Answer:
plasma membrane
Explanation:
The plasma membrane is also known as the cell membrane. It is the boundary between the internal components of a cell and its external surroundings. It controls the entry and exit of substances into or out of the cell and thus, facilitates the exchange of substances between the cells and their external environment.
Complete question:
A student is working on a lab where they are trying to identify an unknown substance. The student decides to smell the solution by taking a big breath over the test tube. They immediately start to cough and their lungs are burning.
Answer and Explanation:
Many chemicals might be recognized by their smell. Some of them might be inoffensive, some others might cause slight damage and some others might be very harmful to the person that inhales them.
In the exposed example, the solution probably damaged the respiratory tract, causing inflammation and irritation.
There are some issues to take into account to avoid an accident by inhaling a chemical:
<u>Precaution</u>:
- Study the security rules of the laboratory
- Always read the label of the substance
- Ask the teacher or the person in charge, about the correct procedure
- Proceed in the correct way, by driving the smelly vapors with your hand toward your nose. Never breathe directly over the test tube.
In case of accidents by inhaling you should:
<u>Response:</u>
- Take the affected person out of the laboratory
- Look for an airy place where the affected person might breath
- Call an emergency service
- Explain exactly what the affected person did and the chemicals that the person inhaled.
The answer is True
Explanation:
A DNA molecule consists of two long polynucleotide chains composed of four types of nucleotide subunits.
The isotope has a half-life of 5730 years.
In 5730 years, the isotope (Carbon-14, to be more exact) will lose 50% of its mass, meaning that in 11460 years, 25 grams of Carbon-14 will remain.
