Question

You are working as an astrobiologist for NASA and are asked to analyze the first ever samples returned to Earth from Mars. How would you recognize if organic molecules were present in the samples? A. Test for isotopes of carbon B. Look for the presence of hydrogen bonds C. Search for chemicals with carbon to hydrogen bonds D. Analyze the percentage of molecules with covalent bonds E. Measure the \(\mathrm{pH}\) of the samples

Short answer

C. Search for chemicals with carbon to hydrogen bonds

Step-by-step solution

Identify the defining feature of organic molecules

Organic molecules are primarily characterized by the presence of carbon atoms bonded to hydrogen atoms (C-H bonds).

Assess the given options

Review each option to determine which method would be the most effective in identifying organic molecules based on the defining feature.

Evaluate Option A

Testing for isotopes of carbon can indicate the presence of carbon, but it doesn't specifically identify organic molecules because it does not focus on C-H bonds.

Evaluate Option B

Looking for hydrogen bonds can suggest the presence of water or other molecules, but it is not specific to organic molecules.

Evaluate Option C

Searching for chemicals with carbon to hydrogen bonds (C-H bonds) is a direct method to identify organic molecules, as it focuses on their defining characteristic.

Evaluate Option D

Analyzing the percentage of molecules with covalent bonds is not specific enough, as many inorganic molecules also have covalent bonds.

Evaluate Option E

Measuring the \( \mathrm{pH} \) of the samples provides information about the acidity or basicity but does not directly indicate the presence of organic molecules.

Select the best option

Based on the evaluations, option C is the most effective method to recognize the presence of organic molecules.

Key concepts

carbon-hydrogen bonds

Carbon-hydrogen bonds (C-H bonds) are the hallmark of organic molecules. These bonds form when a carbon atom shares electrons with a hydrogen atom, creating a covalent bond. The presence of C-H bonds indicates the molecule is organic. Organic molecules are essential for life because they form the basis of carbohydrates, proteins, lipids, and other biological molecules. By identifying these bonds, scientists can determine if biological processes might have occurred in a given sample.

Mars sample analysis

Analyzing samples from Mars involves several steps to look for signs of past or present life. Here are some key methods:

• **Chemical Analysis:** Checking for organic molecules and specific markers like C-H bonds.
• **Isotope Analysis:** Evaluating stable carbon isotopes to understand any biological activity.
• **Microscopy:** Looking for microfossils or structures resembling cells.

These techniques help scientists understand Mars' potential to support life. The methods employed aim to detect organic molecules, among other biomarkers.

organic molecule characteristics

Organic molecules have distinct features:

• **Carbon-Based:** Contain carbon atoms, often bonded to hydrogen, forming the core of the molecule.
• **Variety of Structures:** Can be simple like methane (CH4) or complex like DNA.
• **Functional Groups:** May have diverse functional groups (e.g., hydroxyl, carboxyl) influencing their properties and reactions.

These characteristics enable organic molecules to perform crucial biological roles, from energy storage (like glucose) to coding genetic information (DNA/RNA).

astrobiology methods

Astrobiology integrates various methods to search for life beyond Earth. Some key approaches include:

• **Spectroscopy:** Analyzing light spectra from distant planets to identify chemicals present.
• **Robotic Missions:** Sending spacecraft to collect samples and perform in-situ analysis.
• **Remote Sensing:** Instrumental observations of planetary atmospheres for biosignatures like methane.

Astrobiologists look for organic molecules, water, and other life-supporting conditions. By understanding life's fundamental components, scientists develop strategies to detect life on other planets.