Reproduction: Definition, Examples, Types, Importance, Types Of Reproduction

What is Reproduction?

Reproduction is a fundamental biological process by which living organisms reproduce offspring for its continuation of their respective species. This can happen either in the form of reproduction by an independent single organism or with the combination of genetic material from two organisms.

It is through this process that the survival of the species is guaranteed by way of assurance of genetic variation, adaptability to changing environments, and persistence of the life forms over generations. Reproduction is a necessity if a species is to survive, and similarly, biodiversity cannot be sustained in its absence.

Types of Reproduction

There are two types of reproduction: sexual and asexual.

• Sexual reproduction requires the fertilization of gametes from two parents and is characterized by genetically diverse offspring.

• Asexual reproduction, on the other hand, involves a single organism reproducing itself with no gametes being produced; hence, the offspring are genetically identical to the parent.

Asexual Mode of Reproduction

A method of reproduction that involves a single organism and gives rise to offspring with a replica of the parent's genetic material.

Characteristics of Asexual Reproduction

• Only one organism is needed to reproduce; there are no gametes involved in the process.

• The offspring is an exact genetic replica of the parent and identical; variation does not exist.

• Asexual reproduction is quick, and hence, there is rapid growth in the population.

Methods of Asexual Reproduction in Animals

Asexual reproduction in animals occurs in various forms within the animal kingdom. The methods of asexual reproduction are:

Asexual Reproduction In Plants

Asexual reproduction in plants occurs through different methods. It is mainly categorised into vegetative propagation, apomixis, and sporulation. Some of the major benefits are discussed below:

Advantages and Disadvantages of Asexual Reproduction

Advantages:

• Enables species to colonise environments quickly.

• Useful in areas where mates are in short supply.

• Offspring are identical clones, thus uniform.

Disadvantages:

• Lack of variation.

• Makes populations more susceptible to diseases or changing conditions.

Sexual Mode of Reproduction

Sexual Reproduction is the process by which genetic material from two parents combines, resulting in genetically varied offspring.

• Typically, a male and a female are required to produce offspring.

• In fertilization, male and female gametes combine to form a zygote.

• The resulting offspring contains a combination of genetic material from the two parents. This gives rise to variation.

Sexual Reproduction in Animals

Sexual reproduction in animals is the process by which animals produce offspring involving two parents. It includes the formation and fusion of male and female gametes, leading to the development of a new organism. The sexual reproduction process includes:

Pre-fertilisation Events

• Gamete formation by meiosis

• Cell division in which the number of chromosomes is halved, ending with four haploid cells.

Fertilisation

• Internal fertilisation: It occurs inside the body of the female. Common in mammals and birds.

• External fertilisation: It occurs outside the body. Common in fish and amphibians.

Post-fertilisation Events

• Zygote: Sperm and egg fuse to form a zygote.

• Embryo Development: The zygote starts dividing and growing into an embryo.

• New Organism: The embryo keeps developing into a baby, which is later born (in mammals) or hatches from an egg (in birds, reptiles, etc.).

Types of Sexual Reproduction

Sexual reproduction can occur in different forms depending on the type of gametes involved. The types of sexual reproduction are:

Isogamy

• It is the fusion of morphologically similar gametes.

• Examples: Some algae and fungi.

Anisogamy

• It is the fusion of gametes that differ in size or form.

• Examples: Most animals and plants.

Oogamy

• It is a form of anisogamy where one gamete, the egg, is large and non-motile, and the other gamete, the sperm, is small and motile.

• Examples: Humans, many animals, and plants.

Sexual Reproduction in Plants

Fertilisation in plants is a biological process in which a male and a female gamete combine to form a genetically variable offspring. Such reproduction is necessary for maintaining genetic diversity within populations of plants and thus adjusting to changes in the environment. The process of sexual reproduction in plants is described below:

Pollination is the transfer of pollen from the anther to the stigma.

• Types: Self-pollination, Cross-pollination

• Mechanisms: Wind, water, animals

Fertilisation is the fusion of male and female gametes forms the zygote.

Post-fertilization Events: Seed and fruit formation occur when ovules develop into seeds, and ovaries form fruits after fertilization.

Advantages and Disadvantages of Sexual Reproduction

Advantages:

• Genetic diversity

• Better adaptability to changing environments.

Disadvantages:

• Requires more energy

• Slower reproduction rate.

Reproduction NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Asexual mode of reproduction

• Sexual mode of reproduction

Practice Questions for NEET

Q1. Arrange the following animals in ascending order based on their life span:

Crow, Horse, Parrot, Elephant

1. Horse, Parrot, Crow, Elephant

2. Crow, Parrot, Horse, Elephant

3. Crow, Parrot, Elephant, Horse

4. Crow, Horse, Elephant, Parrot

Correct answer: 4) Crow, Horse, Elephant, Parrot

Explanation:

Among the given animals, the crow has the shortest life span, followed by the horse, elephant, and parrot. Therefore, the correct order, from shortest to longest life span, is Crow, Horse, Elephant, and Parrot. Option 4, "Crow, Horse, Elephant, Parrot," accurately represents this arrangement.

Hence, the correct answer is option 4) Crow, Horse, Elephant, Parrot

Q2. The event of life span in which metabolism slows down is

1. Juvenile phase

2. Old age

3. Senescence

4. More than one

Correct answer: 2) Old age

Explanation:

This is the last phase of the lifespan. The end of the reproductive phase can be considered as one of the parameters of senescence or old age. There are concomitant changes in the body (like slowing of metabolism, etc.) during this last phase of life span. Old age ultimately leads to death.

Hence, the correct answer is option 2) Old age.

Q3. Birth canal is formed during parturition by female accessory ducts namely

1. Uterus and cervix

2. Cervix and labia majora

3. Cervical canal and vagina

4. Oviduct and uterus

Correct answer: 3) Cervical canal and vagina

Explanation:

Just before parturition, the cervix undergoes significant changes to prepare for childbirth. Under the influence of the hormone relaxin, secreted primarily by the placenta and ovaries, the cervix becomes soft, and elastic, and dilates to allow the baby to pass through. This softening is accompanied by the widening of the cervical canal, which, along with the vagina, forms the birth canal—the pathway through which the baby is delivered. These physiological changes are critical for ensuring a smooth delivery process, as they reduce resistance and create a passage wide enough for the baby to pass through safely.

Hence, the correct answer is option 3) Cervical canal and vagina.

Also Read:

• MCQs on Introduction to Reproduction

• Difference Between Sexual and Asexual Reproduction

• Morphallaxis

Recommended Video on Reproduction