The scientist most likely see cell wall and vacuole.

Hooke

Schwann Janssen Hooke

1831: Robert Brown discovered the nucleus of the plant cell. 1839: Theodor Schwann and Matthias Jakob Schleiden lead to the development of cell theory. 1855: Rudolf Virchow published “aphorism omnis cellula e cellula” which means that every cell arises from another cell.

Robert Hooke

All living cells arise from pre-existing cells by division. The cell is the fundamental unit of structure and function in all living organisms. The activity of an organism depends on the total activity of independent cells. Energy flow (metabolism and biochemistry) occurs within cells.

Theodor Schwann

The cell theory states the following: All living things are composed of one or more cells. The cell is the basic unit of life. All cells come from pre-existing cells. The cell theory is true for all living things, regardless of size or complexity.

• 1595 – Jansen credited with 1st compound microscope.
• 1655 – Hooke described ‘cells’ in cork.
• 1674 – Leeuwenhoek discovered protozoa.
• 1833 – Brown descibed the cell nucleus in cells of the orchid.
• 1838 – Schleiden and Schwann proposed cell theory.

Cell Theory is one of the basic principles of biology. Credit for the formulation of this theory is given to German scientists Theodor Schwann (1810–1822), Matthias Schleiden (1804–1881), and Rudolph Virchow (1821–1902).

cell

Antony Van Leeuwenhoek

Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria.

biosphere

By studying 86 different gene families, they’ve discovered DNA sequences that are different enough to suggest they’re beyond the three forms of life that we currently recognise. Those forms are classified as bacteria, archaea, and eukaryotes.

8.7 million different forms

Properties of Life. All living organisms share several key characteristics or functions: order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing. When viewed together, these characteristics serve to define life.

To date, no proof of past or present life has been found on Mars. Cumulative evidence suggests that during the ancient Noachian time period, the surface environment of Mars had liquid water and may have been habitable for microorganisms.

The seven characteristics of life include:

• responsiveness to the environment;
• growth and change;
• ability to reproduce;
• have a metabolism and breathe;
• maintain homeostasis;
• being made of cells; and.
• passing traits onto offspring.

We know that life began at least 3.5 billion years ago, because that is the age of the oldest rocks with fossil evidence of life on earth. These rocks are rare because subsequent geologic processes have reshaped the surface of our planet, often destroying older rocks while making new ones.

Characteristics of living things

Are viruses alive or dead? Most biologists say no. Viruses are not made out of cells, they can’t keep themselves in a stable state, they don’t grow, and they can’t make their own energy. Even though they definitely replicate and adapt to their environment, viruses are more like androids than real living organisms.

Viruses are considered by some biologists to be a life form, because they carry genetic material, reproduce, and evolve through natural selection, although they lack the key characteristics, such as cell structure, that are generally considered necessary criteria for life.

Viruses make us sick by killing cells or disrupting cell function. Our bodies often respond with fever (heat inactivates many viruses), the secretion of a chemical called interferon (which blocks viruses from reproducing), or by marshaling the immune system’s antibodies and other cells to target the invader.

Viruses may have arisen from mobile genetic elements that gained the ability to move between cells. They may be descendants of previously free-living organisms that adapted a parasitic replication strategy. Perhaps viruses existed before, and led to the evolution of, cellular life.

Tobacco mosaic virus

The Brain Boot Sector Virus Brain, the first PC virus, began infecting 5.2″ floppy disks in 1986. As Securelist reports, it was the work of two brothers, Basit and Amjad Farooq Alvi, who ran a computer store in Pakistan.

Here are 15 herbs with powerful antiviral activity.

• Oregano. Oregano is a popular herb in the mint family that’s known for its impressive medicinal qualities.
• Sage.
• Basil.
• Fennel.
• Garlic.
• Lemon balm.
• Peppermint.
• Rosemary.

There are many different types of viruses, and they are highly contagious. Some viruses only infect the skin, but others can move into the bloodstream. The signs and symptoms of viremia depend on which virus you have. Once in the blood, a virus has access to almost every tissue and organ in your body.