Cell Membrane and Photosynthesis

What is the primary function of the cell membrane?

To separate the internal environment of a cell from its external environment.

What are the main components of the cell membrane?

A double layer of phospholipid molecules, embedded proteins, and cholesterol.

What is the structure of a phospholipid molecule?

It has a distinctive head region that is hydrophilic and a tail region that is hydrophobic.

What is passive transport?

The movement of molecules across the cell membrane without the use of energy.

What is active transport?

The movement of molecules against their concentration gradient, requiring energy (ATP).

What is diffusion?

The natural movement of molecules from a region of higher concentration to a region of lower concentration.

What is osmosis?

The diffusion of water across a semi-permeable membrane.

What does it mean for a cell membrane to be selectively permeable?

It allows some molecules to pass through while blocking others.

What is an isotonic solution?

A solution where the solute concentration is equal inside and outside the cell, resulting in no net water movement.

What is a hypertonic solution?

A solution where the solute concentration is higher outside the cell, causing water to move out and the cell to shrink.

What is a hypotonic solution?

A solution where the solute concentration is lower outside the cell, causing water to move in and the cell to swell.

What is photosynthesis?

The process that converts solar energy into chemical energy stored in glucose.

What are the main reactants of photosynthesis?

Carbon dioxide (CO₂), water (H₂O), and sunlight.

What is cellular respiration?

The process of converting glucose into usable energy (ATP) for cellular activities.

What is the role of ATP in cells?

ATP serves as the energy currency for cellular activities.

What are the two main types of metabolic pathways?

Anabolic pathways (building larger molecules) and catabolic pathways (breaking down molecules).

What is activation energy?

The energy required to start a chemical reaction.

What role do enzymes play in metabolism?

Enzymes act as catalysts that lower the activation energy needed for reactions to occur.

What is the structure of chloroplasts?

Chloroplasts have an outer membrane, an inner membrane, and thylakoids stacked in grana.

What are light-dependent reactions?

Reactions in photosynthesis that capture solar energy to produce ATP and NADPH.

What is the stroma?

The fluid inside chloroplasts that contains proteins and chemicals for photosynthesis.

What is the matrix in mitochondria?

The fluid-filled space within the inner membrane that contains chemicals for cellular respiration.

What is the relationship between photosynthesis and cellular respiration?

Photosynthesis stores energy in glucose, while cellular respiration releases that energy for cellular use.

What is the significance of NAD+ in cellular respiration?

NAD+ acts as an oxidizing agent, accepting electrons during metabolic reactions.

What is the general equation for photosynthesis?

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.

What is the general equation for cellular respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP.

What is the function of transport proteins in the cell membrane?

They facilitate the movement of substances across the membrane, either along or against their concentration gradient.

What is the primary function of the light-dependent reactions in photosynthesis?

To capture light energy and convert it into chemical energy in the form of ATP and NADPH.

Where do the light-dependent reactions take place?

In the thylakoid membranes of chloroplasts.

What is the Calvin Cycle?

A series of light-independent reactions that convert carbon dioxide and energy from ATP and NADPH into glucose.

What molecule is split during the light-dependent reactions?

Water (H₂O).

What are the products of the light-dependent reactions?

ATP, NADPH, and oxygen (O₂).

What is the role of chlorophyll in photosynthesis?

Chlorophyll absorbs light energy, primarily at 680 nm, to excite electrons.

What happens to electrons after they are excited in photosystem II?

They are transferred to an electron transport chain.

What is chemiosmosis?

The process by which ATP is produced as hydrogen ions flow back across the thylakoid membrane through ATP synthase.

What are antenna pigment molecules?

Molecules that capture light energy and funnel it to the reaction center of photosystems.

What is the function of ATP synthase?

To synthesize ATP from ADP and inorganic phosphate using energy from the proton gradient.

What is the first step of the Calvin Cycle?

Carbon fixation, where CO₂ is attached to ribulose bisphosphate (RuBP).

What enzyme catalyzes the carbon fixation in the Calvin Cycle?

RuBisCO (ribulose bisphosphate carboxylase/oxygenase).

What is produced during the reduction phase of the Calvin Cycle?

Glyceraldehyde-3-phosphate (G3P).

How many ATP molecules are required to produce one glucose molecule in the Calvin Cycle?

18 ATP molecules.

What is the difference between non-cyclic and cyclic photophosphorylation?

Non-cyclic photophosphorylation produces NADPH and oxygen, while cyclic photophosphorylation only produces ATP.

What is the role of NADPH in photosynthesis?

To provide reducing power for the Calvin Cycle to convert CO₂ into glucose.

What is the significance of the electron transport chain in photosynthesis?

It facilitates the transfer of electrons and the pumping of hydrogen ions to create a proton gradient for ATP synthesis.

What is photolysis?

The splitting of water molecules during the light-dependent reactions to release oxygen and provide electrons.

What is the final product of the Calvin Cycle?

Glucose (or G3P, which can be converted into glucose).

What are carotenoids?

Accessory pigments that absorb light energy from other parts of the light spectrum.

What happens to the excited electrons in photosystem I?

They reduce NADP+ to form NADPH.

What is the role of RuBP in the Calvin Cycle?

RuBP serves as the CO₂ acceptor that initiates the cycle.

What is the significance of the thylakoid membrane in chloroplasts?

It houses the photosystems and the electron transport chain, essential for light-dependent reactions.

What is the relationship between ATP and NADPH in photosynthesis?

Both are produced during the light-dependent reactions and are used in the Calvin Cycle to synthesize glucose.

How does the Calvin Cycle regenerate RuBP?

By rearranging G3P molecules back into RuBP using ATP.

What is the light energy captured by chlorophyll converted into?

Chemical energy in the form of ATP and NADPH.

What is the purpose of the light-dependent reactions?

To convert solar energy into chemical energy for use in the Calvin Cycle.