Types of Fertilisation
Types of Fertilisation
Internal Fertilisation and External Fertilisation
We have just studied that the fusion of a sperm with an egg is called fentilisation Now, the egg (or ovum) is made in the body of a female animal. So, the fertilisation of an egg by a sperm can take place either inside the body of the female animal or outside the body of female animal. This leads to two modes of fertilisation in animals : internal fertilisation, and extenal fertilisation.
The fertilisation which takes place inside the female body is called internal fertilisation. In internal fertilisation, the female animal's eggs are fertilised by sperms inside her body. In internal fertilisation, the male animal puts his sperms into the female animal's body And these sperms then fertilise the eggs inside her body. For example, a man puts his sperms inside a woman's body. These sperms then fertilise the egg inside the woman's body. This type of fertilisation in which the fusion of a male gamete (sperm and a female gamete (egg) occurs inside the body of the female animal, is called internal fertilisation. Internal fertilisation takes place in a very large number of animals such humans, cows, dogs, cats, tigers, lions, rabbits, deer, horse, birds (such as hen, sparrow crow, pigeon, etc.), reptiles (such as lizard, snake and crocodile, etc.), and insects (such as silk moth, housefly and butterfly, etc.). In all these animals, fertilisation occurs inside the body of the female animal.
The fertilisation which takes place outside the female body is called external fertilisation. In external fertilisation, the female animal's eggs are fertilised by sperm outside her body. In frogs and most fishes, the fertilisation of eggs occurs outside the female animal's hody. In extemal fertilisation, the male and female animals release their sperms and eggs in water where fertilisation takes place by collisions between sperms and eggs. For example, the males and females of frogs and fishes release their sperms and eggs in water in which they live. The sperms then collide with the eggs and fertilise them outside the body of female frog or fish. External fertilisation is very common in aquatic animals such as frog, fish and star fish, etc. In these animals, fertilisation takes place in water. We will now describe the external fertilisation in frogs in somewhat detail.
During spring season (or rainy season). frogs move to the water in ponds and slow- moving streams. When the male frog and female frog come together, the female frog lays hundreds of eggs in water (see Figure 4). Unlike the hen's eggs, frog's eggs are not covered by hard shells. The frog's eggs are very delicate. A layer of jelly holds the frog's eggs together and provides protection to the eggs. When the female frog lays hundreds of eggs, at the same time the male frog releases millions of sperms from its body (see Figure 4). The sperms swim randomly in water with the help of their long tails. When the sperms of frog come in contact with the eggs floating in water, then fertilisation takes place. This type of fertilisation in which the fusion of a male gamete (sperm) and a female gamete (egg) takes place ouside the body of the female animal, is called external fertilisation. Just like frogs, external fertilisation also takes place in fish. When the male Gish and female fish come together in water, the female fish lays hundreds of eggs in water and at the same time, the male fish releases millions of sperms in water. When the Sperms come in contact with eggs, the eggs get fertilised. In this way, a female fish's eggs are fertilised by sperms outside its body. This is also an example of external fertilisation.
We will now explain why the animals like frog and fish lay hundreds of eggs at a time (whereas a hen lays only one egg at a time). Though the animals like frog (and fish) which undergo external fertilisation, lay hundreds of eggs, all the eggs do not get fertilised and hence do not develop into new frogs (or fishes). This is because of the following reasons
(i) Frog (and fish) lay eggs and release sperms in water. Many of these eggs and sperms are carried away by the movement of water, wind or rainfall, and hence all the eggs do not get fertilised.
(ii) Many of the eggs of frogs (and fish) are eaten up by other animals which live in water.
(iii) Many of the larvae (young ones) of frog and fish which are hatched from the fertilised eggs are eaten up by other animals in water and fail to develop into adult frogs (or fish).
So, out of hundreds of eggs laid by the female frog (or female fish), only a few will survive to become adult frogs (or adult fish). Since many of the eggs of frogs and fish are carried away by moving water, wind or rain, and many are eaten up by other animals, therefore, the production of a large number of eggs is necessary to ensure the fertilisation of at least a few of them. Out of hundreds of eggs laid by female frog (or female fish) only a few get fertilised and their larvae survive to become adult frogs (or adult fish).
We know that the new cell which is formed by fertilisation is called 'zygote'. And this zygote then grows and develops into a full organism (or baby animal). The method a which a zygote grows and develops into a full organism also varies in different animals. For example, in human beings the zygote grows and develops into a baby inside the female body (mother's body). And then the mother gives birth to the baby. Just like humans, the animals like cats and dogs also give birth to their young ones. But the process it entirely different in those animals (or birds) which lay eggs. For example, a hen sits on its fertilised eggs for a considerable time to give them warmth. During this period, the zygote grows and develops egg by breaking its shell. It is clear from this discussion that all the organisms do not give birth to individuals like humans do.
The type of fertilisation in which the fusion of a male gamete (sperm and a female gamete (egg) occurs inside the body of the female animal, is called ________________ fertilisation. | |||
| Right Option : B | |||
| View Explanation | |||
Which of the following are correct : (a) The fertilisation which takes place outside the female body is called internal fertilisation. (b) The fertilisation which takes place inside the female body is called external fertilisation. | |||
| Right Option : D | |||
| View Explanation | |||
Which of the following are a type of fertilization ? | |||
| Right Option : C | |||
| View Explanation | |||
Students / Parents Reviews [20]
A marvelous experience with Abhyas. I am glad to share that my ward has achieved more than enough at the Ambala ABHYAS centre. Years have passed on and more and more he has gained. May the centre flourish and develop day by day by the grace of God.
Archit Segal
7thOne of the best institutes to develope a child interest in studies.Provides SST and English knowledge also unlike other institutes. Teachers are co operative and friendly online tests andPPT develope practical knowledge also.
Aman Kumar Shrivastava
10thI have spent a wonderful time in Abhyas academy. It has made my reasoning more apt, English more stronger and Maths an interesting subject for me. It has given me a habbit of self studying
Yatharthi Sharma
10thThe experience was nice. I studied here for three years and saw a tremendous change in myself. I started liking subjects like English and SST which earlier I ran from. Extra knowledge gave me confidence to overcome competitive exams. One of the best institutes for secondary education.
Aman Kumar Shrivastava
10thAbhyas is good institution and a innovative institute also. It is a good platform of beginners.Due to Abhyas,he has got knoweledge about reasoning and confidence.My son has improved his vocabulary because of Abhyas.Teacher have very friendly atmosphere also.
Manish Kumar
10thAbhyas is a complete education Institute. Here extreme care is taken by teacher with the help of regular exam. Extra classes also conducted by the institute, if the student is weak.
Om Umang
10thBeing a parent, I saw my daughter improvement in her studies by seeing a good result in all day to day compititive exam TMO, NSO, IEO etc and as well as studies. I have got a fruitful result from my daughter.
Prisha Gupta
8thIt was a good experience with Abhyas Academy. I even faced problems in starting but slowly and steadily overcomed. Especially reasoning classes helped me a lot.
Cheshta
10thMy experience with Abhyas Academy has been very good. When I was not in Abhyas whenever teacher ask questions I could not speak it confidently but when I came in Abhyas, my speaking skills developed and now I am the first one to give the answer of teachers question.
Upmanyu Sharma
7thMy experience was very good with Abhyas academy. I am studying here from 6th class and I am satisfied by its results in my life. I improved a lot here ahead of school syllabus.
Ayan Ghosh
8thUsually we see institutes offering objective based learning which usually causes a lag behind in subjective examinations which is the pattern followed by schools. I think it is really a work of planning to make us students grab the advantages of modes of examination, Objective Subjective and Onli...
Anika Saxena
8thAbhyas academy is great place to learn. I have learnt a lot here they have finished my fear of not answering.It has created a habit of self studying in me.The teachers here are very supportive and helpful. Earlier my maths and science was good but now it has been much better than before.
Barkha Arora
10thMy experience with Abhyas academy is very good. I did not think that my every subject coming here will be so strong. The main thing is that the online tests had made me learn here more things.
Hiya Gupta
8thMy experience with Abhyas is very good. I have learnt many things here like vedic maths and reasoning also. Teachers here first take our doubts and then there are assignments to verify our weak points.
Shivam Rana
7thAbout Abhyas metholodology the teachers are very nice and hardworking toward students.The Centre Head Mrs Anu Sethi is also a brilliant teacher.Abhyas has taught me how to overcome problems and has always taken my doubts and suppoeted me.
Shreya Shrivastava
8thWhen I have not joined Abhyas Academy, my skills of solving maths problems were not clear. But, after joining it, my skills have been developed and my concepts of science and SST are very well. I also came to know about other subjects such as vedic maths and reasoning.
Sharandeep Singh
7thMy experience with Abhyas academy is very nice or it can be said wonderful. I have been studying here from seven class. I have been completing my journey of three years. I am tinking that I should join Abhyas Academy in tenth class as I am seeing much improvement in Maths and English
Hridey Preet
9thAbhyas institute is one of the best coaching institute in the vicinity of Ambala Cantt area. The teachers of the institute are well experienced and very helpful in solving the problems of the students.The good thing of the institute is that it is providing extra classes for the students who are w...
Aman Kumar Shrivastava
10thIn terms of methodology I want to say that institute provides expert guidence and results oriented monitering supplements by requsite study material along with regular tests which help the students to improve their education skills.The techniques of providing education helps the students to asses...
Aman Kumar Shrivastava
10thIt was good as the experience because as we had come here we had been improved in a such envirnment created here.Extra is taught which is beneficial for future.
