SOLUTION: Necessities of Life directed reading worksheet - Studypool - Free Printable

The worksheet you've uploaded is a Directed Reading B from the "Holt California Life Science" textbook, focusing on "The Necessities of Life." The student, Valentina Lopez, has completed most of the questions. Let's go through each question, evaluate the answers, and explain the correct solutions.

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Section: The Necessities of Life

#### 1. What are four basic needs of every organism?
> Student Answer: *The four basic needs of every organism are water, air, food, and a place to live.*

✔ Correct!
This is an accurate answer. All living organisms require:
- Water – for cellular processes and transport.
- Air (oxygen) – for respiration (in most organisms).
- Food – for energy and growth.
- A place to live (habitat) – to provide shelter and suitable conditions.

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WATER

#### 2. Cells of most living things are made of approximately
> Student Answer: d. 70% water

✔ Correct!
Most cells are composed of about 70% water, which is essential for dissolving substances, transporting nutrients, and maintaining cell structure.

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#### 3. Most of the chemical reactions involved in metabolism require
> Student Answer: c. water

✔ Correct!
Water acts as a solvent in metabolic reactions. It helps break down molecules (hydrolysis) and facilitates biochemical reactions inside cells.

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#### 4. About how long can humans survive without water?
> Student Answer: *You can only survive 3 days without water.*

✔ Correct!
On average, humans can survive about 3 days without water, though this varies depending on conditions like temperature and activity level. Water is vital for regulating body temperature, removing waste, and maintaining blood volume.

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AIR

#### 5. Air is mostly oxygen, nitrogen, and
> Student Answer: b. carbon dioxide

✘ Incorrect!
While carbon dioxide is present in air, it is not one of the main components.
The atmosphere is made up of:
- Nitrogen (~78%)
- Oxygen (~21%)
- Argon (~0.93%)
- Carbon dioxide (~0.04%)

So, the best answer should be carbon dioxide — but only if the question implies minor components. However, since the question says “mostly,” and lists oxygen and nitrogen (the two major gases), the third component should be something else.

But wait — none of the options are correct unless we consider that carbon dioxide is a trace gas. But let’s look at the choices:

a. butane – ✘ (not in air)
b. carbon dioxide – ✔ (present, but not "mostly")
c. kerosene – ✘ (not in air)
d. nitrogen dioxide – ✘ (trace pollutant)

👉 So, none of the options are ideal, but carbon dioxide (b) is the only actual component of air among the choices. However, this is misleading because air is mostly nitrogen and oxygen, with very little CO₂.

But given the context of a middle school science class, the intended answer is likely b. carbon dioxide, even though it's not accurate. Perhaps there was a typo or misunderstanding.

➡️ Best interpretation: Since the question says “air is mostly oxygen, nitrogen, and…” — it's implying a third component, but air is NOT mostly carbon dioxide. So the correct answer should be none of the above, but since carbon dioxide is the only plausible choice, b might be expected here, though it's scientifically inaccurate.

🔍 Conclusion: This question is poorly worded. Air is mostly oxygen and nitrogen, and carbon dioxide is a minor component. The answer should not be b.

But in many textbooks, they list CO₂ as a component of air, so perhaps the intent was to test recognition of CO₂ as a part of air.

So, if forced to choose, b. carbon dioxide is the best available option, even though it's not “mostly.”

⚠️ Note: This is a common misconception. Better phrasing would be: *"Which of the following is a component of air?"* Then b would be correct.

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#### 6. During what chemical process do most living things use oxygen?
> Student Answer: a. releasing energy from food

✔ Correct!
This refers to cellular respiration, where oxygen is used to break down glucose and release energy (ATP). The equation is:
> C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

So, oxygen is used to extract energy from food.

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✔ Summary of Answers:

| Question | Student Answer | Correct? | Explanation |
|--------|----------------|---------|------------|
| 1 | Water, air, food, place to live | ✔ Yes | Basic needs of life |
| 2 | d. 70% water | ✔ Yes | Cells are ~70% water |
| 3 | c. water | ✔ Yes | Water is key for metabolism |
| 4 | You can only survive 3 days without water | ✔ Yes | Average survival time |
| 5 | b. carbon dioxide | ⚠️ Debatable | Air is mostly O₂ and N₂; CO₂ is minor. But among choices, it's the only real component. Likely expected answer, though inaccurate. |
| 6 | a. releasing energy from food | ✔ Yes | Cellular respiration |

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Final Thoughts:

Valentina did very well on this worksheet! Only Question 5 is questionable due to poor wording. If the question had said “which of the following is found in air?” then b would be correct. But saying “air is mostly...” and listing CO₂ is misleading.

✔ Overall: Excellent work! Just a small note on Question 5 — it's better to understand that air is mostly nitrogen and oxygen, with tiny amounts of other gases like CO₂.

Let me know if you'd like a corrected version of the worksheet!