Structure of Gametes
Structure of Gametes
Sexual reproduction takes place by the combination of special reproductive cells called 'sex cells'. These sex cells are also known by another name which is gametes'. We can now say that: The cells involved in sexual reproduction are called gametes Gametes are of two types : male gametes, and female gametes. The male gamete in animals is called 'sperm' and the female gamete in animals is called 'egg' (or "ovum'). We will now describe sperms and eggs (or ova) in somewhat detail.
(i) Sperms. The sperms are extremely small cells and we need a microscope to see them. A sperm is about 0.05 mm long. A highly enlarged sketch of sperm is show in Figure 1. A sperm has a head, a middle piece and a tail. A sperm is a single cell with all the usual cell components like nucleus, cytoplasm and cell membrane. The nucleus of sperm cell is tightly packed in its head. The sperm cell has very little cytoplasm. The purpose of tail of sperm is to make it move. The sperm moves by waving its tail from side to side. The term 'sperm' is the short form of the word spermatozoon' (which means male sex cell or male gamete).
(ii) Eggs (or Ova). The eggs (or ova) are also very small and we need a microscope to see them. Eggs (or ova) are, however, much larger than the sperms. The human egg (or ovum) is round and about 0.15 mm in diameter. A highly enlarged sketch of an egg (or ovum) is shown in Figure 2. The egg (or ovum) is also a single cell having a nucleus, cytoplasm and a cell membrane. Outside the cell membrane, an egg (or ovum) has a thin layer of jelly called 'jelly coat' which allows only one sperm to enter into it during fertilisation. Please note that a female gamete (or female sex cell) is known by two names : 'egg' and 'ovum'. So, whether we use the name 'egg' or 'ovum', it will mean the same thing. Another point to be noted is that the plural of ovum is ova. Some of the animals like birds (hen, ostrich, etc.) and reptiles (snakes, crocodiles, etc.) have large eggs.
The nuclei of sperm and egg contain chromosomes which carry genes and transmit the characteristics of parents to the offsprings. The fusion of a male gamete (sperm) with a female gamete (egg) gives rise to a new cell called zygote. Thus, the new cell which is formed by the fusion of a male gamete and a female gamete is called zygote. Zygote is a single cell which contains one nucleus.
Which of the following is/are the parts of sperm ? | |||
| Right Option : D | |||
| View Explanation | |||
Which of the following are correct : (a) Each egg or ovum is a spherical cell much smaller than the sperm. (b) A sperm has a head, a middle piece and a tail. (c) Each egg or ovum is a spherical cell much bigger than the sperm. | |||
| Right Option : B | |||
| View Explanation | |||
Which of the following are correct : (a) Ovum mainly consists of a single nucleus and some reserve food made of lipid droplets. (b) Sperm mainly consists of a single nucleus and some reserve food made of lipid droplets. | |||
| Right Option : A | |||
| View Explanation | |||
Students / Parents Reviews [20]
Abhyas 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
10thMy 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
8thOne 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
10thAbout 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
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
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
7thUsually 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
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
7thMy 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
8thThe 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
10thMy 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
9thIn 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
10thAbhyas Methodology is very good. It is based on according to student and each child manages accordingly to its properly. Methodology has improved the abilities of students to shine them in future.
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
10thAbhyas institute is one of the best coaching institute in the vicinity of Ambala cantt.The institute provides good and quality education to the students.The teachers are well experienced and are very helpful in solving the problems. The major advantages of the institute is extra classes for weak...
Shreya Shrivastava
8thWe started with lot of hope that Abhyas will help in better understnding of complex topics of highers classes. we are not disappointed with the progress our child has made after attending Abhyas. Though need to mention that we expected a lot more. On a scale of 1-10, we would give may be 7.
Manya
8thThird consective year,my ward is in Abhyas with nice experience of admin and transport support.Educational standard of the institute recumbent at satisfactory level. One thing would live to bring in notice that last year study books was distributed after half of the session was over,though study ...
