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Flashcards in Photosynthesis & Respiration Deck (60)
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Why do plants need energy?

-active transport (to take in minerals via their roots)
-DNA replication
-cell division
-protein synthesis


Why do animals need energy?

-muscle contraction
-maintenance of body temp
-active transport
-DNA replication
-cell division
-protein synthesis


What is the purpose of photosynthesis?

light energy is used to make glucose from H2O and CO2 (light energy is converted to chemical energy in the form of glucose)


What is the overall equation for photosynthesis?

6CO2 + 6H2O + energy --> C6H12O6 + 6O2


How do animals obtain glucose?

by eating plants or other animals, then respire the glucose to release energy


How do animal and plant cells release energy?

cells release energy from glucose by respiration


What are the two types of respiration?

aerobic : respiration using O2
anaerobic : respiration without O2


What is the overall equation for aerobic respiration?

C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy


In plants and yeast, what does anaerobic respiration produce?

ethanol and carbon dioxide and releases energy


In humans, what does anaerobic respiration produce?

lactate and releases energy


Why is ATP a good energy source?

-stores or releases a small, manageable amount of energy at a time, so no energy is wasted as heat
-small, soluble molecule so easily transported around cell
-easily broken down so energy released instantaneously
-quickly re-made
-can make other molecules more reactive by transferring one of its phosphate groups to them (phosphorylation)
-can't pass out of cell so cell always has an immediate supply of energy


Define metabolic pathway.

a series of small reactions controlled by enzymes e.g. respiration and photosynthesis


Define phosphorylation.

adding phosphate to a molecule


Define photophosphorylation.

adding phosphate to a molecule using light


Define photolysis.

splitting of a molecule using light energy


Define photoionisation.

when light energy 'excites' electrons in an atom or molecule, giving them more energy and causing them to be released. The release of electrons causes the atom or molecule to become a positively-charged ion


Define hydrolysis.

splitting of a molecule using water


Define decarboxylation.

removal of carbon dioxide from a molecule


Define dehydrogenation.

removal of hydrogen from a molecule


What is a redox reaction?

reaction involving oxidation and reduction


What is a coenzyme?

a molecule that aids the function of an enzyme


How do coenzymes work?

by transferring a chemical group from one molecule to another


What is the coenzyme used in photosynthesis?

NADP transfers hydrogen from one molecule to another - it can reduce or oxidise a molecule


What are the enzymes used in respiration?

NAD and FAD transfer hydrogen from one molecule to another - they can reduce or oxidise a molecule.

Coenzyme A transfers acetate between molecules


Describe how the synthesis and breakdown of ATP meets the energy needs of a cell.

In the cell, ATP is synthesised from ADP and inorganic phosphate using energy from an energy-releasing reaction, e.g. respiration. The energy is stored as chemical energy in the phosphate bond. ATP synthase catalyses this reaction. ATP diffuses to the part of the cell that needs energy. Here, its broken down back into ADP and inorganic phosphate, which is catalysed by ATP hydrolase. Chemical energy is released from the phosphate bond and used by the cell.


Where does photosynthesis take place?

in chloroplasts of plant cells


What is the structure of a chloroplast?

-flattened organelle surrounded by a double membrane
-thylakoids are stacked up into grana, grana are linked by bits of thylakoid membrane called lamellae
-contain photosynthetic pigments (chlorophyll a, chlorophyll b, carotene)


What are photosynthetic pigments?

coloured substances that absorb light energy needed for photosynthesis (in thylakoid membranes, attached to proteins)


What is a photosystem?

protein and pigment


What wavelength of light does PSI absorb best?