krit.club logo

Reproduction in Animals - Asexual Reproduction in Animals

Grade 8CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Asexual reproduction is a mode of reproduction in which only a single parent is involved to produce offspring without the fusion of gametes (spermsperm and ovaova).

•

In this process, the offspring produced are genetically identical to the parent and to each other.

•

Binary Fission: A method where an animal reproduces by dividing into two individuals. For example, in AmoebaAmoeba, the process begins with the division of its nucleus into two nuclei, followed by the division of its body into two parts, each receiving a nucleus.

•

Budding: A method where new individuals develop from outgrowths of the parent body. In HydraHydra, these outgrowths are called 'buds', which eventually detach to become independent organisms.

•

Cloning: The production of an exact copy of a cell, any other living part, or a complete organism. The first mammal to be cloned was a sheep named Dolly, using a technique where the nucleus of a somatic cell is transferred into an enucleatedenucleated egg cell.

📐Formulae

Parent Cell→KaryokinesisDivided Nuclei→Cytokinesis2 Daughter Cells\text{Parent Cell} \xrightarrow{\text{Karyokinesis}} \text{Divided Nuclei} \xrightarrow{\text{Cytokinesis}} 2 \text{ Daughter Cells}

Parent (Hydra)→Developing Bud→New Individual→Detached Offspring\text{Parent (Hydra)} \rightarrow \text{Developing Bud} \rightarrow \text{New Individual} \rightarrow \text{Detached Offspring}

Total Offspring from n generations of Binary Fission=2n\text{Total Offspring from } n \text{ generations of Binary Fission} = 2^n

💡Examples

Problem 1:

Describe the process of binary fission in AmoebaAmoeba.

Solution:

Amoeba (Parent)→Division of Nucleus→Division of Cytoplasm→2 Daughter AmoebaeAmoeba \text{ (Parent)} \rightarrow \text{Division of Nucleus} \rightarrow \text{Division of Cytoplasm} \rightarrow 2 \text{ Daughter } Amoebae

Explanation:

Binary fission in AmoebaAmoeba starts with the division of the nucleus (karyokinesis) into two. This is followed by the division of the cytoplasm (cytokinesis) until two separate daughter cells are formed from a single parent.

Problem 2:

A single AmoebaAmoeba undergoes binary fission every 2020 minutes. How many AmoebaeAmoebae will be produced after 11 hour?

Solution:

Total time = 6060 minutes. Number of cycles (nn) = 6020=3\frac{60}{20} = 3. Total Amoebae=2n=23=8Amoebae = 2^n = 2^3 = 8.

Explanation:

In binary fission, the population doubles with each generation. After 33 cycles of division, one parent produces 88 identical daughter cells.