Viruses

Viruses are microscopic infectious agents that can only replicate inside the cells of living hosts. They are not considered alive because they cannot carry out their own metabolic processes and rely on the host cell's machinery to reproduce.

Structure of a Virus

A typical virus consists of a core of genetic material, either DNA or RNA, surrounded by a protein coat called a capsid. Some viruses also have an outer lipid envelope derived from the host cell membrane.

How Viruses Replicate

When a virus infects a host cell, it releases its genetic material into the cell. The viral genetic material then hijacks the host cell's machinery to produce new virus particles. The newly formed viruses can then go on to infect other cells, spreading the infection.

Effects of Viruses

Viruses can cause a wide range of effects on their hosts, from mild symptoms such as the common cold to severe diseases such as HIV/AIDS, Ebola, and COVID-19. Some viruses can also cause cancer in their hosts.

Preventing Viral Infections

Preventive measures against viral infections include vaccination, practicing good hygiene, and avoiding close contact with infected individuals. Antiviral medications can also be used to treat some viral infections.

Study Guide

What is the structure of a typical virus?
How do viruses replicate inside a host cell?
What are the effects of viruses on their hosts?
What are some preventive measures against viral infections?

◂Science Worksheets and Study Guides Second Grade. What is science?

Vocabulary/Answer key

What is science?

The resources above cover the following skills:

LIFE SCIENCE

Ecosystems: Interactions, Energy, and Dynamics

Obtain information from literature and other media to illustrate that there are many different kinds of living things and that they exist in different places on land and in water (e.g., woodland, tundra, desert, rainforest, ocean, river).

EARTH AND SPACE SCIENCE

Earth’s Systems

Make observations from media to obtain information about Earth’s events that happen over a short period of time (e.g., tornados, volcanic explosions, earthquakes) or over a time period longer than one can observe (e.g., erosion of rocks, melting of glaciers).

Collect and evaluate data to identify water found on Earth and determine whether it is a solid or a liquid (e.g., glaciers as solid forms of water; oceans, lakes, rivers, streams as liquid forms of water).