characteristics of life
read article: 1.4 characteristics of life https://flexbooks.ck12.org/book/ck-12-biology-flexbook/2.0/section/1.4/primary/lesson/characteristics-of-life-bio/
summarize the article in 2-3 academic sentences (using your own words).
answer the following questions based on the the reading material.
1. list and describe the 6 characteristics of life.
i.
ii.
iii.
iv.
v.
vi.
2. refer to the information provided in the article to explain what homeostasis is.

3. what is a cell?

4. assume that you found an object that looks like a dead twig. you wonder if it might be a stick insect. how could you determine if it is a living thing?

5. read the “did you know” blub. explain why a virus is not considered a living thing.

Question

characteristics of life
read article: 1.4 characteristics of life https://flexbooks.ck12.org/book/ck-12-biology-flexbook/2.0/section/1.4/primary/lesson/characteristics-of-life-bio/
summarize the article in 2-3 academic sentences (using your own words).
answer the following questions based on the the reading material.
1. list and describe the 6 characteristics of life.
   i.
   ii.
   iii.
   iv.
   v.
   vi.
2. refer to the information provided in the article to explain what homeostasis is.

3. what is a cell?

4. assume that you found an object that looks like a dead twig. you wonder if it might be a stick insect. how could you determine if it is a living thing?

5. read the “did you know” blub. explain why a virus is not considered a living thing.

Accepted Answer

### Question 1: List and describe the 6 characteristics of life (assuming the standard 6 characteristics from biology)
# Brief Explanations:
1. **Made of Cells**: All living things are composed of one or more cells. Unicellular organisms have a single cell, while multicellular organisms have many cells with specialized functions.
2. **Reproduction**: Living organisms can produce offspring. Sexual reproduction involves two parents, while asexual reproduction (like binary fission in bacteria) involves one parent.
3. **Growth and Development**: Organisms grow (increase in size/number of cells) and develop (change in form/function over time, e.g., a tadpole becoming a frog).
4. **Obtain and Use Energy**: They take in energy (e.g., plants via photosynthesis, animals via eating) and use it for metabolic processes like respiration to sustain life.
5. **Respond to Stimuli**: Living things react to changes in their environment (stimuli), such as a plant bending toward light (phototropism) or an animal fleeing from danger.
6. **Maintain Homeostasis**: They regulate internal conditions (like body temperature in humans, water balance in plants) to stay stable despite external changes.

# Answer:
i. **Made of Cells**: All living organisms are composed of one or more cells, the basic unit of life. Unicellular organisms have a single cell, multicellular ones have specialized cells.
ii. **Reproduction**: Organisms produce offspring; sexual (two parents) or asexual (one parent) to pass on genetic material.
iii. **Growth and Development**: Organisms increase in size (growth) and undergo structural/functional changes (development) over their life cycle.
iv. **Obtain and Use Energy**: They acquire energy (e.g., photosynthesis, eating) and use it for metabolism (e.g., respiration) to power life processes.
v. **Respond to Stimuli**: Living things react to environmental changes (e.g., light, temperature, chemicals), like plants growing toward light.
vi. **Maintain Homeostasis**: They regulate internal conditions (e.g., body temperature, pH) to stay stable despite external fluctuations.

### Question 2: Explain what homeostasis is (based on the article’s context)
# Brief Explanations:
Homeostasis is the process by which living organisms maintain stable internal conditions (like temperature, water balance, or pH) even when external conditions change. For example, humans sweat to cool down and shiver to warm up, keeping body temperature near 37°C. Organisms use feedback mechanisms to detect and correct deviations from optimal internal states, ensuring survival and proper function.

# Answer:
Homeostasis is the ability of a living organism to maintain stable internal conditions (e.g., temperature, water levels, pH) despite changes in the external environment. Organisms use processes (e.g., sweating, shivering in animals; stomatal regulation in plants) to detect and correct deviations from optimal internal states, ensuring survival and proper physiological function.

### Question 3: What is a cell?
# Brief Explanations:
A cell is the basic structural and functional unit of all living organisms. It is the smallest entity that can perform all life processes (like metabolism, growth, response to stimuli). Cells can be prokaryotic (simple, no nucleus, e.g., bacteria) or eukaryotic (complex, with a nucleus and organelles, e.g., plant/animal cells). They are enclosed by a membrane and contain genetic material (DNA/RNA) to direct their activities.

# Answer:
A cell is the fundamental structural and functional unit of all living organisms. It is the smallest entity capable of performing all life processes (e.g., metabolism, growth, reproduction). Cells can be prokaryotic (simple, no nucleus, e.g., bacteria) or eukaryotic (complex, with a nucleus and organelles, e.g., plant/animal cells), enclosed by a membrane and containing genetic material (DNA/RNA) to regulate their activities.

### Question 4: Determine if an object (like a stick insect) is living
# Brief Explanations:
To determine if the object (stick insect) is living, observe if it exhibits the characteristics of life: 1) Check if it is made of cells (microscopic analysis, though not always feasible visually). 2) See if it responds to stimuli (e.g., touch it—does it move? Expose to light—does it react?). 3) Observe growth/development (over time, does it change size/shape? E.g., molt like insects do). 4) Check for energy use (does it eat? If it’s a stick insect, it might feed on plant matter). 5) Look for reproduction (over time, does it lay eggs or produce offspring?). 6) Check homeostasis (e.g., does it regulate water loss? Though harder to see visually). If it shows multiple of these (especially response to stimuli, growth, or energy use), it’s likely living.

# Answer:
To determine if the object (stick insect) is living, test for the characteristics of life:
- **Response to Stimuli**: Touch it (e.g., gently prod with a stick) or expose it to light/temperature changes—does it move, hide, or react?
- **Growth/Development**: Observe over time—does it change size, molt (shed its exoskeleton, typical of insects), or develop (e.g., from nymph to adult)?
- **Energy Use**: Check if it feeds (e.g., place plant matter near it—does it consume it? Stick insects eat leaves).
- **Reproduction**: Over time, does it lay eggs or produce offspring?
- **Cellular Structure**: (Microscopic) Check if it is made of cells (though not always practical visually).

If it exhibits multiple of these (e.g., reacts to touch, grows, feeds), it is a living thing (a stick insect, which is an insect and thus living).

### Question 5: Why a virus is not considered living (based on the “Did you know” blurb, assuming standard biology)
# Brief Explanations:
Viruses are not considered living because they lack key characteristics of life. They are not made of cells (they are acellular, consisting of genetic material and a protein coat). They cannot reproduce independently—they need to invade a host cell and use the host’s machinery to replicate. They do not perform metabolic processes (like obtaining energy or maintaining homeostasis) on their own. Outside a host, viruses are inert (like a chemical particle), only “activating” when infecting a cell. Since they fail to meet criteria like independent reproduction, cellular structure, and metabolic activity, they are non - living.

# Answer:
A virus is not considered living because it lacks key life characteristics:
- **No Cells**: Viruses are acellular (not made of cells), unlike all living organisms.
- **No Independent Reproduction**: They cannot replicate on their own—they must invade a host cell and hijack its machinery to make new viruses.
- **No Metabolic Processes**: Viruses do not obtain/use energy, grow, or maintain homeostasis independently (they are inert outside a host, acting like a chemical particle).

Since they fail to meet criteria like cellular structure, independent reproduction, and metabolic activity, viruses are classified as non - living.

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Question

Explanation:

Question 1: List and describe the 6 characteristics of life (assuming the standard 6 characteristics from biology)

Answer:

Question 2: Explain what homeostasis is (based on the article’s context)