Connect 6-8 Bio

What is the ultimate source of energy for most biological systems on Earth?

• The Ocean

• Heat from the Earth's core

• The Sun

• Earth's daily rotations

Answer explanation

The ultimate source of energy for most biological systems on Earth is the Sun. It provides the light and heat necessary for photosynthesis, which is the foundation of the food chain and energy flow in ecosystems.

Tags

NGSS.HS-LS1-5

NGSS.HS-LS2-5

Energy is most conveniently measured by its conversion to:

• Speed

• Light

• Temperature

• Heat

Answer explanation

Energy is most conveniently measured by its conversion to heat, as it is a common form of energy transfer and can be easily quantified in various processes, unlike speed, light, or temperature.

Tags

NGSS.HS-PS3-4

The two main states of energy are:

• Kinetic energy and chemical energy

• Chemical energy and potential energy

• Kinetic energy and potential energy

• Heat and light energy

Answer explanation

The two main states of energy are kinetic energy, which is the energy of motion, and potential energy, which is stored energy based on position. Therefore, the correct answer is kinetic energy and potential energy.

Tags

NGSS.HS-PS3-3

Which of the following statements accurately describes the amount of potential energy in molecules?

• The oxidized form of a molecule contains more potential energy than its reduced form.

• The oxidized form of a molecule contains the same amount of potential energy as its reduced form.

• The reduced form of a molecule contains more potential energy than its oxidized form.

• Potential energy is only associated with the kinetic form of the molecule.

Answer explanation

The reduced form of a molecule has more potential energy because it contains more electrons and is less oxidized, making it a better energy source during metabolic processes.

Tags

NGSS.HS-PS1-4

An atom or molecule that gains an electron is said to be:

• Harvested

• Oxidized

• Carboxylated

• Reduced

Answer explanation

An atom or molecule that gains an electron undergoes reduction. This process decreases its oxidation state, making 'Reduced' the correct choice, while 'Oxidized' refers to losing electrons.

In a chemical reaction where an electron is transferred from molecule X to molecule Y, which molecule is oxidized?

• Y

• X

Answer explanation

In this reaction, molecule X loses an electron, which means it is oxidized. Oxidation is defined as the loss of electrons, while molecule Y, which gains the electron, is reduced.

Tags

NGSS.HS-PS1-2

Oxidation occurs when which of the following happens to an atom or molecule?

• Protons are added

• Protons are removed

• Electrons are removed

• Electrons are added

Answer explanation

Oxidation is defined as the loss of electrons from an atom or molecule. Therefore, when electrons are removed, oxidation occurs, making "Electrons are removed" the correct choice.

In redox reactions, electrons carry:

• no charge, which is why the reduced form of a molecule has a lower energy level.

• energy, which is why the reduced form of a molecule has a higher energy level.

• energy, which is why the reduced form of a molecule has a lower energy level.

• a positive charge, which is why the oxidized form has a lower energy level.

Answer explanation

In redox reactions, electrons carry energy. When a molecule is reduced, it gains electrons, resulting in a higher energy level for the reduced form compared to the oxidized form.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Which statement is true about oxidized molecules?

• They have more electrons and more energy than reduced molecules.

• They have more electrons but less energy than reduced molecules.

• They have less electrons but more energy than reduced molecules.

• They have less electrons and less energy than reduced molecules.

Answer explanation

Oxidized molecules lose electrons during the reaction, resulting in lower energy compared to reduced molecules, which gain electrons. Therefore, the correct statement is that oxidized molecules have less electrons and less energy than reduced molecules.

Tags

NGSS.HS-PS1-4

What type of reactions play a key role in the transfer of energy within cells?

• Radioactive decay reactions

• Buffer reactions

• Oxidation-reduction reactions

• Rust reactions

Answer explanation

Oxidation-reduction reactions, or redox reactions, are crucial for energy transfer in cells, as they involve the transfer of electrons, which is fundamental in processes like cellular respiration and photosynthesis.

Tags

NGSS.HS-LS1-5

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NGSS.HS-LS2-3

NGSS.HS-LS2-5