Kritika Khadka

Living Characteristics:

1. Reproduction: Viruses have the ability to reproduce, although they require a host cell to do so.
2. Genetic Material: Viruses have genetic material, either DNA or RNA, which they use to replicate inside host cells.
3. Evolution: Viruses can evolve over time and adapt to changing environmental conditions.
4. Mutations: Viruses can mutate, which can sometimes lead to new strains or variants of the virus.
5. Infectivity: Viruses are highly infectious and can rapidly spread through...

A virus is a small infectious agent that replicates only inside the living cells of other organisms, such as animals, plants, and bacteria. It consists of a genetic material (either DNA or RNA) surrounded by a protein coat, and sometimes also an outer lipid membrane envelope.

The genetic material of a virus can be either DNA or RNA, but not both. Some viruses have single-stranded DNA (ssDNA) as their genetic material, while others have double-stranded DNA (dsDNA). Similarly, some viruses have...

Sure, here are some examples of viral diseases that affect humans and the viruses that cause them:

1. COVID-19: caused by the SARS-CoV-2 virus.
2. Influenza: caused by the influenza virus.
3. Measles: caused by the measles virus.
4. Mumps: caused by the mumps virus.
5. Rubella: caused by the rubella virus.
6. Polio: caused by the poliovirus.
7. Rabies: caused by the rabies virus.
8. HIV/AIDS: caused by the human immunodeficiency virus (HIV).
9. Ebola virus disease: caused by the Ebola virus.
10. Zika virus disease: caused...

Viruses act like non living substances outside the host cell however inside the host cell they show living characters, behaving like both living and nonliving things because of which they are also called biological enigma or puzzle.

It is a very complex and long phase. It is further divided into five successive substages.

1. Leptotene or Leptonema
2. Zygotene or Zygonema
3. Pachytene or Pachynema
4. Diplotene or Diplonema
5. Diakinesis

1. Leptotene[ GK: Leptos=thin, tene= Thread ]

• size of nucleus increases
• chromatin thread become shortened and converted into chromosomes which are thread like and single stranded.
• chromosomes passes beaded structure called chromomeres.

2. Zygotene[ GK: Zygo= yolk, tene= thread]

• pairing of homologous...

Crossing over is a process of exchange of genetic materials between the non-sister chromatids of homologus chromosomes. It takes place in pachytene of prophase-I of meiosis.

It has following significances:

1. It produces new combination of genes and trait.
2. it increases variability of organisms.
3. Due to crossing over, different varieties of plants and animals are produced.
4. Crossing over helps in the identity of organism.
5. It is a source of raw material for evolution of life.
6. It increase immunity of...

Furrowing is a type of division of cytoplasm occurs in the bacteria, fungi and animal cells. In this process, a peripheral cleavage furrow appear gradually between the two daughter nuclei.

The furrow deepens and when the edges of the furrow meet in the center of the cell, the protoplasm divides into two daughter cells.