Life Science - 8th Grade - Chapter 4-6 Review

The correct answer is Compound Microscope. A compound microscope is an instrument used to magnify small objects that cannot be seen with the naked eye. It consists of two or more lenses that work together to provide a high level of magnification. This instrument is commonly used in scientific research, education, and medical laboratories to study and analyze microscopic specimens.

The symbol for oxygen is O. The symbol represents the chemical element oxygen in the periodic table. Each element is assigned a unique symbol, typically derived from its English or Latin name. In the case of oxygen, the symbol O is used to represent it in chemical formulas and equations.

A thermometer measures temperature.

Protons, electrons, and neutrons are all part of the structure of an atom. Protons are positively charged particles found in the nucleus of an atom, while electrons are negatively charged particles that orbit around the nucleus. Neutrons are neutral particles also found in the nucleus. However, "hydrons" and "cyclons" are not part of the structure of an atom and are not recognized particles in atomic theory.

Weight is the downward force experienced by an object due to the gravitational pull of the Earth or any other celestial body. It is a measure of the mass of an object and the acceleration due to gravity. The greater the mass of an object, the greater its weight will be. Therefore, weight is a result of the gravitational force acting on an object and is always directed towards the center of the Earth. Hence, the statement "Weight is the downward force of an object due to gravity" is true.

The Bunsen Burner is a common laboratory tool used to provide heat. It consists of a gas burner with an adjustable flame, which can be used for various purposes such as heating solutions, sterilizing equipment, or conducting chemical reactions. The burner is connected to a gas source and can be adjusted to control the intensity of the flame. Therefore, the correct answer is that the Bunsen Burner is used to provide heat in laboratories.

The symbol "Fe" is used to represent the chemical element iron. Each chemical element has a unique symbol, and in this case, "Fe" specifically refers to iron. Zinc, phosphorous, and iodine have different symbols (Zn, P, and I, respectively), so they are not the correct answers for the given symbol "Fe".

Mitochondrion is the organelle responsible for producing energy in a cell through a process called cellular respiration. It is often referred to as the "powerhouse" of the cell because it generates the majority of the cell's adenosine triphosphate (ATP), which is the molecule that provides energy for cellular activities. The mitochondrion contains enzymes and other molecules that facilitate the breakdown of glucose and other nutrients, releasing energy in the form of ATP.

This statement is true because an atom is indeed the smallest unit of an element that retains all the chemical properties of that element. Atoms are made up of subatomic particles such as protons, neutrons, and electrons, and they combine to form molecules. Each element has its own unique type of atom, and the properties of an element are determined by the arrangement and behavior of its atoms. Therefore, an atom can be considered as the fundamental building block of matter and the smallest entity that still exhibits the characteristic properties of an element.

Weight is the downward force of an object due to gravity.
Mass is the amount of matter in an object.

Semipermeable refers to a property of a membrane or material that allows certain molecules or substances to pass through while blocking others. It implies that the membrane or material has selective permeability, meaning it can be penetrated by some molecules but not by others. This allows for the regulation of the movement of substances across the membrane, maintaining a balance and preventing the passage of unwanted or harmful molecules.

A carefully marked tube of glass or plastic that is used to determine the volume of a liquid is called a graduated cylinder. This device is specifically designed to measure the volume of liquids accurately. It has markings along its length that indicate the volume of the liquid it contains. By carefully reading the level of the liquid against these markings, one can determine the volume with precision. The other options listed, such as compound microscope, compound cylinder, graduated microscope, granulated cylinder, and Bunsen Burner, are not relevant to measuring liquid volume.

An atom is the smallest part of an element with all the properties of the element.

A molecule is indeed the smallest part of a compound that retains all the properties of that compound. This means that if you were to break down a compound into its smallest units, which are molecules, each molecule would still possess all the characteristics and properties of the original compound. Therefore, the statement "An molecule is the smallest part of a compound with all the properties of the compound" is true.

Osmosis is the process of diffusion of water through a cell membrane. This means that water molecules move from an area of higher concentration to an area of lower concentration across a semipermeable membrane. Osmosis plays a crucial role in maintaining the balance of water and solutes inside and outside the cell. It allows cells to regulate their internal environment and ensure proper functioning.

The eyepiece, objective lens, stage, arm and nose piece are all parts of the compound microscope. A rider is part of a balance.

The elements in the given options are hydrogen, oxygen, sulfur, and carbon. Elements are substances that cannot be broken down into simpler substances by chemical means. Hydrogen, oxygen, sulfur, and carbon are all examples of elements because they consist of only one type of atom and cannot be further broken down into simpler substances.

Neutrons do not have a charge because they are electrically neutral particles. Protons have a positive charge because they carry a positive electrical charge. Electrons have a negative charge because they carry a negative electrical charge.

Weight is the downward force of an object due to gravity.
Mass is the amount of matter in an object.

Chromosomes are long thread-like chemicals that contain the instructions for the cell. They carry the genetic information in the form of DNA and play a crucial role in the transmission of hereditary traits from one generation to another. Chromosomes are located in the nucleus of a cell and are responsible for controlling the cell's activities and determining its characteristics.

The symbol "Na" corresponds to the chemical element sodium. Sodium is a highly reactive alkali metal that is commonly found in table salt and various other compounds. It is known for its silver-white color and its ability to conduct electricity. Sodium plays a crucial role in various biological processes and is essential for maintaining fluid balance in the body.

The answer to the question is 80, eighty, 80%, or eighty percent. This is because approximately 60% of the human body is made up of water. Therefore, 80 or eighty is the correct answer as it represents 80% of the body weight being water.

All living things are made up of one or more cells. An example of a single cell organism is bacteria.

The statement "Protoplasm is a cell wall" is incorrect. Protoplasm refers to the living content within a cell, which includes the cytoplasm and nucleus. It is not the same as a cell wall, which is a rigid layer found in plant cells that provides support and protection. Therefore, the correct answer is False.

The correct answer is K because K is the chemical symbol for potassium. Chemical symbols are used to represent elements in the periodic table, and K is the symbol specifically assigned to potassium.

The correct answer is "dense center region." The nucleus of an atom is a small, dense region located at the center of the atom. It contains positively charged protons and neutral neutrons, which together make up the majority of the atom's mass. The electrons, which are negatively charged, orbit around the nucleus in specific energy levels. The dense center region of the nucleus is responsible for holding the protons and neutrons together through the strong nuclear force.

Protoplasm is living matter because it is the living substance that makes up the cells of organisms. It contains various organic and inorganic compounds, such as proteins, nucleic acids, and water, which are essential for the functioning and survival of cells. Protoplasm is responsible for carrying out all the vital processes of life, including metabolism, growth, and reproduction. Therefore, it can be concluded that protoplasm is indeed living matter.

Atoms are composed of a nucleus, which contains protons and neutrons, and electrons that orbit around the nucleus. The nucleus makes up a very small fraction of the atom's total volume, while the rest of the space within the atom is mostly empty. Therefore, atoms are mostly made up of empty space.

An element is a simple substance that cannot be broken down by ordinary chemical means. This means that elements are made up of only one type of atom and cannot be further divided into simpler substances through chemical reactions.

All living things are made up of one or more cells. An example of a single cell organism is bacteria.

A molecule is the smallest part of a compound with all the properties of the compound

A neutron is the smallest among the given options. Neutrons are subatomic particles that have no electric charge and are found in the nucleus of an atom. Nucleus refers to the central part of an atom that contains protons and neutrons, making it larger than a neutron. A molecule, on the other hand, consists of two or more atoms bonded together, making it larger than both a neutron and a nucleus. Therefore, the smallest option is a neutron.

The vacuole is usually large in plant cells but small in animal cells. Plant cells have a central vacuole that takes up a significant portion of the cell's volume. This vacuole is responsible for storing water, nutrients, and waste products. In contrast, animal cells have smaller, multiple vacuoles that serve various functions but do not take up as much space as the central vacuole in plant cells.

The diaphragm is the part of the compound microscope that allows you to reduce the light. By adjusting the diaphragm, you can control the amount of light that passes through the specimen. This is important because bright light can scare away many microbes, so reducing the light can help to keep them in place for observation.

The electron is the smallest among the given options. Neutrons and atoms are composed of protons, neutrons, and electrons, but electrons have the smallest mass. Electrons are negatively charged subatomic particles that orbit the nucleus of an atom. They have a mass of approximately 1/1836th the mass of a proton or neutron, making them significantly smaller in size.

It is used to view very small objects, not to measure them.

The statement suggests that there are more than a certain number of kinds of atoms. Out of the given options, 100 is the highest number, indicating that there are more than 100 kinds of atoms.

The nucleus is the smallest among the given options. An atom consists of a nucleus, which contains protons and neutrons, surrounded by electrons. A molecule, on the other hand, is made up of two or more atoms bonded together. Since the nucleus is a part of an atom and a molecule consists of multiple atoms, the nucleus is the smallest component among the three options.

The triple beam balance is also called the pan balance and they both measure the mass of an object.

A molecule is an individual piece of a compound. This means that a molecule is made up of two or more atoms that are chemically bonded together. It is the smallest unit of a compound that retains all the chemical properties of that compound.

Compounds are substances that are made up of two or more elements chemically combined in a fixed ratio. Seawater is a compound because it is a mixture of water and various dissolved salts. Plasma is a compound because it is a mixture of ionized particles. Protoplasm is a compound because it is the living material within a cell, composed of various organic and inorganic substances. Air is a compound because it is a mixture of gases, including oxygen, nitrogen, and carbon dioxide.

Oxygen is the most abundant element in the human body. It makes up about 65% of our body weight. Oxygen is essential for various biological processes, including respiration, where it is used to produce energy. It is also a key component of water and many organic molecules in our body. While water is also abundant, it is composed of oxygen and hydrogen atoms, so oxygen is still the most abundant element on its own. Hydrogen and sodium are present in smaller quantities in the body.

The correct answer is "lyosome" because lysosomes are organelles that contain enzymes responsible for breaking down food molecules. They are involved in digestion and waste removal within the cell. Lysosomes fuse with food vacuoles and release digestive enzymes to break down the food into smaller molecules that can be used by the cell for energy or other purposes. Therefore, the area where food molecules are broken down is the lysosome.

A single drop of water contains a large number of atoms due to the small size of the atoms and the high density of water molecules. The answer of 15 billion trillion suggests an extremely large number of atoms, which is plausible considering the vast number of molecules present in even a small volume of water.