Class 10 Science Chapter 8 How do Organisms Reproduce. We only notice any organism because they do reproduction when a large number of an organism that belongs to single species reproduce, then we are able to notice them.
Like if no animal does the reproduction then they will be extinct and we can’t see any of them. Let’s understand what is reproduction really is?
Reproduction: It may be defined as the biological process by which organisms give rise to their own kind.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce, we are going to learn about the organisms’ reproduction and their variation?
# Do organisms create exact copies of themselves?
In reproduction, the blueprint of body design is further copied. So, the information of blueprint is present in chromosomes in the form of DNA (Deoxyribose Nucleic Acid). DNA is the information source for making proteins. So, reproduction at the smallest level means having a copy of the DNA.
To copy DNA cells organisms use chemical reactions. However, the biochemical reaction is not reliable, which means it doesn’t create exact DNA. So, the copied DNA has some variations in it. So, due to the variation in reproduction we see evolution.
# The Importance of Variation
The population of organisms uses a specific place or niches in the ecosystem. Means lives there uses their resources and reproduce there. So, if there is any kind of change that happens in that niche like a flood, temperature change, etc.
So, the whole population is going to wipe out from there. However, after the reproduction, if there is some variation in a few individuals then, they may survive.
Mode of reproduction used by a single organism
Reproduction is of 2 types i.e. Asexual and Sexual. Let’s learn about these 2 in detail.
1. Asexual
In this, a new generation is created from a single individual. There are 6 methods in asexual reproduction. Let’s about all of them, one by one down in the article.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce, we are going to learn about the types of asexual reproduction?
# Fission
It is only used by unicellular organisms, which means cell division is used for reproduction. Like bacteria, protozoa, and amoeba. Let’s understand some of the examples of this.
Amoeba: For reproduction, it can divide itself from anywhere. It uses binary fission.
Leishmania: For reproduction, it divides from a specific plane or we can say a specific place. It also uses binary fission.
The malaria parasite, Plasmodium: For reproduction, it divides into many daughter cells. It uses multiple fission
# Fragmentation
Simple body-designed organisms use this type such as spirogyra. Let’s understand it from an example.
Spirogyra: When it matures, it simply breaks up into smaller pieces or fragments.
However, not all multi-cellular organisms don’t do this.
# Regeneration
All fully differentiated organisms use this. Let’s learn about differentiated organisms.
Differentiated Organisms: These organisms have completely developed bodies, and their cells and tissues perform a specialized function.
So, If their body will cut into pieces, then the new piece grows into a complete individual body example Hydra and Planaria. Regeneration is only done if the organisms have specialized cells. It is not the same as reproduction because organisms have to depend on others who can cut them into pieces.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? We are going to learn about the types of asexual reproduction about budding, vegetative propagation, and Spore Formation.
Before we learn about this topic lets see the difference between the Fragmentation and Regeneration
| Fragmentation | Regeneration |
|---|---|
| It is done in multi-cellular organisms, whose body design is simple | It is also done in multi-cellular organisms, but the design of the body is complex |
| It is not important to have a specialized cell | In this specialized cell have to be there. |
| Example: Spirogyra | Example: Hydra, Planaria |
# Budding
This is used by Hydra, when there is cell division done on a particular side of it a bud outgrow from there. These buds detect from the parent body and become new individuals when they mature. Example: Hydra, Yeast, and Sponges.
# Vegetative Propagation
Many plants use their root, stem, and leaves for developing new plants also known as vegetative parts. By this, we can use 2 methods in plants i.e. layering or grafting.
Layering: When we put a branch of a plant inside the soil and after some time it forms a new plant.
Grafting: When we cut 2 stems of different plants and joint them together and after some time it forms a new plant.
Those plants which are now can not be produced from seeds, we can use this method on them. Genetically these plants have all the qualities of parents. Likewise, Bryophyllum uses its leaves for reproduction. These types of plants also bear the fruit and flowers earlier than those plants which grow from seed.
Examples of these types of plants are Sugarcane, Roses, and Grapes, etc.
# Spore Formation
In this organism, spores are used for reproduction and not hyphae. All the spores are covered by the thick wall until they come in a contact with the moist surface. Its advantage is it can produce many spores or organisms from a sporangium.
These spores are very light and can easily be distributed to different parts. Also, they have a thick wall around them to keep them safe from unfavorable conditions.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? We are going to learn about sexual reproduction.
# Sexual Reproduction
It is a mode of reproduction that depends on 2 individuals for creating a new generation.
# Why the sexual mode of reproduction?
As we learned that in reproduction there are some variations created in the new generation. But it is a slow process. However, we need this variation more and more in a fast way. So, how can we speed up this process? We have to take 2 different individuals from the population, then their variation increases, as well as speed, also increases.
The sexual mode of reproduction has more variation as compared to the asexual mode of reproduction. But there is a problem in this, if we combine the DNA of 2 individual organisms to create new DNA, then the new organisms have double DNA or we can say twice the amount of DNA.
So, the solution to this is, that multi-cellular organisms have specialized organs in them which have special cells which contain half the number of chromosomes and half the amount of DNA. Also, DNA is located inside the chromosomes.
Human beings have 46 chromosomes, so, these special cells are known as germs cells or we can say sex cells, gametes, or reproductive cells. The combination of 2 germ cells is known as a zygote. So, 1 of the germ cell is large and contains food which is also known as a female gamete. Another germ cell in a zygote is small and movable which is also known as a male gamete.
Fertilization: It is the process of a combination of male and female gamete to form a zygote.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? We are going to learn about sexual reproduction in flowers.
# Sexual Reproduction in flowering plants
The stamen and pistil of a flower are called the reproductive part as it contains germ cells. Flower can be 2 types i.e. uni-sexual like papaya or watermelon it only contains stamen or pistil in it. And another is Bi-sexual like hibiscus and mustard, it contains both stamen and pistil in it.
Stamen: It is a male reproductive part and it produces pollen grains as it’s germs cells. It is made up of 2 parts i.e. Anther and Filament.
Pistil: It is a female reproductive part and it is made up of 3 parts i.e. stigma, style, and ovary. Inside the ovary, it contains an ovule and each ovule contains an egg cell in it. It is also known as a female gamete.
So, the male germ cell fusion with the female germ cell, and it produces a zygote, which further becomes a new plant.
Pollination: It is a process of transfer of pollen grains from the anther to stigma. It is of 2 types self-pollination and cross-pollination.
Self-Pollination: If a flower is bi-sexual and its own pollen is transferred in its own stigma, it is known as self-pollination.
Cross-Pollination: If a flower is uni-sexual and its pollen is transferred from 1 to another flower’s stigma, it is known as cross-pollination. It is done by pollen agents such as air, water, or animals (Butterfly, Bees, etc).
Now, when fertilization is done, the zygote divides into many cells known as embryos. Now, the ovule becomes a protector of an embryo and eventually becomes a seed. Meanwhile, the rest of the part of the flower i.e. sepals, petals, style, stigma, and stamen shrivel and fall off from the flower.
Sepal: It is the protector of the flower in the flower’s initial stage.
Petal: It creates an attraction to the flower so that the insects are attracted to the flower and help the flower in pollination.
So, inside the seed, it contains an embryo which is developed into a new plant this process is also called germination.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? We are going to learn about sexual reproduction in Human Beings.
# Reproduction in Human Beings
We use sexual mode for reproduction. As we become older our body changes. These changes are of 2 types. First, our height increases, we lose our milk teeth, etc. All these are known as growth changes. Second, some changes are done at the age of 12-13 years in the early stage of a teenager.
There are some common changes in both boys and girls. There are 4 types of these changes:
- Hair growth in armpits and in between thighs.
- Thin Hair growth on legs, arms, and face.
- Skin becomes oily and pimples come out.
- We begin to notice our as well as others’ bodies.
Now, there are some changes which are different in boys and girls. So, in girls there are 3 main changes:
- Breast size increases.
- Nipples’ skin becomes dark in color.
- Menstural cycle begins.
Now, in boys, there are also 3 main changes
- Hair grows on the face.
- Voice begins to crack.
- The penis occasionally enlarges and is erect.
All these changes are slow in nature and do not happen with all of them at the same time. All these changes don’t complete quickly after starting. All these changes mean our body is maturing.
Puberty: It is a period in which the reproductive system of boys and girls mature and becomes capable of reproducing. It started during 10-11 years of age.
So, in Human Body to join the germ cells there are 2 methods i.e. external release like in plants or internally releases by joining the body such as sex or mating which is mostly done in animals and humans.
For the transfer of germ cells, we need a special organ. In men, they need a penis, which is capable of erecting. In women, they need a female reproductive organ that is capable of carrying a baby for the long term and a breast that is capable of feeding the baby.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? We are going to learn about the Male reproductive system.
# Male Reproductive System
It divides into 2 parts, 1st part is gametes or germ cells, and 2nd part delivers the gametes or germ cells in the female body.
So, the male gamete is also called sperm, and the process of making sperm is done by the testis. The testis is located inside the scrotum. Testis also releases a hormone named testosterone because of this all the changes in the body of a boy happen in puberty.
The formed sperm deliver through vas deferens and on the way there are some glands that connect path with this i.e. prostate gland, seminal vesicle, and Cowper’s gland.
All 3 of them release fluid in the sperm, so that sperm becomes fluid and transport becomes easy. Also, the fluid got food from which sperm get nutrition.
However, there is the same passage for both sperm and urine in the male body. That passage is also known as the urethra.
# Female Reproductive System
In the female body, the ovary does the same thing that testis do in the male body. The ovary makes the female gamete called eggs or ovum or ova. It also makes hormones named oestrogen which is responsible for changes in girls.
In the ovary, there are already many eggs but all are immature, however, when girls hit puberty these eggs started maturing and the ovary releases 1 egg every month. That egg is collected by the oviduct or fallopian tube and transferred into the uterus or womb.
2 fallopian tubes combined make uterus, the uterus opens in vagina through the cervix. Fertilization happens in the fallopian tube also called the site of fertilization.
After that fertilized egg starts dividing and becomes an embryo and after that, it sticks to the wall of the uterus and develops there it is also called the fetus.
To nurture or to provide nutrition to the baby inside there is a special tissue present named the placenta. Placenta provides a surface area in which the exchange of oxygen, carbon dioxide, glucose, urea, etc happens.
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? We are going to learn about the fertilization of eggs and reproductive health.
# What happens when the egg is not fertilized?
The egg is fertilized or not, it doesn’t mean anything to the uterus, as the uterus still does its work of taking blood and making the wall thick and spongy for the fetus.
But now the egg is not fertilized so this lining is not needed, so now it starts to break and come out through the vagina in form of blood and mucus. This cycle is also known as the menstruation cycle and takes place every month in the female body also it happens for 8 to 10 days.
Menarche: When the menstruation cycle starts at the age of 13 years is known as menarche.
Menopause: When the menstruation cycle permanently stops at the age of 45 years is known as menopause.
# Reproductive Health
For engaging sexually with another human being’s the body needs to be matured fully. If someone started these sexual acts before maturing the body fully, then they have to face some problems or diseases.
There are 2 diseases i.e. bacterial infection and viral infection. Now, due to bacterial infection, the body has to face 2 diseases i.e. gonorrhea and syphilis. Due to viral infection, the body has to face 2 diseases i.e. warts and HIV-AIDS.
What if someone does sex but doesn’t want to get pregnant?\
So, for this, there are some methods also called contraceptive methods. There are 4 types of methods i.e. barrier method, chemical method, intrauterine contraceptive devices, and surgical method.
Let’s learn about these methods in detail.
- Barrier method: In this, we use a condom on the penis or some covering on the vagina.
- Chemical method: In this, you have to take some pills, by this, some hormones are released in the body. So, it changes the balance in the body, so that egg doesn’t release.
- Intrauterine contraceptive method: These are devices such as loop or copper-T, which is used by the female body, they are placed in the uterus to prevent sperms to reach the eggs.
- Surgical method: It is most popular and used for long-term results. In the male body, vas deferens will be blocked. In females, the fallopian tube is blocked in this method.
Q. What is the difference between asexual and sexual reproduction?
| Asexual reproduction | Sexual reproduction |
|---|---|
| No mixing of genetic material, therefore no or less variation in offsprings | Genetic mixing increases variation |
| No gametes are formed | Gametes are formed |
| Normally more offsprings | Fewer offsprings |
| Only 1 parent is involved | Usually, 2 parents are involved |
| It is a rapid process during the favorable condition | Slower process |
Class 10 Science Chapter 8 How do Organisms Reproduce
In this section of Class 10 Science Chapter 8 How do Organisms Reproduce? we are going to see the blueprint and more important things related to this chapter.
To see Class 10 Science Chapter 8 How do Organisms Reproduce blueprint down in the table.
| Class 10 Science Chapter 8 How do Organisms Reproduce | |
|---|---|
| 3 Marker | 1 question |
| 5 Marker | 1 question |
| Total questions | 2 |
| Total marks | 8 |
| Class 10 Science Chapter 8 How do Organisms Reproduce Blueprint 2021-22 | |
The total worth of Class 10 Science Chapter 8 How do Organisms Reproduce in terms of the board exam. According to the table, this chapter contains 3 marks for 1 question and 5 marks for 1 question. Please note that this marking scheme may vary in board exams.
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