube and fuses (joins) with the nucleus of the ovule.
What is emasculation and why is it necessary?
Removal of stamens or anthers or killing the pollen of a flower without the female reproductive organ is known as emasculation. In bisexual flowers, emasculation is essential to prevent of self-pollination.
What does the pollen tube carry?
Pollen tubes act as conduits to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms.
Which one guides the entry of pollen tube?
Filiform apparatus is a prolongation of the synergids beyond the summit of the embryo sac. It helps in guiding the entry of pollen tube into the synergids.
How do pollen grains enter the ovary?
A pollen grain on the stigma grows a tiny tube, all the way down the style to the ovary. This pollen tube carries a male gamete to meet a female gamete in an ovule.
What guides and promotes the growth of pollen tube from the pollen towards the ovule for fertilization?
The ovary releases chemicals from the developing pollen tube that stimulates a positive chemotropic response. In response to the calcium gradient, the tube creates a given growth area for the tip that promotes the directional growth and elongation of the pollen tube.
When pollen tube enters ovule through micropyle it is known as?
Explanation: Entry of pollen tube through the micropyle is the most common method and is called porogamy.
Which movement the pollen tube moves toward the ovum?
Chemotropic movement the pollen tube moves toward the ovum.
In which movement does the pollen tube move towards the ovum?
Thus, the correct answer is ‘Chemotropism‘.
How does a pollen grain reach the ovule in conifers?
The pollen grains of many Pinaceae and Podocarpaceae have air bladders, which orient them in a pollination droplet exuded by the ovules so that, when the droplet is withdrawn back into the ovule, the pollen tube will penetrate the nucellus to the archegonium.
How does the pollen reach the egg?
From the anther the pollen grains are first deposited on the pistil’s surface, the stigma. There they germinate and form pollen tubes, which grow downward through the style toward the ovules. Fertilization occurs as a sperm cell in a pollen tube fuses with the egg cell of an ovule, resulting in a plant embryo.
What is the path followed by pollen to lead to fertilization?
Step one: After pollen has landed on the stigma, it grows a pollen tube down through the style to the ovary. Step two: The nucleus of the pollen grain travels down the pollen tube and fertilises the nucleus in the ovule. Step three: The fertilised ovule develops into a seed.
How does a pollen tube form?
During the pollination process of higher plants, after the pollen germinates on the stigmatic surface, a pollen tube is formed from the pollen and extends down the style into the ovule; nuclei from the pollen travels through the pollen tube to fertilize the ovule.
How does the pollen tube grow through the ovule state different pathway?
In most angiosperms, from pollen landing on the stigma to fertilization inside the ovary, the pollen tube has to traverse an intermediate territory, the style (Figure 1). The pollen tube grows through a stylar canal or a stylar transmitting tissue, and reaches the locule cavity of the ovary where the ovule is located.
What is the difference between pollen tube and style?
Pollen Tube | Style |
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Pollen Tube is a long tube like structure that carries the male gamete from the stigma to the ovules. | Style joins the stigma to the ovary. It is made up of soft tissues which allows the pollen tube to grow downwards towards the ovule. |
Why must the pollen develop the pollen tube?
Without it the pollen can not separate from the egg produced by the same reproductive structure and neither the pollen nor the eggs are able to combine with the gametes of other plants and form seeds. b. Without it the pollen does not begin meiosis and does not produce nuclei that can fertilize eggs.
How does the pollen grains reach the stigma?
Due to the spatial separation between male and female organs, pollen grains from the anther of most flowering plants are transported by wind or animals and deposited onto the receptive surface of the stigma of a different plant [9], [10].
Do all pollen grains germinate?
(v) Count (a) total number of pollen grains seen in the microscope field, and (b) the number of pollen grains that have germinated. Although pollen grains of many species germinate in this medium, the percentage of germinations and the time taken for germination varies in different species.
Why should a breeder need to emasculate a flower?
Emasculation is performed by plant breeders in bisexual flowers to obtain the desired variety of a plant by crossing a particular plant with the desired pollen grain.
What are the different methods of emasculation?
- Hand Emasculation. In species with large flowers, removal of anthers is possible with the help of forceps. …
- Suction Method. It is useful in species with small flowers. …
- Hot Water Treatment. …
- Alcohol Treatment.
Which of the following plants require the union of the pollen and ovule from cones?
Key Points. Gymnosperms produce both male and female cones, each making the gametes needed for fertilization; this makes them heterosporous. Megaspores made in cones develop into the female gametophytes inside the ovules of gymnosperms, while pollen grains develop from cones that produce microspores.
When the pollen tube enters through Chalazal end is called?
A. Porogamy.
When the pollen tube enters into the ovule through?
The pollen tube enters the ovule in majority of cases through micropyle by a process termed porogamy or it may enter through chalaza (chalazogamy) as in Casuarina.
Why is emasculation done in the evening?
Emasculation is to be done in the evening hours before the anthers are dehisce and stigma is likely to become fully receptive. Care must be taken not to injure the gynoecium.
What is the pollen tube called?
The pollen tube (PT) is a unique and specialized structure in plants. Its sole purpose is to deliver sperm cells to the female gametophyte for double fertilization. Essentially, it is a thread–like structure spanning from the pollen shell toward the tip.
When pollen tube directly enters through the base of the ovule?
So, the correct answer is ‘Mesogamy‘
Which of the following part guides the entry of pollen tube into the ovule?
Synergids secretes chemical; which guide the pollen tube. Synergids are present in the embryo sac, and it enters the ovule sac through the micropyle.
Where does the pollen tube break?
Fertilization follows pollination. Pollen which has reached the stigma (1) germinates, growing a pollen tube down through the style into of the ovary (2). Directed by the tube nucleus, the tube breaks into the ovule (right) through the micropyle, and two sperm nuclei enter.
Why do pollen grains only produce tubes in flowers of their own species?
Why do pollen grains only produce tubes in flowers of their own species? Can have chemical signals being specific for cells in the same species. Pollen grain too large to fit down stigma and go down the style.
What guides and promotes the growth of pollen tube?
Plants respond to stimuli and show certain types of movements. During fertilization (a reproductive stage), when a pollen grain is dropped on the stigma, it grows a pollen tube in response to chemicals present on the stigma. The tube then moves towards the ovule. So, the correct answer is option D.
Are all the pollen tubes of equal length if not why?
4)No, pollen tubes are not of equal length. It is so because older germinated pollens will have longer developed tube as compare to newly germinated pollen which will have shorter pollen tube. 5)If pollen germinates on stigma, pollen tube will reach the stigma.
What enzyme does pollen tube secrete?
Secretion and Targeting of Extracellular TGase. The pollen tube TGase is also found in association with different membrane compartments, but mainly with Golgi membranes and the plasma membrane [33].
Where are ovules located in a conifer?
In gymnosperms such as conifers, ovules are borne on the surface of an ovuliferous (ovule-bearing) scale, usually within an ovulate cone (also called megastrobilus). In the early extinct seed ferns, ovules were borne on the surface of leaves.
Do conifers give off pollen?
In fact Conifers, unlike Broadleaf trees, do not have flowers or fruit. They have male and female cones. The botanical name for a cone is a strobilus. Pollen cones, like male flowers, release pollen and Seed cones, like female flowers, receive pollen and develop seeds.
What four cells make up the pollen grain in conifers?
In the Pinaceae, three successive divisions of the microspore produce a four-celled pollen grain within the microsporangium. It has two tiny prothallial cells (the last body remnants of the old free-living gametophyte), a tube cell, and a generative cell.
How does the pollen tube enter the embryo sac to reach the egg?
The pollen tube arrives in the micropyle of the integument of the ovule, and enters the embryo sac. The synergids of the embryo sac literally put their energies together to burst the end of the pollen tube. Meanwhile, the generative cell has followed the pathway digested by the tube cell.
Is pollen the carrier of the egg cell?
The angiosperm pollen grain, upon arriving at a receptive stigma, germinates, producing a tube that extends through the style to deliver its cargo to the ovule, thereby fertilizing the egg, and completing the life cycle of the plant.
Where are pollen sacs present?
Pollen sacs are cavities in the male reproductive system, anther, which produce pollen grains. The pollen sacs contain microspore mother cells which divide to produce four haploid microspores. The microspores further form the pollen grain.
Where does the pollen tube grow quizlet?
Pollen tube grows through the stigma and reaches the ovary, entering the ovules.
What is the path that pollen takes during pollination?
Pollination occurs when pollen grains from the anther land on a stigma. After pollen grains land on the stigma, a pollen tube grows from the pollen grain, through the style, and into the ovary. Sperm cells inside the pollen grain travel down the pollen tube and into the ovary which contains the ovules.
How do you think pollen grains reach the ovary?
A pollen grain on the stigma grows a tiny tube, all the way down the style to the ovary. This pollen tube carries a male gamete to meet a female gamete in an ovule.
Which part of the carpel Does the pollen tube grow into to enable fertilisation to take place?
Fertilisation. When a pollen grain lands on the stigma of a flower of the correct species , a pollen tube begins to grow. It grows through the style until it reaches an ovule inside the ovary.
Which part of the pistil produces ovules?
Ovary: The enlarged basal portion of the pistil where ovules are produced.