Reproduction in Organisms NEET Notes | Biology

Biology is the most important segment in NEET, for it carries the most weightage. In total, 90 questions are asked from biology that carries a total of 360 marks.

There are several topics that are in the syllabus of which reproduction is of utmost importance. Therefore, if you want to excel in the exam, you must prepare important notes of biology for NEET reproduction in organisms. 

Detailed reproduction in organism NEET notes will cover the maximum number of questions in biology. Moreover, if you’re aiming to become a doctor in future, this topic will be essential to study the genetic diversity of animals.  

Types of Reproduction in Organisms

Reproduction is one of the most vital biological processes by which living organisms give birth to new organisms of the same kind. It helps in maintaining diversity and continuity of life on earth. 

Reproduction works through DNA replication, cell divisions, reproduction body formation and developing them into offspring. 

The methods of reproduction can be classified into two types- Asexual and sexual reproduction. 

Asexual Reproduction

Asexual reproduction is the form of reproduction that involves a single organism, that creates a copy of itself. The main feature of this process is mitosis. Generally, unicellular organisms and plants practise this method to reproduce. 

Following is a list of reproduction in organisms NEET notes that you can prepare

1. Binary Fission – In this process, a cell copies its DNA and splits into two daughter cells. Each of these cells carries a copy of the parent DNA after mitosis. For example, amoeba, bacteria and most single-cellular organisms follow this process. 

2. Budding – Some organisms split a part of them and form a new organism while staying attached to their parent cell. Once they mature, they separate from it. For example, hydra and yeast. 

3. Vegetative Propagation – Many plants propagate through a part of their body known as propagule. Typically leaves, stems, roots are used in vegetative propagation. These parts of that plant come in contact with soil, water and nutrients and start growing as new plants. 

Some of the examples are roots- yam, sweet potato, underground stem - lotus, turmeric, bulbs - onion, lilies, tubers-potato, creepers-strawberry, leaves - kalanchoe plant.

Gardeners often use vegetative propagation artificially for economic gain. 

4. Fragmentation – Fragmentation happens when the body of an organism breaks into two, and each of them grows into a new organism. Example: spirogyra, flatworm, etc. 

5. Sporogenesis – It is the method of producing reproductive cells called spores. Spores generally spread via wind and do not require fertilisation. Example: sporulation occurs in several bacteria and protozoans. 

6. Agamenogenesis – This is the process of producing sexual organisms without fertilisation. It happens in different types.

• Parthenogenesis occurs when an unfertilised egg develops into a new organism. It possesses only its mother’s genes.  

• Apomixis takes place when a normal plant reproduces asexually due to lack of male plant to fertilise female gamete. 

• Nucellar embryony is the process through which an embryo is formed from its parents’ tissue without using reproductive cells or mitosis. Primarily this method happens in citrus fruit. 

Sexual Reproduction 

Sexual reproduction takes place when male and female gamete fuse together through fertilisation and give birth to offspring. 

The entire process of sexual reproduction takes place in three stages.

1. Pre-Fertilization

1. Gametogenesis takes place in haploid cells. 

• Homogametes – Male and female gametes look the same. They are seen in some algae. 

• Heterogametes – In most sexually reproduced organisms, two distinct gametes can be seen. The female gamete is called egg or ovum; the male one is called sperm. 

2. Gamete transfer – In most seed plants pollen grains carry male gametes and ovules carry the eggs. In most plants, pollination occurs when pollen grains are transferred to stigma. 

2. Fertilisation – It involves the fusion of gametes and formation of a diploid zygote. 

• In most aquatic creatures, fertilisation happens with the help of the medium, means outside of the body. It is called external fertilisation. 

• In most terrestrial organisms, including mammals, birds, reptiles, it happens inside the body and is called internal fertilisation. 

3. Post-fertilisation

• Embryogenesis is the procedure of forming an embryo from a zygote. During this process, zygote undergoes mitosis and cell differentiation. 

• Oviparous are the animals which lay eggs and the offspring hatch out of it after incubation. Ex - reptiles, birds, etc. 

• Viviparous animals are mostly mammals, including humans. The zygote forms inside the female body, and after certain stages, the baby is delivered. The chance of survival of these babies is higher due to embryonic protection and parental care.  

Reproduction in organisms NEET questions includes a significant part of sexual reproduction. Learn and revise this portion simultaneously so that you don’t miss any concept. 

Reproduction in organisms NEET notes also includes a few comparison charts. The difference between sexual and asexual reproduction is one of those. 

Difference Between Sexual and Asexual Reproduction 

After assessing previous years’ questions, you must have noticed that reproduction in organisms' NEET notes is most important to qualify the exam. For that, keep on practising the above-mentioned topics and solve as many questions as you can. Moreover, sit for mock tests to ensure that you can finish the paper on time. 

Besides, try to incorporate reproduction in organisms class 12 notes for NEET as this portion covers the maximum number of questions.

The Importance of Reproduction in Organisms

In the process of giving birth to new species, reproduction is a crucial phenomenon. Irrespective of the kind of reproduction, sexual or asexual, reproduction would mean that the offspring carries the same DNA as their parent. This will lead to the continuity of the already existing species. As an organism, on earth, survival is the main goal. The process of creating a life without the existing species is a much more difficult and complex task. Moreover, The more complex organisms and animals cannot be simply produced without existing species. Many scientists over the years have tried experimenting, but they could only produce viruses and other simple organisms in the laboratory. Also, the fact that these organisms still do not have any life-like features is our cue to realise how important is natural reproduction in animals and organisms.

Sexual Reproduction in Plants

Since plants cannot move from place to place, it is unlikely that the sexual mode of reproduction is possible. They release their sperm freely in the wind, water or other modes of transportation for the sake of reproducing. Additionally, the insects and birds also help in the transfer of pollen from plant to plant and aid in plant reproduction. 

The Advantages and Disadvantages of Asexual Reproduction

The advantage of asexual reproduction is that when the times are favourable, the population produced can be high. The process of asexual reproduction is rather faster than that of sexual reproduction as the time and energy saved in finding a mate is zero. Only a single parent is involved in producing the new offspring, thus it can take place quickly. But the drawback of asexual reproduction is that In times of unfavourable conditions the fertilization might not happen at all. It completely depends on external factors like water, winds, insects etc.

The Merits and Demerits of Sexual reproduction

The advantage of the sexual mode of reproduction is that the offsprings produced are genetically varied. All the animals are less likely to get affected by a disease. The offspring can survive in the not so good conditions as well.

The disadvantage of sexual preproduction is that the time and energy is consumed in finding a suitable mate.

Hermaphroditism

Hermaphroditism can be defined as a state consisting of both male and female reproductive parts in the same body. Mostly common in invertebrates, these organisms do not have separate sexes and thus, can act as either male or female during the process of mating. They are also called intersex. Many organisms ranging from fishes to earthworms are known to be hermaphrodites. The opposite of hermaphroditism is termed as gonochoric i.e., a state of carrying either male or female reproductive parts.

Notable Advantages of Hermaphroditism

• As both male and female reproductive parts are present in the same organism, there is no effort needed to find a mating partner. The Organism can self fertilize without needing to find a suitable mate.

• The hermaphrodite organisms have lesser chances of being extinct.

Unlike a gonochoric, every hermaphrodite can reproduce an offspring. But so this is not the case in organisms with separate sexes.

Notable Disadvantages of Hermaphroditism

• Since a hermaphrodite is not specialised in either one of the sexes, the ability to reproduce multiple offspring is out of the question.

• The diversity in genes is limited as the offspring are reproduced by only single parent organisms.

• The hermaphrodites need extra energy to maintain both reproductive body parts.

Allogamy and Autogamy

Allogamy is referred to as cross-fertilization, where the ovum of one species is fertilized by the sperm of another individual. The pollination in plants is a good example of allogamy. Also referred to as cross-pollination.

Autogamy, by definition, refers to self-fertilization, where the ovum and sperm come from the same individual. In plants, this process is referred to as self-pollination and occurs mainly in hermaphroditic organisms and plants.

Outbreeding

The technique of fertilising the ovum and spermatozoa of two different breeds is known as outbreeding or outcrossing. This is a widely practised technique to increase genetic diversity as well as get the desired offspring of varied characteristics.