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प्रश्न
Give scientific reason.
Fertilization in plants is called double fertilization.
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उत्तर
- The pollen grain germinates over the stigma and gives rise to pollen tube.
- The pollen tube bursts and releases two male gametes in the embryo sac.
- One male gamete fuses with the egg cell to form the zygote, whereas the second male gamete fuses with two polar nuclei in the embryo sac to form an endosperm.
- Since, in flowering plants, the process of fertilization occurs twice in the same embryo sac, by two male gametes, it is called as double fertilization.
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संबंधित प्रश्न
Name the parts A, B and C shown in the following diagram and state one function of each.
A student has to perform the experiment "To identify the different parts of an embryo of a dicot seed." Select from the following an appropriate group of seeds:
(a) Pea, gram, wheat
(b) Red kidney bean, maize, gram
(c) Maize, wheat, red kidney bean
(d) Red kidney bean, pea, gram
"The chromosomal number of the sexually producing parents and their offspring is the same." Justify this statement.
Mention the changes a flower undergoes after fertilisation.
Write the names of those parts of a flower which serve the same function as the following do in the animals :
(i) testis,
(ii) sperm,
(iii) ovary,
(iv) egg
Explain what you understand by sexual reproduction.
Sketch the reproductive parts of a flower.
How does the process of fertilisation take place in flowers?
What is the function of a flower?
Fill in the following blank with suitable word :
Ovules contain ......... gametes of a plant.
Draw a neat sketch of the stamen of a flower. Mark in it filament and anther.
Explain the term 'fertilisation'.
What type of plants reproduce by sexual reproduction method?
Name the part of a seed which grows into shoot.
What is meant by 'unisexual flowers' and 'bisexual flowers'? Give two examples of each.
The length of pollen tube depends on the distance between :
(a) pollen grain and upper surface of stigma
(b) pollen grain on upper surface of stigma and ovule
(c) pollen grain in anther and upper surface of stigma
(d) upper surface of stigma and lower part of style
In the figure given alongside, the parts marked A, B and C are sequentially :
(a) cotyledon, plumule and radicle
(b) plumule, radicle and cotyledon
(c) plumule, cotyledon and radicle
(d) radicle, cotyledon and plumule
Fill in the blank by selecting suitable word:
A flower bearing only male or female parts is known as __________ flower.
Fill in the blank:
Seeds are formed from________.
Mention the function of Flower.
Mention the function of Anther.
Give one example each of unisexual and bisexual flowers. Differentiate between the two types of pollination that occur in flowers. What happens when a pollen lands on a suitable stigma? Write about the events that occur till the seed formation in the ovary.
You have to perform the experiment, "To identify the different parts of an embryo of a gram seed." Describe the procedure that you would follow.
Explain the process of fertilisation in flowers.
Distinguish between unisexual and bisexual flowers giving one example of each. Draw a diagram showing process of germination of pollen grains on stigma and label the following parts:
(a) Female germ cell
(b) Male germ cell
(c) Ovary
Fill in the blank by selecting suitable word:
Transfer of pollen grains from the anther to the stigma is known as______________.
Draw a diagram of the longitudinal section of a flower and label the following parts.
Pollen grains from anther are transferred to the stigma.
Where does the endothecium layer of anther lobes is present?
Identify the female gametophyte in angiosperms.
Length of pollen tube depends on the distance between ______
Complete the table
| Carly x | ______ | ______ |
| ______ | petal | attract insects |
| Androecium | ______ | Male reproductive part |
| ______ | ______ | Female reproductive part. |
Draw the diagram of a flower and label the four whorls. Write the names of gamete producing organs in the flower.
Trace the path a male gamete takes to fertilise a female gamete after being released from the penis.
State the number of sets of chromosomes present in a zygote.
In a plant flower the female whorl is ______.
Triple fusion involves ______.
Sexual maturation of reproductive tissues and organs are necessary link for reproduction. Elucidate.
What is puberty?
