Asexual and sexual reproduction

Reproduction: Biological process of producing young ones of their own kind by living organisms is called reproduction. Reproduction helps to increase population of any species as well as help for the existence of living organisms in earth.

Types of reproduction

1. Asexual reproduction
2. Sexual reproduction

1) Asexual reproduction

When new offsprings are formed from any part of parents body without the involvement of male and female gamete, this is called asexual reproduction. Features of asexual reproduction:

1. Single parent can reproduce no need of male and female.
2. Offsprings are genetically similar to parent.
3. It is quick method of reproduction.
4. There is involvement of mitosis cell division.

Types of asexual reproduction

1. Fission
2. Budding
3. Fragmentation
4. Regeneration
5. Sporulation
6. vegetative propagation

1. Fission: Unicellular microorganisms reproduce by this method. In this method a mature cell divides into two or more new cells (Organisms). It is of two types:

Binary fission:  In this method, mature cell divides into two new cells. Animals like amoeba and plant like bacteria diatoms reproduce this method.

Multiple Fission: When a mature cell splits into many new cells, it is called multiple fission. Animal like plasmodium and plant like chlamydomonas reproduce by this method.

2. Budding: In this method, finger-like projection called bud is formed at any part of parent’s body which grow continuously and develop into new organism. After its full growth it detaches from parent and start living freely. Animal like hydra and plant like yeast reproduce by this method.

3. Fragmentation: Plants like spirogyra, riccia reproduce by this method. In this method, when plant body splits into many fragments, each of these fragment develops into new organism.

4. Regeneration: In this method when an organism divides into many pieces due to any reason, each of these pieces regenerates their lost part and develop into new individual. Animals like planaria, hydra, tapeworm etc reproduce by this method.

5. Sporulation: The process of asexual reproduction by producing spores is called sporulation.

6. Vegetative propagation: When plants reproduce to the vegetative parts like root, stem, leaf etc. this is called vegetative propagation.

Vegetative propagation through root: sweet potato, Dahlia etc

Vegetative propagation through stem: rose, potato, ginger etc

Vegetative propagation through leaf: bryophyllum ,Begonia eta

Advantages of vegetative propagation:

1. It is easier, quick and economic method of reproduction so it is highly beneficial to farmers and gardeners.
2. Those plants which don’t produce good quality seed like banana, potato etc can reproduce by this method.
3. Good quality of plants can be preserved by this method.

Sexual reproduction:

The process of forming a new offspring by the fusion of male and female gamete is called sexual reproduction.

Feature of sexual reproduction:

1. Involvement of both the male and female parent.
2. Offsprings are not genetically similar to the parent but shows the characters of both the parent.
3. There is involvement of bath the Meiosis and Mitosis cell division.
4. Relatively, It complete in longer period of time.

Sexual reproduction in plants:

1. Pollination: The process of transfer of pollen grains from anther to the stigma of a flower is called pollination. Types of pollination are Self pollination and Cross pollination

2. Fertilization: The process of fusion of male and female gamete to form zygote ic called fertilization.

Double Fertilization: In angiosperm, during fertilization one male gamete fuses with female gamete to form zygote and another male gamete fuses with secondory nucleus to form endosperm this process is called double fertilization.

Triple fusion: Haploid (n) male gamete fuses with diploid (2n) secondary nucleus to form endosperm a triploid (3n) structure, this is called triple fusion.

After fertilization, ovary develops into fruit and ovules develops into seed, zygote develops into embryo which remains inside the seed.

Under favourable condition, seed germinates (embryo develop) and give rice to new plants.

Sexual reproduction in Animals

1. Fertilization:

There are 2 types of fertilization. They are External fertilization and Internal fertilization/

Advantages of sexual reproduction:

1. The variation caused due to the sexual reproduction helps in organic evolution.
2. Offspring produced by this method are genetically different from each other or from the parent.
3. Offspring from sexual reproduction relatively has greater immunity power.

Advantage of asexual reproduction:

1. It is short (quick) and simple method of reproduction.
2. Single parent can reproduce.
3. Offsprings are genetically similar to parent.

Solved exercise

a. Write difference between sperm and ovum.

b. Write difference between ovum and zygote.

c. Write difference between spore and gamete.

d. Gymnosperm doesn’t bear true fruit Why?

In flower of gymnosperm, ovary is missing due to which they don’t bear true fruit.

e. What type of asexual reproduction is found in following organisms:

1. Hydra: Budding, regeneration
2. Onion: Vegetative propagation
3. Sisau : Sexual reproduction
4. Rose: Vegetative propagation
5. Amoeba: Binary fission
6. Mucor: Sporulation
7. Potato: Vegetative propagation
8. Bryophyllum: vegetative propagation
9. Sweet potato: Vegetative propagation

f. Study diagram and answer.

i. Label A, B, ,C D and E.

A: stigma

B: anther

C: style

D: ovile

E: filament

ii. Which one of them is male reproductive organ?

Androecium (B+E) is male reproductive organ.

iii. Which one of them a female reproductive organ?

Gynoecium (A+C+D)

iv. Is it unisexual or bisexual?

It is bisexual.

v. Which one of them grows in seeds?

D