Chapter 7 & 8 Biology

Atoms of the same element with different numbers of neutrons are called isotopes. Isotopes have the same number of protons and electrons, but differ in the number of neutrons. This difference in neutron number leads to variations in the atomic mass of isotopes. Isotopes can have different physical and chemical properties due to their varying atomic masses, but they still belong to the same element because they have the same number of protons.

Atoms of 2 or more elements chemically combined are compounds. Compounds are formed when atoms of different elements combine together through chemical bonds. In a compound, the atoms are held together by strong forces, resulting in a new substance with unique properties. Mixtures, on the other hand, are formed when substances are combined without any chemical bonding, and the components can be separated physically. Hence, compounds are the correct answer in this case.

A neutron has no charge because it is made up of neutral particles called neutrons. Neutrons do not have any positive or negative charge, which means they are electrically neutral. Unlike protons, which have a positive charge, and electrons, which have a negative charge, neutrons do not interact with electric fields. This lack of charge allows neutrons to freely move within the nucleus of an atom without being repelled or attracted by other charged particles.

The center of an atom is called the nucleus. The nucleus is a small, dense region located at the center of an atom. It contains positively charged particles called protons and neutral particles called neutrons. The nucleus is surrounded by a cloud of negatively charged particles called electrons. The nucleus is responsible for holding the atom together and determining its properties, such as its atomic number and mass.

An acid is defined as a substance that forms hydrogen ions (H+) when dissolved in water. These hydrogen ions are responsible for the acidic properties of the substance. Therefore, any substance that forms hydrogen ions in water is considered an acid.

When two atoms share electrons, they form a covalent bond. In a covalent bond, the shared electrons are attracted to the positive nuclei of both atoms, creating a strong bond that holds the atoms together. This type of bond occurs between nonmetal atoms, where they have similar electronegativity values and can share electrons to achieve a stable electron configuration. Ionic bonds, on the other hand, involve the complete transfer of electrons from one atom to another, resulting in the attraction between oppositely charged ions.

The given answer is true because biology can be a fun subject for many people. It involves studying and understanding living organisms, their structures, functions, and interactions with the environment. Exploring the diversity of life, learning about the intricate processes that occur within organisms, and discovering how living things adapt and evolve can be fascinating and enjoyable. Additionally, biology offers opportunities for hands-on experiments, fieldwork, and exploring the wonders of the natural world, making it an engaging and exciting subject for those interested in life sciences.

Carbon-12 and Carbon-14 are isotopes because they have the same number of protons (6) but different numbers of neutrons (6 and 8 respectively). Isotopes of an element have the same atomic number but different atomic masses. In the case of carbon, the atomic number is always 6, but the atomic mass can vary depending on the number of neutrons.

A very strong base would have a high concentration of hydroxide ions (OH-) which would result in a high pH value. The pH scale ranges from 0 to 14, with values below 7 being acidic, 7 being neutral, and values above 7 being basic. Therefore, a pH of 13 indicates that the solution is highly basic, making it a plausible explanation for a very strong base.

The correct answer is ER, E.R., endoplasmic reticulum. The endoplasmic reticulum (ER) is a folded membrane that forms a network of interconnected compartments in the cytoplasm of eukaryotic cells. It plays a crucial role in protein synthesis, lipid metabolism, and the transportation of molecules within the cell. The ER is involved in the production of proteins and lipids, as well as the detoxification of drugs and toxins. It is an essential organelle for the proper functioning of the cell.

Ribosomes are the sites of protein assembly in a cell. They are responsible for translating the genetic information from mRNA into a sequence of amino acids, which then fold into a functional protein. Ribosomes are found in the cytoplasm of the cell, where they can freely move and interact with other cellular components. The cytoplasm provides the necessary environment for protein synthesis to occur efficiently. Therefore, ribosomes and cytoplasm are the correct answers for the sites of protein assembly.

Eukaryotic cells do have a true nucleus. Unlike prokaryotic cells, which lack a nucleus, eukaryotic cells have a membrane-bound nucleus that contains the cell's genetic material. The nucleus is responsible for controlling the cell's activities and storing the DNA. Therefore, the given statement is incorrect.

A vacuole is a membrane-bound fluid-filled sac found in the cells of plants, fungi, and some protists. It is responsible for various functions such as storing water, nutrients, and waste products. Vacuoles also help maintain the cell's shape and regulate the internal pressure. They can be large and central in plant cells, providing structural support and storing water, or smaller and multiple in animal cells, performing various functions depending on the cell type. Overall, a vacuole is an essential organelle involved in maintaining cell homeostasis and performing storage functions.

Plastids are plant organelles that store starches or lipids and contain pigments. They are responsible for various functions such as photosynthesis, storage of nutrients, and pigment synthesis. Plastids include chloroplasts, which are responsible for photosynthesis and contain the pigment chlorophyll, as well as other types of plastids such as chromoplasts (store pigments other than chlorophyll) and amyloplasts (store starch). Therefore, the correct answer is plastids.

The golgi apparatus, also known as the golgi body, is made up of closely stacked, flattened membrane sacs. This organelle is responsible for modifying, sorting, and packaging proteins and lipids for transport to their final destinations within the cell or for secretion outside of the cell. The flattened sacs, called cisternae, allow for efficient processing and sorting of molecules as they move through the golgi apparatus.