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This question group is public and is used in 51 tests.

Author: szeiger
No. Questions: 5
Created: Oct 30, 2015
Last Modified: 5 years ago

Science Characteristics of Life

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All living things share a certain traits. If something is missing even one of these, then it automatically is not alive.

The first characteristic all living things share is that they are made up of one or more cells. A cell is the smallest unit that can support life. Bacteria and many protists are only a single cell, while a human and an elephant are made of trillions of cells. Each cell has its own metabolism that creates energy and rids itself of wastes. In higher organisms, they work together in structures called tissues, organs, and organ systems.

Secondly, all living things use energy. This allows them to carry out their individual processes, such are breaking down food or eliminating waste products. They also use this energy for building things, such as glucose in plant cells.

Living things are able to reproduce. This means they produce similar organisms to themselves. Reproduction can happen asexually, where the organism produces more of itself without the transfer of genetic material (such as binary fission in bacteria or budding in sponges), or sexually, where genetic material is transferred from one organism to another, usually via sperm. Most organisms reproduce in this fashion.

Once reproduction has occurred, living things need to grow. They do this by dividing each cell over and over again. Additionally, each of those cells need to increase in size before it can split. In sexual reproduction, a single cell (the egg) divides thousands of time in order to form the new individual.

If you poke a dog with a stick, it will bark, growl, or at the very least, move. Living things respond to stimuli. Stimuli may be an increase in environmental temperature, a shortage of food supply, or the production of chemicals to keep insects from eating leaves.

The response to stimuli is not to be confused with adapting to the environment. Living things adapt when environmental conditions change. This is not an immediate reaction, like running away, but rather takes a lot of time. Evolution is the result of random mutations in DNA that produce favorable traits in an organism. If the environment has change such that the trait is useful, that organism has an advantage over one that does not have the trait. When that organism reproduces, it will pass along the favorable trait to its offspring. Over time, the entire population will have that trait.

Finally, all living things have a universal genetic code. This means that they all have DNA inside of them that produces their traits. This DNA is the same regardless of into which organism one looks. A mushroom's DNA will have the same structure as that of a tiger shark. It is the sequence of the nitrogen bases in the DNA that makes these creates, and all creatures unique. However, every one of them still has the same four nitrogen bases.

There are some scientists who classify viruses as living things. After a virus is able to reproduce (that is how it infects a cell) and evolve (this is why you need to get a flu shot every year). They may also have DNA or RNA and respond to stimuli (many viruses are temperature sensitive). However, since they do not use energy nor are they made of cells, they cannot be classified as living things. The diagram below shows the anatomy of a virus. The main "head" of the virus is called a capsid. This is where it stores its genetic material.

Common Virus
Grade 10 Main Idea CCSS: CCRA.R.2, RI.9-10.2, RST.9-10.2
What is the main idea of the passage?
  1. Living and non-living organisms are a lot alike.
  2. All living things share a set of characteristics.
  3. All living things use energy.
  4. Living and non-living organisms work together.
Grade 10 Supporting Details CCSS: CCRA.R.5, RI.9-10.5, RST.9-10.5
The author includes the example of poking a dog with a stick. The author includes this example to show:
  1. the process of reproduction.
  2. the difference between living and nonliving organisms.
  3. why dogs are considered alive.
  4. how living things respond to stimuli.
Grade 10 Compare and Contrast CCSS: CCRA.R.3, RI.9-10.3, RST.9-10.3
Based on the information in the passage, what do a mushroom and a tiger shark have in common?
  1. the same ancestors
  2. the same habitat
  3. the same DNA structure
  4. the same reproductive cycle
Grade 10 Compare and Contrast CCSS: CCRA.R.3, RI.9-10.3, RST.9-10.3
Based on the information in the passage, how do higher organisms differ most from other living organism?
  1. They have organs and organ structures.
  2. They produce similar organisms.
  3. They respond to environmental conditions.
  4. They have a universal genetic code.