Table of Contents
- 1 How many pollen grains are needed to fertile a flower?
- 2 What does a pollen grain have to do in order to fertilize an egg?
- 3 How many pollen grains reach the ovary?
- 4 How many male gametes does pollen grain produce?
- 5 What is double fertilization Class 12?
- 6 How does the pollen grains reach the ovules?
- 7 Why do there need to be so many more pollen grains than ovules?
- 8 Where does the pollen grain go to fertilize the egg?
- 9 How many sperm cells are in a pollen grain?
How many pollen grains are needed to fertile a flower?
Out of two male gametes , one fuses with the egg and the other fuses with the secondary nucleus. Therefore, one pollen grain can fertilise only one ovule and four pollen grain will be required to fertilise four ovules.
What does a pollen grain have to do in order to fertilize an 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.
How many pollen grains reach the ovary?
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.
Would a pollen tube fertilize more than one egg?
In double fertilization, a reproductive system unique to flowering plants, two immotile sperm are delivered to an ovule by a pollen tube. A mechanism preventing multiple pollen tubes from entering an ovule would ensure that only two sperm are delivered to female gametes.
Does a flower produce more ovules or pollen grains?
A) A flower has more pollen grains than it does ovules so that the pollen has a better chance of getting to the ovules so they can make seeds so more plants will grow. Fertilization is when the sperm cell in the pollen joins with the egg cell so that a seed can form.
How many male gametes does pollen grain produce?
two male gametes
In flowering plants, two male gametes from a single pollen grain fuse with two female gametes, the egg and central cells, to form the embryo and endosperm, respectively.
What is double fertilization Class 12?
What do you mean by double fertilization? Ans: The process of fusion of one male gamete with egg to form diploid zygote and another male gamete with the polar nuclei or secondary nucleus to form primary endosperm nucleus is called double fertilization.
How does the pollen grains reach the ovules?
A pollen tube grows through the tissues of the flower until it reaches an ovule inside the ovary . The nucleus of the pollen grain (the male gamete ) then passes along the pollen tube and joins with the nucleus of the ovule (the female gamete). A pollen tube grows from the stigma to the ovary.
How many pollen tubes emerge from a pollen grain?
Only a single pollen tube emerges from a pollen grain that contains pollen nuclei. Pollen tube helps the nuclei to reach the ovule. there fertilization takes place.
How many pollen grains are in a pollen tube?
… result of insect pollination is pollen tube competition. When a pollen load of 50–200 pollen grains is deposited on a stigma at one time, each pollen grain grows a pollen tube into the stigmatic tissue. The pollen tubes that grow the fastest reach the ovules first and effect fertilization.
Why do there need to be so many more pollen grains than ovules?
Where does the pollen grain go to fertilize the egg?
There, the pollen grain develops an outgrowth called a pollen tube, which eventually penetrates to the egg cell within one of the archegonia. The sperm cells within the pollen tube then vie to fertilize the egg.
How many sperm cells are in a pollen grain?
A typical pollen grain from a flowering plant (angiosperm) contains a vegetative cell and a reproductive cell containing two nuclei. One of the nuclei from the reproductive cell splits to form two sperm cells.
What does each piece of pollen do to a plant?
This is a mass of small grains released by seed plants. Each individual piece of pollen is called a pollen grain. Each grain contains a reproductive cell that corresponds to a sperm cell in an animal. A pollen grain can fertilize the egg cell of other plant of the same species, eventually forming a seed that can grow into another plant.
When do two sperm cells fertilize the egg cell?
When the pollen tube reaches the embryo sac it bursts open and releases the two sperm cells, the actual sex cells. Then double fertilization occurs. One sperm cell fertilizes the egg cell so that a diploid zygote arises, from which an embryo develops.