What is the largest organ in the human body by surface area?

Chemical properties are characteristics of a substance that describe its ability to undergo a chemical change or reaction with another substance.

Reactivity with acid is a chemical property because it describes how a substance will react with an acid to produce a new substance. Density, melting point, and boiling point are physical properties that describe how a substance behaves under certain conditions but do not involve a chemical change or reaction.

Ribosomes are small, spherical structures found in all living cells, including bacteria, archaea, and eukaryotes. Their primary function is to synthesize proteins using the genetic information stored in the cell's DNA. Ribosomes are composed of two subunits, one large and one small, that come together during protein synthesis.

Ribosomes read the genetic information stored in mRNA (messenger RNA) and use this information to assemble amino acids in the correct order to form a protein. The ribosome moves along the mRNA, adding one amino acid at a time to the growing protein chain until it reaches the end of the mRNA and the protein is complete.

Proteins are essential for a wide variety of cellular functions, including catalyzing chemical reactions, providing structural support, and transporting molecules across cell membranes. Therefore, ribosomes play a critical role in the overall function and survival of a cell.

This reaction is exothermic (releases heat), as indicated by the presence of "Heat" on the product side (C + Heat). According to Le Chatelier's Principle, when the temperature of an exothermic reaction is increased, the equilibrium shifts to counteract the added heat by favoring the reverse reaction (where heat is absorbed).

• As a result, the system will shift towards the left (toward the reactants, A and B), to consume the excess heat.
• Therefore, the concentrations of A and B will increase, and the concentration of C will decrease.

The other options do not align with this behavior:

• A. Incorrect, as the concentration of C will change (decrease).
• B. Incorrect, the reaction will shift away from equilibrium due to the temperature change.
• C. Incorrect, the concentration of C will not increase; it will decrease.

The largest organ in the human body by surface area is the skin. It covers the entire external surface of the body and has an average surface area of about 20 square feet in adults.

Stomach acid is highly acidic, primarily composed of hydrochloric acid (HCl), which means it has a low pH (around 1 to 3). Acids release hydrogen ions (H⁺) in solution, which lowers the pH.

• A. It has a higher pH: Incorrect, as acidic solutions have a lower pH compared to neutral distilled water (which has a pH of 7).
• B. It contains nitrogen: Incorrect, stomach acid is composed mostly of HCl, not nitrogen-containing compounds.
• D. It has more hydroxyl ions: Incorrect, acidic solutions have fewer hydroxyl ions (OH⁻); hydroxyl ions are more common in basic (alkaline) solutions.

In comparison to distilled water, which is neutral, the stomach acid solution has significantly more hydrogen ions, making it more acidic.

The perineum is the region of the body located between the pubic symphysis (in the front) and the coccyx (in the back). It includes the areas surrounding the openings for the urinary, digestive, and reproductive systems, such as the urethra, anus, and, in females, the vaginal opening.

The other options describe different areas of the body:

• A. The area on the back between the neck and the two shoulder blades refers to the upper back and shoulder region, not the perineum.
• C. The area between the nipples on the chest and the belly button describes the mid-torso, not the perineum.
• D. The area between the edges of the eyes and the chin describes the face, not the perineum.

Innate immunity is the first line of defense against pathogens and is present at birth. It provides immediate, non-specific protection against a wide range of pathogens, including bacteria, viruses, and fungi. Innate immunity involves physical barriers, such as skin and mucous membranes, as well as cellular and molecular components, such as phagocytes and cytokines.

Adaptive immunity, on the other hand, is developed over time and provides specific protection against particular pathogens. It involves the recognition of antigens, which are specific components of pathogens, by immune cells called lymphocytes. The lymphocytes then produce antibodies that are specific to the antigens, allowing for a targeted response to the pathogen. This process takes time to develop, as the immune system needs to encounter the pathogen and mount a response.

Overall, innate immunity provides immediate, non-specific protection while adaptive immunity provides specific protection that is tailored to the particular pathogen. Both forms of immunity work together to protect the body against pathogens.

A frameshift mutation is a type of genetic mutation that involves the insertion or deletion of one or more nucleotides in a DNA sequence. This can cause a shift in the reading frame of the genetic code, resulting in a change in the amino acid sequence of the resulting protein. Frameshift mutations can have significant effects on the function of the protein and can lead to genetic disorders or diseases.

Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is also known as trisomy 21, because affected individuals have three copies of chromosome 21 instead of the normal two.

The extra chromosome 21 in Down syndrome occurs due to a random error in cell division, which leads to the production of an abnormal gamete (egg or sperm) with an extra copy of the chromosome. When this gamete fuses with a normal gamete during fertilization, the resulting zygote has 47 chromosomes instead of the usual 46, and develops into a fetus with Down syndrome.

Down syndrome is characterized by a range of physical and intellectual symptoms, including developmental delays, intellectual disability, distinctive facial features, heart defects, and increased risk of certain medical conditions such as leukemia and Alzheimer's disease. However, the severity and expression of these symptoms can vary widely among affected individuals.

The three major pairs of salivary glands are the parotid glands, sublingual glands, and submandibular glands.

• Parotid glands are located just in front of your ears.
• Sublingual glands are located below either side of your tongue, under the floor of your mouth.
• Submandibular glands are located below your jaw.