Ever given a thought as to why organisms reproduce? Or why do offspring resemble their parents in certain aspects while still maintaining their own identities? So, the question remains, what is the need to reproduce? These Class 10 reproduction notes aim to elaborate on all these facts and much more, clearing any doubts about living organisms’ reproduction process. Read on to understand the fascinating world of our living organisms.
What Is Reproduction Class 10 Notes
Reproduction is a biological process in which living organisms produce offspring that are biologically similar to themselves. It is one of the key life processes because living organisms are able to maintain their population through this process. This is a mode by which all living organisms on this earth ensure the preservation and continuity of their generation and the species as a whole.
Are the Offspring Produced Exact Copies of Their Parents?
Whether or not an offspring is identical to the parents depends on a cellular factor called DNA. DNA or deoxyribonucleic acid is a component of chromosome present in the nucleus of all cells. This DNA carries all the necessary information and acts as a basis for determining the inheritance of characters from parents to offspring. DNA is also the information required for the production of proteins in our body. Variations in this information lead to the formation of different proteins, thereby leading to changes in body designs. This proves that creating copies of DNA is the first and basic step of reproduction. However, during the copying of DNA, variations are also generated, leading to similar copies of DNA but not identical sets.
Variations and Their Importance
Variations are referred to the changes that occur in the sequences of DNA during the DNA replication (copy) process and are very important for the survival of a species. Similar body designs are made such that offspring can easily adapt to their niche or environment. But the environment may undergo drastic changes for which an entire population may get wiped off Earth. Variation is thus very useful for the maintenance of a population of species.
Modes of Reproduction Class 10 Notes
In nature, all living organism reproduces by either of the two methods: Asexual reproduction and Sexual reproduction.
The mode of reproduction in which sex cells or gametes are not involved. In this case, only offspring are produced from only one parent. It is of the following types:
Types of Asexual Reproduction
Fission: This is a process of cell division mainly observed in unicellular (single-cell) organisms like Euglena, Amoeba, etc. Fission involves the splitting of the parent cell into identical individual or daughter cells. Fission can again be classified into two types:
Binary fission: The process in which a parent divides into two identical daughter cells.
Multiple fission: The process in which the parent cell splits into many daughter cells.
This mode of reproduction is observed in multicellular organisms having simple body configurations, as in algae. Fragmentation involves the breakdown of the body into smaller parts, whereby each part gives rise to new individuals. E.g., Spirogyra.
In this mode of propagation, fully differentiated organisms such as Planaria can create new individuals from their body parts. However, the latest studies do not consider this a mode of reproduction but only a means through which organisms regrow their lost body parts.
Organisms like Yeast develop a bud (outgrowth) from their body surface, which is later detached from the parent and develops into a new individual.
- Spore formation
Most fungi reproduce through spore formation. Spores are microcellular structures formed and stored in a special structure called sporangia. Bursting of this sporangia leads to the release of spores that therefore grows into new individuals under favourable conditions.
Reproduction in Plants
Plants showcase two forms of reproduction: the vegetative method and the sexual method.
Vegetative Propagation in Plants
The process in which new plants are produced from vegetative parts (root, stem, leaves) of plants is called the vegetative propagation of plants. This process can be widely classified into three types:
Propagation by root: when new individuals are produced from parts of the root. E.g., sweet potato.
Propagation by the stem: when new individuals are produced from stem cutting. E.g., Rose.
Propagation by leaves: when new individuals are produced from buds of leaves. E.g., Bryophyllum.
Sexual Reproduction Class 10 Notes
The mode of reproduction in which offspring are produced due to the fusion of sex cells or the gametes produced from both parents (male and female).
The male gamete is called the sperm cell, while the female gamete is known as the ova (sing. Ovum). The process of fusion of male and female gamete is called fertilisation which leads to the production of the zygote.
Sexual Reproduction in Plants
There is a reason that flowers are not considered vegetative, as flowers help in the sexual reproduction of plants. Each flower is made up of four parts, sepals, petals, stamens, and carpels. Stamens, also called the androecium, form the male reproductive and produce the male sex (gamete) cells called pollens. The female reproductive parts, called carpels or gynoecium, are made up of style, stigma, and ovary and produce the female sex (gamete) cell called the egg cell.
A flower having either the stamens or carpels is known as unisexual (e.g., papaya), while a flower with both the stamens and carpels is called a bisexual flower (e.g., Hibiscus).
Sexual Reproduction in Humans
In humans, specific and specialised reproductive structures are present that help in the process.
The male reproductive structure is made up of the testis, scrotum, seminal vesicles, vas deferens, urethra, and penis.
The female reproductive structures include the ovary, fallopian tube (oviducts), uterus, cervix, and vagina.
Reproduction is brought about when sperm cells fuse with the ovum within the fallopian tube inside the female’s body. This process of fusion of gamete cells inside the female body is called internal fertilisation.
Key Points Related to Sexual Reproduction in Humans
- Reproductive maturity in humans begins with the onset of puberty or adolescence.
- Menstruation: The sexual maturity of females is marked by the onset of the monthly flow of blood from the vagina.
Every month the ovary releases an ovum that is captured by the fallopian tubes and travels along the inner lining of the tube, whereby with the presence of sperm, fertilisation may take place. Parallelly the uterus prepares its walls to embed the embryo and provide nourishment to the growing embryo. However, in the absence of fertilisation, the inner walls of the uterus shed away in the form of monthly blood flow, called menstruation.
The process of onset of menstruation is termed menarche.
- Menopause: The stoppage of the menstruation cycle and, therefore female’s reproductive ability at the age of 45-55 years is called menopause.
We hope these class 10 chapter 8 science notes on reproduction will help you in your upcoming exams. These reproduction class 10 notes are framed as per the CBSE textbook.