Reproduction In Organisms-Concepts

Reproduction In Organisms-Concepts

Advantages and disadvantages of asexual reproduction

Advantages
1. It is uniparental reproduction, therefore, a mate is not required.
2. It involves simple processes of division, amitosis, and mitosis.
3. It is a quick mode of reproduction.
4. A single parent may produce a large number of offspring.
5. The young ones are genetically similar to their parent.

Disadvantages
1. There is no mixing of genetic material, therefore, no variation takes place.
2. Since variations do not occur asexual reproduction has no role in evolution.
3. Due to rapid multiplication, it causes overcrowding.
4. The organisms produced through asexual reproduction have low adaptability to the changing environment.

Difference between sexual and asexual reproduction

	SEXUAL REPRODUCTION	ASEXUAL REPRODUCTION
1.	This mode of reproduction involves the formation and fusion of gametes.	This mode of reproduction does not involve the formation and fusion of gametes.
2.	Requires two parents	Can be performed by one parent
3.	The process to produce offspring needs time. Thus, the increase in number is not that rapid.	Many offspring are produced quickly.
4.	Genetic variations are observed in the offspring.	No variation is seen in the offspring.
5.	Requires special reproductive parts	Does not require special reproductive parts
6.	Examples of organisms which undergo sexual reproduction are a cockroach, human beings, etc.	Examples of organisms that undergo asexual reproduction are Amoeba, Hydra, etc

Bisexual and unisexual animals

1. The male and female gametes in most animals are usually produced by the male and female animals, respectively. Such animals are called unisexual or dioecious.
2. In some animals, both ovaries and testes are present in the same individual i.e. male and female gametes are produced by the same organism.
3. Such animals are called bisexual or monoecious or hermaphrodites.

Difference between external and internal fertilization

Internal fertilization	External fertilization
It takes place in the body of an organism.	It takes place outside the body of an organism in the external environment.
It is generally seen in terrestrial animals.	It is generally seen in aquatic animals.
It protects the embryo from harsh environments and predation.	It does not protect the embryo from a harsh environment and predation.
The success rate is high.	The success rate is low.

Fertilization

1. The fusion of a haploid male gamete and a haploid female gamete to form a diploid zygote is called fertilization.

Binary fission

1. Binary fission is a type of fission where the cells divide into two equal parts.
2. Each part forms daughter cells.
3. It is a type of asexual reproduction.

Budding

1. Budding is a type of asexual reproduction.
2. The small bulb-like projection from the parent plant which grows into a fully grown individual is known as a bud. 
3. The bud has nucleus and cytoplasm which helps it to generate into a new organism.

Multiple fission

1. In some prokaryotic organisms, binary fission occurs in a very unique way which includes dividing into many daughter cells simultaneously by the means of multiple fission.

2. Amoeba withdraws its pseudopodia and secretes a hard covering around itself, which is called cyst formation. When the conditions are unfavourable for Amoeba the nucleus divides into many daughter nuclei. As the cytoplasm divides it gives rise to many daughter cells.3. During favourable conditions, the cyst breaks open and releases many daughter cells.

Fragmentation in Spirogyra

1. Fragmentation is a type of asexual reproduction in which an organism simply breaks into individual pieces at maturity. 

2. These individual small pieces then grow to form a new organism e.g., Spirogyra. 

Vegetative propagation by underground stem

1. Some plants have modified stems.
2. These stem contains nodes and internodes.
3. Axillary buds grow from these nodes.
4. For example, ginger, etc.

Vegetative propagation by leaves

1. Some plants produce buds in the margin of the leaf.
2. When such leaves fall in moist soil, their buds begin to grow as young tiny plants.
3. For example, Bryophyllum. 

Vegetative propagation in potato

1. Vegetative propagation in potatoes takes place by stem.
2. From the activity of growing potato by vegetative propagation it can be found that, new plants grow from the buds within few days.  
3. If such a potato is placed in soil, it has the capability to form a complete plant.

Bulbils

1. These are multicellular fleshy buds that take part in vegetative propagation.
2. For example, Oxalis, pineapple, lily, etc.

Zoospore

1. The zoospores are a special kind of motile and flagellated spores produced inside the zoosporangia.
2. The flagella help to swim in aquatic habitats for proper dispersal.
3. For example, Achlya, Saprolegnia, Albugo, Phytophthora, etc.

Conidia

1. They are formed in Penicillium.
2. These are non-motile spores produced singly or in chains by a constriction at the tip or lateral side of special hyphal branches called conidiophores.