5.2.1 Flashcards
(33 cards)
What are autotrophs?
Organisms that use light energy or chemical energy and inorganic molecules to synthesise complex organic molecules.
Examples include plants and some bacteria.
Define heterotrophs.
Organisms that ingest or digest complex organic molecules, releasing the chemical potential energy stored in them.
Examples include animals and fungi.
What are phototrophs?
Organisms that use energy from sunlight to synthesise organic compounds for nutrition.
What are chemoautotrophs?
Organisms that synthesise complex organic molecules using energy derived from exergonic chemical reactions.
What is photosynthesis?
The process whereby light energy from the Sun is transformed into chemical energy and used to synthesise large organic molecules from inorganic substances.
What is the equation summarising the process of photosynthesis?
6CO2 + 6H2O (+ light energy) → C6H12O6 + 6O2.
What happens after Earth’s atmosphere contained free oxygen?
Organisms evolved that could use the oxygen for aerobic respiration, releasing carbon dioxide back into the atmosphere and producing water.
What is the compensation point in plants?
When photosynthesis and respiration proceed at the same rate, resulting in no net gain or loss of carbohydrate.
What is the structure of a chloroplast?
Disc-shaped, 2-10µm long, with an outer membrane that is permeable to small ions and an inner membrane with transport proteins.
What are photosynthetic pigments?
Molecules that absorb light energy, each with a distinct peak of absorption and reflecting other wavelengths.
What is a photosystem?
A funnel-shaped light-harvesting cluster of photosynthetic pigments held in place in the thylakoid membrane of a chloroplast.
What is the primary pigment in a photosystem?
Chlorophyll a.
What are the accessory pigments found in a photosystem?
Chlorophyll b and carotenoids.
What occurs during non-cyclic photophosphorylation?
Light energy hits photosystem I and II, exciting electrons that move along the electron transport chain.
What is photolysis?
The splitting of water into hydrogen ions, electrons, and oxygen in the presence of light.
What is the light-independent stage of photosynthesis?
Occurs in the stroma, where carbon dioxide combines with ribulose bisphosphate, catalysed by rubisco.
What is the role of ribulose bisphosphate (RuBP) in photosynthesis?
Combines with carbon dioxide in the light-independent stage to facilitate carbon fixation.
What happens to triose phosphate (TP) during photosynthesis?
It is used to regenerate RuBP and can be converted into organic molecules like glucose, amino acids, and lipids.
What are limiting factors in photosynthesis?
Factors that prevent a process from increasing any further, such as carbon dioxide concentration, light intensity, and temperature.
What is the effect of increasing light intensity on photosynthesis?
Increases the rate of photosynthesis as more light energy is available to excite electrons.
What is the importance of measuring photosynthesis?
It helps to understand the rate of photosynthesis by collecting and measuring the volume of oxygen produced.
How does temperature affect the rate of photosynthesis?
Between 0°C and 25°C, the rate approximately doubles for each 10°C rise, but above 25°C, the rate levels off and then falls.
Fill in the blank: The products from the light-dependent stage are used to reduce and phosphorylate GP into another 3C compound, _______.
triose phosphate.
True or False: High temperatures can damage proteins involved in photosynthesis.
True.
