When salt (NaCI) is added to water, it disassociates into Na and Cl-ions. Which of the following types of chemical bond is present in a salt molecule?
A. Covalent bond
B. Ionic bond
C. Hydrogen bond
D. Disulfide bond
i think its B
An example of active immunity is the transfer of
A. antibodies through the placenta.
B. immunoglobulins through breastfeeding.
C. antigens through vaccination.
D. immune cells through a blood transfusion.
i think its C
Which of the following is the pH when the concentrations of hydrogen ions and hydroxide ions in an aqueous solution are equal?
A. 14
B. 7
C. 1
D. 0
i think its B
Which of the following structures is present in both prokaryotic and eukaryotic cells?
A. Golgi apparatus
B. Cell membrane
C. Endoplasmic reticulum
D. Chloroplast
i think its B
Hydrogen Bond C
C antigens throug vaccination
7
Cell membrane
You are correct with your answers!
For the first question, when salt (NaCI) is dissolved in water, it disassociates into Na+ and Cl- ions. This indicates that an ionic bond is present in a salt molecule. Ionic bonds are formed by the complete transfer of electrons from one atom to another, resulting in the attraction between oppositely charged ions.
For the second question, active immunity refers to the immune response that occurs when the body is exposed to a foreign substance, such as a virus or bacteria, and develops immunity against it. Among the options given, the transfer of antigens through vaccination is an example of active immunity. Vaccines contain weakened or inactivated forms of pathogens or their components, which stimulate the immune system to produce an immune response, leading to the production of antibodies and memory cells that provide long-term protection.
Regarding the third question, the pH of a solution is a measure of its acidity or alkalinity. A pH value of 7 indicates a neutral solution, where the concentrations of hydrogen ions (H+) and hydroxide ions (OH-) are equal. Therefore, your answer of B, pH 7, is correct.
Lastly, the cell membrane is present in both prokaryotic and eukaryotic cells. The cell membrane is a thin, flexible barrier that surrounds the content of the cell, separating it from the external environment. It regulates the movement of substances in and out of the cell and provides protection. The other options listed, such as the Golgi apparatus, endoplasmic reticulum, and chloroplast, are structures found in eukaryotic cells but not prokaryotic cells.
Well done on your answers! If you have any further questions, feel free to ask.