Grade 9 Science Final Review

Organisms that obtain their energy and nutrients by breaking down dead organic matter, such as plants and animals, and waste products.

Decomposers are vital to ecosystems because they recycle nutrients back into the environment, making them available to producers.

If the mouse population were to be wiped out, the snake and hawk populations would also decline due to a lack of food sources.

Both photosynthesis and cellular respiration involve the exchange of energy and play crucial roles in the energy cycle of living organisms. They both involve glucose and oxygen as inputs or outputs.

Photosynthesis occurs in plants, algae, and some bacteria, while cellular respiration occurs in all living organisms. Photosynthesis stores energy by converting light energy into glucose, while cellular respiration releases energy by breaking down glucose.

The interaction between a hawk and a snake is predation. Predation occurs when one organism (the predator) benefits by consuming another organism (the prey).

The carbon cycle is a continuous cycle of carbon movement through Earth's systems, including the atmosphere, biosphere, geosphere, and hydrosphere. It involves processes like photosynthesis, respiration, decomposition, and combustion.

The nitrogen cycle is a continuous cycle of nitrogen movement through Earth's systems, including the atmosphere, biosphere, geosphere, and hydrosphere. It involves processes like nitrogen fixation, nitrification, denitrification, and ammonification.

A substance's characteristics that can be observed or measured without changing its chemical composition.

A substance's characteristics that can only be observed when it undergoes a chemical change, resulting in a new substance.

Transformations that alter the physical appearance of a substance but not its chemical composition.

Transformations that result in the formation of a new substance with different chemical properties.

A model that explains the behavior of matter based on the idea that matter is made of tiny particles in constant motion.

A substance composed of only one type of atom. Examples include gold, silver, and oxygen.

A substance composed of two or more elements chemically combined in a fixed ratio. Examples include water (H2O), salt (NaCl), and sugar (C12H22O11).

A mixture that has a uniform composition and properties throughout. Examples include saltwater, air, and sugar dissolved in water.

A mixture that has a non-uniform composition and properties. Examples include sand and water, oil and water, and a salad.

A measure of how much mass is contained in a given volume. It is calculated by dividing the mass of an object by its volume.

The smallest unit of an element that retains the chemical properties of that element. It is composed of a positively charged nucleus containing protons and neutrons, surrounded by negatively charged electrons in orbitals.

The number of protons in the nucleus of an atom, which determines the element's identity.

A subatomic particle that carries a positive charge and resides in the nucleus of an atom. It contributes to the atom's atomic number.

Isotopes are atoms of the same element with different numbers of neutrons, leading to variations in atomic mass. For example, carbon-12, carbon-13, and carbon-14 are isotopes of carbon.

A subatomic particle that carries no charge (neutral) and resides in the nucleus of an atom. It contributes to the atom's mass number.

A negatively charged subatomic particle that orbits the nucleus of an atom in specific energy levels or shells. It determines the atom's chemical reactivity.

Fossil fuels, formed from ancient organic matter, have a distinct isotopic signature with low carbon-14 due to its radioactive decay. This signature is consistent with the increased CO₂ in the atmosphere, indicating that the extra carbon is from fossil fuels.

The total number of protons and neutrons present in the nucleus of an atom. It determines the atom's mass.

The greenhouse effect is the warming of Earth's surface due to heat-trapping gases like CO₂ in the atmosphere. Increased CO₂ levels enhance the greenhouse effect, leading to higher global temperatures.

The increased CO₂ levels in the atmosphere, primarily from fossil fuels, significantly contribute to the enhanced greenhouse effect, leading to global warming and climate change.

Elements arranged in order of increasing atomic number, organized by the number of valence electrons and similar chemical properties. They are grouped into columns (groups/families) and rows (periods).

The outermost electron shell of an atom. Electrons in this shell determine the atom's reactivity and the types of bonds it can form.

The abundance of CO₂ in the atmosphere is a strong indicator of global warming. The data shows that the hottest years on record have occurred in recent decades, highlighting the impact of increased CO₂ levels.

A temporary charge is created when an object is brought near another charged object, causing a redistribution of charges within the object. The charges only last as long as the charged object is nearby.

In a parallel circuit, each component has its own separate path for current flow. If one component fails, the others continue to operate normally.

In a series circuit, all components are connected in a single path, so current flows through each component sequentially. If one component fails, the entire circuit breaks.

Conductors allow electrons to move freely, enabling the flow of electricity. Metals are good conductors due to their loosely bound electrons. Insulators restrict electron flow, hindering the passage of electricity. Nonmetals typically act as insulators.

In a parallel circuit, adding components does not affect the brightness of existing light bulbs. The voltage across each component remains the same. Therefore, the brightness of the bulbs won't change.

In a parallel circuit, the voltage measured across each light bulb is equal to the total voltage supplied by the battery. This occurs because each path in a parallel circuit has the full voltage of the battery.

By carefully placing the switch before a specific light bulb, you can create a branch where only that light bulb is turned off. The other bulbs will continue to receive power as they are on separate paths.

In a parallel circuit, each component experiences the same voltage as the battery. Therefore, the voltage across each light bulb in the given circuit is 240V.