Cells, Ecosystems, and Chemical Reactions

Which structure in a plant or animal cell controls what enters and exits the cell, acting as a selective barrier?

• Cell wall

• Nucleus

• Cell membrane

• Vacuole

Answer explanation

The cell membrane, also known as the plasma membrane, regulates what enters and exits the cell, acting as a selective barrier. It is crucial for maintaining homeostasis in both plant and animal cells.

Tags

NGSS.MS-LS1-2

A student observes two ecosystems: one with 50 different species of plants and animals, and another with only 5 species. A disease wipes out one species in each ecosystem. Which statement best describes the likely outcome?

• Both ecosystems will be equally affected because losing one species has the same impact in any ecosystem.

• The ecosystem with 50 species will be more stable because other species can fill the role of the lost species.

• The ecosystem with 5 species will recover faster because fewer species means less competition.

• The ecosystem with 50 species will collapse because more species means more interdependence.

Answer explanation

The ecosystem with 50 species is more stable because it has greater biodiversity. If one species is lost, others can often fulfill similar roles, maintaining ecosystem balance, unlike the less diverse ecosystem with only 5 species.

Tags

NGSS.MS-LS2-4

NGSS.MS-LS2-1

NGSS.MS-LS2-2

• Carbon, Hydrogen, Oxygen, and Nitrogen

• Carbon, Hydrogen, and Oxygen only

• Carbon, Oxygen, and Sulfur only

• Hydrogen, Oxygen, and Nitrogen only

Answer explanation

The burning of methane involves carbon (C) from CH4, hydrogen (H) from CH4, and oxygen (O) from O2. Nitrogen and sulfur are not present in the reaction, making 'Carbon, Hydrogen, and Oxygen only' the correct choice.

Tags

NGSS.MS-PS1-1

In a chemical reaction, a student starts with 48 grams of reactants. According to the law of conservation of mass, what should be the total mass of the products?

• Less than 48 grams, because energy is released during the reaction

• More than 48 grams, because new atoms are created

• 48 grams, because atoms are rearranged but not created or destroyed

• It depends on the type of chemical reaction

Answer explanation

According to the law of conservation of mass, the total mass of the products must equal the total mass of the reactants. Therefore, with 48 grams of reactants, the products will also have a mass of 48 grams, as atoms are rearranged but not created or destroyed.

Tags

NGSS.MS-PS1-5

Which of the following best describes how energy from the Sun influences weather patterns on Earth?

• The Sun heats Earth's surface unevenly, causing differences in air pressure that drive wind and weather patterns.

• The Sun directly heats the atmosphere, which then heats the oceans and land.

• The Sun's energy is absorbed equally by all parts of Earth, creating stable weather patterns.

• The Sun only affects weather in tropical regions near the equator.

Answer explanation

The correct choice explains that the Sun heats Earth's surface unevenly, leading to variations in air pressure. These differences drive wind and weather patterns, influencing climate globally.

Tags

NGSS.MS-ESS2-5

NGSS.MS-ESS2-6

A student is examining a plant cell under a microscope and notices a rigid outer layer surrounding the cell membrane. What is the function of this structure?

• It controls which substances enter and exit the cell.

• It provides support and protection, helping the cell maintain its shape.

• It produces energy for the cell through cellular respiration.

• It stores water and nutrients for the cell.

Answer explanation

The rigid outer layer is the cell wall, which provides support and protection, helping the plant cell maintain its shape. This distinguishes it from the cell membrane, which controls substance movement.

Tags

NGSS.MS-LS1-2

A coral reef ecosystem contains hundreds of species of fish, coral, algae, and invertebrates. If a disease kills off most of the coral, which statement best explains how biodiversity affects the reef's ability to recover?

• High biodiversity means the reef cannot recover because too many species depend on coral.

• High biodiversity allows the reef to recover more quickly because many species interact and support ecosystem functions.

• Biodiversity has no effect on the reef's ability to recover from disease.

• Low biodiversity would help the reef recover faster because there would be less competition for resources.

Answer explanation

High biodiversity enhances the reef's recovery by ensuring that various species can interact and fulfill essential ecosystem roles, promoting resilience and faster recovery after coral loss.

Tags

NGSS.MS-LS2-4

NGSS.MS-LS2-5

• Hydrogen and Nitrogen

• Helium and Oxygen

• Hydrogen and Oxygen

• Hydrogen, Oxygen, and Carbon

Answer explanation

The reaction shows 2H2 and O2 producing 2H2O. The elements involved are hydrogen (H) and oxygen (O), making the correct choice 'Hydrogen and Oxygen'. Other options include incorrect elements.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-1

• The number of molecules on both sides of the equation is equal.

• The total number of each type of atom on the reactant side equals the total number of each type of atom on the product side.

• The products weigh more than the reactants because glucose is a large molecule.

• New carbon atoms are created during photosynthesis to form glucose.

Answer explanation

The correct choice highlights that the total number of each type of atom is conserved in the reaction. This demonstrates conservation of mass, as atoms are neither created nor destroyed during photosynthesis.

Tags

NGSS.MS-PS1-5

NGSS.MS-LS1-6

Which organelle in a plant cell is responsible for capturing sunlight and converting it into chemical energy through photosynthesis?

• Mitochondria

• Ribosome

• Vacuole

• Chloroplast

Answer explanation

The chloroplast is the organelle in plant cells that captures sunlight and converts it into chemical energy through photosynthesis, making it essential for plant growth and energy production.

Tags

NGSS.MS-LS1-6