Campbell Biology Chapter 10: Photosynthesis

Vocabulary flashcards covering the key terms, structures, and processes of photosynthesis detailed in Reece et al., Campbell Biology, 11th Edition, Chapter 10.

Autotrophs

Self-feeders that sustain themselves without eating anything derived from other organisms, serving as the producers of the biosphere by producing organic molecules from $CO_2$ and other inorganic molecules.

Heterotrophs

Consumers of the biosphere that obtain organic material from other organisms by consuming living organisms, feces, or dead organic material.

Mesophyll

The interior tissue of the leaf where chloroplasts are mainly found, with each cell containing $30$ to $40$ chloroplasts.

Stomata

Microscopic pores in the leaf through which $CO_2$ enters and $O_2$ exits.

Stroma

The dense fluid within a chloroplast surrounded by an envelope of two membranes, in which the Calvin cycle occurs.

Thylakoids

Connected sacs in the chloroplast composing a third membrane system, which can be stacked into columns called grana.

Photophosphorylation

The generation of ATP from ADP using light-driven chemiosmosis during the light reactions of photosynthesis.

Wavelength

The distance between crests of electromagnetic waves, which determines the type of electromagnetic energy.

Electromagnetic spectrum

The entire range of electromagnetic energy, or radiation.

Visible light

Electromagnetic radiation with wavelengths spanning from $380\,nm$ to $750\,nm$ that produce colors visible to humans and drive photosynthesis.

Photons

Discrete particles of light energy that behave as fixed quantities.

Spectrophotometer

An instrument that measures a pigment's ability to absorb various wavelengths by transmitting light through pigments and recording the fraction transmitted at each wavelength.

Chlorophyll a

The key light-capturing pigment in chloroplasts that participates directly in the light reactions.

Carotenoids

Accessory pigments that broaden the spectrum of colors driving photosynthesis and provide photoprotection by absorbing excessive light that would damage chlorophyll or react with oxygen.

Photosystem

A light-harvesting unit in the thylakoid membrane consisting of a reaction-center complex surrounded by light-harvesting complexes.

Reaction-center complex

An association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor.

Light-harvesting complex

A protein-pigment assembly that absorbs photons and transfers their energy to the chlorophyll a molecules in the reaction-center complex.

Primary electron acceptor

A molecule in the reaction center that accepts excited electrons from the reaction-center chlorophyll a and becomes reduced.

$$P680$$

The reaction-center chlorophyll a of Photosystem II, named because it is best at absorbing light at a wavelength of $680\,nm$.

$$P700$$

The reaction-center chlorophyll a of Photosystem I, named because it is best at absorbing light at a wavelength of $700\,nm$.

Linear electron flow

The primary electron pathway of the light reactions that involves both photosystems and produces ATP and NADPH using light energy.

Cyclic electron flow

An alternative light-driven electron route that employs only Photosystem I to generate ATP, producing neither NADPH nor $O_2$.

Glyceraldehyde 3-phosphate (G3P)

The three-carbon sugar output of the Calvin cycle, requiring three cycles fixing three molecules of $CO_2$ for the net synthesis of one molecule.

Rubisco

The enzyme that catalyzes the initial carbon fixation phase of the Calvin cycle by attaching $CO_2$ to ribulose bisphosphate (RuBP).

$C_3$ plants

Plants that carry out initial fixation of $CO_2$ via rubisco, forming the three-carbon compound 3-phosphoglycerate.

Photorespiration

A metabolic pathway in which rubisco incorporates $O_2$ instead of $CO_2$, producing a two-carbon compound and draining up to $50\%$ of the carbon fixed by the Calvin cycle on hot, dry days.