Energy: Sustaining Life

What is the role of an enzyme in a chemical reaction?

• To increase the activation energy required for the reaction

• To decrease the activation energy required for the reaction

• To act as a reactant in the reaction

• To act as a product in the reaction

Answer explanation

To decrease the activation energy required for the reaction

What happens to an enzyme when the temperature is raised too high?

• It speeds up the reaction indefinitely

• It becomes more efficient

• It denatures and stops working

• It remains unchanged

Answer explanation

When the temperature is raised too high, the enzyme denatures and stops working, leading to a loss of its function.

What is the effect of increasing substrate concentration on enzyme activity?

• It always increases the reaction rate

• It has no effect on the reaction rate

• It increases the reaction rate to a certain point

• It decreases the reaction rate

Answer explanation

Increasing substrate concentration initially increases enzyme activity by providing more substrate for the enzyme to act on, but eventually reaches a point where all enzyme active sites are saturated, leading to no further increase in reaction rate.

What is passive transport?

• A type of transport that requires energy

• A type of transport that does not require energy

• A type of transport that moves substances against their concentration gradient

• A type of transport that involves active pumping of substances

Answer explanation

Passive transport is a type of transport that does not require energy, allowing substances to move across a membrane without the need for ATP.

What happens during diffusion in passive transport?

• Substances move from an area of low concentration to an area of high concentration

• Substances move from an area of high concentration to an area of low concentration

• Substances remain stationary

• Substances are actively pumped across the membrane

Answer explanation

During diffusion in passive transport, substances move from an area of high concentration to an area of low concentration.

What is the role of permeability in passive transport?

• It prevents substances from passing through the membrane

• It allows substances to pass through the membrane

• It actively pumps substances across the membrane

• It consumes energy to move substances

Answer explanation

Permeability in passive transport allows substances to pass through the membrane without the need for energy input.

What is equilibrium in the context of passive transport?

• The state at which a substance is equally distributed throughout a space

• The state at which a substance is concentrated in one area

• The state at which a substance is actively transported

• The state at which a substance is completely removed from a space

Answer explanation

The state at which a substance is equally distributed throughout a space

Which type of transport requires an input of energy to occur?

• Passive transport

• Facilitated diffusion

• Active transport

• Osmosis

Answer explanation

Active transport is the type of transport that requires an input of energy to occur, making it the correct choice in this scenario.

What is the primary energy carrier in living things that is used during active transport?

• Glucose

• Adenosine triphosphate (ATP)

• Sodium

• Potassium

Answer explanation

The primary energy carrier in living things used during active transport is Adenosine triphosphate (ATP). ATP provides the energy needed for cellular processes like active transport.

Which of the following substances can easily diffuse across a semipermeable membrane?

• Glucose

• Sodium ions

• Carbon dioxide

• Proteins

Answer explanation

Carbon dioxide can easily diffuse across a semipermeable membrane due to its small size and non-polar nature, unlike glucose, sodium ions, and proteins.